Bug Summary

File:lib/CodeGen/CodeGenPrepare.cpp
Location:line 4223, column 27
Description:Called C++ object pointer is null

Annotated Source Code

1//===- CodeGenPrepare.cpp - Prepare a function for code generation --------===//
2//
3// The LLVM Compiler Infrastructure
4//
5// This file is distributed under the University of Illinois Open Source
6// License. See LICENSE.TXT for details.
7//
8//===----------------------------------------------------------------------===//
9//
10// This pass munges the code in the input function to better prepare it for
11// SelectionDAG-based code generation. This works around limitations in it's
12// basic-block-at-a-time approach. It should eventually be removed.
13//
14//===----------------------------------------------------------------------===//
15
16#include "llvm/CodeGen/Passes.h"
17#include "llvm/ADT/DenseMap.h"
18#include "llvm/ADT/SmallSet.h"
19#include "llvm/ADT/Statistic.h"
20#include "llvm/Analysis/InstructionSimplify.h"
21#include "llvm/Analysis/TargetLibraryInfo.h"
22#include "llvm/Analysis/TargetTransformInfo.h"
23#include "llvm/IR/CallSite.h"
24#include "llvm/IR/Constants.h"
25#include "llvm/IR/DataLayout.h"
26#include "llvm/IR/DerivedTypes.h"
27#include "llvm/IR/Dominators.h"
28#include "llvm/IR/Function.h"
29#include "llvm/IR/GetElementPtrTypeIterator.h"
30#include "llvm/IR/IRBuilder.h"
31#include "llvm/IR/InlineAsm.h"
32#include "llvm/IR/Instructions.h"
33#include "llvm/IR/IntrinsicInst.h"
34#include "llvm/IR/MDBuilder.h"
35#include "llvm/IR/PatternMatch.h"
36#include "llvm/IR/Statepoint.h"
37#include "llvm/IR/ValueHandle.h"
38#include "llvm/IR/ValueMap.h"
39#include "llvm/Pass.h"
40#include "llvm/Support/CommandLine.h"
41#include "llvm/Support/Debug.h"
42#include "llvm/Support/raw_ostream.h"
43#include "llvm/Target/TargetLowering.h"
44#include "llvm/Target/TargetSubtargetInfo.h"
45#include "llvm/Transforms/Utils/BasicBlockUtils.h"
46#include "llvm/Transforms/Utils/BuildLibCalls.h"
47#include "llvm/Transforms/Utils/BypassSlowDivision.h"
48#include "llvm/Transforms/Utils/Local.h"
49#include "llvm/Transforms/Utils/SimplifyLibCalls.h"
50using namespace llvm;
51using namespace llvm::PatternMatch;
52
53#define DEBUG_TYPE"codegenprepare" "codegenprepare"
54
55STATISTIC(NumBlocksElim, "Number of blocks eliminated")static llvm::Statistic NumBlocksElim = { "codegenprepare", "Number of blocks eliminated"
, 0, 0 };
56STATISTIC(NumPHIsElim, "Number of trivial PHIs eliminated")static llvm::Statistic NumPHIsElim = { "codegenprepare", "Number of trivial PHIs eliminated"
, 0, 0 };
57STATISTIC(NumGEPsElim, "Number of GEPs converted to casts")static llvm::Statistic NumGEPsElim = { "codegenprepare", "Number of GEPs converted to casts"
, 0, 0 };
58STATISTIC(NumCmpUses, "Number of uses of Cmp expressions replaced with uses of "static llvm::Statistic NumCmpUses = { "codegenprepare", "Number of uses of Cmp expressions replaced with uses of "
"sunken Cmps", 0, 0 }
59 "sunken Cmps")static llvm::Statistic NumCmpUses = { "codegenprepare", "Number of uses of Cmp expressions replaced with uses of "
"sunken Cmps", 0, 0 };
60STATISTIC(NumCastUses, "Number of uses of Cast expressions replaced with uses "static llvm::Statistic NumCastUses = { "codegenprepare", "Number of uses of Cast expressions replaced with uses "
"of sunken Casts", 0, 0 }
61 "of sunken Casts")static llvm::Statistic NumCastUses = { "codegenprepare", "Number of uses of Cast expressions replaced with uses "
"of sunken Casts", 0, 0 };
62STATISTIC(NumMemoryInsts, "Number of memory instructions whose address "static llvm::Statistic NumMemoryInsts = { "codegenprepare", "Number of memory instructions whose address "
"computations were sunk", 0, 0 }
63 "computations were sunk")static llvm::Statistic NumMemoryInsts = { "codegenprepare", "Number of memory instructions whose address "
"computations were sunk", 0, 0 };
64STATISTIC(NumExtsMoved, "Number of [s|z]ext instructions combined with loads")static llvm::Statistic NumExtsMoved = { "codegenprepare", "Number of [s|z]ext instructions combined with loads"
, 0, 0 };
65STATISTIC(NumExtUses, "Number of uses of [s|z]ext instructions optimized")static llvm::Statistic NumExtUses = { "codegenprepare", "Number of uses of [s|z]ext instructions optimized"
, 0, 0 };
66STATISTIC(NumRetsDup, "Number of return instructions duplicated")static llvm::Statistic NumRetsDup = { "codegenprepare", "Number of return instructions duplicated"
, 0, 0 };
67STATISTIC(NumDbgValueMoved, "Number of debug value instructions moved")static llvm::Statistic NumDbgValueMoved = { "codegenprepare",
"Number of debug value instructions moved", 0, 0 };
68STATISTIC(NumSelectsExpanded, "Number of selects turned into branches")static llvm::Statistic NumSelectsExpanded = { "codegenprepare"
, "Number of selects turned into branches", 0, 0 };
69STATISTIC(NumAndCmpsMoved, "Number of and/cmp's pushed into branches")static llvm::Statistic NumAndCmpsMoved = { "codegenprepare", "Number of and/cmp's pushed into branches"
, 0, 0 };
70STATISTIC(NumStoreExtractExposed, "Number of store(extractelement) exposed")static llvm::Statistic NumStoreExtractExposed = { "codegenprepare"
, "Number of store(extractelement) exposed", 0, 0 };
71
72static cl::opt<bool> DisableBranchOpts(
73 "disable-cgp-branch-opts", cl::Hidden, cl::init(false),
74 cl::desc("Disable branch optimizations in CodeGenPrepare"));
75
76static cl::opt<bool>
77 DisableGCOpts("disable-cgp-gc-opts", cl::Hidden, cl::init(false),
78 cl::desc("Disable GC optimizations in CodeGenPrepare"));
79
80static cl::opt<bool> DisableSelectToBranch(
81 "disable-cgp-select2branch", cl::Hidden, cl::init(false),
82 cl::desc("Disable select to branch conversion."));
83
84static cl::opt<bool> AddrSinkUsingGEPs(
85 "addr-sink-using-gep", cl::Hidden, cl::init(false),
86 cl::desc("Address sinking in CGP using GEPs."));
87
88static cl::opt<bool> EnableAndCmpSinking(
89 "enable-andcmp-sinking", cl::Hidden, cl::init(true),
90 cl::desc("Enable sinkinig and/cmp into branches."));
91
92static cl::opt<bool> DisableStoreExtract(
93 "disable-cgp-store-extract", cl::Hidden, cl::init(false),
94 cl::desc("Disable store(extract) optimizations in CodeGenPrepare"));
95
96static cl::opt<bool> StressStoreExtract(
97 "stress-cgp-store-extract", cl::Hidden, cl::init(false),
98 cl::desc("Stress test store(extract) optimizations in CodeGenPrepare"));
99
100static cl::opt<bool> DisableExtLdPromotion(
101 "disable-cgp-ext-ld-promotion", cl::Hidden, cl::init(false),
102 cl::desc("Disable ext(promotable(ld)) -> promoted(ext(ld)) optimization in "
103 "CodeGenPrepare"));
104
105static cl::opt<bool> StressExtLdPromotion(
106 "stress-cgp-ext-ld-promotion", cl::Hidden, cl::init(false),
107 cl::desc("Stress test ext(promotable(ld)) -> promoted(ext(ld)) "
108 "optimization in CodeGenPrepare"));
109
110namespace {
111typedef SmallPtrSet<Instruction *, 16> SetOfInstrs;
112struct TypeIsSExt {
113 Type *Ty;
114 bool IsSExt;
115 TypeIsSExt(Type *Ty, bool IsSExt) : Ty(Ty), IsSExt(IsSExt) {}
116};
117typedef DenseMap<Instruction *, TypeIsSExt> InstrToOrigTy;
118class TypePromotionTransaction;
119
120 class CodeGenPrepare : public FunctionPass {
121 /// TLI - Keep a pointer of a TargetLowering to consult for determining
122 /// transformation profitability.
123 const TargetMachine *TM;
124 const TargetLowering *TLI;
125 const TargetTransformInfo *TTI;
126 const TargetLibraryInfo *TLInfo;
127 DominatorTree *DT;
128
129 /// CurInstIterator - As we scan instructions optimizing them, this is the
130 /// next instruction to optimize. Xforms that can invalidate this should
131 /// update it.
132 BasicBlock::iterator CurInstIterator;
133
134 /// Keeps track of non-local addresses that have been sunk into a block.
135 /// This allows us to avoid inserting duplicate code for blocks with
136 /// multiple load/stores of the same address.
137 ValueMap<Value*, Value*> SunkAddrs;
138
139 /// Keeps track of all truncates inserted for the current function.
140 SetOfInstrs InsertedTruncsSet;
141 /// Keeps track of the type of the related instruction before their
142 /// promotion for the current function.
143 InstrToOrigTy PromotedInsts;
144
145 /// ModifiedDT - If CFG is modified in anyway, dominator tree may need to
146 /// be updated.
147 bool ModifiedDT;
148
149 /// OptSize - True if optimizing for size.
150 bool OptSize;
151
152 public:
153 static char ID; // Pass identification, replacement for typeid
154 explicit CodeGenPrepare(const TargetMachine *TM = nullptr)
155 : FunctionPass(ID), TM(TM), TLI(nullptr), TTI(nullptr) {
156 initializeCodeGenPreparePass(*PassRegistry::getPassRegistry());
157 }
158 bool runOnFunction(Function &F) override;
159
160 const char *getPassName() const override { return "CodeGen Prepare"; }
161
162 void getAnalysisUsage(AnalysisUsage &AU) const override {
163 AU.addPreserved<DominatorTreeWrapperPass>();
164 AU.addRequired<TargetLibraryInfoWrapperPass>();
165 AU.addRequired<TargetTransformInfoWrapperPass>();
166 }
167
168 private:
169 bool EliminateFallThrough(Function &F);
170 bool EliminateMostlyEmptyBlocks(Function &F);
171 bool CanMergeBlocks(const BasicBlock *BB, const BasicBlock *DestBB) const;
172 void EliminateMostlyEmptyBlock(BasicBlock *BB);
173 bool OptimizeBlock(BasicBlock &BB, bool& ModifiedDT);
174 bool OptimizeInst(Instruction *I, bool& ModifiedDT);
175 bool OptimizeMemoryInst(Instruction *I, Value *Addr, Type *AccessTy);
176 bool OptimizeInlineAsmInst(CallInst *CS);
177 bool OptimizeCallInst(CallInst *CI, bool& ModifiedDT);
178 bool MoveExtToFormExtLoad(Instruction *&I);
179 bool OptimizeExtUses(Instruction *I);
180 bool OptimizeSelectInst(SelectInst *SI);
181 bool OptimizeShuffleVectorInst(ShuffleVectorInst *SI);
182 bool OptimizeExtractElementInst(Instruction *Inst);
183 bool DupRetToEnableTailCallOpts(BasicBlock *BB);
184 bool PlaceDbgValues(Function &F);
185 bool sinkAndCmp(Function &F);
186 bool ExtLdPromotion(TypePromotionTransaction &TPT, LoadInst *&LI,
187 Instruction *&Inst,
188 const SmallVectorImpl<Instruction *> &Exts,
189 unsigned CreatedInst);
190 bool splitBranchCondition(Function &F);
191 bool simplifyOffsetableRelocate(Instruction &I);
192 };
193}
194
195char CodeGenPrepare::ID = 0;
196INITIALIZE_TM_PASS(CodeGenPrepare, "codegenprepare",static void* initializeCodeGenPreparePassOnce(PassRegistry &
Registry) { PassInfo *PI = new PassInfo("Optimize for code generation"
, "codegenprepare", & CodeGenPrepare ::ID, PassInfo::NormalCtor_t
(callDefaultCtor< CodeGenPrepare >), false, false, PassInfo
::TargetMachineCtor_t(callTargetMachineCtor< CodeGenPrepare
>)); Registry.registerPass(*PI, true); return PI; } void llvm
::initializeCodeGenPreparePass(PassRegistry &Registry) { static
volatile sys::cas_flag initialized = 0; sys::cas_flag old_val
= sys::CompareAndSwap(&initialized, 1, 0); if (old_val ==
0) { initializeCodeGenPreparePassOnce(Registry); sys::MemoryFence
(); AnnotateIgnoreWritesBegin("/tmp/buildd/llvm-toolchain-snapshot-3.7~svn228917/lib/CodeGen/CodeGenPrepare.cpp"
, 197); AnnotateHappensBefore("/tmp/buildd/llvm-toolchain-snapshot-3.7~svn228917/lib/CodeGen/CodeGenPrepare.cpp"
, 197, &initialized); initialized = 2; AnnotateIgnoreWritesEnd
("/tmp/buildd/llvm-toolchain-snapshot-3.7~svn228917/lib/CodeGen/CodeGenPrepare.cpp"
, 197); } else { sys::cas_flag tmp = initialized; sys::MemoryFence
(); while (tmp != 2) { tmp = initialized; sys::MemoryFence();
} } AnnotateHappensAfter("/tmp/buildd/llvm-toolchain-snapshot-3.7~svn228917/lib/CodeGen/CodeGenPrepare.cpp"
, 197, &initialized); }
197 "Optimize for code generation", false, false)static void* initializeCodeGenPreparePassOnce(PassRegistry &
Registry) { PassInfo *PI = new PassInfo("Optimize for code generation"
, "codegenprepare", & CodeGenPrepare ::ID, PassInfo::NormalCtor_t
(callDefaultCtor< CodeGenPrepare >), false, false, PassInfo
::TargetMachineCtor_t(callTargetMachineCtor< CodeGenPrepare
>)); Registry.registerPass(*PI, true); return PI; } void llvm
::initializeCodeGenPreparePass(PassRegistry &Registry) { static
volatile sys::cas_flag initialized = 0; sys::cas_flag old_val
= sys::CompareAndSwap(&initialized, 1, 0); if (old_val ==
0) { initializeCodeGenPreparePassOnce(Registry); sys::MemoryFence
(); AnnotateIgnoreWritesBegin("/tmp/buildd/llvm-toolchain-snapshot-3.7~svn228917/lib/CodeGen/CodeGenPrepare.cpp"
, 197); AnnotateHappensBefore("/tmp/buildd/llvm-toolchain-snapshot-3.7~svn228917/lib/CodeGen/CodeGenPrepare.cpp"
, 197, &initialized); initialized = 2; AnnotateIgnoreWritesEnd
("/tmp/buildd/llvm-toolchain-snapshot-3.7~svn228917/lib/CodeGen/CodeGenPrepare.cpp"
, 197); } else { sys::cas_flag tmp = initialized; sys::MemoryFence
(); while (tmp != 2) { tmp = initialized; sys::MemoryFence();
} } AnnotateHappensAfter("/tmp/buildd/llvm-toolchain-snapshot-3.7~svn228917/lib/CodeGen/CodeGenPrepare.cpp"
, 197, &initialized); }
198
199FunctionPass *llvm::createCodeGenPreparePass(const TargetMachine *TM) {
200 return new CodeGenPrepare(TM);
201}
202
203bool CodeGenPrepare::runOnFunction(Function &F) {
204 if (skipOptnoneFunction(F))
205 return false;
206
207 bool EverMadeChange = false;
208 // Clear per function information.
209 InsertedTruncsSet.clear();
210 PromotedInsts.clear();
211
212 ModifiedDT = false;
213 if (TM)
214 TLI = TM->getSubtargetImpl(F)->getTargetLowering();
215 TLInfo = &getAnalysis<TargetLibraryInfoWrapperPass>().getTLI();
216 TTI = &getAnalysis<TargetTransformInfoWrapperPass>().getTTI(F);
217 DominatorTreeWrapperPass *DTWP =
218 getAnalysisIfAvailable<DominatorTreeWrapperPass>();
219 DT = DTWP ? &DTWP->getDomTree() : nullptr;
220 OptSize = F.getAttributes().hasAttribute(AttributeSet::FunctionIndex,
221 Attribute::OptimizeForSize);
222
223 /// This optimization identifies DIV instructions that can be
224 /// profitably bypassed and carried out with a shorter, faster divide.
225 if (!OptSize && TLI && TLI->isSlowDivBypassed()) {
226 const DenseMap<unsigned int, unsigned int> &BypassWidths =
227 TLI->getBypassSlowDivWidths();
228 for (Function::iterator I = F.begin(); I != F.end(); I++)
229 EverMadeChange |= bypassSlowDivision(F, I, BypassWidths);
230 }
231
232 // Eliminate blocks that contain only PHI nodes and an
233 // unconditional branch.
234 EverMadeChange |= EliminateMostlyEmptyBlocks(F);
235
236 // llvm.dbg.value is far away from the value then iSel may not be able
237 // handle it properly. iSel will drop llvm.dbg.value if it can not
238 // find a node corresponding to the value.
239 EverMadeChange |= PlaceDbgValues(F);
240
241 // If there is a mask, compare against zero, and branch that can be combined
242 // into a single target instruction, push the mask and compare into branch
243 // users. Do this before OptimizeBlock -> OptimizeInst ->
244 // OptimizeCmpExpression, which perturbs the pattern being searched for.
245 if (!DisableBranchOpts) {
246 EverMadeChange |= sinkAndCmp(F);
247 EverMadeChange |= splitBranchCondition(F);
248 }
249
250 bool MadeChange = true;
251 while (MadeChange) {
252 MadeChange = false;
253 for (Function::iterator I = F.begin(); I != F.end(); ) {
254 BasicBlock *BB = I++;
255 bool ModifiedDTOnIteration = false;
256 MadeChange |= OptimizeBlock(*BB, ModifiedDTOnIteration);
257
258 // Restart BB iteration if the dominator tree of the Function was changed
259 ModifiedDT |= ModifiedDTOnIteration;
260 if (ModifiedDTOnIteration)
261 break;
262 }
263 EverMadeChange |= MadeChange;
264 }
265
266 SunkAddrs.clear();
267
268 if (!DisableBranchOpts) {
269 MadeChange = false;
270 SmallPtrSet<BasicBlock*, 8> WorkList;
271 for (BasicBlock &BB : F) {
272 SmallVector<BasicBlock *, 2> Successors(succ_begin(&BB), succ_end(&BB));
273 MadeChange |= ConstantFoldTerminator(&BB, true);
274 if (!MadeChange) continue;
275
276 for (SmallVectorImpl<BasicBlock*>::iterator
277 II = Successors.begin(), IE = Successors.end(); II != IE; ++II)
278 if (pred_begin(*II) == pred_end(*II))
279 WorkList.insert(*II);
280 }
281
282 // Delete the dead blocks and any of their dead successors.
283 MadeChange |= !WorkList.empty();
284 while (!WorkList.empty()) {
285 BasicBlock *BB = *WorkList.begin();
286 WorkList.erase(BB);
287 SmallVector<BasicBlock*, 2> Successors(succ_begin(BB), succ_end(BB));
288
289 DeleteDeadBlock(BB);
290
291 for (SmallVectorImpl<BasicBlock*>::iterator
292 II = Successors.begin(), IE = Successors.end(); II != IE; ++II)
293 if (pred_begin(*II) == pred_end(*II))
294 WorkList.insert(*II);
295 }
296
297 // Merge pairs of basic blocks with unconditional branches, connected by
298 // a single edge.
299 if (EverMadeChange || MadeChange)
300 MadeChange |= EliminateFallThrough(F);
301
302 if (MadeChange)
303 ModifiedDT = true;
304 EverMadeChange |= MadeChange;
305 }
306
307 if (!DisableGCOpts) {
308 SmallVector<Instruction *, 2> Statepoints;
309 for (BasicBlock &BB : F)
310 for (Instruction &I : BB)
311 if (isStatepoint(I))
312 Statepoints.push_back(&I);
313 for (auto &I : Statepoints)
314 EverMadeChange |= simplifyOffsetableRelocate(*I);
315 }
316
317 if (ModifiedDT && DT)
318 DT->recalculate(F);
319
320 return EverMadeChange;
321}
322
323/// EliminateFallThrough - Merge basic blocks which are connected
324/// by a single edge, where one of the basic blocks has a single successor
325/// pointing to the other basic block, which has a single predecessor.
326bool CodeGenPrepare::EliminateFallThrough(Function &F) {
327 bool Changed = false;
328 // Scan all of the blocks in the function, except for the entry block.
329 for (Function::iterator I = std::next(F.begin()), E = F.end(); I != E;) {
330 BasicBlock *BB = I++;
331 // If the destination block has a single pred, then this is a trivial
332 // edge, just collapse it.
333 BasicBlock *SinglePred = BB->getSinglePredecessor();
334
335 // Don't merge if BB's address is taken.
336 if (!SinglePred || SinglePred == BB || BB->hasAddressTaken()) continue;
337
338 BranchInst *Term = dyn_cast<BranchInst>(SinglePred->getTerminator());
339 if (Term && !Term->isConditional()) {
340 Changed = true;
341 DEBUG(dbgs() << "To merge:\n"<< *SinglePred << "\n\n\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "To merge:\n"<< *
SinglePred << "\n\n\n"; } } while (0);
342 // Remember if SinglePred was the entry block of the function.
343 // If so, we will need to move BB back to the entry position.
344 bool isEntry = SinglePred == &SinglePred->getParent()->getEntryBlock();
345 MergeBasicBlockIntoOnlyPred(BB, DT);
346
347 if (isEntry && BB != &BB->getParent()->getEntryBlock())
348 BB->moveBefore(&BB->getParent()->getEntryBlock());
349
350 // We have erased a block. Update the iterator.
351 I = BB;
352 }
353 }
354 return Changed;
355}
356
357/// EliminateMostlyEmptyBlocks - eliminate blocks that contain only PHI nodes,
358/// debug info directives, and an unconditional branch. Passes before isel
359/// (e.g. LSR/loopsimplify) often split edges in ways that are non-optimal for
360/// isel. Start by eliminating these blocks so we can split them the way we
361/// want them.
362bool CodeGenPrepare::EliminateMostlyEmptyBlocks(Function &F) {
363 bool MadeChange = false;
364 // Note that this intentionally skips the entry block.
365 for (Function::iterator I = std::next(F.begin()), E = F.end(); I != E;) {
366 BasicBlock *BB = I++;
367
368 // If this block doesn't end with an uncond branch, ignore it.
369 BranchInst *BI = dyn_cast<BranchInst>(BB->getTerminator());
370 if (!BI || !BI->isUnconditional())
371 continue;
372
373 // If the instruction before the branch (skipping debug info) isn't a phi
374 // node, then other stuff is happening here.
375 BasicBlock::iterator BBI = BI;
376 if (BBI != BB->begin()) {
377 --BBI;
378 while (isa<DbgInfoIntrinsic>(BBI)) {
379 if (BBI == BB->begin())
380 break;
381 --BBI;
382 }
383 if (!isa<DbgInfoIntrinsic>(BBI) && !isa<PHINode>(BBI))
384 continue;
385 }
386
387 // Do not break infinite loops.
388 BasicBlock *DestBB = BI->getSuccessor(0);
389 if (DestBB == BB)
390 continue;
391
392 if (!CanMergeBlocks(BB, DestBB))
393 continue;
394
395 EliminateMostlyEmptyBlock(BB);
396 MadeChange = true;
397 }
398 return MadeChange;
399}
400
401/// CanMergeBlocks - Return true if we can merge BB into DestBB if there is a
402/// single uncond branch between them, and BB contains no other non-phi
403/// instructions.
404bool CodeGenPrepare::CanMergeBlocks(const BasicBlock *BB,
405 const BasicBlock *DestBB) const {
406 // We only want to eliminate blocks whose phi nodes are used by phi nodes in
407 // the successor. If there are more complex condition (e.g. preheaders),
408 // don't mess around with them.
409 BasicBlock::const_iterator BBI = BB->begin();
410 while (const PHINode *PN = dyn_cast<PHINode>(BBI++)) {
411 for (const User *U : PN->users()) {
412 const Instruction *UI = cast<Instruction>(U);
413 if (UI->getParent() != DestBB || !isa<PHINode>(UI))
414 return false;
415 // If User is inside DestBB block and it is a PHINode then check
416 // incoming value. If incoming value is not from BB then this is
417 // a complex condition (e.g. preheaders) we want to avoid here.
418 if (UI->getParent() == DestBB) {
419 if (const PHINode *UPN = dyn_cast<PHINode>(UI))
420 for (unsigned I = 0, E = UPN->getNumIncomingValues(); I != E; ++I) {
421 Instruction *Insn = dyn_cast<Instruction>(UPN->getIncomingValue(I));
422 if (Insn && Insn->getParent() == BB &&
423 Insn->getParent() != UPN->getIncomingBlock(I))
424 return false;
425 }
426 }
427 }
428 }
429
430 // If BB and DestBB contain any common predecessors, then the phi nodes in BB
431 // and DestBB may have conflicting incoming values for the block. If so, we
432 // can't merge the block.
433 const PHINode *DestBBPN = dyn_cast<PHINode>(DestBB->begin());
434 if (!DestBBPN) return true; // no conflict.
435
436 // Collect the preds of BB.
437 SmallPtrSet<const BasicBlock*, 16> BBPreds;
438 if (const PHINode *BBPN = dyn_cast<PHINode>(BB->begin())) {
439 // It is faster to get preds from a PHI than with pred_iterator.
440 for (unsigned i = 0, e = BBPN->getNumIncomingValues(); i != e; ++i)
441 BBPreds.insert(BBPN->getIncomingBlock(i));
442 } else {
443 BBPreds.insert(pred_begin(BB), pred_end(BB));
444 }
445
446 // Walk the preds of DestBB.
447 for (unsigned i = 0, e = DestBBPN->getNumIncomingValues(); i != e; ++i) {
448 BasicBlock *Pred = DestBBPN->getIncomingBlock(i);
449 if (BBPreds.count(Pred)) { // Common predecessor?
450 BBI = DestBB->begin();
451 while (const PHINode *PN = dyn_cast<PHINode>(BBI++)) {
452 const Value *V1 = PN->getIncomingValueForBlock(Pred);
453 const Value *V2 = PN->getIncomingValueForBlock(BB);
454
455 // If V2 is a phi node in BB, look up what the mapped value will be.
456 if (const PHINode *V2PN = dyn_cast<PHINode>(V2))
457 if (V2PN->getParent() == BB)
458 V2 = V2PN->getIncomingValueForBlock(Pred);
459
460 // If there is a conflict, bail out.
461 if (V1 != V2) return false;
462 }
463 }
464 }
465
466 return true;
467}
468
469
470/// EliminateMostlyEmptyBlock - Eliminate a basic block that have only phi's and
471/// an unconditional branch in it.
472void CodeGenPrepare::EliminateMostlyEmptyBlock(BasicBlock *BB) {
473 BranchInst *BI = cast<BranchInst>(BB->getTerminator());
474 BasicBlock *DestBB = BI->getSuccessor(0);
475
476 DEBUG(dbgs() << "MERGING MOSTLY EMPTY BLOCKS - BEFORE:\n" << *BB << *DestBB)do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "MERGING MOSTLY EMPTY BLOCKS - BEFORE:\n"
<< *BB << *DestBB; } } while (0);
477
478 // If the destination block has a single pred, then this is a trivial edge,
479 // just collapse it.
480 if (BasicBlock *SinglePred = DestBB->getSinglePredecessor()) {
481 if (SinglePred != DestBB) {
482 // Remember if SinglePred was the entry block of the function. If so, we
483 // will need to move BB back to the entry position.
484 bool isEntry = SinglePred == &SinglePred->getParent()->getEntryBlock();
485 MergeBasicBlockIntoOnlyPred(DestBB, DT);
486
487 if (isEntry && BB != &BB->getParent()->getEntryBlock())
488 BB->moveBefore(&BB->getParent()->getEntryBlock());
489
490 DEBUG(dbgs() << "AFTER:\n" << *DestBB << "\n\n\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "AFTER:\n" << *DestBB
<< "\n\n\n"; } } while (0);
491 return;
492 }
493 }
494
495 // Otherwise, we have multiple predecessors of BB. Update the PHIs in DestBB
496 // to handle the new incoming edges it is about to have.
497 PHINode *PN;
498 for (BasicBlock::iterator BBI = DestBB->begin();
499 (PN = dyn_cast<PHINode>(BBI)); ++BBI) {
500 // Remove the incoming value for BB, and remember it.
501 Value *InVal = PN->removeIncomingValue(BB, false);
502
503 // Two options: either the InVal is a phi node defined in BB or it is some
504 // value that dominates BB.
505 PHINode *InValPhi = dyn_cast<PHINode>(InVal);
506 if (InValPhi && InValPhi->getParent() == BB) {
507 // Add all of the input values of the input PHI as inputs of this phi.
508 for (unsigned i = 0, e = InValPhi->getNumIncomingValues(); i != e; ++i)
509 PN->addIncoming(InValPhi->getIncomingValue(i),
510 InValPhi->getIncomingBlock(i));
511 } else {
512 // Otherwise, add one instance of the dominating value for each edge that
513 // we will be adding.
514 if (PHINode *BBPN = dyn_cast<PHINode>(BB->begin())) {
515 for (unsigned i = 0, e = BBPN->getNumIncomingValues(); i != e; ++i)
516 PN->addIncoming(InVal, BBPN->getIncomingBlock(i));
517 } else {
518 for (pred_iterator PI = pred_begin(BB), E = pred_end(BB); PI != E; ++PI)
519 PN->addIncoming(InVal, *PI);
520 }
521 }
522 }
523
524 // The PHIs are now updated, change everything that refers to BB to use
525 // DestBB and remove BB.
526 BB->replaceAllUsesWith(DestBB);
527 if (DT && !ModifiedDT) {
528 BasicBlock *BBIDom = DT->getNode(BB)->getIDom()->getBlock();
529 BasicBlock *DestBBIDom = DT->getNode(DestBB)->getIDom()->getBlock();
530 BasicBlock *NewIDom = DT->findNearestCommonDominator(BBIDom, DestBBIDom);
531 DT->changeImmediateDominator(DestBB, NewIDom);
532 DT->eraseNode(BB);
533 }
534 BB->eraseFromParent();
535 ++NumBlocksElim;
536
537 DEBUG(dbgs() << "AFTER:\n" << *DestBB << "\n\n\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "AFTER:\n" << *DestBB
<< "\n\n\n"; } } while (0);
538}
539
540// Computes a map of base pointer relocation instructions to corresponding
541// derived pointer relocation instructions given a vector of all relocate calls
542static void computeBaseDerivedRelocateMap(
543 const SmallVectorImpl<User *> &AllRelocateCalls,
544 DenseMap<IntrinsicInst *, SmallVector<IntrinsicInst *, 2>> &
545 RelocateInstMap) {
546 // Collect information in two maps: one primarily for locating the base object
547 // while filling the second map; the second map is the final structure holding
548 // a mapping between Base and corresponding Derived relocate calls
549 DenseMap<std::pair<unsigned, unsigned>, IntrinsicInst *> RelocateIdxMap;
550 for (auto &U : AllRelocateCalls) {
551 GCRelocateOperands ThisRelocate(U);
552 IntrinsicInst *I = cast<IntrinsicInst>(U);
553 auto K = std::make_pair(ThisRelocate.basePtrIndex(),
554 ThisRelocate.derivedPtrIndex());
555 RelocateIdxMap.insert(std::make_pair(K, I));
556 }
557 for (auto &Item : RelocateIdxMap) {
558 std::pair<unsigned, unsigned> Key = Item.first;
559 if (Key.first == Key.second)
560 // Base relocation: nothing to insert
561 continue;
562
563 IntrinsicInst *I = Item.second;
564 auto BaseKey = std::make_pair(Key.first, Key.first);
565 IntrinsicInst *Base = RelocateIdxMap[BaseKey];
566 if (!Base)
567 // TODO: We might want to insert a new base object relocate and gep off
568 // that, if there are enough derived object relocates.
569 continue;
570 RelocateInstMap[Base].push_back(I);
571 }
572}
573
574// Accepts a GEP and extracts the operands into a vector provided they're all
575// small integer constants
576static bool getGEPSmallConstantIntOffsetV(GetElementPtrInst *GEP,
577 SmallVectorImpl<Value *> &OffsetV) {
578 for (unsigned i = 1; i < GEP->getNumOperands(); i++) {
579 // Only accept small constant integer operands
580 auto Op = dyn_cast<ConstantInt>(GEP->getOperand(i));
581 if (!Op || Op->getZExtValue() > 20)
582 return false;
583 }
584
585 for (unsigned i = 1; i < GEP->getNumOperands(); i++)
586 OffsetV.push_back(GEP->getOperand(i));
587 return true;
588}
589
590// Takes a RelocatedBase (base pointer relocation instruction) and Targets to
591// replace, computes a replacement, and affects it.
592static bool
593simplifyRelocatesOffABase(IntrinsicInst *RelocatedBase,
594 const SmallVectorImpl<IntrinsicInst *> &Targets) {
595 bool MadeChange = false;
596 for (auto &ToReplace : Targets) {
597 GCRelocateOperands MasterRelocate(RelocatedBase);
598 GCRelocateOperands ThisRelocate(ToReplace);
599
600 assert(ThisRelocate.basePtrIndex() == MasterRelocate.basePtrIndex() &&((ThisRelocate.basePtrIndex() == MasterRelocate.basePtrIndex(
) && "Not relocating a derived object of the original base object"
) ? static_cast<void> (0) : __assert_fail ("ThisRelocate.basePtrIndex() == MasterRelocate.basePtrIndex() && \"Not relocating a derived object of the original base object\""
, "/tmp/buildd/llvm-toolchain-snapshot-3.7~svn228917/lib/CodeGen/CodeGenPrepare.cpp"
, 601, __PRETTY_FUNCTION__))
601 "Not relocating a derived object of the original base object")((ThisRelocate.basePtrIndex() == MasterRelocate.basePtrIndex(
) && "Not relocating a derived object of the original base object"
) ? static_cast<void> (0) : __assert_fail ("ThisRelocate.basePtrIndex() == MasterRelocate.basePtrIndex() && \"Not relocating a derived object of the original base object\""
, "/tmp/buildd/llvm-toolchain-snapshot-3.7~svn228917/lib/CodeGen/CodeGenPrepare.cpp"
, 601, __PRETTY_FUNCTION__));
602 if (ThisRelocate.basePtrIndex() == ThisRelocate.derivedPtrIndex()) {
603 // A duplicate relocate call. TODO: coalesce duplicates.
604 continue;
605 }
606
607 Value *Base = ThisRelocate.basePtr();
608 auto Derived = dyn_cast<GetElementPtrInst>(ThisRelocate.derivedPtr());
609 if (!Derived || Derived->getPointerOperand() != Base)
610 continue;
611
612 SmallVector<Value *, 2> OffsetV;
613 if (!getGEPSmallConstantIntOffsetV(Derived, OffsetV))
614 continue;
615
616 // Create a Builder and replace the target callsite with a gep
617 IRBuilder<> Builder(ToReplace);
618 Builder.SetCurrentDebugLocation(ToReplace->getDebugLoc());
619 Value *Replacement =
620 Builder.CreateGEP(RelocatedBase, makeArrayRef(OffsetV));
621 Instruction *ReplacementInst = cast<Instruction>(Replacement);
622 ReplacementInst->removeFromParent();
623 ReplacementInst->insertAfter(RelocatedBase);
624 Replacement->takeName(ToReplace);
625 ToReplace->replaceAllUsesWith(Replacement);
626 ToReplace->eraseFromParent();
627
628 MadeChange = true;
629 }
630 return MadeChange;
631}
632
633// Turns this:
634//
635// %base = ...
636// %ptr = gep %base + 15
637// %tok = statepoint (%fun, i32 0, i32 0, i32 0, %base, %ptr)
638// %base' = relocate(%tok, i32 4, i32 4)
639// %ptr' = relocate(%tok, i32 4, i32 5)
640// %val = load %ptr'
641//
642// into this:
643//
644// %base = ...
645// %ptr = gep %base + 15
646// %tok = statepoint (%fun, i32 0, i32 0, i32 0, %base, %ptr)
647// %base' = gc.relocate(%tok, i32 4, i32 4)
648// %ptr' = gep %base' + 15
649// %val = load %ptr'
650bool CodeGenPrepare::simplifyOffsetableRelocate(Instruction &I) {
651 bool MadeChange = false;
652 SmallVector<User *, 2> AllRelocateCalls;
653
654 for (auto *U : I.users())
655 if (isGCRelocate(dyn_cast<Instruction>(U)))
656 // Collect all the relocate calls associated with a statepoint
657 AllRelocateCalls.push_back(U);
658
659 // We need atleast one base pointer relocation + one derived pointer
660 // relocation to mangle
661 if (AllRelocateCalls.size() < 2)
662 return false;
663
664 // RelocateInstMap is a mapping from the base relocate instruction to the
665 // corresponding derived relocate instructions
666 DenseMap<IntrinsicInst *, SmallVector<IntrinsicInst *, 2>> RelocateInstMap;
667 computeBaseDerivedRelocateMap(AllRelocateCalls, RelocateInstMap);
668 if (RelocateInstMap.empty())
669 return false;
670
671 for (auto &Item : RelocateInstMap)
672 // Item.first is the RelocatedBase to offset against
673 // Item.second is the vector of Targets to replace
674 MadeChange = simplifyRelocatesOffABase(Item.first, Item.second);
675 return MadeChange;
676}
677
678/// SinkCast - Sink the specified cast instruction into its user blocks
679static bool SinkCast(CastInst *CI) {
680 BasicBlock *DefBB = CI->getParent();
681
682 /// InsertedCasts - Only insert a cast in each block once.
683 DenseMap<BasicBlock*, CastInst*> InsertedCasts;
684
685 bool MadeChange = false;
686 for (Value::user_iterator UI = CI->user_begin(), E = CI->user_end();
687 UI != E; ) {
688 Use &TheUse = UI.getUse();
689 Instruction *User = cast<Instruction>(*UI);
690
691 // Figure out which BB this cast is used in. For PHI's this is the
692 // appropriate predecessor block.
693 BasicBlock *UserBB = User->getParent();
694 if (PHINode *PN = dyn_cast<PHINode>(User)) {
695 UserBB = PN->getIncomingBlock(TheUse);
696 }
697
698 // Preincrement use iterator so we don't invalidate it.
699 ++UI;
700
701 // If this user is in the same block as the cast, don't change the cast.
702 if (UserBB == DefBB) continue;
703
704 // If we have already inserted a cast into this block, use it.
705 CastInst *&InsertedCast = InsertedCasts[UserBB];
706
707 if (!InsertedCast) {
708 BasicBlock::iterator InsertPt = UserBB->getFirstInsertionPt();
709 InsertedCast =
710 CastInst::Create(CI->getOpcode(), CI->getOperand(0), CI->getType(), "",
711 InsertPt);
712 MadeChange = true;
713 }
714
715 // Replace a use of the cast with a use of the new cast.
716 TheUse = InsertedCast;
717 ++NumCastUses;
718 }
719
720 // If we removed all uses, nuke the cast.
721 if (CI->use_empty()) {
722 CI->eraseFromParent();
723 MadeChange = true;
724 }
725
726 return MadeChange;
727}
728
729/// OptimizeNoopCopyExpression - If the specified cast instruction is a noop
730/// copy (e.g. it's casting from one pointer type to another, i32->i8 on PPC),
731/// sink it into user blocks to reduce the number of virtual
732/// registers that must be created and coalesced.
733///
734/// Return true if any changes are made.
735///
736static bool OptimizeNoopCopyExpression(CastInst *CI, const TargetLowering &TLI){
737 // If this is a noop copy,
738 EVT SrcVT = TLI.getValueType(CI->getOperand(0)->getType());
739 EVT DstVT = TLI.getValueType(CI->getType());
740
741 // This is an fp<->int conversion?
742 if (SrcVT.isInteger() != DstVT.isInteger())
743 return false;
744
745 // If this is an extension, it will be a zero or sign extension, which
746 // isn't a noop.
747 if (SrcVT.bitsLT(DstVT)) return false;
748
749 // If these values will be promoted, find out what they will be promoted
750 // to. This helps us consider truncates on PPC as noop copies when they
751 // are.
752 if (TLI.getTypeAction(CI->getContext(), SrcVT) ==
753 TargetLowering::TypePromoteInteger)
754 SrcVT = TLI.getTypeToTransformTo(CI->getContext(), SrcVT);
755 if (TLI.getTypeAction(CI->getContext(), DstVT) ==
756 TargetLowering::TypePromoteInteger)
757 DstVT = TLI.getTypeToTransformTo(CI->getContext(), DstVT);
758
759 // If, after promotion, these are the same types, this is a noop copy.
760 if (SrcVT != DstVT)
761 return false;
762
763 return SinkCast(CI);
764}
765
766/// OptimizeCmpExpression - sink the given CmpInst into user blocks to reduce
767/// the number of virtual registers that must be created and coalesced. This is
768/// a clear win except on targets with multiple condition code registers
769/// (PowerPC), where it might lose; some adjustment may be wanted there.
770///
771/// Return true if any changes are made.
772static bool OptimizeCmpExpression(CmpInst *CI) {
773 BasicBlock *DefBB = CI->getParent();
774
775 /// InsertedCmp - Only insert a cmp in each block once.
776 DenseMap<BasicBlock*, CmpInst*> InsertedCmps;
777
778 bool MadeChange = false;
779 for (Value::user_iterator UI = CI->user_begin(), E = CI->user_end();
780 UI != E; ) {
781 Use &TheUse = UI.getUse();
782 Instruction *User = cast<Instruction>(*UI);
783
784 // Preincrement use iterator so we don't invalidate it.
785 ++UI;
786
787 // Don't bother for PHI nodes.
788 if (isa<PHINode>(User))
789 continue;
790
791 // Figure out which BB this cmp is used in.
792 BasicBlock *UserBB = User->getParent();
793
794 // If this user is in the same block as the cmp, don't change the cmp.
795 if (UserBB == DefBB) continue;
796
797 // If we have already inserted a cmp into this block, use it.
798 CmpInst *&InsertedCmp = InsertedCmps[UserBB];
799
800 if (!InsertedCmp) {
801 BasicBlock::iterator InsertPt = UserBB->getFirstInsertionPt();
802 InsertedCmp =
803 CmpInst::Create(CI->getOpcode(),
804 CI->getPredicate(), CI->getOperand(0),
805 CI->getOperand(1), "", InsertPt);
806 MadeChange = true;
807 }
808
809 // Replace a use of the cmp with a use of the new cmp.
810 TheUse = InsertedCmp;
811 ++NumCmpUses;
812 }
813
814 // If we removed all uses, nuke the cmp.
815 if (CI->use_empty())
816 CI->eraseFromParent();
817
818 return MadeChange;
819}
820
821/// isExtractBitsCandidateUse - Check if the candidates could
822/// be combined with shift instruction, which includes:
823/// 1. Truncate instruction
824/// 2. And instruction and the imm is a mask of the low bits:
825/// imm & (imm+1) == 0
826static bool isExtractBitsCandidateUse(Instruction *User) {
827 if (!isa<TruncInst>(User)) {
828 if (User->getOpcode() != Instruction::And ||
829 !isa<ConstantInt>(User->getOperand(1)))
830 return false;
831
832 const APInt &Cimm = cast<ConstantInt>(User->getOperand(1))->getValue();
833
834 if ((Cimm & (Cimm + 1)).getBoolValue())
835 return false;
836 }
837 return true;
838}
839
840/// SinkShiftAndTruncate - sink both shift and truncate instruction
841/// to the use of truncate's BB.
842static bool
843SinkShiftAndTruncate(BinaryOperator *ShiftI, Instruction *User, ConstantInt *CI,
844 DenseMap<BasicBlock *, BinaryOperator *> &InsertedShifts,
845 const TargetLowering &TLI) {
846 BasicBlock *UserBB = User->getParent();
847 DenseMap<BasicBlock *, CastInst *> InsertedTruncs;
848 TruncInst *TruncI = dyn_cast<TruncInst>(User);
849 bool MadeChange = false;
850
851 for (Value::user_iterator TruncUI = TruncI->user_begin(),
852 TruncE = TruncI->user_end();
853 TruncUI != TruncE;) {
854
855 Use &TruncTheUse = TruncUI.getUse();
856 Instruction *TruncUser = cast<Instruction>(*TruncUI);
857 // Preincrement use iterator so we don't invalidate it.
858
859 ++TruncUI;
860
861 int ISDOpcode = TLI.InstructionOpcodeToISD(TruncUser->getOpcode());
862 if (!ISDOpcode)
863 continue;
864
865 // If the use is actually a legal node, there will not be an
866 // implicit truncate.
867 // FIXME: always querying the result type is just an
868 // approximation; some nodes' legality is determined by the
869 // operand or other means. There's no good way to find out though.
870 if (TLI.isOperationLegalOrCustom(
871 ISDOpcode, TLI.getValueType(TruncUser->getType(), true)))
872 continue;
873
874 // Don't bother for PHI nodes.
875 if (isa<PHINode>(TruncUser))
876 continue;
877
878 BasicBlock *TruncUserBB = TruncUser->getParent();
879
880 if (UserBB == TruncUserBB)
881 continue;
882
883 BinaryOperator *&InsertedShift = InsertedShifts[TruncUserBB];
884 CastInst *&InsertedTrunc = InsertedTruncs[TruncUserBB];
885
886 if (!InsertedShift && !InsertedTrunc) {
887 BasicBlock::iterator InsertPt = TruncUserBB->getFirstInsertionPt();
888 // Sink the shift
889 if (ShiftI->getOpcode() == Instruction::AShr)
890 InsertedShift =
891 BinaryOperator::CreateAShr(ShiftI->getOperand(0), CI, "", InsertPt);
892 else
893 InsertedShift =
894 BinaryOperator::CreateLShr(ShiftI->getOperand(0), CI, "", InsertPt);
895
896 // Sink the trunc
897 BasicBlock::iterator TruncInsertPt = TruncUserBB->getFirstInsertionPt();
898 TruncInsertPt++;
899
900 InsertedTrunc = CastInst::Create(TruncI->getOpcode(), InsertedShift,
901 TruncI->getType(), "", TruncInsertPt);
902
903 MadeChange = true;
904
905 TruncTheUse = InsertedTrunc;
906 }
907 }
908 return MadeChange;
909}
910
911/// OptimizeExtractBits - sink the shift *right* instruction into user blocks if
912/// the uses could potentially be combined with this shift instruction and
913/// generate BitExtract instruction. It will only be applied if the architecture
914/// supports BitExtract instruction. Here is an example:
915/// BB1:
916/// %x.extract.shift = lshr i64 %arg1, 32
917/// BB2:
918/// %x.extract.trunc = trunc i64 %x.extract.shift to i16
919/// ==>
920///
921/// BB2:
922/// %x.extract.shift.1 = lshr i64 %arg1, 32
923/// %x.extract.trunc = trunc i64 %x.extract.shift.1 to i16
924///
925/// CodeGen will recoginze the pattern in BB2 and generate BitExtract
926/// instruction.
927/// Return true if any changes are made.
928static bool OptimizeExtractBits(BinaryOperator *ShiftI, ConstantInt *CI,
929 const TargetLowering &TLI) {
930 BasicBlock *DefBB = ShiftI->getParent();
931
932 /// Only insert instructions in each block once.
933 DenseMap<BasicBlock *, BinaryOperator *> InsertedShifts;
934
935 bool shiftIsLegal = TLI.isTypeLegal(TLI.getValueType(ShiftI->getType()));
936
937 bool MadeChange = false;
938 for (Value::user_iterator UI = ShiftI->user_begin(), E = ShiftI->user_end();
939 UI != E;) {
940 Use &TheUse = UI.getUse();
941 Instruction *User = cast<Instruction>(*UI);
942 // Preincrement use iterator so we don't invalidate it.
943 ++UI;
944
945 // Don't bother for PHI nodes.
946 if (isa<PHINode>(User))
947 continue;
948
949 if (!isExtractBitsCandidateUse(User))
950 continue;
951
952 BasicBlock *UserBB = User->getParent();
953
954 if (UserBB == DefBB) {
955 // If the shift and truncate instruction are in the same BB. The use of
956 // the truncate(TruncUse) may still introduce another truncate if not
957 // legal. In this case, we would like to sink both shift and truncate
958 // instruction to the BB of TruncUse.
959 // for example:
960 // BB1:
961 // i64 shift.result = lshr i64 opnd, imm
962 // trunc.result = trunc shift.result to i16
963 //
964 // BB2:
965 // ----> We will have an implicit truncate here if the architecture does
966 // not have i16 compare.
967 // cmp i16 trunc.result, opnd2
968 //
969 if (isa<TruncInst>(User) && shiftIsLegal
970 // If the type of the truncate is legal, no trucate will be
971 // introduced in other basic blocks.
972 && (!TLI.isTypeLegal(TLI.getValueType(User->getType()))))
973 MadeChange =
974 SinkShiftAndTruncate(ShiftI, User, CI, InsertedShifts, TLI);
975
976 continue;
977 }
978 // If we have already inserted a shift into this block, use it.
979 BinaryOperator *&InsertedShift = InsertedShifts[UserBB];
980
981 if (!InsertedShift) {
982 BasicBlock::iterator InsertPt = UserBB->getFirstInsertionPt();
983
984 if (ShiftI->getOpcode() == Instruction::AShr)
985 InsertedShift =
986 BinaryOperator::CreateAShr(ShiftI->getOperand(0), CI, "", InsertPt);
987 else
988 InsertedShift =
989 BinaryOperator::CreateLShr(ShiftI->getOperand(0), CI, "", InsertPt);
990
991 MadeChange = true;
992 }
993
994 // Replace a use of the shift with a use of the new shift.
995 TheUse = InsertedShift;
996 }
997
998 // If we removed all uses, nuke the shift.
999 if (ShiftI->use_empty())
1000 ShiftI->eraseFromParent();
1001
1002 return MadeChange;
1003}
1004
1005// ScalarizeMaskedLoad() translates masked load intrinsic, like
1006// <16 x i32 > @llvm.masked.load( <16 x i32>* %addr, i32 align,
1007// <16 x i1> %mask, <16 x i32> %passthru)
1008// to a chain of basic blocks, whith loading element one-by-one if
1009// the appropriate mask bit is set
1010//
1011// %1 = bitcast i8* %addr to i32*
1012// %2 = extractelement <16 x i1> %mask, i32 0
1013// %3 = icmp eq i1 %2, true
1014// br i1 %3, label %cond.load, label %else
1015//
1016//cond.load: ; preds = %0
1017// %4 = getelementptr i32* %1, i32 0
1018// %5 = load i32* %4
1019// %6 = insertelement <16 x i32> undef, i32 %5, i32 0
1020// br label %else
1021//
1022//else: ; preds = %0, %cond.load
1023// %res.phi.else = phi <16 x i32> [ %6, %cond.load ], [ undef, %0 ]
1024// %7 = extractelement <16 x i1> %mask, i32 1
1025// %8 = icmp eq i1 %7, true
1026// br i1 %8, label %cond.load1, label %else2
1027//
1028//cond.load1: ; preds = %else
1029// %9 = getelementptr i32* %1, i32 1
1030// %10 = load i32* %9
1031// %11 = insertelement <16 x i32> %res.phi.else, i32 %10, i32 1
1032// br label %else2
1033//
1034//else2: ; preds = %else, %cond.load1
1035// %res.phi.else3 = phi <16 x i32> [ %11, %cond.load1 ], [ %res.phi.else, %else ]
1036// %12 = extractelement <16 x i1> %mask, i32 2
1037// %13 = icmp eq i1 %12, true
1038// br i1 %13, label %cond.load4, label %else5
1039//
1040static void ScalarizeMaskedLoad(CallInst *CI) {
1041 Value *Ptr = CI->getArgOperand(0);
1042 Value *Src0 = CI->getArgOperand(3);
1043 Value *Mask = CI->getArgOperand(2);
1044 VectorType *VecType = dyn_cast<VectorType>(CI->getType());
1045 Type *EltTy = VecType->getElementType();
1046
1047 assert(VecType && "Unexpected return type of masked load intrinsic")((VecType && "Unexpected return type of masked load intrinsic"
) ? static_cast<void> (0) : __assert_fail ("VecType && \"Unexpected return type of masked load intrinsic\""
, "/tmp/buildd/llvm-toolchain-snapshot-3.7~svn228917/lib/CodeGen/CodeGenPrepare.cpp"
, 1047, __PRETTY_FUNCTION__));
1048
1049 IRBuilder<> Builder(CI->getContext());
1050 Instruction *InsertPt = CI;
1051 BasicBlock *IfBlock = CI->getParent();
1052 BasicBlock *CondBlock = nullptr;
1053 BasicBlock *PrevIfBlock = CI->getParent();
1054 Builder.SetInsertPoint(InsertPt);
1055
1056 Builder.SetCurrentDebugLocation(CI->getDebugLoc());
1057
1058 // Bitcast %addr fron i8* to EltTy*
1059 Type *NewPtrType =
1060 EltTy->getPointerTo(cast<PointerType>(Ptr->getType())->getAddressSpace());
1061 Value *FirstEltPtr = Builder.CreateBitCast(Ptr, NewPtrType);
1062 Value *UndefVal = UndefValue::get(VecType);
1063
1064 // The result vector
1065 Value *VResult = UndefVal;
1066
1067 PHINode *Phi = nullptr;
1068 Value *PrevPhi = UndefVal;
1069
1070 unsigned VectorWidth = VecType->getNumElements();
1071 for (unsigned Idx = 0; Idx < VectorWidth; ++Idx) {
1072
1073 // Fill the "else" block, created in the previous iteration
1074 //
1075 // %res.phi.else3 = phi <16 x i32> [ %11, %cond.load1 ], [ %res.phi.else, %else ]
1076 // %mask_1 = extractelement <16 x i1> %mask, i32 Idx
1077 // %to_load = icmp eq i1 %mask_1, true
1078 // br i1 %to_load, label %cond.load, label %else
1079 //
1080 if (Idx > 0) {
1081 Phi = Builder.CreatePHI(VecType, 2, "res.phi.else");
1082 Phi->addIncoming(VResult, CondBlock);
1083 Phi->addIncoming(PrevPhi, PrevIfBlock);
1084 PrevPhi = Phi;
1085 VResult = Phi;
1086 }
1087
1088 Value *Predicate = Builder.CreateExtractElement(Mask, Builder.getInt32(Idx));
1089 Value *Cmp = Builder.CreateICmp(ICmpInst::ICMP_EQ, Predicate,
1090 ConstantInt::get(Predicate->getType(), 1));
1091
1092 // Create "cond" block
1093 //
1094 // %EltAddr = getelementptr i32* %1, i32 0
1095 // %Elt = load i32* %EltAddr
1096 // VResult = insertelement <16 x i32> VResult, i32 %Elt, i32 Idx
1097 //
1098 CondBlock = IfBlock->splitBasicBlock(InsertPt, "cond.load");
1099 Builder.SetInsertPoint(InsertPt);
1100
1101 Value* Gep = Builder.CreateInBoundsGEP(FirstEltPtr, Builder.getInt32(Idx));
1102 LoadInst* Load = Builder.CreateLoad(Gep, false);
1103 VResult = Builder.CreateInsertElement(VResult, Load, Builder.getInt32(Idx));
1104
1105 // Create "else" block, fill it in the next iteration
1106 BasicBlock *NewIfBlock = CondBlock->splitBasicBlock(InsertPt, "else");
1107 Builder.SetInsertPoint(InsertPt);
1108 Instruction *OldBr = IfBlock->getTerminator();
1109 BranchInst::Create(CondBlock, NewIfBlock, Cmp, OldBr);
1110 OldBr->eraseFromParent();
1111 PrevIfBlock = IfBlock;
1112 IfBlock = NewIfBlock;
1113 }
1114
1115 Phi = Builder.CreatePHI(VecType, 2, "res.phi.select");
1116 Phi->addIncoming(VResult, CondBlock);
1117 Phi->addIncoming(PrevPhi, PrevIfBlock);
1118 Value *NewI = Builder.CreateSelect(Mask, Phi, Src0);
1119 CI->replaceAllUsesWith(NewI);
1120 CI->eraseFromParent();
1121}
1122
1123// ScalarizeMaskedStore() translates masked store intrinsic, like
1124// void @llvm.masked.store(<16 x i32> %src, <16 x i32>* %addr, i32 align,
1125// <16 x i1> %mask)
1126// to a chain of basic blocks, that stores element one-by-one if
1127// the appropriate mask bit is set
1128//
1129// %1 = bitcast i8* %addr to i32*
1130// %2 = extractelement <16 x i1> %mask, i32 0
1131// %3 = icmp eq i1 %2, true
1132// br i1 %3, label %cond.store, label %else
1133//
1134// cond.store: ; preds = %0
1135// %4 = extractelement <16 x i32> %val, i32 0
1136// %5 = getelementptr i32* %1, i32 0
1137// store i32 %4, i32* %5
1138// br label %else
1139//
1140// else: ; preds = %0, %cond.store
1141// %6 = extractelement <16 x i1> %mask, i32 1
1142// %7 = icmp eq i1 %6, true
1143// br i1 %7, label %cond.store1, label %else2
1144//
1145// cond.store1: ; preds = %else
1146// %8 = extractelement <16 x i32> %val, i32 1
1147// %9 = getelementptr i32* %1, i32 1
1148// store i32 %8, i32* %9
1149// br label %else2
1150// . . .
1151static void ScalarizeMaskedStore(CallInst *CI) {
1152 Value *Ptr = CI->getArgOperand(1);
1153 Value *Src = CI->getArgOperand(0);
1154 Value *Mask = CI->getArgOperand(3);
1155
1156 VectorType *VecType = dyn_cast<VectorType>(Src->getType());
1157 Type *EltTy = VecType->getElementType();
1158
1159 assert(VecType && "Unexpected data type in masked store intrinsic")((VecType && "Unexpected data type in masked store intrinsic"
) ? static_cast<void> (0) : __assert_fail ("VecType && \"Unexpected data type in masked store intrinsic\""
, "/tmp/buildd/llvm-toolchain-snapshot-3.7~svn228917/lib/CodeGen/CodeGenPrepare.cpp"
, 1159, __PRETTY_FUNCTION__));
1160
1161 IRBuilder<> Builder(CI->getContext());
1162 Instruction *InsertPt = CI;
1163 BasicBlock *IfBlock = CI->getParent();
1164 Builder.SetInsertPoint(InsertPt);
1165 Builder.SetCurrentDebugLocation(CI->getDebugLoc());
1166
1167 // Bitcast %addr fron i8* to EltTy*
1168 Type *NewPtrType =
1169 EltTy->getPointerTo(cast<PointerType>(Ptr->getType())->getAddressSpace());
1170 Value *FirstEltPtr = Builder.CreateBitCast(Ptr, NewPtrType);
1171
1172 unsigned VectorWidth = VecType->getNumElements();
1173 for (unsigned Idx = 0; Idx < VectorWidth; ++Idx) {
1174
1175 // Fill the "else" block, created in the previous iteration
1176 //
1177 // %mask_1 = extractelement <16 x i1> %mask, i32 Idx
1178 // %to_store = icmp eq i1 %mask_1, true
1179 // br i1 %to_load, label %cond.store, label %else
1180 //
1181 Value *Predicate = Builder.CreateExtractElement(Mask, Builder.getInt32(Idx));
1182 Value *Cmp = Builder.CreateICmp(ICmpInst::ICMP_EQ, Predicate,
1183 ConstantInt::get(Predicate->getType(), 1));
1184
1185 // Create "cond" block
1186 //
1187 // %OneElt = extractelement <16 x i32> %Src, i32 Idx
1188 // %EltAddr = getelementptr i32* %1, i32 0
1189 // %store i32 %OneElt, i32* %EltAddr
1190 //
1191 BasicBlock *CondBlock = IfBlock->splitBasicBlock(InsertPt, "cond.store");
1192 Builder.SetInsertPoint(InsertPt);
1193
1194 Value *OneElt = Builder.CreateExtractElement(Src, Builder.getInt32(Idx));
1195 Value* Gep = Builder.CreateInBoundsGEP(FirstEltPtr, Builder.getInt32(Idx));
1196 Builder.CreateStore(OneElt, Gep);
1197
1198 // Create "else" block, fill it in the next iteration
1199 BasicBlock *NewIfBlock = CondBlock->splitBasicBlock(InsertPt, "else");
1200 Builder.SetInsertPoint(InsertPt);
1201 Instruction *OldBr = IfBlock->getTerminator();
1202 BranchInst::Create(CondBlock, NewIfBlock, Cmp, OldBr);
1203 OldBr->eraseFromParent();
1204 IfBlock = NewIfBlock;
1205 }
1206 CI->eraseFromParent();
1207}
1208
1209bool CodeGenPrepare::OptimizeCallInst(CallInst *CI, bool& ModifiedDT) {
1210 BasicBlock *BB = CI->getParent();
1211
1212 // Lower inline assembly if we can.
1213 // If we found an inline asm expession, and if the target knows how to
1214 // lower it to normal LLVM code, do so now.
1215 if (TLI && isa<InlineAsm>(CI->getCalledValue())) {
1216 if (TLI->ExpandInlineAsm(CI)) {
1217 // Avoid invalidating the iterator.
1218 CurInstIterator = BB->begin();
1219 // Avoid processing instructions out of order, which could cause
1220 // reuse before a value is defined.
1221 SunkAddrs.clear();
1222 return true;
1223 }
1224 // Sink address computing for memory operands into the block.
1225 if (OptimizeInlineAsmInst(CI))
1226 return true;
1227 }
1228
1229 IntrinsicInst *II = dyn_cast<IntrinsicInst>(CI);
1230 if (II) {
1231 switch (II->getIntrinsicID()) {
1232 default: break;
1233 case Intrinsic::objectsize: {
1234 // Lower all uses of llvm.objectsize.*
1235 bool Min = (cast<ConstantInt>(II->getArgOperand(1))->getZExtValue() == 1);
1236 Type *ReturnTy = CI->getType();
1237 Constant *RetVal = ConstantInt::get(ReturnTy, Min ? 0 : -1ULL);
1238
1239 // Substituting this can cause recursive simplifications, which can
1240 // invalidate our iterator. Use a WeakVH to hold onto it in case this
1241 // happens.
1242 WeakVH IterHandle(CurInstIterator);
1243
1244 replaceAndRecursivelySimplify(CI, RetVal,
1245 TLI ? TLI->getDataLayout() : nullptr,
1246 TLInfo, ModifiedDT ? nullptr : DT);
1247
1248 // If the iterator instruction was recursively deleted, start over at the
1249 // start of the block.
1250 if (IterHandle != CurInstIterator) {
1251 CurInstIterator = BB->begin();
1252 SunkAddrs.clear();
1253 }
1254 return true;
1255 }
1256 case Intrinsic::masked_load: {
1257 // Scalarize unsupported vector masked load
1258 if (!TTI->isLegalMaskedLoad(CI->getType(), 1)) {
1259 ScalarizeMaskedLoad(CI);
1260 ModifiedDT = true;
1261 return true;
1262 }
1263 return false;
1264 }
1265 case Intrinsic::masked_store: {
1266 if (!TTI->isLegalMaskedStore(CI->getArgOperand(0)->getType(), 1)) {
1267 ScalarizeMaskedStore(CI);
1268 ModifiedDT = true;
1269 return true;
1270 }
1271 return false;
1272 }
1273 }
1274
1275 if (TLI) {
1276 SmallVector<Value*, 2> PtrOps;
1277 Type *AccessTy;
1278 if (TLI->GetAddrModeArguments(II, PtrOps, AccessTy))
1279 while (!PtrOps.empty())
1280 if (OptimizeMemoryInst(II, PtrOps.pop_back_val(), AccessTy))
1281 return true;
1282 }
1283 }
1284
1285 // From here on out we're working with named functions.
1286 if (!CI->getCalledFunction()) return false;
1287
1288 // We'll need DataLayout from here on out.
1289 const DataLayout *TD = TLI ? TLI->getDataLayout() : nullptr;
1290 if (!TD) return false;
1291
1292 // Lower all default uses of _chk calls. This is very similar
1293 // to what InstCombineCalls does, but here we are only lowering calls
1294 // to fortified library functions (e.g. __memcpy_chk) that have the default
1295 // "don't know" as the objectsize. Anything else should be left alone.
1296 FortifiedLibCallSimplifier Simplifier(TD, TLInfo, true);
1297 if (Value *V = Simplifier.optimizeCall(CI)) {
1298 CI->replaceAllUsesWith(V);
1299 CI->eraseFromParent();
1300 return true;
1301 }
1302 return false;
1303}
1304
1305/// DupRetToEnableTailCallOpts - Look for opportunities to duplicate return
1306/// instructions to the predecessor to enable tail call optimizations. The
1307/// case it is currently looking for is:
1308/// @code
1309/// bb0:
1310/// %tmp0 = tail call i32 @f0()
1311/// br label %return
1312/// bb1:
1313/// %tmp1 = tail call i32 @f1()
1314/// br label %return
1315/// bb2:
1316/// %tmp2 = tail call i32 @f2()
1317/// br label %return
1318/// return:
1319/// %retval = phi i32 [ %tmp0, %bb0 ], [ %tmp1, %bb1 ], [ %tmp2, %bb2 ]
1320/// ret i32 %retval
1321/// @endcode
1322///
1323/// =>
1324///
1325/// @code
1326/// bb0:
1327/// %tmp0 = tail call i32 @f0()
1328/// ret i32 %tmp0
1329/// bb1:
1330/// %tmp1 = tail call i32 @f1()
1331/// ret i32 %tmp1
1332/// bb2:
1333/// %tmp2 = tail call i32 @f2()
1334/// ret i32 %tmp2
1335/// @endcode
1336bool CodeGenPrepare::DupRetToEnableTailCallOpts(BasicBlock *BB) {
1337 if (!TLI)
1338 return false;
1339
1340 ReturnInst *RI = dyn_cast<ReturnInst>(BB->getTerminator());
1341 if (!RI)
1342 return false;
1343
1344 PHINode *PN = nullptr;
1345 BitCastInst *BCI = nullptr;
1346 Value *V = RI->getReturnValue();
1347 if (V) {
1348 BCI = dyn_cast<BitCastInst>(V);
1349 if (BCI)
1350 V = BCI->getOperand(0);
1351
1352 PN = dyn_cast<PHINode>(V);
1353 if (!PN)
1354 return false;
1355 }
1356
1357 if (PN && PN->getParent() != BB)
1358 return false;
1359
1360 // It's not safe to eliminate the sign / zero extension of the return value.
1361 // See llvm::isInTailCallPosition().
1362 const Function *F = BB->getParent();
1363 AttributeSet CallerAttrs = F->getAttributes();
1364 if (CallerAttrs.hasAttribute(AttributeSet::ReturnIndex, Attribute::ZExt) ||
1365 CallerAttrs.hasAttribute(AttributeSet::ReturnIndex, Attribute::SExt))
1366 return false;
1367
1368 // Make sure there are no instructions between the PHI and return, or that the
1369 // return is the first instruction in the block.
1370 if (PN) {
1371 BasicBlock::iterator BI = BB->begin();
1372 do { ++BI; } while (isa<DbgInfoIntrinsic>(BI));
1373 if (&*BI == BCI)
1374 // Also skip over the bitcast.
1375 ++BI;
1376 if (&*BI != RI)
1377 return false;
1378 } else {
1379 BasicBlock::iterator BI = BB->begin();
1380 while (isa<DbgInfoIntrinsic>(BI)) ++BI;
1381 if (&*BI != RI)
1382 return false;
1383 }
1384
1385 /// Only dup the ReturnInst if the CallInst is likely to be emitted as a tail
1386 /// call.
1387 SmallVector<CallInst*, 4> TailCalls;
1388 if (PN) {
1389 for (unsigned I = 0, E = PN->getNumIncomingValues(); I != E; ++I) {
1390 CallInst *CI = dyn_cast<CallInst>(PN->getIncomingValue(I));
1391 // Make sure the phi value is indeed produced by the tail call.
1392 if (CI && CI->hasOneUse() && CI->getParent() == PN->getIncomingBlock(I) &&
1393 TLI->mayBeEmittedAsTailCall(CI))
1394 TailCalls.push_back(CI);
1395 }
1396 } else {
1397 SmallPtrSet<BasicBlock*, 4> VisitedBBs;
1398 for (pred_iterator PI = pred_begin(BB), PE = pred_end(BB); PI != PE; ++PI) {
1399 if (!VisitedBBs.insert(*PI).second)
1400 continue;
1401
1402 BasicBlock::InstListType &InstList = (*PI)->getInstList();
1403 BasicBlock::InstListType::reverse_iterator RI = InstList.rbegin();
1404 BasicBlock::InstListType::reverse_iterator RE = InstList.rend();
1405 do { ++RI; } while (RI != RE && isa<DbgInfoIntrinsic>(&*RI));
1406 if (RI == RE)
1407 continue;
1408
1409 CallInst *CI = dyn_cast<CallInst>(&*RI);
1410 if (CI && CI->use_empty() && TLI->mayBeEmittedAsTailCall(CI))
1411 TailCalls.push_back(CI);
1412 }
1413 }
1414
1415 bool Changed = false;
1416 for (unsigned i = 0, e = TailCalls.size(); i != e; ++i) {
1417 CallInst *CI = TailCalls[i];
1418 CallSite CS(CI);
1419
1420 // Conservatively require the attributes of the call to match those of the
1421 // return. Ignore noalias because it doesn't affect the call sequence.
1422 AttributeSet CalleeAttrs = CS.getAttributes();
1423 if (AttrBuilder(CalleeAttrs, AttributeSet::ReturnIndex).
1424 removeAttribute(Attribute::NoAlias) !=
1425 AttrBuilder(CalleeAttrs, AttributeSet::ReturnIndex).
1426 removeAttribute(Attribute::NoAlias))
1427 continue;
1428
1429 // Make sure the call instruction is followed by an unconditional branch to
1430 // the return block.
1431 BasicBlock *CallBB = CI->getParent();
1432 BranchInst *BI = dyn_cast<BranchInst>(CallBB->getTerminator());
1433 if (!BI || !BI->isUnconditional() || BI->getSuccessor(0) != BB)
1434 continue;
1435
1436 // Duplicate the return into CallBB.
1437 (void)FoldReturnIntoUncondBranch(RI, BB, CallBB);
1438 ModifiedDT = Changed = true;
1439 ++NumRetsDup;
1440 }
1441
1442 // If we eliminated all predecessors of the block, delete the block now.
1443 if (Changed && !BB->hasAddressTaken() && pred_begin(BB) == pred_end(BB))
1444 BB->eraseFromParent();
1445
1446 return Changed;
1447}
1448
1449//===----------------------------------------------------------------------===//
1450// Memory Optimization
1451//===----------------------------------------------------------------------===//
1452
1453namespace {
1454
1455/// ExtAddrMode - This is an extended version of TargetLowering::AddrMode
1456/// which holds actual Value*'s for register values.
1457struct ExtAddrMode : public TargetLowering::AddrMode {
1458 Value *BaseReg;
1459 Value *ScaledReg;
1460 ExtAddrMode() : BaseReg(nullptr), ScaledReg(nullptr) {}
1461 void print(raw_ostream &OS) const;
1462 void dump() const;
1463
1464 bool operator==(const ExtAddrMode& O) const {
1465 return (BaseReg == O.BaseReg) && (ScaledReg == O.ScaledReg) &&
1466 (BaseGV == O.BaseGV) && (BaseOffs == O.BaseOffs) &&
1467 (HasBaseReg == O.HasBaseReg) && (Scale == O.Scale);
1468 }
1469};
1470
1471#ifndef NDEBUG
1472static inline raw_ostream &operator<<(raw_ostream &OS, const ExtAddrMode &AM) {
1473 AM.print(OS);
1474 return OS;
1475}
1476#endif
1477
1478void ExtAddrMode::print(raw_ostream &OS) const {
1479 bool NeedPlus = false;
1480 OS << "[";
1481 if (BaseGV) {
1482 OS << (NeedPlus ? " + " : "")
1483 << "GV:";
1484 BaseGV->printAsOperand(OS, /*PrintType=*/false);
1485 NeedPlus = true;
1486 }
1487
1488 if (BaseOffs) {
1489 OS << (NeedPlus ? " + " : "")
1490 << BaseOffs;
1491 NeedPlus = true;
1492 }
1493
1494 if (BaseReg) {
1495 OS << (NeedPlus ? " + " : "")
1496 << "Base:";
1497 BaseReg->printAsOperand(OS, /*PrintType=*/false);
1498 NeedPlus = true;
1499 }
1500 if (Scale) {
1501 OS << (NeedPlus ? " + " : "")
1502 << Scale << "*";
1503 ScaledReg->printAsOperand(OS, /*PrintType=*/false);
1504 }
1505
1506 OS << ']';
1507}
1508
1509#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
1510void ExtAddrMode::dump() const {
1511 print(dbgs());
1512 dbgs() << '\n';
1513}
1514#endif
1515
1516/// \brief This class provides transaction based operation on the IR.
1517/// Every change made through this class is recorded in the internal state and
1518/// can be undone (rollback) until commit is called.
1519class TypePromotionTransaction {
1520
1521 /// \brief This represents the common interface of the individual transaction.
1522 /// Each class implements the logic for doing one specific modification on
1523 /// the IR via the TypePromotionTransaction.
1524 class TypePromotionAction {
1525 protected:
1526 /// The Instruction modified.
1527 Instruction *Inst;
1528
1529 public:
1530 /// \brief Constructor of the action.
1531 /// The constructor performs the related action on the IR.
1532 TypePromotionAction(Instruction *Inst) : Inst(Inst) {}
1533
1534 virtual ~TypePromotionAction() {}
1535
1536 /// \brief Undo the modification done by this action.
1537 /// When this method is called, the IR must be in the same state as it was
1538 /// before this action was applied.
1539 /// \pre Undoing the action works if and only if the IR is in the exact same
1540 /// state as it was directly after this action was applied.
1541 virtual void undo() = 0;
1542
1543 /// \brief Advocate every change made by this action.
1544 /// When the results on the IR of the action are to be kept, it is important
1545 /// to call this function, otherwise hidden information may be kept forever.
1546 virtual void commit() {
1547 // Nothing to be done, this action is not doing anything.
1548 }
1549 };
1550
1551 /// \brief Utility to remember the position of an instruction.
1552 class InsertionHandler {
1553 /// Position of an instruction.
1554 /// Either an instruction:
1555 /// - Is the first in a basic block: BB is used.
1556 /// - Has a previous instructon: PrevInst is used.
1557 union {
1558 Instruction *PrevInst;
1559 BasicBlock *BB;
1560 } Point;
1561 /// Remember whether or not the instruction had a previous instruction.
1562 bool HasPrevInstruction;
1563
1564 public:
1565 /// \brief Record the position of \p Inst.
1566 InsertionHandler(Instruction *Inst) {
1567 BasicBlock::iterator It = Inst;
1568 HasPrevInstruction = (It != (Inst->getParent()->begin()));
1569 if (HasPrevInstruction)
1570 Point.PrevInst = --It;
1571 else
1572 Point.BB = Inst->getParent();
1573 }
1574
1575 /// \brief Insert \p Inst at the recorded position.
1576 void insert(Instruction *Inst) {
1577 if (HasPrevInstruction) {
1578 if (Inst->getParent())
1579 Inst->removeFromParent();
1580 Inst->insertAfter(Point.PrevInst);
1581 } else {
1582 Instruction *Position = Point.BB->getFirstInsertionPt();
1583 if (Inst->getParent())
1584 Inst->moveBefore(Position);
1585 else
1586 Inst->insertBefore(Position);
1587 }
1588 }
1589 };
1590
1591 /// \brief Move an instruction before another.
1592 class InstructionMoveBefore : public TypePromotionAction {
1593 /// Original position of the instruction.
1594 InsertionHandler Position;
1595
1596 public:
1597 /// \brief Move \p Inst before \p Before.
1598 InstructionMoveBefore(Instruction *Inst, Instruction *Before)
1599 : TypePromotionAction(Inst), Position(Inst) {
1600 DEBUG(dbgs() << "Do: move: " << *Inst << "\nbefore: " << *Before << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Do: move: " << *
Inst << "\nbefore: " << *Before << "\n"; } }
while (0);
1601 Inst->moveBefore(Before);
1602 }
1603
1604 /// \brief Move the instruction back to its original position.
1605 void undo() override {
1606 DEBUG(dbgs() << "Undo: moveBefore: " << *Inst << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Undo: moveBefore: " <<
*Inst << "\n"; } } while (0);
1607 Position.insert(Inst);
1608 }
1609 };
1610
1611 /// \brief Set the operand of an instruction with a new value.
1612 class OperandSetter : public TypePromotionAction {
1613 /// Original operand of the instruction.
1614 Value *Origin;
1615 /// Index of the modified instruction.
1616 unsigned Idx;
1617
1618 public:
1619 /// \brief Set \p Idx operand of \p Inst with \p NewVal.
1620 OperandSetter(Instruction *Inst, unsigned Idx, Value *NewVal)
1621 : TypePromotionAction(Inst), Idx(Idx) {
1622 DEBUG(dbgs() << "Do: setOperand: " << Idx << "\n"do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Do: setOperand: " <<
Idx << "\n" << "for:" << *Inst << "\n"
<< "with:" << *NewVal << "\n"; } } while (
0)
1623 << "for:" << *Inst << "\n"do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Do: setOperand: " <<
Idx << "\n" << "for:" << *Inst << "\n"
<< "with:" << *NewVal << "\n"; } } while (
0)
1624 << "with:" << *NewVal << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Do: setOperand: " <<
Idx << "\n" << "for:" << *Inst << "\n"
<< "with:" << *NewVal << "\n"; } } while (
0);
1625 Origin = Inst->getOperand(Idx);
1626 Inst->setOperand(Idx, NewVal);
1627 }
1628
1629 /// \brief Restore the original value of the instruction.
1630 void undo() override {
1631 DEBUG(dbgs() << "Undo: setOperand:" << Idx << "\n"do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Undo: setOperand:" <<
Idx << "\n" << "for: " << *Inst << "\n"
<< "with: " << *Origin << "\n"; } } while (
0)
1632 << "for: " << *Inst << "\n"do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Undo: setOperand:" <<
Idx << "\n" << "for: " << *Inst << "\n"
<< "with: " << *Origin << "\n"; } } while (
0)
1633 << "with: " << *Origin << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Undo: setOperand:" <<
Idx << "\n" << "for: " << *Inst << "\n"
<< "with: " << *Origin << "\n"; } } while (
0);
1634 Inst->setOperand(Idx, Origin);
1635 }
1636 };
1637
1638 /// \brief Hide the operands of an instruction.
1639 /// Do as if this instruction was not using any of its operands.
1640 class OperandsHider : public TypePromotionAction {
1641 /// The list of original operands.
1642 SmallVector<Value *, 4> OriginalValues;
1643
1644 public:
1645 /// \brief Remove \p Inst from the uses of the operands of \p Inst.
1646 OperandsHider(Instruction *Inst) : TypePromotionAction(Inst) {
1647 DEBUG(dbgs() << "Do: OperandsHider: " << *Inst << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Do: OperandsHider: " <<
*Inst << "\n"; } } while (0);
1648 unsigned NumOpnds = Inst->getNumOperands();
1649 OriginalValues.reserve(NumOpnds);
1650 for (unsigned It = 0; It < NumOpnds; ++It) {
1651 // Save the current operand.
1652 Value *Val = Inst->getOperand(It);
1653 OriginalValues.push_back(Val);
1654 // Set a dummy one.
1655 // We could use OperandSetter here, but that would implied an overhead
1656 // that we are not willing to pay.
1657 Inst->setOperand(It, UndefValue::get(Val->getType()));
1658 }
1659 }
1660
1661 /// \brief Restore the original list of uses.
1662 void undo() override {
1663 DEBUG(dbgs() << "Undo: OperandsHider: " << *Inst << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Undo: OperandsHider: "
<< *Inst << "\n"; } } while (0);
1664 for (unsigned It = 0, EndIt = OriginalValues.size(); It != EndIt; ++It)
1665 Inst->setOperand(It, OriginalValues[It]);
1666 }
1667 };
1668
1669 /// \brief Build a truncate instruction.
1670 class TruncBuilder : public TypePromotionAction {
1671 Value *Val;
1672 public:
1673 /// \brief Build a truncate instruction of \p Opnd producing a \p Ty
1674 /// result.
1675 /// trunc Opnd to Ty.
1676 TruncBuilder(Instruction *Opnd, Type *Ty) : TypePromotionAction(Opnd) {
1677 IRBuilder<> Builder(Opnd);
1678 Val = Builder.CreateTrunc(Opnd, Ty, "promoted");
1679 DEBUG(dbgs() << "Do: TruncBuilder: " << *Val << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Do: TruncBuilder: " <<
*Val << "\n"; } } while (0);
1680 }
1681
1682 /// \brief Get the built value.
1683 Value *getBuiltValue() { return Val; }
1684
1685 /// \brief Remove the built instruction.
1686 void undo() override {
1687 DEBUG(dbgs() << "Undo: TruncBuilder: " << *Val << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Undo: TruncBuilder: " <<
*Val << "\n"; } } while (0);
1688 if (Instruction *IVal = dyn_cast<Instruction>(Val))
1689 IVal->eraseFromParent();
1690 }
1691 };
1692
1693 /// \brief Build a sign extension instruction.
1694 class SExtBuilder : public TypePromotionAction {
1695 Value *Val;
1696 public:
1697 /// \brief Build a sign extension instruction of \p Opnd producing a \p Ty
1698 /// result.
1699 /// sext Opnd to Ty.
1700 SExtBuilder(Instruction *InsertPt, Value *Opnd, Type *Ty)
1701 : TypePromotionAction(InsertPt) {
1702 IRBuilder<> Builder(InsertPt);
1703 Val = Builder.CreateSExt(Opnd, Ty, "promoted");
1704 DEBUG(dbgs() << "Do: SExtBuilder: " << *Val << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Do: SExtBuilder: " <<
*Val << "\n"; } } while (0);
1705 }
1706
1707 /// \brief Get the built value.
1708 Value *getBuiltValue() { return Val; }
1709
1710 /// \brief Remove the built instruction.
1711 void undo() override {
1712 DEBUG(dbgs() << "Undo: SExtBuilder: " << *Val << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Undo: SExtBuilder: " <<
*Val << "\n"; } } while (0);
1713 if (Instruction *IVal = dyn_cast<Instruction>(Val))
1714 IVal->eraseFromParent();
1715 }
1716 };
1717
1718 /// \brief Build a zero extension instruction.
1719 class ZExtBuilder : public TypePromotionAction {
1720 Value *Val;
1721 public:
1722 /// \brief Build a zero extension instruction of \p Opnd producing a \p Ty
1723 /// result.
1724 /// zext Opnd to Ty.
1725 ZExtBuilder(Instruction *InsertPt, Value *Opnd, Type *Ty)
1726 : TypePromotionAction(InsertPt) {
1727 IRBuilder<> Builder(InsertPt);
1728 Val = Builder.CreateZExt(Opnd, Ty, "promoted");
1729 DEBUG(dbgs() << "Do: ZExtBuilder: " << *Val << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Do: ZExtBuilder: " <<
*Val << "\n"; } } while (0);
1730 }
1731
1732 /// \brief Get the built value.
1733 Value *getBuiltValue() { return Val; }
1734
1735 /// \brief Remove the built instruction.
1736 void undo() override {
1737 DEBUG(dbgs() << "Undo: ZExtBuilder: " << *Val << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Undo: ZExtBuilder: " <<
*Val << "\n"; } } while (0);
1738 if (Instruction *IVal = dyn_cast<Instruction>(Val))
1739 IVal->eraseFromParent();
1740 }
1741 };
1742
1743 /// \brief Mutate an instruction to another type.
1744 class TypeMutator : public TypePromotionAction {
1745 /// Record the original type.
1746 Type *OrigTy;
1747
1748 public:
1749 /// \brief Mutate the type of \p Inst into \p NewTy.
1750 TypeMutator(Instruction *Inst, Type *NewTy)
1751 : TypePromotionAction(Inst), OrigTy(Inst->getType()) {
1752 DEBUG(dbgs() << "Do: MutateType: " << *Inst << " with " << *NewTydo { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Do: MutateType: " <<
*Inst << " with " << *NewTy << "\n"; } } while
(0)
1753 << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Do: MutateType: " <<
*Inst << " with " << *NewTy << "\n"; } } while
(0);
1754 Inst->mutateType(NewTy);
1755 }
1756
1757 /// \brief Mutate the instruction back to its original type.
1758 void undo() override {
1759 DEBUG(dbgs() << "Undo: MutateType: " << *Inst << " with " << *OrigTydo { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Undo: MutateType: " <<
*Inst << " with " << *OrigTy << "\n"; } } while
(0)
1760 << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Undo: MutateType: " <<
*Inst << " with " << *OrigTy << "\n"; } } while
(0);
1761 Inst->mutateType(OrigTy);
1762 }
1763 };
1764
1765 /// \brief Replace the uses of an instruction by another instruction.
1766 class UsesReplacer : public TypePromotionAction {
1767 /// Helper structure to keep track of the replaced uses.
1768 struct InstructionAndIdx {
1769 /// The instruction using the instruction.
1770 Instruction *Inst;
1771 /// The index where this instruction is used for Inst.
1772 unsigned Idx;
1773 InstructionAndIdx(Instruction *Inst, unsigned Idx)
1774 : Inst(Inst), Idx(Idx) {}
1775 };
1776
1777 /// Keep track of the original uses (pair Instruction, Index).
1778 SmallVector<InstructionAndIdx, 4> OriginalUses;
1779 typedef SmallVectorImpl<InstructionAndIdx>::iterator use_iterator;
1780
1781 public:
1782 /// \brief Replace all the use of \p Inst by \p New.
1783 UsesReplacer(Instruction *Inst, Value *New) : TypePromotionAction(Inst) {
1784 DEBUG(dbgs() << "Do: UsersReplacer: " << *Inst << " with " << *Newdo { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Do: UsersReplacer: " <<
*Inst << " with " << *New << "\n"; } } while
(0)
1785 << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Do: UsersReplacer: " <<
*Inst << " with " << *New << "\n"; } } while
(0);
1786 // Record the original uses.
1787 for (Use &U : Inst->uses()) {
1788 Instruction *UserI = cast<Instruction>(U.getUser());
1789 OriginalUses.push_back(InstructionAndIdx(UserI, U.getOperandNo()));
1790 }
1791 // Now, we can replace the uses.
1792 Inst->replaceAllUsesWith(New);
1793 }
1794
1795 /// \brief Reassign the original uses of Inst to Inst.
1796 void undo() override {
1797 DEBUG(dbgs() << "Undo: UsersReplacer: " << *Inst << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Undo: UsersReplacer: "
<< *Inst << "\n"; } } while (0);
1798 for (use_iterator UseIt = OriginalUses.begin(),
1799 EndIt = OriginalUses.end();
1800 UseIt != EndIt; ++UseIt) {
1801 UseIt->Inst->setOperand(UseIt->Idx, Inst);
1802 }
1803 }
1804 };
1805
1806 /// \brief Remove an instruction from the IR.
1807 class InstructionRemover : public TypePromotionAction {
1808 /// Original position of the instruction.
1809 InsertionHandler Inserter;
1810 /// Helper structure to hide all the link to the instruction. In other
1811 /// words, this helps to do as if the instruction was removed.
1812 OperandsHider Hider;
1813 /// Keep track of the uses replaced, if any.
1814 UsesReplacer *Replacer;
1815
1816 public:
1817 /// \brief Remove all reference of \p Inst and optinally replace all its
1818 /// uses with New.
1819 /// \pre If !Inst->use_empty(), then New != nullptr
1820 InstructionRemover(Instruction *Inst, Value *New = nullptr)
1821 : TypePromotionAction(Inst), Inserter(Inst), Hider(Inst),
1822 Replacer(nullptr) {
1823 if (New)
1824 Replacer = new UsesReplacer(Inst, New);
1825 DEBUG(dbgs() << "Do: InstructionRemover: " << *Inst << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Do: InstructionRemover: "
<< *Inst << "\n"; } } while (0);
1826 Inst->removeFromParent();
1827 }
1828
1829 ~InstructionRemover() { delete Replacer; }
1830
1831 /// \brief Really remove the instruction.
1832 void commit() override { delete Inst; }
1833
1834 /// \brief Resurrect the instruction and reassign it to the proper uses if
1835 /// new value was provided when build this action.
1836 void undo() override {
1837 DEBUG(dbgs() << "Undo: InstructionRemover: " << *Inst << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Undo: InstructionRemover: "
<< *Inst << "\n"; } } while (0);
1838 Inserter.insert(Inst);
1839 if (Replacer)
1840 Replacer->undo();
1841 Hider.undo();
1842 }
1843 };
1844
1845public:
1846 /// Restoration point.
1847 /// The restoration point is a pointer to an action instead of an iterator
1848 /// because the iterator may be invalidated but not the pointer.
1849 typedef const TypePromotionAction *ConstRestorationPt;
1850 /// Advocate every changes made in that transaction.
1851 void commit();
1852 /// Undo all the changes made after the given point.
1853 void rollback(ConstRestorationPt Point);
1854 /// Get the current restoration point.
1855 ConstRestorationPt getRestorationPoint() const;
1856
1857 /// \name API for IR modification with state keeping to support rollback.
1858 /// @{
1859 /// Same as Instruction::setOperand.
1860 void setOperand(Instruction *Inst, unsigned Idx, Value *NewVal);
1861 /// Same as Instruction::eraseFromParent.
1862 void eraseInstruction(Instruction *Inst, Value *NewVal = nullptr);
1863 /// Same as Value::replaceAllUsesWith.
1864 void replaceAllUsesWith(Instruction *Inst, Value *New);
1865 /// Same as Value::mutateType.
1866 void mutateType(Instruction *Inst, Type *NewTy);
1867 /// Same as IRBuilder::createTrunc.
1868 Value *createTrunc(Instruction *Opnd, Type *Ty);
1869 /// Same as IRBuilder::createSExt.
1870 Value *createSExt(Instruction *Inst, Value *Opnd, Type *Ty);
1871 /// Same as IRBuilder::createZExt.
1872 Value *createZExt(Instruction *Inst, Value *Opnd, Type *Ty);
1873 /// Same as Instruction::moveBefore.
1874 void moveBefore(Instruction *Inst, Instruction *Before);
1875 /// @}
1876
1877private:
1878 /// The ordered list of actions made so far.
1879 SmallVector<std::unique_ptr<TypePromotionAction>, 16> Actions;
1880 typedef SmallVectorImpl<std::unique_ptr<TypePromotionAction>>::iterator CommitPt;
1881};
1882
1883void TypePromotionTransaction::setOperand(Instruction *Inst, unsigned Idx,
1884 Value *NewVal) {
1885 Actions.push_back(
1886 make_unique<TypePromotionTransaction::OperandSetter>(Inst, Idx, NewVal));
1887}
1888
1889void TypePromotionTransaction::eraseInstruction(Instruction *Inst,
1890 Value *NewVal) {
1891 Actions.push_back(
1892 make_unique<TypePromotionTransaction::InstructionRemover>(Inst, NewVal));
1893}
1894
1895void TypePromotionTransaction::replaceAllUsesWith(Instruction *Inst,
1896 Value *New) {
1897 Actions.push_back(make_unique<TypePromotionTransaction::UsesReplacer>(Inst, New));
1898}
1899
1900void TypePromotionTransaction::mutateType(Instruction *Inst, Type *NewTy) {
1901 Actions.push_back(make_unique<TypePromotionTransaction::TypeMutator>(Inst, NewTy));
1902}
1903
1904Value *TypePromotionTransaction::createTrunc(Instruction *Opnd,
1905 Type *Ty) {
1906 std::unique_ptr<TruncBuilder> Ptr(new TruncBuilder(Opnd, Ty));
1907 Value *Val = Ptr->getBuiltValue();
1908 Actions.push_back(std::move(Ptr));
1909 return Val;
1910}
1911
1912Value *TypePromotionTransaction::createSExt(Instruction *Inst,
1913 Value *Opnd, Type *Ty) {
1914 std::unique_ptr<SExtBuilder> Ptr(new SExtBuilder(Inst, Opnd, Ty));
1915 Value *Val = Ptr->getBuiltValue();
1916 Actions.push_back(std::move(Ptr));
1917 return Val;
1918}
1919
1920Value *TypePromotionTransaction::createZExt(Instruction *Inst,
1921 Value *Opnd, Type *Ty) {
1922 std::unique_ptr<ZExtBuilder> Ptr(new ZExtBuilder(Inst, Opnd, Ty));
1923 Value *Val = Ptr->getBuiltValue();
1924 Actions.push_back(std::move(Ptr));
1925 return Val;
1926}
1927
1928void TypePromotionTransaction::moveBefore(Instruction *Inst,
1929 Instruction *Before) {
1930 Actions.push_back(
1931 make_unique<TypePromotionTransaction::InstructionMoveBefore>(Inst, Before));
1932}
1933
1934TypePromotionTransaction::ConstRestorationPt
1935TypePromotionTransaction::getRestorationPoint() const {
1936 return !Actions.empty() ? Actions.back().get() : nullptr;
1937}
1938
1939void TypePromotionTransaction::commit() {
1940 for (CommitPt It = Actions.begin(), EndIt = Actions.end(); It != EndIt;
1941 ++It)
1942 (*It)->commit();
1943 Actions.clear();
1944}
1945
1946void TypePromotionTransaction::rollback(
1947 TypePromotionTransaction::ConstRestorationPt Point) {
1948 while (!Actions.empty() && Point != Actions.back().get()) {
1949 std::unique_ptr<TypePromotionAction> Curr = Actions.pop_back_val();
1950 Curr->undo();
1951 }
1952}
1953
1954/// \brief A helper class for matching addressing modes.
1955///
1956/// This encapsulates the logic for matching the target-legal addressing modes.
1957class AddressingModeMatcher {
1958 SmallVectorImpl<Instruction*> &AddrModeInsts;
1959 const TargetLowering &TLI;
1960
1961 /// AccessTy/MemoryInst - This is the type for the access (e.g. double) and
1962 /// the memory instruction that we're computing this address for.
1963 Type *AccessTy;
1964 Instruction *MemoryInst;
1965
1966 /// AddrMode - This is the addressing mode that we're building up. This is
1967 /// part of the return value of this addressing mode matching stuff.
1968 ExtAddrMode &AddrMode;
1969
1970 /// The truncate instruction inserted by other CodeGenPrepare optimizations.
1971 const SetOfInstrs &InsertedTruncs;
1972 /// A map from the instructions to their type before promotion.
1973 InstrToOrigTy &PromotedInsts;
1974 /// The ongoing transaction where every action should be registered.
1975 TypePromotionTransaction &TPT;
1976
1977 /// IgnoreProfitability - This is set to true when we should not do
1978 /// profitability checks. When true, IsProfitableToFoldIntoAddressingMode
1979 /// always returns true.
1980 bool IgnoreProfitability;
1981
1982 AddressingModeMatcher(SmallVectorImpl<Instruction*> &AMI,
1983 const TargetLowering &T, Type *AT,
1984 Instruction *MI, ExtAddrMode &AM,
1985 const SetOfInstrs &InsertedTruncs,
1986 InstrToOrigTy &PromotedInsts,
1987 TypePromotionTransaction &TPT)
1988 : AddrModeInsts(AMI), TLI(T), AccessTy(AT), MemoryInst(MI), AddrMode(AM),
1989 InsertedTruncs(InsertedTruncs), PromotedInsts(PromotedInsts), TPT(TPT) {
1990 IgnoreProfitability = false;
1991 }
1992public:
1993
1994 /// Match - Find the maximal addressing mode that a load/store of V can fold,
1995 /// give an access type of AccessTy. This returns a list of involved
1996 /// instructions in AddrModeInsts.
1997 /// \p InsertedTruncs The truncate instruction inserted by other
1998 /// CodeGenPrepare
1999 /// optimizations.
2000 /// \p PromotedInsts maps the instructions to their type before promotion.
2001 /// \p The ongoing transaction where every action should be registered.
2002 static ExtAddrMode Match(Value *V, Type *AccessTy,
2003 Instruction *MemoryInst,
2004 SmallVectorImpl<Instruction*> &AddrModeInsts,
2005 const TargetLowering &TLI,
2006 const SetOfInstrs &InsertedTruncs,
2007 InstrToOrigTy &PromotedInsts,
2008 TypePromotionTransaction &TPT) {
2009 ExtAddrMode Result;
2010
2011 bool Success = AddressingModeMatcher(AddrModeInsts, TLI, AccessTy,
2012 MemoryInst, Result, InsertedTruncs,
2013 PromotedInsts, TPT).MatchAddr(V, 0);
2014 (void)Success; assert(Success && "Couldn't select *anything*?")((Success && "Couldn't select *anything*?") ? static_cast
<void> (0) : __assert_fail ("Success && \"Couldn't select *anything*?\""
, "/tmp/buildd/llvm-toolchain-snapshot-3.7~svn228917/lib/CodeGen/CodeGenPrepare.cpp"
, 2014, __PRETTY_FUNCTION__));
2015 return Result;
2016 }
2017private:
2018 bool MatchScaledValue(Value *ScaleReg, int64_t Scale, unsigned Depth);
2019 bool MatchAddr(Value *V, unsigned Depth);
2020 bool MatchOperationAddr(User *Operation, unsigned Opcode, unsigned Depth,
2021 bool *MovedAway = nullptr);
2022 bool IsProfitableToFoldIntoAddressingMode(Instruction *I,
2023 ExtAddrMode &AMBefore,
2024 ExtAddrMode &AMAfter);
2025 bool ValueAlreadyLiveAtInst(Value *Val, Value *KnownLive1, Value *KnownLive2);
2026 bool IsPromotionProfitable(unsigned MatchedSize, unsigned SizeWithPromotion,
2027 Value *PromotedOperand) const;
2028};
2029
2030/// MatchScaledValue - Try adding ScaleReg*Scale to the current addressing mode.
2031/// Return true and update AddrMode if this addr mode is legal for the target,
2032/// false if not.
2033bool AddressingModeMatcher::MatchScaledValue(Value *ScaleReg, int64_t Scale,
2034 unsigned Depth) {
2035 // If Scale is 1, then this is the same as adding ScaleReg to the addressing
2036 // mode. Just process that directly.
2037 if (Scale == 1)
2038 return MatchAddr(ScaleReg, Depth);
2039
2040 // If the scale is 0, it takes nothing to add this.
2041 if (Scale == 0)
2042 return true;
2043
2044 // If we already have a scale of this value, we can add to it, otherwise, we
2045 // need an available scale field.
2046 if (AddrMode.Scale != 0 && AddrMode.ScaledReg != ScaleReg)
2047 return false;
2048
2049 ExtAddrMode TestAddrMode = AddrMode;
2050
2051 // Add scale to turn X*4+X*3 -> X*7. This could also do things like
2052 // [A+B + A*7] -> [B+A*8].
2053 TestAddrMode.Scale += Scale;
2054 TestAddrMode.ScaledReg = ScaleReg;
2055
2056 // If the new address isn't legal, bail out.
2057 if (!TLI.isLegalAddressingMode(TestAddrMode, AccessTy))
2058 return false;
2059
2060 // It was legal, so commit it.
2061 AddrMode = TestAddrMode;
2062
2063 // Okay, we decided that we can add ScaleReg+Scale to AddrMode. Check now
2064 // to see if ScaleReg is actually X+C. If so, we can turn this into adding
2065 // X*Scale + C*Scale to addr mode.
2066 ConstantInt *CI = nullptr; Value *AddLHS = nullptr;
2067 if (isa<Instruction>(ScaleReg) && // not a constant expr.
2068 match(ScaleReg, m_Add(m_Value(AddLHS), m_ConstantInt(CI)))) {
2069 TestAddrMode.ScaledReg = AddLHS;
2070 TestAddrMode.BaseOffs += CI->getSExtValue()*TestAddrMode.Scale;
2071
2072 // If this addressing mode is legal, commit it and remember that we folded
2073 // this instruction.
2074 if (TLI.isLegalAddressingMode(TestAddrMode, AccessTy)) {
2075 AddrModeInsts.push_back(cast<Instruction>(ScaleReg));
2076 AddrMode = TestAddrMode;
2077 return true;
2078 }
2079 }
2080
2081 // Otherwise, not (x+c)*scale, just return what we have.
2082 return true;
2083}
2084
2085/// MightBeFoldableInst - This is a little filter, which returns true if an
2086/// addressing computation involving I might be folded into a load/store
2087/// accessing it. This doesn't need to be perfect, but needs to accept at least
2088/// the set of instructions that MatchOperationAddr can.
2089static bool MightBeFoldableInst(Instruction *I) {
2090 switch (I->getOpcode()) {
2091 case Instruction::BitCast:
2092 case Instruction::AddrSpaceCast:
2093 // Don't touch identity bitcasts.
2094 if (I->getType() == I->getOperand(0)->getType())
2095 return false;
2096 return I->getType()->isPointerTy() || I->getType()->isIntegerTy();
2097 case Instruction::PtrToInt:
2098 // PtrToInt is always a noop, as we know that the int type is pointer sized.
2099 return true;
2100 case Instruction::IntToPtr:
2101 // We know the input is intptr_t, so this is foldable.
2102 return true;
2103 case Instruction::Add:
2104 return true;
2105 case Instruction::Mul:
2106 case Instruction::Shl:
2107 // Can only handle X*C and X << C.
2108 return isa<ConstantInt>(I->getOperand(1));
2109 case Instruction::GetElementPtr:
2110 return true;
2111 default:
2112 return false;
2113 }
2114}
2115
2116/// \brief Check whether or not \p Val is a legal instruction for \p TLI.
2117/// \note \p Val is assumed to be the product of some type promotion.
2118/// Therefore if \p Val has an undefined state in \p TLI, this is assumed
2119/// to be legal, as the non-promoted value would have had the same state.
2120static bool isPromotedInstructionLegal(const TargetLowering &TLI, Value *Val) {
2121 Instruction *PromotedInst = dyn_cast<Instruction>(Val);
2122 if (!PromotedInst)
2123 return false;
2124 int ISDOpcode = TLI.InstructionOpcodeToISD(PromotedInst->getOpcode());
2125 // If the ISDOpcode is undefined, it was undefined before the promotion.
2126 if (!ISDOpcode)
2127 return true;
2128 // Otherwise, check if the promoted instruction is legal or not.
2129 return TLI.isOperationLegalOrCustom(
2130 ISDOpcode, TLI.getValueType(PromotedInst->getType()));
2131}
2132
2133/// \brief Hepler class to perform type promotion.
2134class TypePromotionHelper {
2135 /// \brief Utility function to check whether or not a sign or zero extension
2136 /// of \p Inst with \p ConsideredExtType can be moved through \p Inst by
2137 /// either using the operands of \p Inst or promoting \p Inst.
2138 /// The type of the extension is defined by \p IsSExt.
2139 /// In other words, check if:
2140 /// ext (Ty Inst opnd1 opnd2 ... opndN) to ConsideredExtType.
2141 /// #1 Promotion applies:
2142 /// ConsideredExtType Inst (ext opnd1 to ConsideredExtType, ...).
2143 /// #2 Operand reuses:
2144 /// ext opnd1 to ConsideredExtType.
2145 /// \p PromotedInsts maps the instructions to their type before promotion.
2146 static bool canGetThrough(const Instruction *Inst, Type *ConsideredExtType,
2147 const InstrToOrigTy &PromotedInsts, bool IsSExt);
2148
2149 /// \brief Utility function to determine if \p OpIdx should be promoted when
2150 /// promoting \p Inst.
2151 static bool shouldExtOperand(const Instruction *Inst, int OpIdx) {
2152 if (isa<SelectInst>(Inst) && OpIdx == 0)
2153 return false;
2154 return true;
2155 }
2156
2157 /// \brief Utility function to promote the operand of \p Ext when this
2158 /// operand is a promotable trunc or sext or zext.
2159 /// \p PromotedInsts maps the instructions to their type before promotion.
2160 /// \p CreatedInsts[out] contains how many non-free instructions have been
2161 /// created to promote the operand of Ext.
2162 /// Newly added extensions are inserted in \p Exts.
2163 /// Newly added truncates are inserted in \p Truncs.
2164 /// Should never be called directly.
2165 /// \return The promoted value which is used instead of Ext.
2166 static Value *promoteOperandForTruncAndAnyExt(
2167 Instruction *Ext, TypePromotionTransaction &TPT,
2168 InstrToOrigTy &PromotedInsts, unsigned &CreatedInsts,
2169 SmallVectorImpl<Instruction *> *Exts,
2170 SmallVectorImpl<Instruction *> *Truncs);
2171
2172 /// \brief Utility function to promote the operand of \p Ext when this
2173 /// operand is promotable and is not a supported trunc or sext.
2174 /// \p PromotedInsts maps the instructions to their type before promotion.
2175 /// \p CreatedInsts[out] contains how many non-free instructions have been
2176 /// created to promote the operand of Ext.
2177 /// Newly added extensions are inserted in \p Exts.
2178 /// Newly added truncates are inserted in \p Truncs.
2179 /// Should never be called directly.
2180 /// \return The promoted value which is used instead of Ext.
2181 static Value *
2182 promoteOperandForOther(Instruction *Ext, TypePromotionTransaction &TPT,
2183 InstrToOrigTy &PromotedInsts, unsigned &CreatedInsts,
2184 SmallVectorImpl<Instruction *> *Exts,
2185 SmallVectorImpl<Instruction *> *Truncs, bool IsSExt);
2186
2187 /// \see promoteOperandForOther.
2188 static Value *
2189 signExtendOperandForOther(Instruction *Ext, TypePromotionTransaction &TPT,
2190 InstrToOrigTy &PromotedInsts,
2191 unsigned &CreatedInsts,
2192 SmallVectorImpl<Instruction *> *Exts,
2193 SmallVectorImpl<Instruction *> *Truncs) {
2194 return promoteOperandForOther(Ext, TPT, PromotedInsts, CreatedInsts, Exts,
2195 Truncs, true);
2196 }
2197
2198 /// \see promoteOperandForOther.
2199 static Value *
2200 zeroExtendOperandForOther(Instruction *Ext, TypePromotionTransaction &TPT,
2201 InstrToOrigTy &PromotedInsts,
2202 unsigned &CreatedInsts,
2203 SmallVectorImpl<Instruction *> *Exts,
2204 SmallVectorImpl<Instruction *> *Truncs) {
2205 return promoteOperandForOther(Ext, TPT, PromotedInsts, CreatedInsts, Exts,
2206 Truncs, false);
2207 }
2208
2209public:
2210 /// Type for the utility function that promotes the operand of Ext.
2211 typedef Value *(*Action)(Instruction *Ext, TypePromotionTransaction &TPT,
2212 InstrToOrigTy &PromotedInsts, unsigned &CreatedInsts,
2213 SmallVectorImpl<Instruction *> *Exts,
2214 SmallVectorImpl<Instruction *> *Truncs);
2215 /// \brief Given a sign/zero extend instruction \p Ext, return the approriate
2216 /// action to promote the operand of \p Ext instead of using Ext.
2217 /// \return NULL if no promotable action is possible with the current
2218 /// sign extension.
2219 /// \p InsertedTruncs keeps track of all the truncate instructions inserted by
2220 /// the others CodeGenPrepare optimizations. This information is important
2221 /// because we do not want to promote these instructions as CodeGenPrepare
2222 /// will reinsert them later. Thus creating an infinite loop: create/remove.
2223 /// \p PromotedInsts maps the instructions to their type before promotion.
2224 static Action getAction(Instruction *Ext, const SetOfInstrs &InsertedTruncs,
2225 const TargetLowering &TLI,
2226 const InstrToOrigTy &PromotedInsts);
2227};
2228
2229bool TypePromotionHelper::canGetThrough(const Instruction *Inst,
2230 Type *ConsideredExtType,
2231 const InstrToOrigTy &PromotedInsts,
2232 bool IsSExt) {
2233 // The promotion helper does not know how to deal with vector types yet.
2234 // To be able to fix that, we would need to fix the places where we
2235 // statically extend, e.g., constants and such.
2236 if (Inst->getType()->isVectorTy())
2237 return false;
2238
2239 // We can always get through zext.
2240 if (isa<ZExtInst>(Inst))
2241 return true;
2242
2243 // sext(sext) is ok too.
2244 if (IsSExt && isa<SExtInst>(Inst))
2245 return true;
2246
2247 // We can get through binary operator, if it is legal. In other words, the
2248 // binary operator must have a nuw or nsw flag.
2249 const BinaryOperator *BinOp = dyn_cast<BinaryOperator>(Inst);
2250 if (BinOp && isa<OverflowingBinaryOperator>(BinOp) &&
2251 ((!IsSExt && BinOp->hasNoUnsignedWrap()) ||
2252 (IsSExt && BinOp->hasNoSignedWrap())))
2253 return true;
2254
2255 // Check if we can do the following simplification.
2256 // ext(trunc(opnd)) --> ext(opnd)
2257 if (!isa<TruncInst>(Inst))
2258 return false;
2259
2260 Value *OpndVal = Inst->getOperand(0);
2261 // Check if we can use this operand in the extension.
2262 // If the type is larger than the result type of the extension,
2263 // we cannot.
2264 if (!OpndVal->getType()->isIntegerTy() ||
2265 OpndVal->getType()->getIntegerBitWidth() >
2266 ConsideredExtType->getIntegerBitWidth())
2267 return false;
2268
2269 // If the operand of the truncate is not an instruction, we will not have
2270 // any information on the dropped bits.
2271 // (Actually we could for constant but it is not worth the extra logic).
2272 Instruction *Opnd = dyn_cast<Instruction>(OpndVal);
2273 if (!Opnd)
2274 return false;
2275
2276 // Check if the source of the type is narrow enough.
2277 // I.e., check that trunc just drops extended bits of the same kind of
2278 // the extension.
2279 // #1 get the type of the operand and check the kind of the extended bits.
2280 const Type *OpndType;
2281 InstrToOrigTy::const_iterator It = PromotedInsts.find(Opnd);
2282 if (It != PromotedInsts.end() && It->second.IsSExt == IsSExt)
2283 OpndType = It->second.Ty;
2284 else if ((IsSExt && isa<SExtInst>(Opnd)) || (!IsSExt && isa<ZExtInst>(Opnd)))
2285 OpndType = Opnd->getOperand(0)->getType();
2286 else
2287 return false;
2288
2289 // #2 check that the truncate just drop extended bits.
2290 if (Inst->getType()->getIntegerBitWidth() >= OpndType->getIntegerBitWidth())
2291 return true;
2292
2293 return false;
2294}
2295
2296TypePromotionHelper::Action TypePromotionHelper::getAction(
2297 Instruction *Ext, const SetOfInstrs &InsertedTruncs,
2298 const TargetLowering &TLI, const InstrToOrigTy &PromotedInsts) {
2299 assert((isa<SExtInst>(Ext) || isa<ZExtInst>(Ext)) &&(((isa<SExtInst>(Ext) || isa<ZExtInst>(Ext)) &&
"Unexpected instruction type") ? static_cast<void> (0)
: __assert_fail ("(isa<SExtInst>(Ext) || isa<ZExtInst>(Ext)) && \"Unexpected instruction type\""
, "/tmp/buildd/llvm-toolchain-snapshot-3.7~svn228917/lib/CodeGen/CodeGenPrepare.cpp"
, 2300, __PRETTY_FUNCTION__))
2300 "Unexpected instruction type")(((isa<SExtInst>(Ext) || isa<ZExtInst>(Ext)) &&
"Unexpected instruction type") ? static_cast<void> (0)
: __assert_fail ("(isa<SExtInst>(Ext) || isa<ZExtInst>(Ext)) && \"Unexpected instruction type\""
, "/tmp/buildd/llvm-toolchain-snapshot-3.7~svn228917/lib/CodeGen/CodeGenPrepare.cpp"
, 2300, __PRETTY_FUNCTION__));
2301 Instruction *ExtOpnd = dyn_cast<Instruction>(Ext->getOperand(0));
2302 Type *ExtTy = Ext->getType();
2303 bool IsSExt = isa<SExtInst>(Ext);
2304 // If the operand of the extension is not an instruction, we cannot
2305 // get through.
2306 // If it, check we can get through.
2307 if (!ExtOpnd || !canGetThrough(ExtOpnd, ExtTy, PromotedInsts, IsSExt))
2308 return nullptr;
2309
2310 // Do not promote if the operand has been added by codegenprepare.
2311 // Otherwise, it means we are undoing an optimization that is likely to be
2312 // redone, thus causing potential infinite loop.
2313 if (isa<TruncInst>(ExtOpnd) && InsertedTruncs.count(ExtOpnd))
2314 return nullptr;
2315
2316 // SExt or Trunc instructions.
2317 // Return the related handler.
2318 if (isa<SExtInst>(ExtOpnd) || isa<TruncInst>(ExtOpnd) ||
2319 isa<ZExtInst>(ExtOpnd))
2320 return promoteOperandForTruncAndAnyExt;
2321
2322 // Regular instruction.
2323 // Abort early if we will have to insert non-free instructions.
2324 if (!ExtOpnd->hasOneUse() && !TLI.isTruncateFree(ExtTy, ExtOpnd->getType()))
2325 return nullptr;
2326 return IsSExt ? signExtendOperandForOther : zeroExtendOperandForOther;
2327}
2328
2329Value *TypePromotionHelper::promoteOperandForTruncAndAnyExt(
2330 llvm::Instruction *SExt, TypePromotionTransaction &TPT,
2331 InstrToOrigTy &PromotedInsts, unsigned &CreatedInsts,
2332 SmallVectorImpl<Instruction *> *Exts,
2333 SmallVectorImpl<Instruction *> *Truncs) {
2334 // By construction, the operand of SExt is an instruction. Otherwise we cannot
2335 // get through it and this method should not be called.
2336 Instruction *SExtOpnd = cast<Instruction>(SExt->getOperand(0));
2337 Value *ExtVal = SExt;
2338 if (isa<ZExtInst>(SExtOpnd)) {
2339 // Replace s|zext(zext(opnd))
2340 // => zext(opnd).
2341 Value *ZExt =
2342 TPT.createZExt(SExt, SExtOpnd->getOperand(0), SExt->getType());
2343 TPT.replaceAllUsesWith(SExt, ZExt);
2344 TPT.eraseInstruction(SExt);
2345 ExtVal = ZExt;
2346 } else {
2347 // Replace z|sext(trunc(opnd)) or sext(sext(opnd))
2348 // => z|sext(opnd).
2349 TPT.setOperand(SExt, 0, SExtOpnd->getOperand(0));
2350 }
2351 CreatedInsts = 0;
2352
2353 // Remove dead code.
2354 if (SExtOpnd->use_empty())
2355 TPT.eraseInstruction(SExtOpnd);
2356
2357 // Check if the extension is still needed.
2358 Instruction *ExtInst = dyn_cast<Instruction>(ExtVal);
2359 if (!ExtInst || ExtInst->getType() != ExtInst->getOperand(0)->getType()) {
2360 if (ExtInst && Exts)
2361 Exts->push_back(ExtInst);
2362 return ExtVal;
2363 }
2364
2365 // At this point we have: ext ty opnd to ty.
2366 // Reassign the uses of ExtInst to the opnd and remove ExtInst.
2367 Value *NextVal = ExtInst->getOperand(0);
2368 TPT.eraseInstruction(ExtInst, NextVal);
2369 return NextVal;
2370}
2371
2372Value *TypePromotionHelper::promoteOperandForOther(
2373 Instruction *Ext, TypePromotionTransaction &TPT,
2374 InstrToOrigTy &PromotedInsts, unsigned &CreatedInsts,
2375 SmallVectorImpl<Instruction *> *Exts,
2376 SmallVectorImpl<Instruction *> *Truncs, bool IsSExt) {
2377 // By construction, the operand of Ext is an instruction. Otherwise we cannot
2378 // get through it and this method should not be called.
2379 Instruction *ExtOpnd = cast<Instruction>(Ext->getOperand(0));
2380 CreatedInsts = 0;
2381 if (!ExtOpnd->hasOneUse()) {
2382 // ExtOpnd will be promoted.
2383 // All its uses, but Ext, will need to use a truncated value of the
2384 // promoted version.
2385 // Create the truncate now.
2386 Value *Trunc = TPT.createTrunc(Ext, ExtOpnd->getType());
2387 if (Instruction *ITrunc = dyn_cast<Instruction>(Trunc)) {
2388 ITrunc->removeFromParent();
2389 // Insert it just after the definition.
2390 ITrunc->insertAfter(ExtOpnd);
2391 if (Truncs)
2392 Truncs->push_back(ITrunc);
2393 }
2394
2395 TPT.replaceAllUsesWith(ExtOpnd, Trunc);
2396 // Restore the operand of Ext (which has been replace by the previous call
2397 // to replaceAllUsesWith) to avoid creating a cycle trunc <-> sext.
2398 TPT.setOperand(Ext, 0, ExtOpnd);
2399 }
2400
2401 // Get through the Instruction:
2402 // 1. Update its type.
2403 // 2. Replace the uses of Ext by Inst.
2404 // 3. Extend each operand that needs to be extended.
2405
2406 // Remember the original type of the instruction before promotion.
2407 // This is useful to know that the high bits are sign extended bits.
2408 PromotedInsts.insert(std::pair<Instruction *, TypeIsSExt>(
2409 ExtOpnd, TypeIsSExt(ExtOpnd->getType(), IsSExt)));
2410 // Step #1.
2411 TPT.mutateType(ExtOpnd, Ext->getType());
2412 // Step #2.
2413 TPT.replaceAllUsesWith(Ext, ExtOpnd);
2414 // Step #3.
2415 Instruction *ExtForOpnd = Ext;
2416
2417 DEBUG(dbgs() << "Propagate Ext to operands\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Propagate Ext to operands\n"
; } } while (0);
2418 for (int OpIdx = 0, EndOpIdx = ExtOpnd->getNumOperands(); OpIdx != EndOpIdx;
2419 ++OpIdx) {
2420 DEBUG(dbgs() << "Operand:\n" << *(ExtOpnd->getOperand(OpIdx)) << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Operand:\n" << *
(ExtOpnd->getOperand(OpIdx)) << '\n'; } } while (0);
2421 if (ExtOpnd->getOperand(OpIdx)->getType() == Ext->getType() ||
2422 !shouldExtOperand(ExtOpnd, OpIdx)) {
2423 DEBUG(dbgs() << "No need to propagate\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "No need to propagate\n"
; } } while (0);
2424 continue;
2425 }
2426 // Check if we can statically extend the operand.
2427 Value *Opnd = ExtOpnd->getOperand(OpIdx);
2428 if (const ConstantInt *Cst = dyn_cast<ConstantInt>(Opnd)) {
2429 DEBUG(dbgs() << "Statically extend\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Statically extend\n"; }
} while (0);
2430 unsigned BitWidth = Ext->getType()->getIntegerBitWidth();
2431 APInt CstVal = IsSExt ? Cst->getValue().sext(BitWidth)
2432 : Cst->getValue().zext(BitWidth);
2433 TPT.setOperand(ExtOpnd, OpIdx, ConstantInt::get(Ext->getType(), CstVal));
2434 continue;
2435 }
2436 // UndefValue are typed, so we have to statically sign extend them.
2437 if (isa<UndefValue>(Opnd)) {
2438 DEBUG(dbgs() << "Statically extend\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Statically extend\n"; }
} while (0);
2439 TPT.setOperand(ExtOpnd, OpIdx, UndefValue::get(Ext->getType()));
2440 continue;
2441 }
2442
2443 // Otherwise we have to explicity sign extend the operand.
2444 // Check if Ext was reused to extend an operand.
2445 if (!ExtForOpnd) {
2446 // If yes, create a new one.
2447 DEBUG(dbgs() << "More operands to ext\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "More operands to ext\n"
; } } while (0);
2448 Value *ValForExtOpnd = IsSExt ? TPT.createSExt(Ext, Opnd, Ext->getType())
2449 : TPT.createZExt(Ext, Opnd, Ext->getType());
2450 if (!isa<Instruction>(ValForExtOpnd)) {
2451 TPT.setOperand(ExtOpnd, OpIdx, ValForExtOpnd);
2452 continue;
2453 }
2454 ExtForOpnd = cast<Instruction>(ValForExtOpnd);
2455 ++CreatedInsts;
2456 }
2457 if (Exts)
2458 Exts->push_back(ExtForOpnd);
2459 TPT.setOperand(ExtForOpnd, 0, Opnd);
2460
2461 // Move the sign extension before the insertion point.
2462 TPT.moveBefore(ExtForOpnd, ExtOpnd);
2463 TPT.setOperand(ExtOpnd, OpIdx, ExtForOpnd);
2464 // If more sext are required, new instructions will have to be created.
2465 ExtForOpnd = nullptr;
2466 }
2467 if (ExtForOpnd == Ext) {
2468 DEBUG(dbgs() << "Extension is useless now\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Extension is useless now\n"
; } } while (0);
2469 TPT.eraseInstruction(Ext);
2470 }
2471 return ExtOpnd;
2472}
2473
2474/// IsPromotionProfitable - Check whether or not promoting an instruction
2475/// to a wider type was profitable.
2476/// \p MatchedSize gives the number of instructions that have been matched
2477/// in the addressing mode after the promotion was applied.
2478/// \p SizeWithPromotion gives the number of created instructions for
2479/// the promotion plus the number of instructions that have been
2480/// matched in the addressing mode before the promotion.
2481/// \p PromotedOperand is the value that has been promoted.
2482/// \return True if the promotion is profitable, false otherwise.
2483bool
2484AddressingModeMatcher::IsPromotionProfitable(unsigned MatchedSize,
2485 unsigned SizeWithPromotion,
2486 Value *PromotedOperand) const {
2487 // We folded less instructions than what we created to promote the operand.
2488 // This is not profitable.
2489 if (MatchedSize < SizeWithPromotion)
2490 return false;
2491 if (MatchedSize > SizeWithPromotion)
2492 return true;
2493 // The promotion is neutral but it may help folding the sign extension in
2494 // loads for instance.
2495 // Check that we did not create an illegal instruction.
2496 return isPromotedInstructionLegal(TLI, PromotedOperand);
2497}
2498
2499/// MatchOperationAddr - Given an instruction or constant expr, see if we can
2500/// fold the operation into the addressing mode. If so, update the addressing
2501/// mode and return true, otherwise return false without modifying AddrMode.
2502/// If \p MovedAway is not NULL, it contains the information of whether or
2503/// not AddrInst has to be folded into the addressing mode on success.
2504/// If \p MovedAway == true, \p AddrInst will not be part of the addressing
2505/// because it has been moved away.
2506/// Thus AddrInst must not be added in the matched instructions.
2507/// This state can happen when AddrInst is a sext, since it may be moved away.
2508/// Therefore, AddrInst may not be valid when MovedAway is true and it must
2509/// not be referenced anymore.
2510bool AddressingModeMatcher::MatchOperationAddr(User *AddrInst, unsigned Opcode,
2511 unsigned Depth,
2512 bool *MovedAway) {
2513 // Avoid exponential behavior on extremely deep expression trees.
2514 if (Depth >= 5) return false;
2515
2516 // By default, all matched instructions stay in place.
2517 if (MovedAway)
2518 *MovedAway = false;
2519
2520 switch (Opcode) {
2521 case Instruction::PtrToInt:
2522 // PtrToInt is always a noop, as we know that the int type is pointer sized.
2523 return MatchAddr(AddrInst->getOperand(0), Depth);
2524 case Instruction::IntToPtr:
2525 // This inttoptr is a no-op if the integer type is pointer sized.
2526 if (TLI.getValueType(AddrInst->getOperand(0)->getType()) ==
2527 TLI.getPointerTy(AddrInst->getType()->getPointerAddressSpace()))
2528 return MatchAddr(AddrInst->getOperand(0), Depth);
2529 return false;
2530 case Instruction::BitCast:
2531 case Instruction::AddrSpaceCast:
2532 // BitCast is always a noop, and we can handle it as long as it is
2533 // int->int or pointer->pointer (we don't want int<->fp or something).
2534 if ((AddrInst->getOperand(0)->getType()->isPointerTy() ||
2535 AddrInst->getOperand(0)->getType()->isIntegerTy()) &&
2536 // Don't touch identity bitcasts. These were probably put here by LSR,
2537 // and we don't want to mess around with them. Assume it knows what it
2538 // is doing.
2539 AddrInst->getOperand(0)->getType() != AddrInst->getType())
2540 return MatchAddr(AddrInst->getOperand(0), Depth);
2541 return false;
2542 case Instruction::Add: {
2543 // Check to see if we can merge in the RHS then the LHS. If so, we win.
2544 ExtAddrMode BackupAddrMode = AddrMode;
2545 unsigned OldSize = AddrModeInsts.size();
2546 // Start a transaction at this point.
2547 // The LHS may match but not the RHS.
2548 // Therefore, we need a higher level restoration point to undo partially
2549 // matched operation.
2550 TypePromotionTransaction::ConstRestorationPt LastKnownGood =
2551 TPT.getRestorationPoint();
2552
2553 if (MatchAddr(AddrInst->getOperand(1), Depth+1) &&
2554 MatchAddr(AddrInst->getOperand(0), Depth+1))
2555 return true;
2556
2557 // Restore the old addr mode info.
2558 AddrMode = BackupAddrMode;
2559 AddrModeInsts.resize(OldSize);
2560 TPT.rollback(LastKnownGood);
2561
2562 // Otherwise this was over-aggressive. Try merging in the LHS then the RHS.
2563 if (MatchAddr(AddrInst->getOperand(0), Depth+1) &&
2564 MatchAddr(AddrInst->getOperand(1), Depth+1))
2565 return true;
2566
2567 // Otherwise we definitely can't merge the ADD in.
2568 AddrMode = BackupAddrMode;
2569 AddrModeInsts.resize(OldSize);
2570 TPT.rollback(LastKnownGood);
2571 break;
2572 }
2573 //case Instruction::Or:
2574 // TODO: We can handle "Or Val, Imm" iff this OR is equivalent to an ADD.
2575 //break;
2576 case Instruction::Mul:
2577 case Instruction::Shl: {
2578 // Can only handle X*C and X << C.
2579 ConstantInt *RHS = dyn_cast<ConstantInt>(AddrInst->getOperand(1));
2580 if (!RHS)
2581 return false;
2582 int64_t Scale = RHS->getSExtValue();
2583 if (Opcode == Instruction::Shl)
2584 Scale = 1LL << Scale;
2585
2586 return MatchScaledValue(AddrInst->getOperand(0), Scale, Depth);
2587 }
2588 case Instruction::GetElementPtr: {
2589 // Scan the GEP. We check it if it contains constant offsets and at most
2590 // one variable offset.
2591 int VariableOperand = -1;
2592 unsigned VariableScale = 0;
2593
2594 int64_t ConstantOffset = 0;
2595 const DataLayout *TD = TLI.getDataLayout();
2596 gep_type_iterator GTI = gep_type_begin(AddrInst);
2597 for (unsigned i = 1, e = AddrInst->getNumOperands(); i != e; ++i, ++GTI) {
2598 if (StructType *STy = dyn_cast<StructType>(*GTI)) {
2599 const StructLayout *SL = TD->getStructLayout(STy);
2600 unsigned Idx =
2601 cast<ConstantInt>(AddrInst->getOperand(i))->getZExtValue();
2602 ConstantOffset += SL->getElementOffset(Idx);
2603 } else {
2604 uint64_t TypeSize = TD->getTypeAllocSize(GTI.getIndexedType());
2605 if (ConstantInt *CI = dyn_cast<ConstantInt>(AddrInst->getOperand(i))) {
2606 ConstantOffset += CI->getSExtValue()*TypeSize;
2607 } else if (TypeSize) { // Scales of zero don't do anything.
2608 // We only allow one variable index at the moment.
2609 if (VariableOperand != -1)
2610 return false;
2611
2612 // Remember the variable index.
2613 VariableOperand = i;
2614 VariableScale = TypeSize;
2615 }
2616 }
2617 }
2618
2619 // A common case is for the GEP to only do a constant offset. In this case,
2620 // just add it to the disp field and check validity.
2621 if (VariableOperand == -1) {
2622 AddrMode.BaseOffs += ConstantOffset;
2623 if (ConstantOffset == 0 || TLI.isLegalAddressingMode(AddrMode, AccessTy)){
2624 // Check to see if we can fold the base pointer in too.
2625 if (MatchAddr(AddrInst->getOperand(0), Depth+1))
2626 return true;
2627 }
2628 AddrMode.BaseOffs -= ConstantOffset;
2629 return false;
2630 }
2631
2632 // Save the valid addressing mode in case we can't match.
2633 ExtAddrMode BackupAddrMode = AddrMode;
2634 unsigned OldSize = AddrModeInsts.size();
2635
2636 // See if the scale and offset amount is valid for this target.
2637 AddrMode.BaseOffs += ConstantOffset;
2638
2639 // Match the base operand of the GEP.
2640 if (!MatchAddr(AddrInst->getOperand(0), Depth+1)) {
2641 // If it couldn't be matched, just stuff the value in a register.
2642 if (AddrMode.HasBaseReg) {
2643 AddrMode = BackupAddrMode;
2644 AddrModeInsts.resize(OldSize);
2645 return false;
2646 }
2647 AddrMode.HasBaseReg = true;
2648 AddrMode.BaseReg = AddrInst->getOperand(0);
2649 }
2650
2651 // Match the remaining variable portion of the GEP.
2652 if (!MatchScaledValue(AddrInst->getOperand(VariableOperand), VariableScale,
2653 Depth)) {
2654 // If it couldn't be matched, try stuffing the base into a register
2655 // instead of matching it, and retrying the match of the scale.
2656 AddrMode = BackupAddrMode;
2657 AddrModeInsts.resize(OldSize);
2658 if (AddrMode.HasBaseReg)
2659 return false;
2660 AddrMode.HasBaseReg = true;
2661 AddrMode.BaseReg = AddrInst->getOperand(0);
2662 AddrMode.BaseOffs += ConstantOffset;
2663 if (!MatchScaledValue(AddrInst->getOperand(VariableOperand),
2664 VariableScale, Depth)) {
2665 // If even that didn't work, bail.
2666 AddrMode = BackupAddrMode;
2667 AddrModeInsts.resize(OldSize);
2668 return false;
2669 }
2670 }
2671
2672 return true;
2673 }
2674 case Instruction::SExt:
2675 case Instruction::ZExt: {
2676 Instruction *Ext = dyn_cast<Instruction>(AddrInst);
2677 if (!Ext)
2678 return false;
2679
2680 // Try to move this ext out of the way of the addressing mode.
2681 // Ask for a method for doing so.
2682 TypePromotionHelper::Action TPH =
2683 TypePromotionHelper::getAction(Ext, InsertedTruncs, TLI, PromotedInsts);
2684 if (!TPH)
2685 return false;
2686
2687 TypePromotionTransaction::ConstRestorationPt LastKnownGood =
2688 TPT.getRestorationPoint();
2689 unsigned CreatedInsts = 0;
2690 Value *PromotedOperand =
2691 TPH(Ext, TPT, PromotedInsts, CreatedInsts, nullptr, nullptr);
2692 // SExt has been moved away.
2693 // Thus either it will be rematched later in the recursive calls or it is
2694 // gone. Anyway, we must not fold it into the addressing mode at this point.
2695 // E.g.,
2696 // op = add opnd, 1
2697 // idx = ext op
2698 // addr = gep base, idx
2699 // is now:
2700 // promotedOpnd = ext opnd <- no match here
2701 // op = promoted_add promotedOpnd, 1 <- match (later in recursive calls)
2702 // addr = gep base, op <- match
2703 if (MovedAway)
2704 *MovedAway = true;
2705
2706 assert(PromotedOperand &&((PromotedOperand && "TypePromotionHelper should have filtered out those cases"
) ? static_cast<void> (0) : __assert_fail ("PromotedOperand && \"TypePromotionHelper should have filtered out those cases\""
, "/tmp/buildd/llvm-toolchain-snapshot-3.7~svn228917/lib/CodeGen/CodeGenPrepare.cpp"
, 2707, __PRETTY_FUNCTION__))
2707 "TypePromotionHelper should have filtered out those cases")((PromotedOperand && "TypePromotionHelper should have filtered out those cases"
) ? static_cast<void> (0) : __assert_fail ("PromotedOperand && \"TypePromotionHelper should have filtered out those cases\""
, "/tmp/buildd/llvm-toolchain-snapshot-3.7~svn228917/lib/CodeGen/CodeGenPrepare.cpp"
, 2707, __PRETTY_FUNCTION__));
2708
2709 ExtAddrMode BackupAddrMode = AddrMode;
2710 unsigned OldSize = AddrModeInsts.size();
2711
2712 if (!MatchAddr(PromotedOperand, Depth) ||
2713 !IsPromotionProfitable(AddrModeInsts.size(), OldSize + CreatedInsts,
2714 PromotedOperand)) {
2715 AddrMode = BackupAddrMode;
2716 AddrModeInsts.resize(OldSize);
2717 DEBUG(dbgs() << "Sign extension does not pay off: rollback\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Sign extension does not pay off: rollback\n"
; } } while (0);
2718 TPT.rollback(LastKnownGood);
2719 return false;
2720 }
2721 return true;
2722 }
2723 }
2724 return false;
2725}
2726
2727/// MatchAddr - If we can, try to add the value of 'Addr' into the current
2728/// addressing mode. If Addr can't be added to AddrMode this returns false and
2729/// leaves AddrMode unmodified. This assumes that Addr is either a pointer type
2730/// or intptr_t for the target.
2731///
2732bool AddressingModeMatcher::MatchAddr(Value *Addr, unsigned Depth) {
2733 // Start a transaction at this point that we will rollback if the matching
2734 // fails.
2735 TypePromotionTransaction::ConstRestorationPt LastKnownGood =
2736 TPT.getRestorationPoint();
2737 if (ConstantInt *CI = dyn_cast<ConstantInt>(Addr)) {
2738 // Fold in immediates if legal for the target.
2739 AddrMode.BaseOffs += CI->getSExtValue();
2740 if (TLI.isLegalAddressingMode(AddrMode, AccessTy))
2741 return true;
2742 AddrMode.BaseOffs -= CI->getSExtValue();
2743 } else if (GlobalValue *GV = dyn_cast<GlobalValue>(Addr)) {
2744 // If this is a global variable, try to fold it into the addressing mode.
2745 if (!AddrMode.BaseGV) {
2746 AddrMode.BaseGV = GV;
2747 if (TLI.isLegalAddressingMode(AddrMode, AccessTy))
2748 return true;
2749 AddrMode.BaseGV = nullptr;
2750 }
2751 } else if (Instruction *I = dyn_cast<Instruction>(Addr)) {
2752 ExtAddrMode BackupAddrMode = AddrMode;
2753 unsigned OldSize = AddrModeInsts.size();
2754
2755 // Check to see if it is possible to fold this operation.
2756 bool MovedAway = false;
2757 if (MatchOperationAddr(I, I->getOpcode(), Depth, &MovedAway)) {
2758 // This instruction may have been move away. If so, there is nothing
2759 // to check here.
2760 if (MovedAway)
2761 return true;
2762 // Okay, it's possible to fold this. Check to see if it is actually
2763 // *profitable* to do so. We use a simple cost model to avoid increasing
2764 // register pressure too much.
2765 if (I->hasOneUse() ||
2766 IsProfitableToFoldIntoAddressingMode(I, BackupAddrMode, AddrMode)) {
2767 AddrModeInsts.push_back(I);
2768 return true;
2769 }
2770
2771 // It isn't profitable to do this, roll back.
2772 //cerr << "NOT FOLDING: " << *I;
2773 AddrMode = BackupAddrMode;
2774 AddrModeInsts.resize(OldSize);
2775 TPT.rollback(LastKnownGood);
2776 }
2777 } else if (ConstantExpr *CE = dyn_cast<ConstantExpr>(Addr)) {
2778 if (MatchOperationAddr(CE, CE->getOpcode(), Depth))
2779 return true;
2780 TPT.rollback(LastKnownGood);
2781 } else if (isa<ConstantPointerNull>(Addr)) {
2782 // Null pointer gets folded without affecting the addressing mode.
2783 return true;
2784 }
2785
2786 // Worse case, the target should support [reg] addressing modes. :)
2787 if (!AddrMode.HasBaseReg) {
2788 AddrMode.HasBaseReg = true;
2789 AddrMode.BaseReg = Addr;
2790 // Still check for legality in case the target supports [imm] but not [i+r].
2791 if (TLI.isLegalAddressingMode(AddrMode, AccessTy))
2792 return true;
2793 AddrMode.HasBaseReg = false;
2794 AddrMode.BaseReg = nullptr;
2795 }
2796
2797 // If the base register is already taken, see if we can do [r+r].
2798 if (AddrMode.Scale == 0) {
2799 AddrMode.Scale = 1;
2800 AddrMode.ScaledReg = Addr;
2801 if (TLI.isLegalAddressingMode(AddrMode, AccessTy))
2802 return true;
2803 AddrMode.Scale = 0;
2804 AddrMode.ScaledReg = nullptr;
2805 }
2806 // Couldn't match.
2807 TPT.rollback(LastKnownGood);
2808 return false;
2809}
2810
2811/// IsOperandAMemoryOperand - Check to see if all uses of OpVal by the specified
2812/// inline asm call are due to memory operands. If so, return true, otherwise
2813/// return false.
2814static bool IsOperandAMemoryOperand(CallInst *CI, InlineAsm *IA, Value *OpVal,
2815 const TargetLowering &TLI) {
2816 TargetLowering::AsmOperandInfoVector TargetConstraints = TLI.ParseConstraints(ImmutableCallSite(CI));
2817 for (unsigned i = 0, e = TargetConstraints.size(); i != e; ++i) {
2818 TargetLowering::AsmOperandInfo &OpInfo = TargetConstraints[i];
2819
2820 // Compute the constraint code and ConstraintType to use.
2821 TLI.ComputeConstraintToUse(OpInfo, SDValue());
2822
2823 // If this asm operand is our Value*, and if it isn't an indirect memory
2824 // operand, we can't fold it!
2825 if (OpInfo.CallOperandVal == OpVal &&
2826 (OpInfo.ConstraintType != TargetLowering::C_Memory ||
2827 !OpInfo.isIndirect))
2828 return false;
2829 }
2830
2831 return true;
2832}
2833
2834/// FindAllMemoryUses - Recursively walk all the uses of I until we find a
2835/// memory use. If we find an obviously non-foldable instruction, return true.
2836/// Add the ultimately found memory instructions to MemoryUses.
2837static bool FindAllMemoryUses(Instruction *I,
2838 SmallVectorImpl<std::pair<Instruction*,unsigned> > &MemoryUses,
2839 SmallPtrSetImpl<Instruction*> &ConsideredInsts,
2840 const TargetLowering &TLI) {
2841 // If we already considered this instruction, we're done.
2842 if (!ConsideredInsts.insert(I).second)
2843 return false;
2844
2845 // If this is an obviously unfoldable instruction, bail out.
2846 if (!MightBeFoldableInst(I))
2847 return true;
2848
2849 // Loop over all the uses, recursively processing them.
2850 for (Use &U : I->uses()) {
2851 Instruction *UserI = cast<Instruction>(U.getUser());
2852
2853 if (LoadInst *LI = dyn_cast<LoadInst>(UserI)) {
2854 MemoryUses.push_back(std::make_pair(LI, U.getOperandNo()));
2855 continue;
2856 }
2857
2858 if (StoreInst *SI = dyn_cast<StoreInst>(UserI)) {
2859 unsigned opNo = U.getOperandNo();
2860 if (opNo == 0) return true; // Storing addr, not into addr.
2861 MemoryUses.push_back(std::make_pair(SI, opNo));
2862 continue;
2863 }
2864
2865 if (CallInst *CI = dyn_cast<CallInst>(UserI)) {
2866 InlineAsm *IA = dyn_cast<InlineAsm>(CI->getCalledValue());
2867 if (!IA) return true;
2868
2869 // If this is a memory operand, we're cool, otherwise bail out.
2870 if (!IsOperandAMemoryOperand(CI, IA, I, TLI))
2871 return true;
2872 continue;
2873 }
2874
2875 if (FindAllMemoryUses(UserI, MemoryUses, ConsideredInsts, TLI))
2876 return true;
2877 }
2878
2879 return false;
2880}
2881
2882/// ValueAlreadyLiveAtInst - Retrn true if Val is already known to be live at
2883/// the use site that we're folding it into. If so, there is no cost to
2884/// include it in the addressing mode. KnownLive1 and KnownLive2 are two values
2885/// that we know are live at the instruction already.
2886bool AddressingModeMatcher::ValueAlreadyLiveAtInst(Value *Val,Value *KnownLive1,
2887 Value *KnownLive2) {
2888 // If Val is either of the known-live values, we know it is live!
2889 if (Val == nullptr || Val == KnownLive1 || Val == KnownLive2)
2890 return true;
2891
2892 // All values other than instructions and arguments (e.g. constants) are live.
2893 if (!isa<Instruction>(Val) && !isa<Argument>(Val)) return true;
2894
2895 // If Val is a constant sized alloca in the entry block, it is live, this is
2896 // true because it is just a reference to the stack/frame pointer, which is
2897 // live for the whole function.
2898 if (AllocaInst *AI = dyn_cast<AllocaInst>(Val))
2899 if (AI->isStaticAlloca())
2900 return true;
2901
2902 // Check to see if this value is already used in the memory instruction's
2903 // block. If so, it's already live into the block at the very least, so we
2904 // can reasonably fold it.
2905 return Val->isUsedInBasicBlock(MemoryInst->getParent());
2906}
2907
2908/// IsProfitableToFoldIntoAddressingMode - It is possible for the addressing
2909/// mode of the machine to fold the specified instruction into a load or store
2910/// that ultimately uses it. However, the specified instruction has multiple
2911/// uses. Given this, it may actually increase register pressure to fold it
2912/// into the load. For example, consider this code:
2913///
2914/// X = ...
2915/// Y = X+1
2916/// use(Y) -> nonload/store
2917/// Z = Y+1
2918/// load Z
2919///
2920/// In this case, Y has multiple uses, and can be folded into the load of Z
2921/// (yielding load [X+2]). However, doing this will cause both "X" and "X+1" to
2922/// be live at the use(Y) line. If we don't fold Y into load Z, we use one
2923/// fewer register. Since Y can't be folded into "use(Y)" we don't increase the
2924/// number of computations either.
2925///
2926/// Note that this (like most of CodeGenPrepare) is just a rough heuristic. If
2927/// X was live across 'load Z' for other reasons, we actually *would* want to
2928/// fold the addressing mode in the Z case. This would make Y die earlier.
2929bool AddressingModeMatcher::
2930IsProfitableToFoldIntoAddressingMode(Instruction *I, ExtAddrMode &AMBefore,
2931 ExtAddrMode &AMAfter) {
2932 if (IgnoreProfitability) return true;
2933
2934 // AMBefore is the addressing mode before this instruction was folded into it,
2935 // and AMAfter is the addressing mode after the instruction was folded. Get
2936 // the set of registers referenced by AMAfter and subtract out those
2937 // referenced by AMBefore: this is the set of values which folding in this
2938 // address extends the lifetime of.
2939 //
2940 // Note that there are only two potential values being referenced here,
2941 // BaseReg and ScaleReg (global addresses are always available, as are any
2942 // folded immediates).
2943 Value *BaseReg = AMAfter.BaseReg, *ScaledReg = AMAfter.ScaledReg;
2944
2945 // If the BaseReg or ScaledReg was referenced by the previous addrmode, their
2946 // lifetime wasn't extended by adding this instruction.
2947 if (ValueAlreadyLiveAtInst(BaseReg, AMBefore.BaseReg, AMBefore.ScaledReg))
2948 BaseReg = nullptr;
2949 if (ValueAlreadyLiveAtInst(ScaledReg, AMBefore.BaseReg, AMBefore.ScaledReg))
2950 ScaledReg = nullptr;
2951
2952 // If folding this instruction (and it's subexprs) didn't extend any live
2953 // ranges, we're ok with it.
2954 if (!BaseReg && !ScaledReg)
2955 return true;
2956
2957 // If all uses of this instruction are ultimately load/store/inlineasm's,
2958 // check to see if their addressing modes will include this instruction. If
2959 // so, we can fold it into all uses, so it doesn't matter if it has multiple
2960 // uses.
2961 SmallVector<std::pair<Instruction*,unsigned>, 16> MemoryUses;
2962 SmallPtrSet<Instruction*, 16> ConsideredInsts;
2963 if (FindAllMemoryUses(I, MemoryUses, ConsideredInsts, TLI))
2964 return false; // Has a non-memory, non-foldable use!
2965
2966 // Now that we know that all uses of this instruction are part of a chain of
2967 // computation involving only operations that could theoretically be folded
2968 // into a memory use, loop over each of these uses and see if they could
2969 // *actually* fold the instruction.
2970 SmallVector<Instruction*, 32> MatchedAddrModeInsts;
2971 for (unsigned i = 0, e = MemoryUses.size(); i != e; ++i) {
2972 Instruction *User = MemoryUses[i].first;
2973 unsigned OpNo = MemoryUses[i].second;
2974
2975 // Get the access type of this use. If the use isn't a pointer, we don't
2976 // know what it accesses.
2977 Value *Address = User->getOperand(OpNo);
2978 if (!Address->getType()->isPointerTy())
2979 return false;
2980 Type *AddressAccessTy = Address->getType()->getPointerElementType();
2981
2982 // Do a match against the root of this address, ignoring profitability. This
2983 // will tell us if the addressing mode for the memory operation will
2984 // *actually* cover the shared instruction.
2985 ExtAddrMode Result;
2986 TypePromotionTransaction::ConstRestorationPt LastKnownGood =
2987 TPT.getRestorationPoint();
2988 AddressingModeMatcher Matcher(MatchedAddrModeInsts, TLI, AddressAccessTy,
2989 MemoryInst, Result, InsertedTruncs,
2990 PromotedInsts, TPT);
2991 Matcher.IgnoreProfitability = true;
2992 bool Success = Matcher.MatchAddr(Address, 0);
2993 (void)Success; assert(Success && "Couldn't select *anything*?")((Success && "Couldn't select *anything*?") ? static_cast
<void> (0) : __assert_fail ("Success && \"Couldn't select *anything*?\""
, "/tmp/buildd/llvm-toolchain-snapshot-3.7~svn228917/lib/CodeGen/CodeGenPrepare.cpp"
, 2993, __PRETTY_FUNCTION__));
2994
2995 // The match was to check the profitability, the changes made are not
2996 // part of the original matcher. Therefore, they should be dropped
2997 // otherwise the original matcher will not present the right state.
2998 TPT.rollback(LastKnownGood);
2999
3000 // If the match didn't cover I, then it won't be shared by it.
3001 if (std::find(MatchedAddrModeInsts.begin(), MatchedAddrModeInsts.end(),
3002 I) == MatchedAddrModeInsts.end())
3003 return false;
3004
3005 MatchedAddrModeInsts.clear();
3006 }
3007
3008 return true;
3009}
3010
3011} // end anonymous namespace
3012
3013/// IsNonLocalValue - Return true if the specified values are defined in a
3014/// different basic block than BB.
3015static bool IsNonLocalValue(Value *V, BasicBlock *BB) {
3016 if (Instruction *I = dyn_cast<Instruction>(V))
3017 return I->getParent() != BB;
3018 return false;
3019}
3020
3021/// OptimizeMemoryInst - Load and Store Instructions often have
3022/// addressing modes that can do significant amounts of computation. As such,
3023/// instruction selection will try to get the load or store to do as much
3024/// computation as possible for the program. The problem is that isel can only
3025/// see within a single block. As such, we sink as much legal addressing mode
3026/// stuff into the block as possible.
3027///
3028/// This method is used to optimize both load/store and inline asms with memory
3029/// operands.
3030bool CodeGenPrepare::OptimizeMemoryInst(Instruction *MemoryInst, Value *Addr,
3031 Type *AccessTy) {
3032 Value *Repl = Addr;
3033
3034 // Try to collapse single-value PHI nodes. This is necessary to undo
3035 // unprofitable PRE transformations.
3036 SmallVector<Value*, 8> worklist;
3037 SmallPtrSet<Value*, 16> Visited;
3038 worklist.push_back(Addr);
3039
3040 // Use a worklist to iteratively look through PHI nodes, and ensure that
3041 // the addressing mode obtained from the non-PHI roots of the graph
3042 // are equivalent.
3043 Value *Consensus = nullptr;
3044 unsigned NumUsesConsensus = 0;
3045 bool IsNumUsesConsensusValid = false;
3046 SmallVector<Instruction*, 16> AddrModeInsts;
3047 ExtAddrMode AddrMode;
3048 TypePromotionTransaction TPT;
3049 TypePromotionTransaction::ConstRestorationPt LastKnownGood =
3050 TPT.getRestorationPoint();
3051 while (!worklist.empty()) {
3052 Value *V = worklist.back();
3053 worklist.pop_back();
3054
3055 // Break use-def graph loops.
3056 if (!Visited.insert(V).second) {
3057 Consensus = nullptr;
3058 break;
3059 }
3060
3061 // For a PHI node, push all of its incoming values.
3062 if (PHINode *P = dyn_cast<PHINode>(V)) {
3063 for (unsigned i = 0, e = P->getNumIncomingValues(); i != e; ++i)
3064 worklist.push_back(P->getIncomingValue(i));
3065 continue;
3066 }
3067
3068 // For non-PHIs, determine the addressing mode being computed.
3069 SmallVector<Instruction*, 16> NewAddrModeInsts;
3070 ExtAddrMode NewAddrMode = AddressingModeMatcher::Match(
3071 V, AccessTy, MemoryInst, NewAddrModeInsts, *TLI, InsertedTruncsSet,
3072 PromotedInsts, TPT);
3073
3074 // This check is broken into two cases with very similar code to avoid using
3075 // getNumUses() as much as possible. Some values have a lot of uses, so
3076 // calling getNumUses() unconditionally caused a significant compile-time
3077 // regression.
3078 if (!Consensus) {
3079 Consensus = V;
3080 AddrMode = NewAddrMode;
3081 AddrModeInsts = NewAddrModeInsts;
3082 continue;
3083 } else if (NewAddrMode == AddrMode) {
3084 if (!IsNumUsesConsensusValid) {
3085 NumUsesConsensus = Consensus->getNumUses();
3086 IsNumUsesConsensusValid = true;
3087 }
3088
3089 // Ensure that the obtained addressing mode is equivalent to that obtained
3090 // for all other roots of the PHI traversal. Also, when choosing one
3091 // such root as representative, select the one with the most uses in order
3092 // to keep the cost modeling heuristics in AddressingModeMatcher
3093 // applicable.
3094 unsigned NumUses = V->getNumUses();
3095 if (NumUses > NumUsesConsensus) {
3096 Consensus = V;
3097 NumUsesConsensus = NumUses;
3098 AddrModeInsts = NewAddrModeInsts;
3099 }
3100 continue;
3101 }
3102
3103 Consensus = nullptr;
3104 break;
3105 }
3106
3107 // If the addressing mode couldn't be determined, or if multiple different
3108 // ones were determined, bail out now.
3109 if (!Consensus) {
3110 TPT.rollback(LastKnownGood);
3111 return false;
3112 }
3113 TPT.commit();
3114
3115 // Check to see if any of the instructions supersumed by this addr mode are
3116 // non-local to I's BB.
3117 bool AnyNonLocal = false;
3118 for (unsigned i = 0, e = AddrModeInsts.size(); i != e; ++i) {
3119 if (IsNonLocalValue(AddrModeInsts[i], MemoryInst->getParent())) {
3120 AnyNonLocal = true;
3121 break;
3122 }
3123 }
3124
3125 // If all the instructions matched are already in this BB, don't do anything.
3126 if (!AnyNonLocal) {
3127 DEBUG(dbgs() << "CGP: Found local addrmode: " << AddrMode << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "CGP: Found local addrmode: "
<< AddrMode << "\n"; } } while (0);
3128 return false;
3129 }
3130
3131 // Insert this computation right after this user. Since our caller is
3132 // scanning from the top of the BB to the bottom, reuse of the expr are
3133 // guaranteed to happen later.
3134 IRBuilder<> Builder(MemoryInst);
3135
3136 // Now that we determined the addressing expression we want to use and know
3137 // that we have to sink it into this block. Check to see if we have already
3138 // done this for some other load/store instr in this block. If so, reuse the
3139 // computation.
3140 Value *&SunkAddr = SunkAddrs[Addr];
3141 if (SunkAddr) {
3142 DEBUG(dbgs() << "CGP: Reusing nonlocal addrmode: " << AddrMode << " for "do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "CGP: Reusing nonlocal addrmode: "
<< AddrMode << " for " << *MemoryInst <<
"\n"; } } while (0)
3143 << *MemoryInst << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "CGP: Reusing nonlocal addrmode: "
<< AddrMode << " for " << *MemoryInst <<
"\n"; } } while (0);
3144 if (SunkAddr->getType() != Addr->getType())
3145 SunkAddr = Builder.CreateBitCast(SunkAddr, Addr->getType());
3146 } else if (AddrSinkUsingGEPs ||
3147 (!AddrSinkUsingGEPs.getNumOccurrences() && TM &&
3148 TM->getSubtargetImpl(*MemoryInst->getParent()->getParent())
3149 ->useAA())) {
3150 // By default, we use the GEP-based method when AA is used later. This
3151 // prevents new inttoptr/ptrtoint pairs from degrading AA capabilities.
3152 DEBUG(dbgs() << "CGP: SINKING nonlocal addrmode: " << AddrMode << " for "do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "CGP: SINKING nonlocal addrmode: "
<< AddrMode << " for " << *MemoryInst <<
"\n"; } } while (0)
3153 << *MemoryInst << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "CGP: SINKING nonlocal addrmode: "
<< AddrMode << " for " << *MemoryInst <<
"\n"; } } while (0);
3154 Type *IntPtrTy = TLI->getDataLayout()->getIntPtrType(Addr->getType());
3155 Value *ResultPtr = nullptr, *ResultIndex = nullptr;
3156
3157 // First, find the pointer.
3158 if (AddrMode.BaseReg && AddrMode.BaseReg->getType()->isPointerTy()) {
3159 ResultPtr = AddrMode.BaseReg;
3160 AddrMode.BaseReg = nullptr;
3161 }
3162
3163 if (AddrMode.Scale && AddrMode.ScaledReg->getType()->isPointerTy()) {
3164 // We can't add more than one pointer together, nor can we scale a
3165 // pointer (both of which seem meaningless).
3166 if (ResultPtr || AddrMode.Scale != 1)
3167 return false;
3168
3169 ResultPtr = AddrMode.ScaledReg;
3170 AddrMode.Scale = 0;
3171 }
3172
3173 if (AddrMode.BaseGV) {
3174 if (ResultPtr)
3175 return false;
3176
3177 ResultPtr = AddrMode.BaseGV;
3178 }
3179
3180 // If the real base value actually came from an inttoptr, then the matcher
3181 // will look through it and provide only the integer value. In that case,
3182 // use it here.
3183 if (!ResultPtr && AddrMode.BaseReg) {
3184 ResultPtr =
3185 Builder.CreateIntToPtr(AddrMode.BaseReg, Addr->getType(), "sunkaddr");
3186 AddrMode.BaseReg = nullptr;
3187 } else if (!ResultPtr && AddrMode.Scale == 1) {
3188 ResultPtr =
3189 Builder.CreateIntToPtr(AddrMode.ScaledReg, Addr->getType(), "sunkaddr");
3190 AddrMode.Scale = 0;
3191 }
3192
3193 if (!ResultPtr &&
3194 !AddrMode.BaseReg && !AddrMode.Scale && !AddrMode.BaseOffs) {
3195 SunkAddr = Constant::getNullValue(Addr->getType());
3196 } else if (!ResultPtr) {
3197 return false;
3198 } else {
3199 Type *I8PtrTy =
3200 Builder.getInt8PtrTy(Addr->getType()->getPointerAddressSpace());
3201
3202 // Start with the base register. Do this first so that subsequent address
3203 // matching finds it last, which will prevent it from trying to match it
3204 // as the scaled value in case it happens to be a mul. That would be
3205 // problematic if we've sunk a different mul for the scale, because then
3206 // we'd end up sinking both muls.
3207 if (AddrMode.BaseReg) {
3208 Value *V = AddrMode.BaseReg;
3209 if (V->getType() != IntPtrTy)
3210 V = Builder.CreateIntCast(V, IntPtrTy, /*isSigned=*/true, "sunkaddr");
3211
3212 ResultIndex = V;
3213 }
3214
3215 // Add the scale value.
3216 if (AddrMode.Scale) {
3217 Value *V = AddrMode.ScaledReg;
3218 if (V->getType() == IntPtrTy) {
3219 // done.
3220 } else if (cast<IntegerType>(IntPtrTy)->getBitWidth() <
3221 cast<IntegerType>(V->getType())->getBitWidth()) {
3222 V = Builder.CreateTrunc(V, IntPtrTy, "sunkaddr");
3223 } else {
3224 // It is only safe to sign extend the BaseReg if we know that the math
3225 // required to create it did not overflow before we extend it. Since
3226 // the original IR value was tossed in favor of a constant back when
3227 // the AddrMode was created we need to bail out gracefully if widths
3228 // do not match instead of extending it.
3229 Instruction *I = dyn_cast_or_null<Instruction>(ResultIndex);
3230 if (I && (ResultIndex != AddrMode.BaseReg))
3231 I->eraseFromParent();
3232 return false;
3233 }
3234
3235 if (AddrMode.Scale != 1)
3236 V = Builder.CreateMul(V, ConstantInt::get(IntPtrTy, AddrMode.Scale),
3237 "sunkaddr");
3238 if (ResultIndex)
3239 ResultIndex = Builder.CreateAdd(ResultIndex, V, "sunkaddr");
3240 else
3241 ResultIndex = V;
3242 }
3243
3244 // Add in the Base Offset if present.
3245 if (AddrMode.BaseOffs) {
3246 Value *V = ConstantInt::get(IntPtrTy, AddrMode.BaseOffs);
3247 if (ResultIndex) {
3248 // We need to add this separately from the scale above to help with
3249 // SDAG consecutive load/store merging.
3250 if (ResultPtr->getType() != I8PtrTy)
3251 ResultPtr = Builder.CreateBitCast(ResultPtr, I8PtrTy);
3252 ResultPtr = Builder.CreateGEP(ResultPtr, ResultIndex, "sunkaddr");
3253 }
3254
3255 ResultIndex = V;
3256 }
3257
3258 if (!ResultIndex) {
3259 SunkAddr = ResultPtr;
3260 } else {
3261 if (ResultPtr->getType() != I8PtrTy)
3262 ResultPtr = Builder.CreateBitCast(ResultPtr, I8PtrTy);
3263 SunkAddr = Builder.CreateGEP(ResultPtr, ResultIndex, "sunkaddr");
3264 }
3265
3266 if (SunkAddr->getType() != Addr->getType())
3267 SunkAddr = Builder.CreateBitCast(SunkAddr, Addr->getType());
3268 }
3269 } else {
3270 DEBUG(dbgs() << "CGP: SINKING nonlocal addrmode: " << AddrMode << " for "do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "CGP: SINKING nonlocal addrmode: "
<< AddrMode << " for " << *MemoryInst <<
"\n"; } } while (0)
3271 << *MemoryInst << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "CGP: SINKING nonlocal addrmode: "
<< AddrMode << " for " << *MemoryInst <<
"\n"; } } while (0);
3272 Type *IntPtrTy = TLI->getDataLayout()->getIntPtrType(Addr->getType());
3273 Value *Result = nullptr;
3274
3275 // Start with the base register. Do this first so that subsequent address
3276 // matching finds it last, which will prevent it from trying to match it
3277 // as the scaled value in case it happens to be a mul. That would be
3278 // problematic if we've sunk a different mul for the scale, because then
3279 // we'd end up sinking both muls.
3280 if (AddrMode.BaseReg) {
3281 Value *V = AddrMode.BaseReg;
3282 if (V->getType()->isPointerTy())
3283 V = Builder.CreatePtrToInt(V, IntPtrTy, "sunkaddr");
3284 if (V->getType() != IntPtrTy)
3285 V = Builder.CreateIntCast(V, IntPtrTy, /*isSigned=*/true, "sunkaddr");
3286 Result = V;
3287 }
3288
3289 // Add the scale value.
3290 if (AddrMode.Scale) {
3291 Value *V = AddrMode.ScaledReg;
3292 if (V->getType() == IntPtrTy) {
3293 // done.
3294 } else if (V->getType()->isPointerTy()) {
3295 V = Builder.CreatePtrToInt(V, IntPtrTy, "sunkaddr");
3296 } else if (cast<IntegerType>(IntPtrTy)->getBitWidth() <
3297 cast<IntegerType>(V->getType())->getBitWidth()) {
3298 V = Builder.CreateTrunc(V, IntPtrTy, "sunkaddr");
3299 } else {
3300 // It is only safe to sign extend the BaseReg if we know that the math
3301 // required to create it did not overflow before we extend it. Since
3302 // the original IR value was tossed in favor of a constant back when
3303 // the AddrMode was created we need to bail out gracefully if widths
3304 // do not match instead of extending it.
3305 Instruction *I = dyn_cast_or_null<Instruction>(Result);
3306 if (I && (Result != AddrMode.BaseReg))
3307 I->eraseFromParent();
3308 return false;
3309 }
3310 if (AddrMode.Scale != 1)
3311 V = Builder.CreateMul(V, ConstantInt::get(IntPtrTy, AddrMode.Scale),
3312 "sunkaddr");
3313 if (Result)
3314 Result = Builder.CreateAdd(Result, V, "sunkaddr");
3315 else
3316 Result = V;
3317 }
3318
3319 // Add in the BaseGV if present.
3320 if (AddrMode.BaseGV) {
3321 Value *V = Builder.CreatePtrToInt(AddrMode.BaseGV, IntPtrTy, "sunkaddr");
3322 if (Result)
3323 Result = Builder.CreateAdd(Result, V, "sunkaddr");
3324 else
3325 Result = V;
3326 }
3327
3328 // Add in the Base Offset if present.
3329 if (AddrMode.BaseOffs) {
3330 Value *V = ConstantInt::get(IntPtrTy, AddrMode.BaseOffs);
3331 if (Result)
3332 Result = Builder.CreateAdd(Result, V, "sunkaddr");
3333 else
3334 Result = V;
3335 }
3336
3337 if (!Result)
3338 SunkAddr = Constant::getNullValue(Addr->getType());
3339 else
3340 SunkAddr = Builder.CreateIntToPtr(Result, Addr->getType(), "sunkaddr");
3341 }
3342
3343 MemoryInst->replaceUsesOfWith(Repl, SunkAddr);
3344
3345 // If we have no uses, recursively delete the value and all dead instructions
3346 // using it.
3347 if (Repl->use_empty()) {
3348 // This can cause recursive deletion, which can invalidate our iterator.
3349 // Use a WeakVH to hold onto it in case this happens.
3350 WeakVH IterHandle(CurInstIterator);
3351 BasicBlock *BB = CurInstIterator->getParent();
3352
3353 RecursivelyDeleteTriviallyDeadInstructions(Repl, TLInfo);
3354
3355 if (IterHandle != CurInstIterator) {
3356 // If the iterator instruction was recursively deleted, start over at the
3357 // start of the block.
3358 CurInstIterator = BB->begin();
3359 SunkAddrs.clear();
3360 }
3361 }
3362 ++NumMemoryInsts;
3363 return true;
3364}
3365
3366/// OptimizeInlineAsmInst - If there are any memory operands, use
3367/// OptimizeMemoryInst to sink their address computing into the block when
3368/// possible / profitable.
3369bool CodeGenPrepare::OptimizeInlineAsmInst(CallInst *CS) {
3370 bool MadeChange = false;
3371
3372 TargetLowering::AsmOperandInfoVector
3373 TargetConstraints = TLI->ParseConstraints(CS);
3374 unsigned ArgNo = 0;
3375 for (unsigned i = 0, e = TargetConstraints.size(); i != e; ++i) {
3376 TargetLowering::AsmOperandInfo &OpInfo = TargetConstraints[i];
3377
3378 // Compute the constraint code and ConstraintType to use.
3379 TLI->ComputeConstraintToUse(OpInfo, SDValue());
3380
3381 if (OpInfo.ConstraintType == TargetLowering::C_Memory &&
3382 OpInfo.isIndirect) {
3383 Value *OpVal = CS->getArgOperand(ArgNo++);
3384 MadeChange |= OptimizeMemoryInst(CS, OpVal, OpVal->getType());
3385 } else if (OpInfo.Type == InlineAsm::isInput)
3386 ArgNo++;
3387 }
3388
3389 return MadeChange;
3390}
3391
3392/// \brief Check if all the uses of \p Inst are equivalent (or free) zero or
3393/// sign extensions.
3394static bool hasSameExtUse(Instruction *Inst, const TargetLowering &TLI) {
3395 assert(!Inst->use_empty() && "Input must have at least one use")((!Inst->use_empty() && "Input must have at least one use"
) ? static_cast<void> (0) : __assert_fail ("!Inst->use_empty() && \"Input must have at least one use\""
, "/tmp/buildd/llvm-toolchain-snapshot-3.7~svn228917/lib/CodeGen/CodeGenPrepare.cpp"
, 3395, __PRETTY_FUNCTION__));
3396 const Instruction *FirstUser = cast<Instruction>(*Inst->user_begin());
3397 bool IsSExt = isa<SExtInst>(FirstUser);
3398 Type *ExtTy = FirstUser->getType();
3399 for (const User *U : Inst->users()) {
3400 const Instruction *UI = cast<Instruction>(U);
3401 if ((IsSExt && !isa<SExtInst>(UI)) || (!IsSExt && !isa<ZExtInst>(UI)))
3402 return false;
3403 Type *CurTy = UI->getType();
3404 // Same input and output types: Same instruction after CSE.
3405 if (CurTy == ExtTy)
3406 continue;
3407
3408 // If IsSExt is true, we are in this situation:
3409 // a = Inst
3410 // b = sext ty1 a to ty2
3411 // c = sext ty1 a to ty3
3412 // Assuming ty2 is shorter than ty3, this could be turned into:
3413 // a = Inst
3414 // b = sext ty1 a to ty2
3415 // c = sext ty2 b to ty3
3416 // However, the last sext is not free.
3417 if (IsSExt)
3418 return false;
3419
3420 // This is a ZExt, maybe this is free to extend from one type to another.
3421 // In that case, we would not account for a different use.
3422 Type *NarrowTy;
3423 Type *LargeTy;
3424 if (ExtTy->getScalarType()->getIntegerBitWidth() >
3425 CurTy->getScalarType()->getIntegerBitWidth()) {
3426 NarrowTy = CurTy;
3427 LargeTy = ExtTy;
3428 } else {
3429 NarrowTy = ExtTy;
3430 LargeTy = CurTy;
3431 }
3432
3433 if (!TLI.isZExtFree(NarrowTy, LargeTy))
3434 return false;
3435 }
3436 // All uses are the same or can be derived from one another for free.
3437 return true;
3438}
3439
3440/// \brief Try to form ExtLd by promoting \p Exts until they reach a
3441/// load instruction.
3442/// If an ext(load) can be formed, it is returned via \p LI for the load
3443/// and \p Inst for the extension.
3444/// Otherwise LI == nullptr and Inst == nullptr.
3445/// When some promotion happened, \p TPT contains the proper state to
3446/// revert them.
3447///
3448/// \return true when promoting was necessary to expose the ext(load)
3449/// opportunity, false otherwise.
3450///
3451/// Example:
3452/// \code
3453/// %ld = load i32* %addr
3454/// %add = add nuw i32 %ld, 4
3455/// %zext = zext i32 %add to i64
3456/// \endcode
3457/// =>
3458/// \code
3459/// %ld = load i32* %addr
3460/// %zext = zext i32 %ld to i64
3461/// %add = add nuw i64 %zext, 4
3462/// \encode
3463/// Thanks to the promotion, we can match zext(load i32*) to i64.
3464bool CodeGenPrepare::ExtLdPromotion(TypePromotionTransaction &TPT,
3465 LoadInst *&LI, Instruction *&Inst,
3466 const SmallVectorImpl<Instruction *> &Exts,
3467 unsigned CreatedInsts = 0) {
3468 // Iterate over all the extensions to see if one form an ext(load).
3469 for (auto I : Exts) {
3470 // Check if we directly have ext(load).
3471 if ((LI = dyn_cast<LoadInst>(I->getOperand(0)))) {
3472 Inst = I;
3473 // No promotion happened here.
3474 return false;
3475 }
3476 // Check whether or not we want to do any promotion.
3477 if (!TLI || !TLI->enableExtLdPromotion() || DisableExtLdPromotion)
3478 continue;
3479 // Get the action to perform the promotion.
3480 TypePromotionHelper::Action TPH = TypePromotionHelper::getAction(
3481 I, InsertedTruncsSet, *TLI, PromotedInsts);
3482 // Check if we can promote.
3483 if (!TPH)
3484 continue;
3485 // Save the current state.
3486 TypePromotionTransaction::ConstRestorationPt LastKnownGood =
3487 TPT.getRestorationPoint();
3488 SmallVector<Instruction *, 4> NewExts;
3489 unsigned NewCreatedInsts = 0;
3490 // Promote.
3491 Value *PromotedVal =
3492 TPH(I, TPT, PromotedInsts, NewCreatedInsts, &NewExts, nullptr);
3493 assert(PromotedVal &&((PromotedVal && "TypePromotionHelper should have filtered out those cases"
) ? static_cast<void> (0) : __assert_fail ("PromotedVal && \"TypePromotionHelper should have filtered out those cases\""
, "/tmp/buildd/llvm-toolchain-snapshot-3.7~svn228917/lib/CodeGen/CodeGenPrepare.cpp"
, 3494, __PRETTY_FUNCTION__))
3494 "TypePromotionHelper should have filtered out those cases")((PromotedVal && "TypePromotionHelper should have filtered out those cases"
) ? static_cast<void> (0) : __assert_fail ("PromotedVal && \"TypePromotionHelper should have filtered out those cases\""
, "/tmp/buildd/llvm-toolchain-snapshot-3.7~svn228917/lib/CodeGen/CodeGenPrepare.cpp"
, 3494, __PRETTY_FUNCTION__));
3495
3496 // We would be able to merge only one extension in a load.
3497 // Therefore, if we have more than 1 new extension we heuristically
3498 // cut this search path, because it means we degrade the code quality.
3499 // With exactly 2, the transformation is neutral, because we will merge
3500 // one extension but leave one. However, we optimistically keep going,
3501 // because the new extension may be removed too.
3502 unsigned TotalCreatedInsts = CreatedInsts + NewCreatedInsts;
3503 if (!StressExtLdPromotion &&
3504 (TotalCreatedInsts > 1 ||
3505 !isPromotedInstructionLegal(*TLI, PromotedVal))) {
3506 // The promotion is not profitable, rollback to the previous state.
3507 TPT.rollback(LastKnownGood);
3508 continue;
3509 }
3510 // The promotion is profitable.
3511 // Check if it exposes an ext(load).
3512 (void)ExtLdPromotion(TPT, LI, Inst, NewExts, TotalCreatedInsts);
3513 if (LI && (StressExtLdPromotion || NewCreatedInsts == 0 ||
3514 // If we have created a new extension, i.e., now we have two
3515 // extensions. We must make sure one of them is merged with
3516 // the load, otherwise we may degrade the code quality.
3517 (LI->hasOneUse() || hasSameExtUse(LI, *TLI))))
3518 // Promotion happened.
3519 return true;
3520 // If this does not help to expose an ext(load) then, rollback.
3521 TPT.rollback(LastKnownGood);
3522 }
3523 // None of the extension can form an ext(load).
3524 LI = nullptr;
3525 Inst = nullptr;
3526 return false;
3527}
3528
3529/// MoveExtToFormExtLoad - Move a zext or sext fed by a load into the same
3530/// basic block as the load, unless conditions are unfavorable. This allows
3531/// SelectionDAG to fold the extend into the load.
3532/// \p I[in/out] the extension may be modified during the process if some
3533/// promotions apply.
3534///
3535bool CodeGenPrepare::MoveExtToFormExtLoad(Instruction *&I) {
3536 // Try to promote a chain of computation if it allows to form
3537 // an extended load.
3538 TypePromotionTransaction TPT;
3539 TypePromotionTransaction::ConstRestorationPt LastKnownGood =
3540 TPT.getRestorationPoint();
3541 SmallVector<Instruction *, 1> Exts;
3542 Exts.push_back(I);
3543 // Look for a load being extended.
3544 LoadInst *LI = nullptr;
3545 Instruction *OldExt = I;
3546 bool HasPromoted = ExtLdPromotion(TPT, LI, I, Exts);
3547 if (!LI || !I) {
3548 assert(!HasPromoted && !LI && "If we did not match any load instruction "((!HasPromoted && !LI && "If we did not match any load instruction "
"the code must remain the same") ? static_cast<void> (
0) : __assert_fail ("!HasPromoted && !LI && \"If we did not match any load instruction \" \"the code must remain the same\""
, "/tmp/buildd/llvm-toolchain-snapshot-3.7~svn228917/lib/CodeGen/CodeGenPrepare.cpp"
, 3549, __PRETTY_FUNCTION__))
3549 "the code must remain the same")((!HasPromoted && !LI && "If we did not match any load instruction "
"the code must remain the same") ? static_cast<void> (
0) : __assert_fail ("!HasPromoted && !LI && \"If we did not match any load instruction \" \"the code must remain the same\""
, "/tmp/buildd/llvm-toolchain-snapshot-3.7~svn228917/lib/CodeGen/CodeGenPrepare.cpp"
, 3549, __PRETTY_FUNCTION__));
3550 I = OldExt;
3551 return false;
3552 }
3553
3554 // If they're already in the same block, there's nothing to do.
3555 // Make the cheap checks first if we did not promote.
3556 // If we promoted, we need to check if it is indeed profitable.
3557 if (!HasPromoted && LI->getParent() == I->getParent())
3558 return false;
3559
3560 EVT VT = TLI->getValueType(I->getType());
3561 EVT LoadVT = TLI->getValueType(LI->getType());
3562
3563 // If the load has other users and the truncate is not free, this probably
3564 // isn't worthwhile.
3565 if (!LI->hasOneUse() && TLI &&
3566 (TLI->isTypeLegal(LoadVT) || !TLI->isTypeLegal(VT)) &&
3567 !TLI->isTruncateFree(I->getType(), LI->getType())) {
3568 I = OldExt;
3569 TPT.rollback(LastKnownGood);
3570 return false;
3571 }
3572
3573 // Check whether the target supports casts folded into loads.
3574 unsigned LType;
3575 if (isa<ZExtInst>(I))
3576 LType = ISD::ZEXTLOAD;
3577 else {
3578 assert(isa<SExtInst>(I) && "Unexpected ext type!")((isa<SExtInst>(I) && "Unexpected ext type!") ?
static_cast<void> (0) : __assert_fail ("isa<SExtInst>(I) && \"Unexpected ext type!\""
, "/tmp/buildd/llvm-toolchain-snapshot-3.7~svn228917/lib/CodeGen/CodeGenPrepare.cpp"
, 3578, __PRETTY_FUNCTION__));
3579 LType = ISD::SEXTLOAD;
3580 }
3581 if (TLI && !TLI->isLoadExtLegal(LType, VT, LoadVT)) {
3582 I = OldExt;
3583 TPT.rollback(LastKnownGood);
3584 return false;
3585 }
3586
3587 // Move the extend into the same block as the load, so that SelectionDAG
3588 // can fold it.
3589 TPT.commit();
3590 I->removeFromParent();
3591 I->insertAfter(LI);
3592 ++NumExtsMoved;
3593 return true;
3594}
3595
3596bool CodeGenPrepare::OptimizeExtUses(Instruction *I) {
3597 BasicBlock *DefBB = I->getParent();
3598
3599 // If the result of a {s|z}ext and its source are both live out, rewrite all
3600 // other uses of the source with result of extension.
3601 Value *Src = I->getOperand(0);
3602 if (Src->hasOneUse())
3603 return false;
3604
3605 // Only do this xform if truncating is free.
3606 if (TLI && !TLI->isTruncateFree(I->getType(), Src->getType()))
3607 return false;
3608
3609 // Only safe to perform the optimization if the source is also defined in
3610 // this block.
3611 if (!isa<Instruction>(Src) || DefBB != cast<Instruction>(Src)->getParent())
3612 return false;
3613
3614 bool DefIsLiveOut = false;
3615 for (User *U : I->users()) {
3616 Instruction *UI = cast<Instruction>(U);
3617
3618 // Figure out which BB this ext is used in.
3619 BasicBlock *UserBB = UI->getParent();
3620 if (UserBB == DefBB) continue;
3621 DefIsLiveOut = true;
3622 break;
3623 }
3624 if (!DefIsLiveOut)
3625 return false;
3626
3627 // Make sure none of the uses are PHI nodes.
3628 for (User *U : Src->users()) {
3629 Instruction *UI = cast<Instruction>(U);
3630 BasicBlock *UserBB = UI->getParent();
3631 if (UserBB == DefBB) continue;
3632 // Be conservative. We don't want this xform to end up introducing
3633 // reloads just before load / store instructions.
3634 if (isa<PHINode>(UI) || isa<LoadInst>(UI) || isa<StoreInst>(UI))
3635 return false;
3636 }
3637
3638 // InsertedTruncs - Only insert one trunc in each block once.
3639 DenseMap<BasicBlock*, Instruction*> InsertedTruncs;
3640
3641 bool MadeChange = false;
3642 for (Use &U : Src->uses()) {
3643 Instruction *User = cast<Instruction>(U.getUser());
3644
3645 // Figure out which BB this ext is used in.
3646 BasicBlock *UserBB = User->getParent();
3647 if (UserBB == DefBB) continue;
3648
3649 // Both src and def are live in this block. Rewrite the use.
3650 Instruction *&InsertedTrunc = InsertedTruncs[UserBB];
3651
3652 if (!InsertedTrunc) {
3653 BasicBlock::iterator InsertPt = UserBB->getFirstInsertionPt();
3654 InsertedTrunc = new TruncInst(I, Src->getType(), "", InsertPt);
3655 InsertedTruncsSet.insert(InsertedTrunc);
3656 }
3657
3658 // Replace a use of the {s|z}ext source with a use of the result.
3659 U = InsertedTrunc;
3660 ++NumExtUses;
3661 MadeChange = true;
3662 }
3663
3664 return MadeChange;
3665}
3666
3667/// isFormingBranchFromSelectProfitable - Returns true if a SelectInst should be
3668/// turned into an explicit branch.
3669static bool isFormingBranchFromSelectProfitable(SelectInst *SI) {
3670 // FIXME: This should use the same heuristics as IfConversion to determine
3671 // whether a select is better represented as a branch. This requires that
3672 // branch probability metadata is preserved for the select, which is not the
3673 // case currently.
3674
3675 CmpInst *Cmp = dyn_cast<CmpInst>(SI->getCondition());
3676
3677 // If the branch is predicted right, an out of order CPU can avoid blocking on
3678 // the compare. Emit cmovs on compares with a memory operand as branches to
3679 // avoid stalls on the load from memory. If the compare has more than one use
3680 // there's probably another cmov or setcc around so it's not worth emitting a
3681 // branch.
3682 if (!Cmp)
3683 return false;
3684
3685 Value *CmpOp0 = Cmp->getOperand(0);
3686 Value *CmpOp1 = Cmp->getOperand(1);
3687
3688 // We check that the memory operand has one use to avoid uses of the loaded
3689 // value directly after the compare, making branches unprofitable.
3690 return Cmp->hasOneUse() &&
3691 ((isa<LoadInst>(CmpOp0) && CmpOp0->hasOneUse()) ||
3692 (isa<LoadInst>(CmpOp1) && CmpOp1->hasOneUse()));
3693}
3694
3695
3696/// If we have a SelectInst that will likely profit from branch prediction,
3697/// turn it into a branch.
3698bool CodeGenPrepare::OptimizeSelectInst(SelectInst *SI) {
3699 bool VectorCond = !SI->getCondition()->getType()->isIntegerTy(1);
3700
3701 // Can we convert the 'select' to CF ?
3702 if (DisableSelectToBranch || OptSize || !TLI || VectorCond)
3703 return false;
3704
3705 TargetLowering::SelectSupportKind SelectKind;
3706 if (VectorCond)
3707 SelectKind = TargetLowering::VectorMaskSelect;
3708 else if (SI->getType()->isVectorTy())
3709 SelectKind = TargetLowering::ScalarCondVectorVal;
3710 else
3711 SelectKind = TargetLowering::ScalarValSelect;
3712
3713 // Do we have efficient codegen support for this kind of 'selects' ?
3714 if (TLI->isSelectSupported(SelectKind)) {
3715 // We have efficient codegen support for the select instruction.
3716 // Check if it is profitable to keep this 'select'.
3717 if (!TLI->isPredictableSelectExpensive() ||
3718 !isFormingBranchFromSelectProfitable(SI))
3719 return false;
3720 }
3721
3722 ModifiedDT = true;
3723
3724 // First, we split the block containing the select into 2 blocks.
3725 BasicBlock *StartBlock = SI->getParent();
3726 BasicBlock::iterator SplitPt = ++(BasicBlock::iterator(SI));
3727 BasicBlock *NextBlock = StartBlock->splitBasicBlock(SplitPt, "select.end");
3728
3729 // Create a new block serving as the landing pad for the branch.
3730 BasicBlock *SmallBlock = BasicBlock::Create(SI->getContext(), "select.mid",
3731 NextBlock->getParent(), NextBlock);
3732
3733 // Move the unconditional branch from the block with the select in it into our
3734 // landing pad block.
3735 StartBlock->getTerminator()->eraseFromParent();
3736 BranchInst::Create(NextBlock, SmallBlock);
3737
3738 // Insert the real conditional branch based on the original condition.
3739 BranchInst::Create(NextBlock, SmallBlock, SI->getCondition(), SI);
3740
3741 // The select itself is replaced with a PHI Node.
3742 PHINode *PN = PHINode::Create(SI->getType(), 2, "", NextBlock->begin());
3743 PN->takeName(SI);
3744 PN->addIncoming(SI->getTrueValue(), StartBlock);
3745 PN->addIncoming(SI->getFalseValue(), SmallBlock);
3746 SI->replaceAllUsesWith(PN);
3747 SI->eraseFromParent();
3748
3749 // Instruct OptimizeBlock to skip to the next block.
3750 CurInstIterator = StartBlock->end();
3751 ++NumSelectsExpanded;
3752 return true;
3753}
3754
3755static bool isBroadcastShuffle(ShuffleVectorInst *SVI) {
3756 SmallVector<int, 16> Mask(SVI->getShuffleMask());
3757 int SplatElem = -1;
3758 for (unsigned i = 0; i < Mask.size(); ++i) {
3759 if (SplatElem != -1 && Mask[i] != -1 && Mask[i] != SplatElem)
3760 return false;
3761 SplatElem = Mask[i];
3762 }
3763
3764 return true;
3765}
3766
3767/// Some targets have expensive vector shifts if the lanes aren't all the same
3768/// (e.g. x86 only introduced "vpsllvd" and friends with AVX2). In these cases
3769/// it's often worth sinking a shufflevector splat down to its use so that
3770/// codegen can spot all lanes are identical.
3771bool CodeGenPrepare::OptimizeShuffleVectorInst(ShuffleVectorInst *SVI) {
3772 BasicBlock *DefBB = SVI->getParent();
3773
3774 // Only do this xform if variable vector shifts are particularly expensive.
3775 if (!TLI || !TLI->isVectorShiftByScalarCheap(SVI->getType()))
3776 return false;
3777
3778 // We only expect better codegen by sinking a shuffle if we can recognise a
3779 // constant splat.
3780 if (!isBroadcastShuffle(SVI))
3781 return false;
3782
3783 // InsertedShuffles - Only insert a shuffle in each block once.
3784 DenseMap<BasicBlock*, Instruction*> InsertedShuffles;
3785
3786 bool MadeChange = false;
3787 for (User *U : SVI->users()) {
3788 Instruction *UI = cast<Instruction>(U);
3789
3790 // Figure out which BB this ext is used in.
3791 BasicBlock *UserBB = UI->getParent();
3792 if (UserBB == DefBB) continue;
3793
3794 // For now only apply this when the splat is used by a shift instruction.
3795 if (!UI->isShift()) continue;
3796
3797 // Everything checks out, sink the shuffle if the user's block doesn't
3798 // already have a copy.
3799 Instruction *&InsertedShuffle = InsertedShuffles[UserBB];
3800
3801 if (!InsertedShuffle) {
3802 BasicBlock::iterator InsertPt = UserBB->getFirstInsertionPt();
3803 InsertedShuffle = new ShuffleVectorInst(SVI->getOperand(0),
3804 SVI->getOperand(1),
3805 SVI->getOperand(2), "", InsertPt);
3806 }
3807
3808 UI->replaceUsesOfWith(SVI, InsertedShuffle);
3809 MadeChange = true;
3810 }
3811
3812 // If we removed all uses, nuke the shuffle.
3813 if (SVI->use_empty()) {
3814 SVI->eraseFromParent();
3815 MadeChange = true;
3816 }
3817
3818 return MadeChange;
3819}
3820
3821namespace {
3822/// \brief Helper class to promote a scalar operation to a vector one.
3823/// This class is used to move downward extractelement transition.
3824/// E.g.,
3825/// a = vector_op <2 x i32>
3826/// b = extractelement <2 x i32> a, i32 0
3827/// c = scalar_op b
3828/// store c
3829///
3830/// =>
3831/// a = vector_op <2 x i32>
3832/// c = vector_op a (equivalent to scalar_op on the related lane)
3833/// * d = extractelement <2 x i32> c, i32 0
3834/// * store d
3835/// Assuming both extractelement and store can be combine, we get rid of the
3836/// transition.
3837class VectorPromoteHelper {
3838 /// Used to perform some checks on the legality of vector operations.
3839 const TargetLowering &TLI;
3840
3841 /// Used to estimated the cost of the promoted chain.
3842 const TargetTransformInfo &TTI;
3843
3844 /// The transition being moved downwards.
3845 Instruction *Transition;
3846 /// The sequence of instructions to be promoted.
3847 SmallVector<Instruction *, 4> InstsToBePromoted;
3848 /// Cost of combining a store and an extract.
3849 unsigned StoreExtractCombineCost;
3850 /// Instruction that will be combined with the transition.
3851 Instruction *CombineInst;
3852
3853 /// \brief The instruction that represents the current end of the transition.
3854 /// Since we are faking the promotion until we reach the end of the chain
3855 /// of computation, we need a way to get the current end of the transition.
3856 Instruction *getEndOfTransition() const {
3857 if (InstsToBePromoted.empty())
3858 return Transition;
3859 return InstsToBePromoted.back();
3860 }
3861
3862 /// \brief Return the index of the original value in the transition.
3863 /// E.g., for "extractelement <2 x i32> c, i32 1" the original value,
3864 /// c, is at index 0.
3865 unsigned getTransitionOriginalValueIdx() const {
3866 assert(isa<ExtractElementInst>(Transition) &&((isa<ExtractElementInst>(Transition) && "Other kind of transitions are not supported yet"
) ? static_cast<void> (0) : __assert_fail ("isa<ExtractElementInst>(Transition) && \"Other kind of transitions are not supported yet\""
, "/tmp/buildd/llvm-toolchain-snapshot-3.7~svn228917/lib/CodeGen/CodeGenPrepare.cpp"
, 3867, __PRETTY_FUNCTION__))
3867 "Other kind of transitions are not supported yet")((isa<ExtractElementInst>(Transition) && "Other kind of transitions are not supported yet"
) ? static_cast<void> (0) : __assert_fail ("isa<ExtractElementInst>(Transition) && \"Other kind of transitions are not supported yet\""
, "/tmp/buildd/llvm-toolchain-snapshot-3.7~svn228917/lib/CodeGen/CodeGenPrepare.cpp"
, 3867, __PRETTY_FUNCTION__));
3868 return 0;
3869 }
3870
3871 /// \brief Return the index of the index in the transition.
3872 /// E.g., for "extractelement <2 x i32> c, i32 0" the index
3873 /// is at index 1.
3874 unsigned getTransitionIdx() const {
3875 assert(isa<ExtractElementInst>(Transition) &&((isa<ExtractElementInst>(Transition) && "Other kind of transitions are not supported yet"
) ? static_cast<void> (0) : __assert_fail ("isa<ExtractElementInst>(Transition) && \"Other kind of transitions are not supported yet\""
, "/tmp/buildd/llvm-toolchain-snapshot-3.7~svn228917/lib/CodeGen/CodeGenPrepare.cpp"
, 3876, __PRETTY_FUNCTION__))
3876 "Other kind of transitions are not supported yet")((isa<ExtractElementInst>(Transition) && "Other kind of transitions are not supported yet"
) ? static_cast<void> (0) : __assert_fail ("isa<ExtractElementInst>(Transition) && \"Other kind of transitions are not supported yet\""
, "/tmp/buildd/llvm-toolchain-snapshot-3.7~svn228917/lib/CodeGen/CodeGenPrepare.cpp"
, 3876, __PRETTY_FUNCTION__));
3877 return 1;
3878 }
3879
3880 /// \brief Get the type of the transition.
3881 /// This is the type of the original value.
3882 /// E.g., for "extractelement <2 x i32> c, i32 1" the type of the
3883 /// transition is <2 x i32>.
3884 Type *getTransitionType() const {
3885 return Transition->getOperand(getTransitionOriginalValueIdx())->getType();
3886 }
3887
3888 /// \brief Promote \p ToBePromoted by moving \p Def downward through.
3889 /// I.e., we have the following sequence:
3890 /// Def = Transition <ty1> a to <ty2>
3891 /// b = ToBePromoted <ty2> Def, ...
3892 /// =>
3893 /// b = ToBePromoted <ty1> a, ...
3894 /// Def = Transition <ty1> ToBePromoted to <ty2>
3895 void promoteImpl(Instruction *ToBePromoted);
3896
3897 /// \brief Check whether or not it is profitable to promote all the
3898 /// instructions enqueued to be promoted.
3899 bool isProfitableToPromote() {
3900 Value *ValIdx = Transition->getOperand(getTransitionOriginalValueIdx());
3901 unsigned Index = isa<ConstantInt>(ValIdx)
3902 ? cast<ConstantInt>(ValIdx)->getZExtValue()
3903 : -1;
3904 Type *PromotedType = getTransitionType();
3905
3906 StoreInst *ST = cast<StoreInst>(CombineInst);
3907 unsigned AS = ST->getPointerAddressSpace();
3908 unsigned Align = ST->getAlignment();
3909 // Check if this store is supported.
3910 if (!TLI.allowsMisalignedMemoryAccesses(
3911 TLI.getValueType(ST->getValueOperand()->getType()), AS, Align)) {
3912 // If this is not supported, there is no way we can combine
3913 // the extract with the store.
3914 return false;
3915 }
3916
3917 // The scalar chain of computation has to pay for the transition
3918 // scalar to vector.
3919 // The vector chain has to account for the combining cost.
3920 uint64_t ScalarCost =
3921 TTI.getVectorInstrCost(Transition->getOpcode(), PromotedType, Index);
3922 uint64_t VectorCost = StoreExtractCombineCost;
3923 for (const auto &Inst : InstsToBePromoted) {
3924 // Compute the cost.
3925 // By construction, all instructions being promoted are arithmetic ones.
3926 // Moreover, one argument is a constant that can be viewed as a splat
3927 // constant.
3928 Value *Arg0 = Inst->getOperand(0);
3929 bool IsArg0Constant = isa<UndefValue>(Arg0) || isa<ConstantInt>(Arg0) ||
3930 isa<ConstantFP>(Arg0);
3931 TargetTransformInfo::OperandValueKind Arg0OVK =
3932 IsArg0Constant ? TargetTransformInfo::OK_UniformConstantValue
3933 : TargetTransformInfo::OK_AnyValue;
3934 TargetTransformInfo::OperandValueKind Arg1OVK =
3935 !IsArg0Constant ? TargetTransformInfo::OK_UniformConstantValue
3936 : TargetTransformInfo::OK_AnyValue;
3937 ScalarCost += TTI.getArithmeticInstrCost(
3938 Inst->getOpcode(), Inst->getType(), Arg0OVK, Arg1OVK);
3939 VectorCost += TTI.getArithmeticInstrCost(Inst->getOpcode(), PromotedType,
3940 Arg0OVK, Arg1OVK);
3941 }
3942 DEBUG(dbgs() << "Estimated cost of computation to be promoted:\nScalar: "do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Estimated cost of computation to be promoted:\nScalar: "
<< ScalarCost << "\nVector: " << VectorCost
<< '\n'; } } while (0)
3943 << ScalarCost << "\nVector: " << VectorCost << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Estimated cost of computation to be promoted:\nScalar: "
<< ScalarCost << "\nVector: " << VectorCost
<< '\n'; } } while (0);
3944 return ScalarCost > VectorCost;
3945 }
3946
3947 /// \brief Generate a constant vector with \p Val with the same
3948 /// number of elements as the transition.
3949 /// \p UseSplat defines whether or not \p Val should be replicated
3950 /// accross the whole vector.
3951 /// In other words, if UseSplat == true, we generate <Val, Val, ..., Val>,
3952 /// otherwise we generate a vector with as many undef as possible:
3953 /// <undef, ..., undef, Val, undef, ..., undef> where \p Val is only
3954 /// used at the index of the extract.
3955 Value *getConstantVector(Constant *Val, bool UseSplat) const {
3956 unsigned ExtractIdx = UINT_MAX(2147483647 *2U +1U);
3957 if (!UseSplat) {
3958 // If we cannot determine where the constant must be, we have to
3959 // use a splat constant.
3960 Value *ValExtractIdx = Transition->getOperand(getTransitionIdx());
3961 if (ConstantInt *CstVal = dyn_cast<ConstantInt>(ValExtractIdx))
3962 ExtractIdx = CstVal->getSExtValue();
3963 else
3964 UseSplat = true;
3965 }
3966
3967 unsigned End = getTransitionType()->getVectorNumElements();
3968 if (UseSplat)
3969 return ConstantVector::getSplat(End, Val);
3970
3971 SmallVector<Constant *, 4> ConstVec;
3972 UndefValue *UndefVal = UndefValue::get(Val->getType());
3973 for (unsigned Idx = 0; Idx != End; ++Idx) {
3974 if (Idx == ExtractIdx)
3975 ConstVec.push_back(Val);
3976 else
3977 ConstVec.push_back(UndefVal);
3978 }
3979 return ConstantVector::get(ConstVec);
3980 }
3981
3982 /// \brief Check if promoting to a vector type an operand at \p OperandIdx
3983 /// in \p Use can trigger undefined behavior.
3984 static bool canCauseUndefinedBehavior(const Instruction *Use,
3985 unsigned OperandIdx) {
3986 // This is not safe to introduce undef when the operand is on
3987 // the right hand side of a division-like instruction.
3988 if (OperandIdx != 1)
3989 return false;
3990 switch (Use->getOpcode()) {
3991 default:
3992 return false;
3993 case Instruction::SDiv:
3994 case Instruction::UDiv:
3995 case Instruction::SRem:
3996 case Instruction::URem:
3997 return true;
3998 case Instruction::FDiv:
3999 case Instruction::FRem:
4000 return !Use->hasNoNaNs();
4001 }
4002 llvm_unreachable(nullptr)::llvm::llvm_unreachable_internal(nullptr, "/tmp/buildd/llvm-toolchain-snapshot-3.7~svn228917/lib/CodeGen/CodeGenPrepare.cpp"
, 4002);
4003 }
4004
4005public:
4006 VectorPromoteHelper(const TargetLowering &TLI, const TargetTransformInfo &TTI,
4007 Instruction *Transition, unsigned CombineCost)
4008 : TLI(TLI), TTI(TTI), Transition(Transition),
4009 StoreExtractCombineCost(CombineCost), CombineInst(nullptr) {
4010 assert(Transition && "Do not know how to promote null")((Transition && "Do not know how to promote null") ? static_cast
<void> (0) : __assert_fail ("Transition && \"Do not know how to promote null\""
, "/tmp/buildd/llvm-toolchain-snapshot-3.7~svn228917/lib/CodeGen/CodeGenPrepare.cpp"
, 4010, __PRETTY_FUNCTION__));
4011 }
4012
4013 /// \brief Check if we can promote \p ToBePromoted to \p Type.
4014 bool canPromote(const Instruction *ToBePromoted) const {
4015 // We could support CastInst too.
4016 return isa<BinaryOperator>(ToBePromoted);
4017 }
4018
4019 /// \brief Check if it is profitable to promote \p ToBePromoted
4020 /// by moving downward the transition through.
4021 bool shouldPromote(const Instruction *ToBePromoted) const {
4022 // Promote only if all the operands can be statically expanded.
4023 // Indeed, we do not want to introduce any new kind of transitions.
4024 for (const Use &U : ToBePromoted->operands()) {
4025 const Value *Val = U.get();
4026 if (Val == getEndOfTransition()) {
4027 // If the use is a division and the transition is on the rhs,
4028 // we cannot promote the operation, otherwise we may create a
4029 // division by zero.
4030 if (canCauseUndefinedBehavior(ToBePromoted, U.getOperandNo()))
4031 return false;
4032 continue;
4033 }
4034 if (!isa<ConstantInt>(Val) && !isa<UndefValue>(Val) &&
4035 !isa<ConstantFP>(Val))
4036 return false;
4037 }
4038 // Check that the resulting operation is legal.
4039 int ISDOpcode = TLI.InstructionOpcodeToISD(ToBePromoted->getOpcode());
4040 if (!ISDOpcode)
4041 return false;
4042 return StressStoreExtract ||
4043 TLI.isOperationLegalOrCustom(
4044 ISDOpcode, TLI.getValueType(getTransitionType(), true));
4045 }
4046
4047 /// \brief Check whether or not \p Use can be combined
4048 /// with the transition.
4049 /// I.e., is it possible to do Use(Transition) => AnotherUse?
4050 bool canCombine(const Instruction *Use) { return isa<StoreInst>(Use); }
4051
4052 /// \brief Record \p ToBePromoted as part of the chain to be promoted.
4053 void enqueueForPromotion(Instruction *ToBePromoted) {
4054 InstsToBePromoted.push_back(ToBePromoted);
4055 }
4056
4057 /// \brief Set the instruction that will be combined with the transition.
4058 void recordCombineInstruction(Instruction *ToBeCombined) {
4059 assert(canCombine(ToBeCombined) && "Unsupported instruction to combine")((canCombine(ToBeCombined) && "Unsupported instruction to combine"
) ? static_cast<void> (0) : __assert_fail ("canCombine(ToBeCombined) && \"Unsupported instruction to combine\""
, "/tmp/buildd/llvm-toolchain-snapshot-3.7~svn228917/lib/CodeGen/CodeGenPrepare.cpp"
, 4059, __PRETTY_FUNCTION__));
4060 CombineInst = ToBeCombined;
4061 }
4062
4063 /// \brief Promote all the instructions enqueued for promotion if it is
4064 /// is profitable.
4065 /// \return True if the promotion happened, false otherwise.
4066 bool promote() {
4067 // Check if there is something to promote.
4068 // Right now, if we do not have anything to combine with,
4069 // we assume the promotion is not profitable.
4070 if (InstsToBePromoted.empty() || !CombineInst)
4071 return false;
4072
4073 // Check cost.
4074 if (!StressStoreExtract && !isProfitableToPromote())
4075 return false;
4076
4077 // Promote.
4078 for (auto &ToBePromoted : InstsToBePromoted)
4079 promoteImpl(ToBePromoted);
4080 InstsToBePromoted.clear();
4081 return true;
4082 }
4083};
4084} // End of anonymous namespace.
4085
4086void VectorPromoteHelper::promoteImpl(Instruction *ToBePromoted) {
4087 // At this point, we know that all the operands of ToBePromoted but Def
4088 // can be statically promoted.
4089 // For Def, we need to use its parameter in ToBePromoted:
4090 // b = ToBePromoted ty1 a
4091 // Def = Transition ty1 b to ty2
4092 // Move the transition down.
4093 // 1. Replace all uses of the promoted operation by the transition.
4094 // = ... b => = ... Def.
4095 assert(ToBePromoted->getType() == Transition->getType() &&((ToBePromoted->getType() == Transition->getType() &&
"The type of the result of the transition does not match " "the final type"
) ? static_cast<void> (0) : __assert_fail ("ToBePromoted->getType() == Transition->getType() && \"The type of the result of the transition does not match \" \"the final type\""
, "/tmp/buildd/llvm-toolchain-snapshot-3.7~svn228917/lib/CodeGen/CodeGenPrepare.cpp"
, 4097, __PRETTY_FUNCTION__))
4096 "The type of the result of the transition does not match "((ToBePromoted->getType() == Transition->getType() &&
"The type of the result of the transition does not match " "the final type"
) ? static_cast<void> (0) : __assert_fail ("ToBePromoted->getType() == Transition->getType() && \"The type of the result of the transition does not match \" \"the final type\""
, "/tmp/buildd/llvm-toolchain-snapshot-3.7~svn228917/lib/CodeGen/CodeGenPrepare.cpp"
, 4097, __PRETTY_FUNCTION__))
4097 "the final type")((ToBePromoted->getType() == Transition->getType() &&
"The type of the result of the transition does not match " "the final type"
) ? static_cast<void> (0) : __assert_fail ("ToBePromoted->getType() == Transition->getType() && \"The type of the result of the transition does not match \" \"the final type\""
, "/tmp/buildd/llvm-toolchain-snapshot-3.7~svn228917/lib/CodeGen/CodeGenPrepare.cpp"
, 4097, __PRETTY_FUNCTION__));
4098 ToBePromoted->replaceAllUsesWith(Transition);
4099 // 2. Update the type of the uses.
4100 // b = ToBePromoted ty2 Def => b = ToBePromoted ty1 Def.
4101 Type *TransitionTy = getTransitionType();
4102 ToBePromoted->mutateType(TransitionTy);
4103 // 3. Update all the operands of the promoted operation with promoted
4104 // operands.
4105 // b = ToBePromoted ty1 Def => b = ToBePromoted ty1 a.
4106 for (Use &U : ToBePromoted->operands()) {
4107 Value *Val = U.get();
4108 Value *NewVal = nullptr;
4109 if (Val == Transition)
4110 NewVal = Transition->getOperand(getTransitionOriginalValueIdx());
4111 else if (isa<UndefValue>(Val) || isa<ConstantInt>(Val) ||
4112 isa<ConstantFP>(Val)) {
4113 // Use a splat constant if it is not safe to use undef.
4114 NewVal = getConstantVector(
4115 cast<Constant>(Val),
4116 isa<UndefValue>(Val) ||
4117 canCauseUndefinedBehavior(ToBePromoted, U.getOperandNo()));
4118 } else
4119 llvm_unreachable("Did you modified shouldPromote and forgot to update "::llvm::llvm_unreachable_internal("Did you modified shouldPromote and forgot to update "
"this?", "/tmp/buildd/llvm-toolchain-snapshot-3.7~svn228917/lib/CodeGen/CodeGenPrepare.cpp"
, 4120)
4120 "this?")::llvm::llvm_unreachable_internal("Did you modified shouldPromote and forgot to update "
"this?", "/tmp/buildd/llvm-toolchain-snapshot-3.7~svn228917/lib/CodeGen/CodeGenPrepare.cpp"
, 4120);
4121 ToBePromoted->setOperand(U.getOperandNo(), NewVal);
4122 }
4123 Transition->removeFromParent();
4124 Transition->insertAfter(ToBePromoted);
4125 Transition->setOperand(getTransitionOriginalValueIdx(), ToBePromoted);
4126}
4127
4128// See if we can speculate calls to intrinsic cttz/ctlz.
4129//
4130// Example:
4131// entry:
4132// ...
4133// %cmp = icmp eq i64 %val, 0
4134// br i1 %cmp, label %end.bb, label %then.bb
4135//
4136// then.bb:
4137// %c = tail call i64 @llvm.cttz.i64(i64 %val, i1 true)
4138// br label %EndBB
4139//
4140// end.bb:
4141// %cond = phi i64 [ %c, %then.bb ], [ 64, %entry ]
4142//
4143// ==>
4144//
4145// entry:
4146// ...
4147// %c = tail call i64 @llvm.cttz.i64(i64 %val, i1 false)
4148//
4149static bool OptimizeBranchInst(BranchInst *BrInst, const TargetLowering &TLI) {
4150 assert(BrInst->isConditional() && "Expected a conditional branch!")((BrInst->isConditional() && "Expected a conditional branch!"
) ? static_cast<void> (0) : __assert_fail ("BrInst->isConditional() && \"Expected a conditional branch!\""
, "/tmp/buildd/llvm-toolchain-snapshot-3.7~svn228917/lib/CodeGen/CodeGenPrepare.cpp"
, 4150, __PRETTY_FUNCTION__));
4151 BasicBlock *ThenBB = BrInst->getSuccessor(1);
4152 BasicBlock *EndBB = BrInst->getSuccessor(0);
4153
4154 // See if ThenBB contains only one instruction (excluding the
4155 // terminator and DbgInfoIntrinsic calls).
4156 IntrinsicInst *II = nullptr;
19
←
'II' initialized to a null pointer value
→
4157 CastInst *CI = nullptr;
4158 for (BasicBlock::iterator I = ThenBB->begin(),
20
←
Loop condition is false. Execution continues on line 4210
→
4159 E = std::prev(ThenBB->end()); I != E; ++I) {
4160 // Skip debug info.
4161 if (isa<DbgInfoIntrinsic>(I))
4162 continue;
4163
4164 // Check if this is a zero extension or a truncate of a previously
4165 // matched call to intrinsic cttz/ctlz.
4166 if (II) {
4167 // Early exit if we already found a "free" zero extend/truncate.
4168 if (CI)
4169 return false;
4170
4171 Type *SrcTy = II->getType();
4172 Type *DestTy = I->getType();
4173 Value *V;
4174
4175 if (match(cast<Instruction>(I), m_ZExt(m_Value(V))) && V == II) {
4176 // Speculate this zero extend only if it is "free" for the target.
4177 if (TLI.isZExtFree(SrcTy, DestTy)) {
4178 CI = cast<CastInst>(I);
4179 continue;
4180 }
4181 } else if (match(cast<Instruction>(I), m_Trunc(m_Value(V))) && V == II) {
4182 // Speculate this truncate only if it is "free" for the target.
4183 if (TLI.isTruncateFree(SrcTy, DestTy)) {
4184 CI = cast<CastInst>(I);
4185 continue;
4186 }
4187 } else {
4188 // Avoid speculating more than one instruction.
4189 return false;
4190 }
4191 }
4192
4193 // See if this is a call to intrinsic cttz/ctlz.
4194 if (match(cast<Instruction>(I), m_Intrinsic<Intrinsic::cttz>())) {
4195 // Avoid speculating expensive intrinsic calls.
4196 if (!TLI.isCheapToSpeculateCttz())
4197 return false;
4198 }
4199 else if (match(cast<Instruction>(I), m_Intrinsic<Intrinsic::ctlz>())) {
4200 // Avoid speculating expensive intrinsic calls.
4201 if (!TLI.isCheapToSpeculateCtlz())
4202 return false;
4203 } else
4204 return false;
4205
4206 II = cast<IntrinsicInst>(I);
4207 }
4208
4209 // Look for PHI nodes with 'II' as the incoming value from 'ThenBB'.
4210 BasicBlock *EntryBB = BrInst->getParent();
4211 for (BasicBlock::iterator I = EndBB->begin();
21
←
Loop condition is true. Entering loop body
→
4212 PHINode *PN = dyn_cast<PHINode>(I); ++I) {
4213 Value *ThenV = PN->getIncomingValueForBlock(ThenBB);
4214 Value *OrigV = PN->getIncomingValueForBlock(EntryBB);
4215
4216 if (!OrigV)
22
←
Assuming 'OrigV' is non-null
→
23
←
Taking false branch
→
4217 return false;
4218
4219 if (ThenV != II && (!CI || ThenV != CI))
4220 return false;
4221
4222 if (ConstantInt *CInt = dyn_cast<ConstantInt>(OrigV)) {
24
←
Assuming 'CInt' is non-null
→
25
←
Taking true branch
→
4223 unsigned BitWidth = II->getType()->getIntegerBitWidth();
26
←
Called C++ object pointer is null
4224
4225 // Don't try to simplify this phi node if 'ThenV' is a cttz/ctlz
4226 // intrinsic call, but 'OrigV' is not equal to the 'size-of' in bits
4227 // of the value in input to the cttz/ctlz.
4228 if (CInt->getValue() != BitWidth)
4229 return false;
4230
4231 // Hoist the call to cttz/ctlz from ThenBB into EntryBB.
4232 EntryBB->getInstList().splice(BrInst, ThenBB->getInstList(),
4233 ThenBB->begin(), std::prev(ThenBB->end()));
4234
4235 // Update PN setting ThenV as the incoming value from both 'EntryBB'
4236 // and 'ThenBB'. Eventually, method 'OptimizeInst' will fold this
4237 // phi node if all the incoming values are the same.
4238 PN->setIncomingValue(PN->getBasicBlockIndex(EntryBB), ThenV);
4239 PN->setIncomingValue(PN->getBasicBlockIndex(ThenBB), ThenV);
4240
4241 // Clear the 'undef on zero' flag of the cttz/ctlz intrinsic call.
4242 if (cast<ConstantInt>(II->getArgOperand(1))->isOne()) {
4243 Type *Ty = II->getArgOperand(0)->getType();
4244 Value *Args[] = { II->getArgOperand(0),
4245 ConstantInt::getFalse(II->getContext()) };
4246 Module *M = EntryBB->getParent()->getParent();
4247 Value *IF = Intrinsic::getDeclaration(M, II->getIntrinsicID(), Ty);
4248 IRBuilder<> Builder(II);
4249 Instruction *NewI = Builder.CreateCall(IF, Args);
4250
4251 // Replace the old call to cttz/ctlz.
4252 II->replaceAllUsesWith(NewI);
4253 II->eraseFromParent();
4254 }
4255
4256 // Update BrInst condition so that the branch to EndBB is always taken.
4257 // Later on, method 'ConstantFoldTerminator' will simplify this branch
4258 // replacing it with a direct branch to 'EndBB'.
4259 // As a side effect, CodeGenPrepare will attempt to simplify the control
4260 // flow graph by deleting basic block 'ThenBB' and merging 'EntryBB' into
4261 // 'EndBB' (calling method 'EliminateFallThrough').
4262 BrInst->setCondition(ConstantInt::getTrue(BrInst->getContext()));
4263 return true;
4264 }
4265 }
4266
4267 return false;
4268}
4269
4270/// Some targets can do store(extractelement) with one instruction.
4271/// Try to push the extractelement towards the stores when the target
4272/// has this feature and this is profitable.
4273bool CodeGenPrepare::OptimizeExtractElementInst(Instruction *Inst) {
4274 unsigned CombineCost = UINT_MAX(2147483647 *2U +1U);
4275 if (DisableStoreExtract || !TLI ||
4276 (!StressStoreExtract &&
4277 !TLI->canCombineStoreAndExtract(Inst->getOperand(0)->getType(),
4278 Inst->getOperand(1), CombineCost)))
4279 return false;
4280
4281 // At this point we know that Inst is a vector to scalar transition.
4282 // Try to move it down the def-use chain, until:
4283 // - We can combine the transition with its single use
4284 // => we got rid of the transition.
4285 // - We escape the current basic block
4286 // => we would need to check that we are moving it at a cheaper place and
4287 // we do not do that for now.
4288 BasicBlock *Parent = Inst->getParent();
4289 DEBUG(dbgs() << "Found an interesting transition: " << *Inst << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Found an interesting transition: "
<< *Inst << '\n'; } } while (0);
4290 VectorPromoteHelper VPH(*TLI, *TTI, Inst, CombineCost);
4291 // If the transition has more than one use, assume this is not going to be
4292 // beneficial.
4293 while (Inst->hasOneUse()) {
4294 Instruction *ToBePromoted = cast<Instruction>(*Inst->user_begin());
4295 DEBUG(dbgs() << "Use: " << *ToBePromoted << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Use: " << *ToBePromoted
<< '\n'; } } while (0);
4296
4297 if (ToBePromoted->getParent() != Parent) {
4298 DEBUG(dbgs() << "Instruction to promote is in a different block ("do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Instruction to promote is in a different block ("
<< ToBePromoted->getParent()->getName() <<
") than the transition (" << Parent->getName() <<
").\n"; } } while (0)
4299 << ToBePromoted->getParent()->getName()do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Instruction to promote is in a different block ("
<< ToBePromoted->getParent()->getName() <<
") than the transition (" << Parent->getName() <<
").\n"; } } while (0)
4300 << ") than the transition (" << Parent->getName() << ").\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Instruction to promote is in a different block ("
<< ToBePromoted->getParent()->getName() <<
") than the transition (" << Parent->getName() <<
").\n"; } } while (0);
4301 return false;
4302 }
4303
4304 if (VPH.canCombine(ToBePromoted)) {
4305 DEBUG(dbgs() << "Assume " << *Inst << '\n'do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Assume " << *Inst
<< '\n' << "will be combined with: " << *ToBePromoted
<< '\n'; } } while (0)
4306 << "will be combined with: " << *ToBePromoted << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Assume " << *Inst
<< '\n' << "will be combined with: " << *ToBePromoted
<< '\n'; } } while (0);
4307 VPH.recordCombineInstruction(ToBePromoted);
4308 bool Changed = VPH.promote();
4309 NumStoreExtractExposed += Changed;
4310 return Changed;
4311 }
4312
4313 DEBUG(dbgs() << "Try promoting.\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Try promoting.\n"; } }
while (0);
4314 if (!VPH.canPromote(ToBePromoted) || !VPH.shouldPromote(ToBePromoted))
4315 return false;
4316
4317 DEBUG(dbgs() << "Promoting is possible... Enqueue for promotion!\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Promoting is possible... Enqueue for promotion!\n"
; } } while (0);
4318
4319 VPH.enqueueForPromotion(ToBePromoted);
4320 Inst = ToBePromoted;
4321 }
4322 return false;
4323}
4324
4325bool CodeGenPrepare::OptimizeInst(Instruction *I, bool& ModifiedDT) {
4326 if (PHINode *P = dyn_cast<PHINode>(I)) {
1
Taking false branch
→
4327 // It is possible for very late stage optimizations (such as SimplifyCFG)
4328 // to introduce PHI nodes too late to be cleaned up. If we detect such a
4329 // trivial PHI, go ahead and zap it here.
4330 if (Value *V = SimplifyInstruction(P, TLI ? TLI->getDataLayout() : nullptr,
4331 TLInfo, DT)) {
4332 P->replaceAllUsesWith(V);
4333 P->eraseFromParent();
4334 ++NumPHIsElim;
4335 return true;
4336 }
4337 return false;
4338 }
4339
4340 if (CastInst *CI = dyn_cast<CastInst>(I)) {
2
←
Taking false branch
→
4341 // If the source of the cast is a constant, then this should have
4342 // already been constant folded. The only reason NOT to constant fold
4343 // it is if something (e.g. LSR) was careful to place the constant
4344 // evaluation in a block other than then one that uses it (e.g. to hoist
4345 // the address of globals out of a loop). If this is the case, we don't
4346 // want to forward-subst the cast.
4347 if (isa<Constant>(CI->getOperand(0)))
4348 return false;
4349
4350 if (TLI && OptimizeNoopCopyExpression(CI, *TLI))
4351 return true;
4352
4353 if (isa<ZExtInst>(I) || isa<SExtInst>(I)) {
4354 /// Sink a zext or sext into its user blocks if the target type doesn't
4355 /// fit in one register
4356 if (TLI && TLI->getTypeAction(CI->getContext(),
4357 TLI->getValueType(CI->getType())) ==
4358 TargetLowering::TypeExpandInteger) {
4359 return SinkCast(CI);
4360 } else {
4361 bool MadeChange = MoveExtToFormExtLoad(I);
4362 return MadeChange | OptimizeExtUses(I);
4363 }
4364 }
4365 return false;
4366 }
4367
4368 if (CmpInst *CI = dyn_cast<CmpInst>(I))
3
←
Taking false branch
→
4369 if (!TLI || !TLI->hasMultipleConditionRegisters())
4370 return OptimizeCmpExpression(CI);
4371
4372 if (LoadInst *LI = dyn_cast<LoadInst>(I)) {
4
←
Taking false branch
→
4373 if (TLI)
4374 return OptimizeMemoryInst(I, I->getOperand(0), LI->getType());
4375 return false;
4376 }
4377
4378 if (StoreInst *SI = dyn_cast<StoreInst>(I)) {
5
←
Taking false branch
→
4379 if (TLI)
4380 return OptimizeMemoryInst(I, SI->getOperand(1),
4381 SI->getOperand(0)->getType());
4382 return false;
4383 }
4384
4385 BinaryOperator *BinOp = dyn_cast<BinaryOperator>(I);
4386
4387 if (BinOp && (BinOp->getOpcode() == Instruction::AShr ||
4388 BinOp->getOpcode() == Instruction::LShr)) {
4389 ConstantInt *CI = dyn_cast<ConstantInt>(BinOp->getOperand(1));
4390 if (TLI && CI && TLI->hasExtractBitsInsn())
4391 return OptimizeExtractBits(BinOp, CI, *TLI);
4392
4393 return false;
4394 }
4395
4396 if (GetElementPtrInst *GEPI = dyn_cast<GetElementPtrInst>(I)) {
6
←
Taking false branch
→
4397 if (GEPI->hasAllZeroIndices()) {
4398 /// The GEP operand must be a pointer, so must its result -> BitCast
4399 Instruction *NC = new BitCastInst(GEPI->getOperand(0), GEPI->getType(),
4400 GEPI->getName(), GEPI);
4401 GEPI->replaceAllUsesWith(NC);
4402 GEPI->eraseFromParent();
4403 ++NumGEPsElim;
4404 OptimizeInst(NC, ModifiedDT);
4405 return true;
4406 }
4407 return false;
4408 }
4409
4410 if (CallInst *CI = dyn_cast<CallInst>(I))
7
←
Taking false branch
→
4411 return OptimizeCallInst(CI, ModifiedDT);
4412
4413 if (SelectInst *SI = dyn_cast<SelectInst>(I))
8
←
Taking false branch
→
4414 return OptimizeSelectInst(SI);
4415
4416 if (ShuffleVectorInst *SVI = dyn_cast<ShuffleVectorInst>(I))
9
←
Taking false branch
→
4417 return OptimizeShuffleVectorInst(SVI);
4418
4419 if (isa<ExtractElementInst>(I))
10
←
Taking false branch
→
4420 return OptimizeExtractElementInst(I);
4421
4422 if (BranchInst *BI = dyn_cast<BranchInst>(I)) {
11
←
Assuming 'BI' is non-null
→
12
←
Taking true branch
→
4423 if (TLI && BI->isConditional() && BI->getCondition()->hasOneUse()) {
13
←
Taking true branch
→
4424 // Check if the branch condition compares a value agaist zero.
4425 if (ICmpInst *ICI = dyn_cast<ICmpInst>(BI->getCondition())) {
14
←
Assuming 'ICI' is non-null
→
15
←
Taking true branch
→
4426 if (ICI->getPredicate() == ICmpInst::ICMP_EQ &&
16
←
Taking true branch
→
4427 match(ICI->getOperand(1), m_Zero())) {
4428 BasicBlock *ThenBB = BI->getSuccessor(1);
4429 BasicBlock *EndBB = BI->getSuccessor(0);
4430
4431 // Check if ThenBB is only reachable from this basic block; also,
4432 // check if EndBB has more than one predecessor.
4433 if (ThenBB->getSinglePredecessor() &&
17
←
Taking true branch
→
4434 !EndBB->getSinglePredecessor()) {
4435 TerminatorInst *TI = ThenBB->getTerminator();
4436
4437 if (TI->getNumSuccessors() == 1 && TI->getSuccessor(0) == EndBB &&
4438 // Try to speculate calls to intrinsic cttz/ctlz from 'ThenBB'.
4439 OptimizeBranchInst(BI, *TLI)) {
18
←
Calling 'OptimizeBranchInst'
→
4440 ModifiedDT = true;
4441 return true;
4442 }
4443 }
4444 }
4445 }
4446 }
4447 return false;
4448 }
4449
4450 return false;
4451}
4452
4453// In this pass we look for GEP and cast instructions that are used
4454// across basic blocks and rewrite them to improve basic-block-at-a-time
4455// selection.
4456bool CodeGenPrepare::OptimizeBlock(BasicBlock &BB, bool& ModifiedDT) {
4457 SunkAddrs.clear();
4458 bool MadeChange = false;
4459
4460 CurInstIterator = BB.begin();
4461 while (CurInstIterator != BB.end()) {
4462 MadeChange |= OptimizeInst(CurInstIterator++, ModifiedDT);
4463 if (ModifiedDT)
4464 return true;
4465 }
4466 MadeChange |= DupRetToEnableTailCallOpts(&BB);
4467
4468 return MadeChange;
4469}
4470
4471// llvm.dbg.value is far away from the value then iSel may not be able
4472// handle it properly. iSel will drop llvm.dbg.value if it can not
4473// find a node corresponding to the value.
4474bool CodeGenPrepare::PlaceDbgValues(Function &F) {
4475 bool MadeChange = false;
4476 for (BasicBlock &BB : F) {
4477 Instruction *PrevNonDbgInst = nullptr;
4478 for (BasicBlock::iterator BI = BB.begin(), BE = BB.end(); BI != BE;) {
4479 Instruction *Insn = BI++;
4480 DbgValueInst *DVI = dyn_cast<DbgValueInst>(Insn);
4481 // Leave dbg.values that refer to an alloca alone. These
4482 // instrinsics describe the address of a variable (= the alloca)
4483 // being taken. They should not be moved next to the alloca
4484 // (and to the beginning of the scope), but rather stay close to
4485 // where said address is used.
4486 if (!DVI || (DVI->getValue() && isa<AllocaInst>(DVI->getValue()))) {
4487 PrevNonDbgInst = Insn;
4488 continue;
4489 }
4490
4491 Instruction *VI = dyn_cast_or_null<Instruction>(DVI->getValue());
4492 if (VI && VI != PrevNonDbgInst && !VI->isTerminator()) {
4493 DEBUG(dbgs() << "Moving Debug Value before :\n" << *DVI << ' ' << *VI)do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Moving Debug Value before :\n"
<< *DVI << ' ' << *VI; } } while (0);
4494 DVI->removeFromParent();
4495 if (isa<PHINode>(VI))
4496 DVI->insertBefore(VI->getParent()->getFirstInsertionPt());
4497 else
4498 DVI->insertAfter(VI);
4499 MadeChange = true;
4500 ++NumDbgValueMoved;
4501 }
4502 }
4503 }
4504 return MadeChange;
4505}
4506
4507// If there is a sequence that branches based on comparing a single bit
4508// against zero that can be combined into a single instruction, and the
4509// target supports folding these into a single instruction, sink the
4510// mask and compare into the branch uses. Do this before OptimizeBlock ->
4511// OptimizeInst -> OptimizeCmpExpression, which perturbs the pattern being
4512// searched for.
4513bool CodeGenPrepare::sinkAndCmp(Function &F) {
4514 if (!EnableAndCmpSinking)
4515 return false;
4516 if (!TLI || !TLI->isMaskAndBranchFoldingLegal())
4517 return false;
4518 bool MadeChange = false;
4519 for (Function::iterator I = F.begin(), E = F.end(); I != E; ) {
4520 BasicBlock *BB = I++;
4521
4522 // Does this BB end with the following?
4523 // %andVal = and %val, #single-bit-set
4524 // %icmpVal = icmp %andResult, 0
4525 // br i1 %cmpVal label %dest1, label %dest2"
4526 BranchInst *Brcc = dyn_cast<BranchInst>(BB->getTerminator());
4527 if (!Brcc || !Brcc->isConditional())
4528 continue;
4529 ICmpInst *Cmp = dyn_cast<ICmpInst>(Brcc->getOperand(0));
4530 if (!Cmp || Cmp->getParent() != BB)
4531 continue;
4532 ConstantInt *Zero = dyn_cast<ConstantInt>(Cmp->getOperand(1));
4533 if (!Zero || !Zero->isZero())
4534 continue;
4535 Instruction *And = dyn_cast<Instruction>(Cmp->getOperand(0));
4536 if (!And || And->getOpcode() != Instruction::And || And->getParent() != BB)
4537 continue;
4538 ConstantInt* Mask = dyn_cast<ConstantInt>(And->getOperand(1));
4539 if (!Mask || !Mask->getUniqueInteger().isPowerOf2())
4540 continue;
4541 DEBUG(dbgs() << "found and; icmp ?,0; brcc\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "found and; icmp ?,0; brcc\n"
; } } while (0); DEBUG(BB->dump())do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { BB->dump(); } } while (0);
4542
4543 // Push the "and; icmp" for any users that are conditional branches.
4544 // Since there can only be one branch use per BB, we don't need to keep
4545 // track of which BBs we insert into.
4546 for (Value::use_iterator UI = Cmp->use_begin(), E = Cmp->use_end();
4547 UI != E; ) {
4548 Use &TheUse = *UI;
4549 // Find brcc use.
4550 BranchInst *BrccUser = dyn_cast<BranchInst>(*UI);
4551 ++UI;
4552 if (!BrccUser || !BrccUser->isConditional())
4553 continue;
4554 BasicBlock *UserBB = BrccUser->getParent();
4555 if (UserBB == BB) continue;
4556 DEBUG(dbgs() << "found Brcc use\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "found Brcc use\n"; } }
while (0);
4557
4558 // Sink the "and; icmp" to use.
4559 MadeChange = true;
4560 BinaryOperator *NewAnd =
4561 BinaryOperator::CreateAnd(And->getOperand(0), And->getOperand(1), "",
4562 BrccUser);
4563 CmpInst *NewCmp =
4564 CmpInst::Create(Cmp->getOpcode(), Cmp->getPredicate(), NewAnd, Zero,
4565 "", BrccUser);
4566 TheUse = NewCmp;
4567 ++NumAndCmpsMoved;
4568 DEBUG(BrccUser->getParent()->dump())do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { BrccUser->getParent()->dump(); } }
while (0);
4569 }
4570 }
4571 return MadeChange;
4572}
4573
4574/// \brief Retrieve the probabilities of a conditional branch. Returns true on
4575/// success, or returns false if no or invalid metadata was found.
4576static bool extractBranchMetadata(BranchInst *BI,
4577 uint64_t &ProbTrue, uint64_t &ProbFalse) {
4578 assert(BI->isConditional() &&((BI->isConditional() && "Looking for probabilities on unconditional branch?"
) ? static_cast<void> (0) : __assert_fail ("BI->isConditional() && \"Looking for probabilities on unconditional branch?\""
, "/tmp/buildd/llvm-toolchain-snapshot-3.7~svn228917/lib/CodeGen/CodeGenPrepare.cpp"
, 4579, __PRETTY_FUNCTION__))
4579 "Looking for probabilities on unconditional branch?")((BI->isConditional() && "Looking for probabilities on unconditional branch?"
) ? static_cast<void> (0) : __assert_fail ("BI->isConditional() && \"Looking for probabilities on unconditional branch?\""
, "/tmp/buildd/llvm-toolchain-snapshot-3.7~svn228917/lib/CodeGen/CodeGenPrepare.cpp"
, 4579, __PRETTY_FUNCTION__));
4580 auto *ProfileData = BI->getMetadata(LLVMContext::MD_prof);
4581 if (!ProfileData || ProfileData->getNumOperands() != 3)
4582 return false;
4583
4584 const auto *CITrue =
4585 mdconst::dyn_extract<ConstantInt>(ProfileData->getOperand(1));
4586 const auto *CIFalse =
4587 mdconst::dyn_extract<ConstantInt>(ProfileData->getOperand(2));
4588 if (!CITrue || !CIFalse)
4589 return false;
4590
4591 ProbTrue = CITrue->getValue().getZExtValue();
4592 ProbFalse = CIFalse->getValue().getZExtValue();
4593
4594 return true;
4595}
4596
4597/// \brief Scale down both weights to fit into uint32_t.
4598static void scaleWeights(uint64_t &NewTrue, uint64_t &NewFalse) {
4599 uint64_t NewMax = (NewTrue > NewFalse) ? NewTrue : NewFalse;
4600 uint32_t Scale = (NewMax / UINT32_MAX(4294967295U)) + 1;
4601 NewTrue = NewTrue / Scale;
4602 NewFalse = NewFalse / Scale;
4603}
4604
4605/// \brief Some targets prefer to split a conditional branch like:
4606/// \code
4607/// %0 = icmp ne i32 %a, 0
4608/// %1 = icmp ne i32 %b, 0
4609/// %or.cond = or i1 %0, %1
4610/// br i1 %or.cond, label %TrueBB, label %FalseBB
4611/// \endcode
4612/// into multiple branch instructions like:
4613/// \code
4614/// bb1:
4615/// %0 = icmp ne i32 %a, 0
4616/// br i1 %0, label %TrueBB, label %bb2
4617/// bb2:
4618/// %1 = icmp ne i32 %b, 0
4619/// br i1 %1, label %TrueBB, label %FalseBB
4620/// \endcode
4621/// This usually allows instruction selection to do even further optimizations
4622/// and combine the compare with the branch instruction. Currently this is
4623/// applied for targets which have "cheap" jump instructions.
4624///
4625/// FIXME: Remove the (equivalent?) implementation in SelectionDAG.
4626///
4627bool CodeGenPrepare::splitBranchCondition(Function &F) {
4628 if (!TM || TM->Options.EnableFastISel != true ||
4629 !TLI || TLI->isJumpExpensive())
4630 return false;
4631
4632 bool MadeChange = false;
4633 for (auto &BB : F) {
4634 // Does this BB end with the following?
4635 // %cond1 = icmp|fcmp|binary instruction ...
4636 // %cond2 = icmp|fcmp|binary instruction ...
4637 // %cond.or = or|and i1 %cond1, cond2
4638 // br i1 %cond.or label %dest1, label %dest2"
4639 BinaryOperator *LogicOp;
4640 BasicBlock *TBB, *FBB;
4641 if (!match(BB.getTerminator(), m_Br(m_OneUse(m_BinOp(LogicOp)), TBB, FBB)))
4642 continue;
4643
4644 unsigned Opc;
4645 Value *Cond1, *Cond2;
4646 if (match(LogicOp, m_And(m_OneUse(m_Value(Cond1)),
4647 m_OneUse(m_Value(Cond2)))))
4648 Opc = Instruction::And;
4649 else if (match(LogicOp, m_Or(m_OneUse(m_Value(Cond1)),
4650 m_OneUse(m_Value(Cond2)))))
4651 Opc = Instruction::Or;
4652 else
4653 continue;
4654
4655 if (!match(Cond1, m_CombineOr(m_Cmp(), m_BinOp())) ||
4656 !match(Cond2, m_CombineOr(m_Cmp(), m_BinOp())) )
4657 continue;
4658
4659 DEBUG(dbgs() << "Before branch condition splitting\n"; BB.dump())do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Before branch condition splitting\n"
; BB.dump(); } } while (0);
4660
4661 // Create a new BB.
4662 auto *InsertBefore = std::next(Function::iterator(BB))
4663 .getNodePtrUnchecked();
4664 auto TmpBB = BasicBlock::Create(BB.getContext(),
4665 BB.getName() + ".cond.split",
4666 BB.getParent(), InsertBefore);
4667
4668 // Update original basic block by using the first condition directly by the
4669 // branch instruction and removing the no longer needed and/or instruction.
4670 auto *Br1 = cast<BranchInst>(BB.getTerminator());
4671 Br1->setCondition(Cond1);
4672 LogicOp->eraseFromParent();
4673
4674 // Depending on the conditon we have to either replace the true or the false
4675 // successor of the original branch instruction.
4676 if (Opc == Instruction::And)
4677 Br1->setSuccessor(0, TmpBB);
4678 else
4679 Br1->setSuccessor(1, TmpBB);
4680
4681 // Fill in the new basic block.
4682 auto *Br2 = IRBuilder<>(TmpBB).CreateCondBr(Cond2, TBB, FBB);
4683 if (auto *I = dyn_cast<Instruction>(Cond2)) {
4684 I->removeFromParent();
4685 I->insertBefore(Br2);
4686 }
4687
4688 // Update PHI nodes in both successors. The original BB needs to be
4689 // replaced in one succesor's PHI nodes, because the branch comes now from
4690 // the newly generated BB (NewBB). In the other successor we need to add one
4691 // incoming edge to the PHI nodes, because both branch instructions target
4692 // now the same successor. Depending on the original branch condition
4693 // (and/or) we have to swap the successors (TrueDest, FalseDest), so that
4694 // we perfrom the correct update for the PHI nodes.
4695 // This doesn't change the successor order of the just created branch
4696 // instruction (or any other instruction).
4697 if (Opc == Instruction::Or)
4698 std::swap(TBB, FBB);
4699
4700 // Replace the old BB with the new BB.
4701 for (auto &I : *TBB) {
4702 PHINode *PN = dyn_cast<PHINode>(&I);
4703 if (!PN)
4704 break;
4705 int i;
4706 while ((i = PN->getBasicBlockIndex(&BB)) >= 0)
4707 PN->setIncomingBlock(i, TmpBB);
4708 }
4709
4710 // Add another incoming edge form the new BB.
4711 for (auto &I : *FBB) {
4712 PHINode *PN = dyn_cast<PHINode>(&I);
4713 if (!PN)
4714 break;
4715 auto *Val = PN->getIncomingValueForBlock(&BB);
4716 PN->addIncoming(Val, TmpBB);
4717 }
4718
4719 // Update the branch weights (from SelectionDAGBuilder::
4720 // FindMergedConditions).
4721 if (Opc == Instruction::Or) {
4722 // Codegen X | Y as:
4723 // BB1:
4724 // jmp_if_X TBB
4725 // jmp TmpBB
4726 // TmpBB:
4727 // jmp_if_Y TBB
4728 // jmp FBB
4729 //
4730
4731 // We have flexibility in setting Prob for BB1 and Prob for NewBB.
4732 // The requirement is that
4733 // TrueProb for BB1 + (FalseProb for BB1 * TrueProb for TmpBB)
4734 // = TrueProb for orignal BB.
4735 // Assuming the orignal weights are A and B, one choice is to set BB1's
4736 // weights to A and A+2B, and set TmpBB's weights to A and 2B. This choice
4737 // assumes that
4738 // TrueProb for BB1 == FalseProb for BB1 * TrueProb for TmpBB.
4739 // Another choice is to assume TrueProb for BB1 equals to TrueProb for
4740 // TmpBB, but the math is more complicated.
4741 uint64_t TrueWeight, FalseWeight;
4742 if (extractBranchMetadata(Br1, TrueWeight, FalseWeight)) {
4743 uint64_t NewTrueWeight = TrueWeight;
4744 uint64_t NewFalseWeight = TrueWeight + 2 * FalseWeight;
4745 scaleWeights(NewTrueWeight, NewFalseWeight);
4746 Br1->setMetadata(LLVMContext::MD_prof, MDBuilder(Br1->getContext())
4747 .createBranchWeights(TrueWeight, FalseWeight));
4748
4749 NewTrueWeight = TrueWeight;
4750 NewFalseWeight = 2 * FalseWeight;
4751 scaleWeights(NewTrueWeight, NewFalseWeight);
4752 Br2->setMetadata(LLVMContext::MD_prof, MDBuilder(Br2->getContext())
4753 .createBranchWeights(TrueWeight, FalseWeight));
4754 }
4755 } else {
4756 // Codegen X & Y as:
4757 // BB1:
4758 // jmp_if_X TmpBB
4759 // jmp FBB
4760 // TmpBB:
4761 // jmp_if_Y TBB
4762 // jmp FBB
4763 //
4764 // This requires creation of TmpBB after CurBB.
4765
4766 // We have flexibility in setting Prob for BB1 and Prob for TmpBB.
4767 // The requirement is that
4768 // FalseProb for BB1 + (TrueProb for BB1 * FalseProb for TmpBB)
4769 // = FalseProb for orignal BB.
4770 // Assuming the orignal weights are A and B, one choice is to set BB1's
4771 // weights to 2A+B and B, and set TmpBB's weights to 2A and B. This choice
4772 // assumes that
4773 // FalseProb for BB1 == TrueProb for BB1 * FalseProb for TmpBB.
4774 uint64_t TrueWeight, FalseWeight;
4775 if (extractBranchMetadata(Br1, TrueWeight, FalseWeight)) {
4776 uint64_t NewTrueWeight = 2 * TrueWeight + FalseWeight;
4777 uint64_t NewFalseWeight = FalseWeight;
4778 scaleWeights(NewTrueWeight, NewFalseWeight);
4779 Br1->setMetadata(LLVMContext::MD_prof, MDBuilder(Br1->getContext())
4780 .createBranchWeights(TrueWeight, FalseWeight));
4781
4782 NewTrueWeight = 2 * TrueWeight;
4783 NewFalseWeight = FalseWeight;
4784 scaleWeights(NewTrueWeight, NewFalseWeight);
4785 Br2->setMetadata(LLVMContext::MD_prof, MDBuilder(Br2->getContext())
4786 .createBranchWeights(TrueWeight, FalseWeight));
4787 }
4788 }
4789
4790 // Request DOM Tree update.
4791 // Note: No point in getting fancy here, since the DT info is never
4792 // available to CodeGenPrepare and the existing update code is broken
4793 // anyways.
4794 ModifiedDT = true;
4795
4796 MadeChange = true;
4797
4798 DEBUG(dbgs() << "After branch condition splitting\n"; BB.dump();do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "After branch condition splitting\n"
; BB.dump(); TmpBB->dump(); } } while (0)
4799 TmpBB->dump())do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "After branch condition splitting\n"
; BB.dump(); TmpBB->dump(); } } while (0);
4800 }
4801 return MadeChange;
4802}