Bug Summary

File:lib/Transforms/IPO/MergeFunctions.cpp
Warning:line 688, column 24
Called C++ object pointer is null

Annotated Source Code

1//===- MergeFunctions.cpp - Merge identical functions ---------------------===//
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 looks for equivalent functions that are mergable and folds them.
11//
12// Order relation is defined on set of functions. It was made through
13// special function comparison procedure that returns
14// 0 when functions are equal,
15// -1 when Left function is less than right function, and
16// 1 for opposite case. We need total-ordering, so we need to maintain
17// four properties on the functions set:
18// a <= a (reflexivity)
19// if a <= b and b <= a then a = b (antisymmetry)
20// if a <= b and b <= c then a <= c (transitivity).
21// for all a and b: a <= b or b <= a (totality).
22//
23// Comparison iterates through each instruction in each basic block.
24// Functions are kept on binary tree. For each new function F we perform
25// lookup in binary tree.
26// In practice it works the following way:
27// -- We define Function* container class with custom "operator<" (FunctionPtr).
28// -- "FunctionPtr" instances are stored in std::set collection, so every
29// std::set::insert operation will give you result in log(N) time.
30//
31// As an optimization, a hash of the function structure is calculated first, and
32// two functions are only compared if they have the same hash. This hash is
33// cheap to compute, and has the property that if function F == G according to
34// the comparison function, then hash(F) == hash(G). This consistency property
35// is critical to ensuring all possible merging opportunities are exploited.
36// Collisions in the hash affect the speed of the pass but not the correctness
37// or determinism of the resulting transformation.
38//
39// When a match is found the functions are folded. If both functions are
40// overridable, we move the functionality into a new internal function and
41// leave two overridable thunks to it.
42//
43//===----------------------------------------------------------------------===//
44//
45// Future work:
46//
47// * virtual functions.
48//
49// Many functions have their address taken by the virtual function table for
50// the object they belong to. However, as long as it's only used for a lookup
51// and call, this is irrelevant, and we'd like to fold such functions.
52//
53// * be smarter about bitcasts.
54//
55// In order to fold functions, we will sometimes add either bitcast instructions
56// or bitcast constant expressions. Unfortunately, this can confound further
57// analysis since the two functions differ where one has a bitcast and the
58// other doesn't. We should learn to look through bitcasts.
59//
60// * Compare complex types with pointer types inside.
61// * Compare cross-reference cases.
62// * Compare complex expressions.
63//
64// All the three issues above could be described as ability to prove that
65// fA == fB == fC == fE == fF == fG in example below:
66//
67// void fA() {
68// fB();
69// }
70// void fB() {
71// fA();
72// }
73//
74// void fE() {
75// fF();
76// }
77// void fF() {
78// fG();
79// }
80// void fG() {
81// fE();
82// }
83//
84// Simplest cross-reference case (fA <--> fB) was implemented in previous
85// versions of MergeFunctions, though it presented only in two function pairs
86// in test-suite (that counts >50k functions)
87// Though possibility to detect complex cross-referencing (e.g.: A->B->C->D->A)
88// could cover much more cases.
89//
90//===----------------------------------------------------------------------===//
91
92#include "llvm/ADT/Hashing.h"
93#include "llvm/ADT/STLExtras.h"
94#include "llvm/ADT/SmallSet.h"
95#include "llvm/ADT/Statistic.h"
96#include "llvm/IR/CallSite.h"
97#include "llvm/IR/Constants.h"
98#include "llvm/IR/DataLayout.h"
99#include "llvm/IR/DebugInfo.h"
100#include "llvm/IR/IRBuilder.h"
101#include "llvm/IR/Instructions.h"
102#include "llvm/IR/IntrinsicInst.h"
103#include "llvm/IR/LLVMContext.h"
104#include "llvm/IR/Module.h"
105#include "llvm/IR/ValueHandle.h"
106#include "llvm/IR/ValueMap.h"
107#include "llvm/Pass.h"
108#include "llvm/Support/CommandLine.h"
109#include "llvm/Support/Debug.h"
110#include "llvm/Support/ErrorHandling.h"
111#include "llvm/Support/raw_ostream.h"
112#include "llvm/Transforms/IPO.h"
113#include "llvm/Transforms/Utils/FunctionComparator.h"
114#include <vector>
115
116using namespace llvm;
117
118#define DEBUG_TYPE"mergefunc" "mergefunc"
119
120STATISTIC(NumFunctionsMerged, "Number of functions merged")static llvm::Statistic NumFunctionsMerged = {"mergefunc", "NumFunctionsMerged"
, "Number of functions merged", {0}, false}
;
121STATISTIC(NumThunksWritten, "Number of thunks generated")static llvm::Statistic NumThunksWritten = {"mergefunc", "NumThunksWritten"
, "Number of thunks generated", {0}, false}
;
122STATISTIC(NumAliasesWritten, "Number of aliases generated")static llvm::Statistic NumAliasesWritten = {"mergefunc", "NumAliasesWritten"
, "Number of aliases generated", {0}, false}
;
123STATISTIC(NumDoubleWeak, "Number of new functions created")static llvm::Statistic NumDoubleWeak = {"mergefunc", "NumDoubleWeak"
, "Number of new functions created", {0}, false}
;
124
125static cl::opt<unsigned> NumFunctionsForSanityCheck(
126 "mergefunc-sanity",
127 cl::desc("How many functions in module could be used for "
128 "MergeFunctions pass sanity check. "
129 "'0' disables this check. Works only with '-debug' key."),
130 cl::init(0), cl::Hidden);
131
132// Under option -mergefunc-preserve-debug-info we:
133// - Do not create a new function for a thunk.
134// - Retain the debug info for a thunk's parameters (and associated
135// instructions for the debug info) from the entry block.
136// Note: -debug will display the algorithm at work.
137// - Create debug-info for the call (to the shared implementation) made by
138// a thunk and its return value.
139// - Erase the rest of the function, retaining the (minimally sized) entry
140// block to create a thunk.
141// - Preserve a thunk's call site to point to the thunk even when both occur
142// within the same translation unit, to aid debugability. Note that this
143// behaviour differs from the underlying -mergefunc implementation which
144// modifies the thunk's call site to point to the shared implementation
145// when both occur within the same translation unit.
146static cl::opt<bool>
147 MergeFunctionsPDI("mergefunc-preserve-debug-info", cl::Hidden,
148 cl::init(false),
149 cl::desc("Preserve debug info in thunk when mergefunc "
150 "transformations are made."));
151
152namespace {
153
154class FunctionNode {
155 mutable AssertingVH<Function> F;
156 FunctionComparator::FunctionHash Hash;
157public:
158 // Note the hash is recalculated potentially multiple times, but it is cheap.
159 FunctionNode(Function *F)
160 : F(F), Hash(FunctionComparator::functionHash(*F)) {}
161 Function *getFunc() const { return F; }
162 FunctionComparator::FunctionHash getHash() const { return Hash; }
163
164 /// Replace the reference to the function F by the function G, assuming their
165 /// implementations are equal.
166 void replaceBy(Function *G) const {
167 F = G;
168 }
169
170 void release() { F = nullptr; }
171};
172
173/// MergeFunctions finds functions which will generate identical machine code,
174/// by considering all pointer types to be equivalent. Once identified,
175/// MergeFunctions will fold them by replacing a call to one to a call to a
176/// bitcast of the other.
177///
178class MergeFunctions : public ModulePass {
179public:
180 static char ID;
181 MergeFunctions()
182 : ModulePass(ID), FnTree(FunctionNodeCmp(&GlobalNumbers)), FNodesInTree(),
183 HasGlobalAliases(false) {
184 initializeMergeFunctionsPass(*PassRegistry::getPassRegistry());
185 }
186
187 bool runOnModule(Module &M) override;
188
189private:
190 // The function comparison operator is provided here so that FunctionNodes do
191 // not need to become larger with another pointer.
192 class FunctionNodeCmp {
193 GlobalNumberState* GlobalNumbers;
194 public:
195 FunctionNodeCmp(GlobalNumberState* GN) : GlobalNumbers(GN) {}
196 bool operator()(const FunctionNode &LHS, const FunctionNode &RHS) const {
197 // Order first by hashes, then full function comparison.
198 if (LHS.getHash() != RHS.getHash())
199 return LHS.getHash() < RHS.getHash();
200 FunctionComparator FCmp(LHS.getFunc(), RHS.getFunc(), GlobalNumbers);
201 return FCmp.compare() == -1;
202 }
203 };
204 typedef std::set<FunctionNode, FunctionNodeCmp> FnTreeType;
205
206 GlobalNumberState GlobalNumbers;
207
208 /// A work queue of functions that may have been modified and should be
209 /// analyzed again.
210 std::vector<WeakVH> Deferred;
211
212 /// Checks the rules of order relation introduced among functions set.
213 /// Returns true, if sanity check has been passed, and false if failed.
214 bool doSanityCheck(std::vector<WeakVH> &Worklist);
215
216 /// Insert a ComparableFunction into the FnTree, or merge it away if it's
217 /// equal to one that's already present.
218 bool insert(Function *NewFunction);
219
220 /// Remove a Function from the FnTree and queue it up for a second sweep of
221 /// analysis.
222 void remove(Function *F);
223
224 /// Find the functions that use this Value and remove them from FnTree and
225 /// queue the functions.
226 void removeUsers(Value *V);
227
228 /// Replace all direct calls of Old with calls of New. Will bitcast New if
229 /// necessary to make types match.
230 void replaceDirectCallers(Function *Old, Function *New);
231
232 /// Merge two equivalent functions. Upon completion, G may be deleted, or may
233 /// be converted into a thunk. In either case, it should never be visited
234 /// again.
235 void mergeTwoFunctions(Function *F, Function *G);
236
237 /// Replace G with a thunk or an alias to F. Deletes G.
238 void writeThunkOrAlias(Function *F, Function *G);
239
240 /// Fill PDIUnrelatedWL with instructions from the entry block that are
241 /// unrelated to parameter related debug info.
242 void filterInstsUnrelatedToPDI(BasicBlock *GEntryBlock,
243 std::vector<Instruction *> &PDIUnrelatedWL);
244
245 /// Erase the rest of the CFG (i.e. barring the entry block).
246 void eraseTail(Function *G);
247
248 /// Erase the instructions in PDIUnrelatedWL as they are unrelated to the
249 /// parameter debug info, from the entry block.
250 void eraseInstsUnrelatedToPDI(std::vector<Instruction *> &PDIUnrelatedWL);
251
252 /// Replace G with a simple tail call to bitcast(F). Also (unless
253 /// MergeFunctionsPDI holds) replace direct uses of G with bitcast(F),
254 /// delete G.
255 void writeThunk(Function *F, Function *G);
256
257 /// Replace G with an alias to F. Deletes G.
258 void writeAlias(Function *F, Function *G);
259
260 /// Replace function F with function G in the function tree.
261 void replaceFunctionInTree(const FunctionNode &FN, Function *G);
262
263 /// The set of all distinct functions. Use the insert() and remove() methods
264 /// to modify it. The map allows efficient lookup and deferring of Functions.
265 FnTreeType FnTree;
266 // Map functions to the iterators of the FunctionNode which contains them
267 // in the FnTree. This must be updated carefully whenever the FnTree is
268 // modified, i.e. in insert(), remove(), and replaceFunctionInTree(), to avoid
269 // dangling iterators into FnTree. The invariant that preserves this is that
270 // there is exactly one mapping F -> FN for each FunctionNode FN in FnTree.
271 ValueMap<Function*, FnTreeType::iterator> FNodesInTree;
272
273 /// Whether or not the target supports global aliases.
274 bool HasGlobalAliases;
275};
276
277} // end anonymous namespace
278
279char MergeFunctions::ID = 0;
280INITIALIZE_PASS(MergeFunctions, "mergefunc", "Merge Functions", false, false)static void *initializeMergeFunctionsPassOnce(PassRegistry &
Registry) { PassInfo *PI = new PassInfo( "Merge Functions", "mergefunc"
, &MergeFunctions::ID, PassInfo::NormalCtor_t(callDefaultCtor
<MergeFunctions>), false, false); Registry.registerPass
(*PI, true); return PI; } static llvm::once_flag InitializeMergeFunctionsPassFlag
; void llvm::initializeMergeFunctionsPass(PassRegistry &Registry
) { llvm::call_once(InitializeMergeFunctionsPassFlag, initializeMergeFunctionsPassOnce
, std::ref(Registry)); }
281
282ModulePass *llvm::createMergeFunctionsPass() {
283 return new MergeFunctions();
284}
285
286bool MergeFunctions::doSanityCheck(std::vector<WeakVH> &Worklist) {
287 if (const unsigned Max = NumFunctionsForSanityCheck) {
288 unsigned TripleNumber = 0;
289 bool Valid = true;
290
291 dbgs() << "MERGEFUNC-SANITY: Started for first " << Max << " functions.\n";
292
293 unsigned i = 0;
294 for (std::vector<WeakVH>::iterator I = Worklist.begin(), E = Worklist.end();
295 I != E && i < Max; ++I, ++i) {
296 unsigned j = i;
297 for (std::vector<WeakVH>::iterator J = I; J != E && j < Max; ++J, ++j) {
298 Function *F1 = cast<Function>(*I);
299 Function *F2 = cast<Function>(*J);
300 int Res1 = FunctionComparator(F1, F2, &GlobalNumbers).compare();
301 int Res2 = FunctionComparator(F2, F1, &GlobalNumbers).compare();
302
303 // If F1 <= F2, then F2 >= F1, otherwise report failure.
304 if (Res1 != -Res2) {
305 dbgs() << "MERGEFUNC-SANITY: Non-symmetric; triple: " << TripleNumber
306 << "\n";
307 dbgs() << *F1 << '\n' << *F2 << '\n';
308 Valid = false;
309 }
310
311 if (Res1 == 0)
312 continue;
313
314 unsigned k = j;
315 for (std::vector<WeakVH>::iterator K = J; K != E && k < Max;
316 ++k, ++K, ++TripleNumber) {
317 if (K == J)
318 continue;
319
320 Function *F3 = cast<Function>(*K);
321 int Res3 = FunctionComparator(F1, F3, &GlobalNumbers).compare();
322 int Res4 = FunctionComparator(F2, F3, &GlobalNumbers).compare();
323
324 bool Transitive = true;
325
326 if (Res1 != 0 && Res1 == Res4) {
327 // F1 > F2, F2 > F3 => F1 > F3
328 Transitive = Res3 == Res1;
329 } else if (Res3 != 0 && Res3 == -Res4) {
330 // F1 > F3, F3 > F2 => F1 > F2
331 Transitive = Res3 == Res1;
332 } else if (Res4 != 0 && -Res3 == Res4) {
333 // F2 > F3, F3 > F1 => F2 > F1
334 Transitive = Res4 == -Res1;
335 }
336
337 if (!Transitive) {
338 dbgs() << "MERGEFUNC-SANITY: Non-transitive; triple: "
339 << TripleNumber << "\n";
340 dbgs() << "Res1, Res3, Res4: " << Res1 << ", " << Res3 << ", "
341 << Res4 << "\n";
342 dbgs() << *F1 << '\n' << *F2 << '\n' << *F3 << '\n';
343 Valid = false;
344 }
345 }
346 }
347 }
348
349 dbgs() << "MERGEFUNC-SANITY: " << (Valid ? "Passed." : "Failed.") << "\n";
350 return Valid;
351 }
352 return true;
353}
354
355bool MergeFunctions::runOnModule(Module &M) {
356 if (skipModule(M))
357 return false;
358
359 bool Changed = false;
360
361 // All functions in the module, ordered by hash. Functions with a unique
362 // hash value are easily eliminated.
363 std::vector<std::pair<FunctionComparator::FunctionHash, Function *>>
364 HashedFuncs;
365 for (Function &Func : M) {
366 if (!Func.isDeclaration() && !Func.hasAvailableExternallyLinkage()) {
367 HashedFuncs.push_back({FunctionComparator::functionHash(Func), &Func});
368 }
369 }
370
371 std::stable_sort(
372 HashedFuncs.begin(), HashedFuncs.end(),
373 [](const std::pair<FunctionComparator::FunctionHash, Function *> &a,
374 const std::pair<FunctionComparator::FunctionHash, Function *> &b) {
375 return a.first < b.first;
376 });
377
378 auto S = HashedFuncs.begin();
379 for (auto I = HashedFuncs.begin(), IE = HashedFuncs.end(); I != IE; ++I) {
380 // If the hash value matches the previous value or the next one, we must
381 // consider merging it. Otherwise it is dropped and never considered again.
382 if ((I != S && std::prev(I)->first == I->first) ||
383 (std::next(I) != IE && std::next(I)->first == I->first) ) {
384 Deferred.push_back(WeakVH(I->second));
385 }
386 }
387
388 do {
389 std::vector<WeakVH> Worklist;
390 Deferred.swap(Worklist);
391
392 DEBUG(doSanityCheck(Worklist))do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("mergefunc")) { doSanityCheck(Worklist); } } while (false)
;
393
394 DEBUG(dbgs() << "size of module: " << M.size() << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("mergefunc")) { dbgs() << "size of module: " << M
.size() << '\n'; } } while (false)
;
395 DEBUG(dbgs() << "size of worklist: " << Worklist.size() << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("mergefunc")) { dbgs() << "size of worklist: " <<
Worklist.size() << '\n'; } } while (false)
;
396
397 // Insert functions and merge them.
398 for (WeakVH &I : Worklist) {
399 if (!I)
400 continue;
401 Function *F = cast<Function>(I);
402 if (!F->isDeclaration() && !F->hasAvailableExternallyLinkage()) {
403 Changed |= insert(F);
404 }
405 }
406 DEBUG(dbgs() << "size of FnTree: " << FnTree.size() << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("mergefunc")) { dbgs() << "size of FnTree: " << FnTree
.size() << '\n'; } } while (false)
;
407 } while (!Deferred.empty());
408
409 FnTree.clear();
410 GlobalNumbers.clear();
411
412 return Changed;
413}
414
415// Replace direct callers of Old with New.
416void MergeFunctions::replaceDirectCallers(Function *Old, Function *New) {
417 Constant *BitcastNew = ConstantExpr::getBitCast(New, Old->getType());
418 for (auto UI = Old->use_begin(), UE = Old->use_end(); UI != UE;) {
419 Use *U = &*UI;
420 ++UI;
421 CallSite CS(U->getUser());
422 if (CS && CS.isCallee(U)) {
423 // Transfer the called function's attributes to the call site. Due to the
424 // bitcast we will 'lose' ABI changing attributes because the 'called
425 // function' is no longer a Function* but the bitcast. Code that looks up
426 // the attributes from the called function will fail.
427
428 // FIXME: This is not actually true, at least not anymore. The callsite
429 // will always have the same ABI affecting attributes as the callee,
430 // because otherwise the original input has UB. Note that Old and New
431 // always have matching ABI, so no attributes need to be changed.
432 // Transferring other attributes may help other optimizations, but that
433 // should be done uniformly and not in this ad-hoc way.
434 auto &Context = New->getContext();
435 auto NewPAL = New->getAttributes();
436 SmallVector<AttributeSet, 4> NewArgAttrs;
437 for (unsigned argIdx = 0; argIdx < CS.arg_size(); argIdx++)
438 NewArgAttrs.push_back(NewPAL.getParamAttributes(argIdx));
439 // Don't transfer attributes from the function to the callee. Function
440 // attributes typically aren't relevant to the calling convention or ABI.
441 CS.setAttributes(AttributeList::get(Context, /*FnAttrs=*/AttributeSet(),
442 NewPAL.getRetAttributes(),
443 NewArgAttrs));
444
445 remove(CS.getInstruction()->getParent()->getParent());
446 U->set(BitcastNew);
447 }
448 }
449}
450
451// Replace G with an alias to F if possible, or else a thunk to F. Deletes G.
452void MergeFunctions::writeThunkOrAlias(Function *F, Function *G) {
453 if (HasGlobalAliases && G->hasGlobalUnnamedAddr()) {
454 if (G->hasExternalLinkage() || G->hasLocalLinkage() ||
455 G->hasWeakLinkage()) {
456 writeAlias(F, G);
457 return;
458 }
459 }
460
461 writeThunk(F, G);
462}
463
464// Helper for writeThunk,
465// Selects proper bitcast operation,
466// but a bit simpler then CastInst::getCastOpcode.
467static Value *createCast(IRBuilder<> &Builder, Value *V, Type *DestTy) {
468 Type *SrcTy = V->getType();
469 if (SrcTy->isStructTy()) {
470 assert(DestTy->isStructTy())((DestTy->isStructTy()) ? static_cast<void> (0) : __assert_fail
("DestTy->isStructTy()", "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn301389/lib/Transforms/IPO/MergeFunctions.cpp"
, 470, __PRETTY_FUNCTION__))
;
471 assert(SrcTy->getStructNumElements() == DestTy->getStructNumElements())((SrcTy->getStructNumElements() == DestTy->getStructNumElements
()) ? static_cast<void> (0) : __assert_fail ("SrcTy->getStructNumElements() == DestTy->getStructNumElements()"
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn301389/lib/Transforms/IPO/MergeFunctions.cpp"
, 471, __PRETTY_FUNCTION__))
;
472 Value *Result = UndefValue::get(DestTy);
473 for (unsigned int I = 0, E = SrcTy->getStructNumElements(); I < E; ++I) {
474 Value *Element = createCast(
475 Builder, Builder.CreateExtractValue(V, makeArrayRef(I)),
476 DestTy->getStructElementType(I));
477
478 Result =
479 Builder.CreateInsertValue(Result, Element, makeArrayRef(I));
480 }
481 return Result;
482 }
483 assert(!DestTy->isStructTy())((!DestTy->isStructTy()) ? static_cast<void> (0) : __assert_fail
("!DestTy->isStructTy()", "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn301389/lib/Transforms/IPO/MergeFunctions.cpp"
, 483, __PRETTY_FUNCTION__))
;
484 if (SrcTy->isIntegerTy() && DestTy->isPointerTy())
485 return Builder.CreateIntToPtr(V, DestTy);
486 else if (SrcTy->isPointerTy() && DestTy->isIntegerTy())
487 return Builder.CreatePtrToInt(V, DestTy);
488 else
489 return Builder.CreateBitCast(V, DestTy);
490}
491
492// Erase the instructions in PDIUnrelatedWL as they are unrelated to the
493// parameter debug info, from the entry block.
494void MergeFunctions::eraseInstsUnrelatedToPDI(
495 std::vector<Instruction *> &PDIUnrelatedWL) {
496
497 DEBUG(dbgs() << " Erasing instructions (in reverse order of appearance in "do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("mergefunc")) { dbgs() << " Erasing instructions (in reverse order of appearance in "
"entry block) unrelated to parameter debug info from entry "
"block: {\n"; } } while (false)
498 "entry block) unrelated to parameter debug info from entry "do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("mergefunc")) { dbgs() << " Erasing instructions (in reverse order of appearance in "
"entry block) unrelated to parameter debug info from entry "
"block: {\n"; } } while (false)
499 "block: {\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("mergefunc")) { dbgs() << " Erasing instructions (in reverse order of appearance in "
"entry block) unrelated to parameter debug info from entry "
"block: {\n"; } } while (false)
;
500 while (!PDIUnrelatedWL.empty()) {
501 Instruction *I = PDIUnrelatedWL.back();
502 DEBUG(dbgs() << " Deleting Instruction: ")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("mergefunc")) { dbgs() << " Deleting Instruction: "; }
} while (false)
;
503 DEBUG(I->print(dbgs()))do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("mergefunc")) { I->print(dbgs()); } } while (false)
;
504 DEBUG(dbgs() << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("mergefunc")) { dbgs() << "\n"; } } while (false)
;
505 I->eraseFromParent();
506 PDIUnrelatedWL.pop_back();
507 }
508 DEBUG(dbgs() << " } // Done erasing instructions unrelated to parameter "do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("mergefunc")) { dbgs() << " } // Done erasing instructions unrelated to parameter "
"debug info from entry block. \n"; } } while (false)
509 "debug info from entry block. \n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("mergefunc")) { dbgs() << " } // Done erasing instructions unrelated to parameter "
"debug info from entry block. \n"; } } while (false)
;
510}
511
512// Reduce G to its entry block.
513void MergeFunctions::eraseTail(Function *G) {
514
515 std::vector<BasicBlock *> WorklistBB;
516 for (Function::iterator BBI = std::next(G->begin()), BBE = G->end();
517 BBI != BBE; ++BBI) {
518 BBI->dropAllReferences();
519 WorklistBB.push_back(&*BBI);
520 }
521 while (!WorklistBB.empty()) {
522 BasicBlock *BB = WorklistBB.back();
523 BB->eraseFromParent();
524 WorklistBB.pop_back();
525 }
526}
527
528// We are interested in the following instructions from the entry block as being
529// related to parameter debug info:
530// - @llvm.dbg.declare
531// - stores from the incoming parameters to locations on the stack-frame
532// - allocas that create these locations on the stack-frame
533// - @llvm.dbg.value
534// - the entry block's terminator
535// The rest are unrelated to debug info for the parameters; fill up
536// PDIUnrelatedWL with such instructions.
537void MergeFunctions::filterInstsUnrelatedToPDI(
538 BasicBlock *GEntryBlock, std::vector<Instruction *> &PDIUnrelatedWL) {
539
540 std::set<Instruction *> PDIRelated;
541 for (BasicBlock::iterator BI = GEntryBlock->begin(), BIE = GEntryBlock->end();
542 BI != BIE; ++BI) {
543 if (auto *DVI = dyn_cast<DbgValueInst>(&*BI)) {
544 DEBUG(dbgs() << " Deciding: ")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("mergefunc")) { dbgs() << " Deciding: "; } } while (false
)
;
545 DEBUG(BI->print(dbgs()))do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("mergefunc")) { BI->print(dbgs()); } } while (false)
;
546 DEBUG(dbgs() << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("mergefunc")) { dbgs() << "\n"; } } while (false)
;
547 DILocalVariable *DILocVar = DVI->getVariable();
548 if (DILocVar->isParameter()) {
549 DEBUG(dbgs() << " Include (parameter): ")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("mergefunc")) { dbgs() << " Include (parameter): "; }
} while (false)
;
550 DEBUG(BI->print(dbgs()))do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("mergefunc")) { BI->print(dbgs()); } } while (false)
;
551 DEBUG(dbgs() << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("mergefunc")) { dbgs() << "\n"; } } while (false)
;
552 PDIRelated.insert(&*BI);
553 } else {
554 DEBUG(dbgs() << " Delete (!parameter): ")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("mergefunc")) { dbgs() << " Delete (!parameter): "; }
} while (false)
;
555 DEBUG(BI->print(dbgs()))do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("mergefunc")) { BI->print(dbgs()); } } while (false)
;
556 DEBUG(dbgs() << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("mergefunc")) { dbgs() << "\n"; } } while (false)
;
557 }
558 } else if (auto *DDI = dyn_cast<DbgDeclareInst>(&*BI)) {
559 DEBUG(dbgs() << " Deciding: ")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("mergefunc")) { dbgs() << " Deciding: "; } } while (false
)
;
560 DEBUG(BI->print(dbgs()))do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("mergefunc")) { BI->print(dbgs()); } } while (false)
;
561 DEBUG(dbgs() << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("mergefunc")) { dbgs() << "\n"; } } while (false)
;
562 DILocalVariable *DILocVar = DDI->getVariable();
563 if (DILocVar->isParameter()) {
564 DEBUG(dbgs() << " Parameter: ")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("mergefunc")) { dbgs() << " Parameter: "; } } while (
false)
;
565 DEBUG(DILocVar->print(dbgs()))do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("mergefunc")) { DILocVar->print(dbgs()); } } while (false
)
;
566 AllocaInst *AI = dyn_cast_or_null<AllocaInst>(DDI->getAddress());
567 if (AI) {
568 DEBUG(dbgs() << " Processing alloca users: ")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("mergefunc")) { dbgs() << " Processing alloca users: "
; } } while (false)
;
569 DEBUG(dbgs() << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("mergefunc")) { dbgs() << "\n"; } } while (false)
;
570 for (User *U : AI->users()) {
571 if (StoreInst *SI = dyn_cast<StoreInst>(U)) {
572 if (Value *Arg = SI->getValueOperand()) {
573 if (dyn_cast<Argument>(Arg)) {
574 DEBUG(dbgs() << " Include: ")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("mergefunc")) { dbgs() << " Include: "; } } while (false
)
;
575 DEBUG(AI->print(dbgs()))do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("mergefunc")) { AI->print(dbgs()); } } while (false)
;
576 DEBUG(dbgs() << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("mergefunc")) { dbgs() << "\n"; } } while (false)
;
577 PDIRelated.insert(AI);
578 DEBUG(dbgs() << " Include (parameter): ")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("mergefunc")) { dbgs() << " Include (parameter): "; }
} while (false)
;
579 DEBUG(SI->print(dbgs()))do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("mergefunc")) { SI->print(dbgs()); } } while (false)
;
580 DEBUG(dbgs() << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("mergefunc")) { dbgs() << "\n"; } } while (false)
;
581 PDIRelated.insert(SI);
582 DEBUG(dbgs() << " Include: ")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("mergefunc")) { dbgs() << " Include: "; } } while (false
)
;
583 DEBUG(BI->print(dbgs()))do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("mergefunc")) { BI->print(dbgs()); } } while (false)
;
584 DEBUG(dbgs() << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("mergefunc")) { dbgs() << "\n"; } } while (false)
;
585 PDIRelated.insert(&*BI);
586 } else {
587 DEBUG(dbgs() << " Delete (!parameter): ")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("mergefunc")) { dbgs() << " Delete (!parameter): "; }
} while (false)
;
588 DEBUG(SI->print(dbgs()))do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("mergefunc")) { SI->print(dbgs()); } } while (false)
;
589 DEBUG(dbgs() << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("mergefunc")) { dbgs() << "\n"; } } while (false)
;
590 }
591 }
592 } else {
593 DEBUG(dbgs() << " Defer: ")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("mergefunc")) { dbgs() << " Defer: "; } } while (false
)
;
594 DEBUG(U->print(dbgs()))do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("mergefunc")) { U->print(dbgs()); } } while (false)
;
595 DEBUG(dbgs() << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("mergefunc")) { dbgs() << "\n"; } } while (false)
;
596 }
597 }
598 } else {
599 DEBUG(dbgs() << " Delete (alloca NULL): ")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("mergefunc")) { dbgs() << " Delete (alloca NULL): "; }
} while (false)
;
600 DEBUG(BI->print(dbgs()))do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("mergefunc")) { BI->print(dbgs()); } } while (false)
;
601 DEBUG(dbgs() << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("mergefunc")) { dbgs() << "\n"; } } while (false)
;
602 }
603 } else {
604 DEBUG(dbgs() << " Delete (!parameter): ")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("mergefunc")) { dbgs() << " Delete (!parameter): "; }
} while (false)
;
605 DEBUG(BI->print(dbgs()))do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("mergefunc")) { BI->print(dbgs()); } } while (false)
;
606 DEBUG(dbgs() << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("mergefunc")) { dbgs() << "\n"; } } while (false)
;
607 }
608 } else if (dyn_cast<TerminatorInst>(BI) == GEntryBlock->getTerminator()) {
609 DEBUG(dbgs() << " Will Include Terminator: ")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("mergefunc")) { dbgs() << " Will Include Terminator: "
; } } while (false)
;
610 DEBUG(BI->print(dbgs()))do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("mergefunc")) { BI->print(dbgs()); } } while (false)
;
611 DEBUG(dbgs() << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("mergefunc")) { dbgs() << "\n"; } } while (false)
;
612 PDIRelated.insert(&*BI);
613 } else {
614 DEBUG(dbgs() << " Defer: ")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("mergefunc")) { dbgs() << " Defer: "; } } while (false
)
;
615 DEBUG(BI->print(dbgs()))do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("mergefunc")) { BI->print(dbgs()); } } while (false)
;
616 DEBUG(dbgs() << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("mergefunc")) { dbgs() << "\n"; } } while (false)
;
617 }
618 }
619 DEBUG(dbgs()do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("mergefunc")) { dbgs() << " Report parameter debug info related/related instructions: {\n"
; } } while (false)
620 << " Report parameter debug info related/related instructions: {\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("mergefunc")) { dbgs() << " Report parameter debug info related/related instructions: {\n"
; } } while (false)
;
621 for (BasicBlock::iterator BI = GEntryBlock->begin(), BE = GEntryBlock->end();
622 BI != BE; ++BI) {
623
624 Instruction *I = &*BI;
625 if (PDIRelated.find(I) == PDIRelated.end()) {
626 DEBUG(dbgs() << " !PDIRelated: ")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("mergefunc")) { dbgs() << " !PDIRelated: "; } } while
(false)
;
627 DEBUG(I->print(dbgs()))do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("mergefunc")) { I->print(dbgs()); } } while (false)
;
628 DEBUG(dbgs() << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("mergefunc")) { dbgs() << "\n"; } } while (false)
;
629 PDIUnrelatedWL.push_back(I);
630 } else {
631 DEBUG(dbgs() << " PDIRelated: ")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("mergefunc")) { dbgs() << " PDIRelated: "; } } while
(false)
;
632 DEBUG(I->print(dbgs()))do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("mergefunc")) { I->print(dbgs()); } } while (false)
;
633 DEBUG(dbgs() << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("mergefunc")) { dbgs() << "\n"; } } while (false)
;
634 }
635 }
636 DEBUG(dbgs() << " }\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("mergefunc")) { dbgs() << " }\n"; } } while (false)
;
637}
638
639// Replace G with a simple tail call to bitcast(F). Also (unless
640// MergeFunctionsPDI holds) replace direct uses of G with bitcast(F),
641// delete G. Under MergeFunctionsPDI, we use G itself for creating
642// the thunk as we preserve the debug info (and associated instructions)
643// from G's entry block pertaining to G's incoming arguments which are
644// passed on as corresponding arguments in the call that G makes to F.
645// For better debugability, under MergeFunctionsPDI, we do not modify G's
646// call sites to point to F even when within the same translation unit.
647void MergeFunctions::writeThunk(Function *F, Function *G) {
648 if (!G->isInterposable() && !MergeFunctionsPDI) {
1
Assuming the condition is false
2
Taking false branch
649 // Redirect direct callers of G to F. (See note on MergeFunctionsPDI
650 // above).
651 replaceDirectCallers(G, F);
652 }
653
654 // If G was internal then we may have replaced all uses of G with F. If so,
655 // stop here and delete G. There's no need for a thunk. (See note on
656 // MergeFunctionsPDI above).
657 if (G->hasLocalLinkage() && G->use_empty() && !MergeFunctionsPDI) {
658 G->eraseFromParent();
659 return;
660 }
661
662 BasicBlock *GEntryBlock = nullptr;
663 std::vector<Instruction *> PDIUnrelatedWL;
664 BasicBlock *BB = nullptr;
665 Function *NewG = nullptr;
3
'NewG' initialized to a null pointer value
666 if (MergeFunctionsPDI) {
4
Taking true branch
667 DEBUG(dbgs() << "writeThunk: (MergeFunctionsPDI) Do not create a new "do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("mergefunc")) { dbgs() << "writeThunk: (MergeFunctionsPDI) Do not create a new "
"function as thunk; retain original: " << G->getName
() << "()\n"; } } while (false)
668 "function as thunk; retain original: "do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("mergefunc")) { dbgs() << "writeThunk: (MergeFunctionsPDI) Do not create a new "
"function as thunk; retain original: " << G->getName
() << "()\n"; } } while (false)
669 << G->getName() << "()\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("mergefunc")) { dbgs() << "writeThunk: (MergeFunctionsPDI) Do not create a new "
"function as thunk; retain original: " << G->getName
() << "()\n"; } } while (false)
;
670 GEntryBlock = &G->getEntryBlock();
671 DEBUG(dbgs() << "writeThunk: (MergeFunctionsPDI) filter parameter related "do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("mergefunc")) { dbgs() << "writeThunk: (MergeFunctionsPDI) filter parameter related "
"debug info for " << G->getName() << "() {\n"
; } } while (false)
672 "debug info for "do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("mergefunc")) { dbgs() << "writeThunk: (MergeFunctionsPDI) filter parameter related "
"debug info for " << G->getName() << "() {\n"
; } } while (false)
673 << G->getName() << "() {\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("mergefunc")) { dbgs() << "writeThunk: (MergeFunctionsPDI) filter parameter related "
"debug info for " << G->getName() << "() {\n"
; } } while (false)
;
674 filterInstsUnrelatedToPDI(GEntryBlock, PDIUnrelatedWL);
675 GEntryBlock->getTerminator()->eraseFromParent();
676 BB = GEntryBlock;
677 } else {
678 NewG = Function::Create(G->getFunctionType(), G->getLinkage(), "",
679 G->getParent());
680 BB = BasicBlock::Create(F->getContext(), "", NewG);
681 }
682
683 IRBuilder<> Builder(BB);
684 Function *H = MergeFunctionsPDI ? G : NewG;
5
Assuming the condition is false
6
'?' condition is false
7
'H' initialized to a null pointer value
685 SmallVector<Value *, 16> Args;
686 unsigned i = 0;
687 FunctionType *FFTy = F->getFunctionType();
688 for (Argument & AI : H->args()) {
8
Called C++ object pointer is null
689 Args.push_back(createCast(Builder, &AI, FFTy->getParamType(i)));
690 ++i;
691 }
692
693 CallInst *CI = Builder.CreateCall(F, Args);
694 ReturnInst *RI = nullptr;
695 CI->setTailCall();
696 CI->setCallingConv(F->getCallingConv());
697 CI->setAttributes(F->getAttributes());
698 if (H->getReturnType()->isVoidTy()) {
699 RI = Builder.CreateRetVoid();
700 } else {
701 RI = Builder.CreateRet(createCast(Builder, CI, H->getReturnType()));
702 }
703
704 if (MergeFunctionsPDI) {
705 DISubprogram *DIS = G->getSubprogram();
706 if (DIS) {
707 DebugLoc CIDbgLoc = DebugLoc::get(DIS->getScopeLine(), 0, DIS);
708 DebugLoc RIDbgLoc = DebugLoc::get(DIS->getScopeLine(), 0, DIS);
709 CI->setDebugLoc(CIDbgLoc);
710 RI->setDebugLoc(RIDbgLoc);
711 } else {
712 DEBUG(dbgs() << "writeThunk: (MergeFunctionsPDI) No DISubprogram for "do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("mergefunc")) { dbgs() << "writeThunk: (MergeFunctionsPDI) No DISubprogram for "
<< G->getName() << "()\n"; } } while (false)
713 << G->getName() << "()\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("mergefunc")) { dbgs() << "writeThunk: (MergeFunctionsPDI) No DISubprogram for "
<< G->getName() << "()\n"; } } while (false)
;
714 }
715 eraseTail(G);
716 eraseInstsUnrelatedToPDI(PDIUnrelatedWL);
717 DEBUG(dbgs() << "} // End of parameter related debug info filtering for: "do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("mergefunc")) { dbgs() << "} // End of parameter related debug info filtering for: "
<< G->getName() << "()\n"; } } while (false)
718 << G->getName() << "()\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("mergefunc")) { dbgs() << "} // End of parameter related debug info filtering for: "
<< G->getName() << "()\n"; } } while (false)
;
719 } else {
720 NewG->copyAttributesFrom(G);
721 NewG->takeName(G);
722 removeUsers(G);
723 G->replaceAllUsesWith(NewG);
724 G->eraseFromParent();
725 }
726
727 DEBUG(dbgs() << "writeThunk: " << H->getName() << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("mergefunc")) { dbgs() << "writeThunk: " << H->
getName() << '\n'; } } while (false)
;
728 ++NumThunksWritten;
729}
730
731// Replace G with an alias to F and delete G.
732void MergeFunctions::writeAlias(Function *F, Function *G) {
733 auto *GA = GlobalAlias::create(G->getLinkage(), "", F);
734 F->setAlignment(std::max(F->getAlignment(), G->getAlignment()));
735 GA->takeName(G);
736 GA->setVisibility(G->getVisibility());
737 removeUsers(G);
738 G->replaceAllUsesWith(GA);
739 G->eraseFromParent();
740
741 DEBUG(dbgs() << "writeAlias: " << GA->getName() << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("mergefunc")) { dbgs() << "writeAlias: " << GA->
getName() << '\n'; } } while (false)
;
742 ++NumAliasesWritten;
743}
744
745// Merge two equivalent functions. Upon completion, Function G is deleted.
746void MergeFunctions::mergeTwoFunctions(Function *F, Function *G) {
747 if (F->isInterposable()) {
748 assert(G->isInterposable())((G->isInterposable()) ? static_cast<void> (0) : __assert_fail
("G->isInterposable()", "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn301389/lib/Transforms/IPO/MergeFunctions.cpp"
, 748, __PRETTY_FUNCTION__))
;
749
750 // Make them both thunks to the same internal function.
751 Function *H = Function::Create(F->getFunctionType(), F->getLinkage(), "",
752 F->getParent());
753 H->copyAttributesFrom(F);
754 H->takeName(F);
755 removeUsers(F);
756 F->replaceAllUsesWith(H);
757
758 unsigned MaxAlignment = std::max(G->getAlignment(), H->getAlignment());
759
760 if (HasGlobalAliases) {
761 writeAlias(F, G);
762 writeAlias(F, H);
763 } else {
764 writeThunk(F, G);
765 writeThunk(F, H);
766 }
767
768 F->setAlignment(MaxAlignment);
769 F->setLinkage(GlobalValue::PrivateLinkage);
770 ++NumDoubleWeak;
771 } else {
772 writeThunkOrAlias(F, G);
773 }
774
775 ++NumFunctionsMerged;
776}
777
778/// Replace function F by function G.
779void MergeFunctions::replaceFunctionInTree(const FunctionNode &FN,
780 Function *G) {
781 Function *F = FN.getFunc();
782 assert(FunctionComparator(F, G, &GlobalNumbers).compare() == 0 &&((FunctionComparator(F, G, &GlobalNumbers).compare() == 0
&& "The two functions must be equal") ? static_cast<
void> (0) : __assert_fail ("FunctionComparator(F, G, &GlobalNumbers).compare() == 0 && \"The two functions must be equal\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn301389/lib/Transforms/IPO/MergeFunctions.cpp"
, 783, __PRETTY_FUNCTION__))
783 "The two functions must be equal")((FunctionComparator(F, G, &GlobalNumbers).compare() == 0
&& "The two functions must be equal") ? static_cast<
void> (0) : __assert_fail ("FunctionComparator(F, G, &GlobalNumbers).compare() == 0 && \"The two functions must be equal\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn301389/lib/Transforms/IPO/MergeFunctions.cpp"
, 783, __PRETTY_FUNCTION__))
;
784
785 auto I = FNodesInTree.find(F);
786 assert(I != FNodesInTree.end() && "F should be in FNodesInTree")((I != FNodesInTree.end() && "F should be in FNodesInTree"
) ? static_cast<void> (0) : __assert_fail ("I != FNodesInTree.end() && \"F should be in FNodesInTree\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn301389/lib/Transforms/IPO/MergeFunctions.cpp"
, 786, __PRETTY_FUNCTION__))
;
787 assert(FNodesInTree.count(G) == 0 && "FNodesInTree should not contain G")((FNodesInTree.count(G) == 0 && "FNodesInTree should not contain G"
) ? static_cast<void> (0) : __assert_fail ("FNodesInTree.count(G) == 0 && \"FNodesInTree should not contain G\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn301389/lib/Transforms/IPO/MergeFunctions.cpp"
, 787, __PRETTY_FUNCTION__))
;
788
789 FnTreeType::iterator IterToFNInFnTree = I->second;
790 assert(&(*IterToFNInFnTree) == &FN && "F should map to FN in FNodesInTree.")((&(*IterToFNInFnTree) == &FN && "F should map to FN in FNodesInTree."
) ? static_cast<void> (0) : __assert_fail ("&(*IterToFNInFnTree) == &FN && \"F should map to FN in FNodesInTree.\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn301389/lib/Transforms/IPO/MergeFunctions.cpp"
, 790, __PRETTY_FUNCTION__))
;
791 // Remove F -> FN and insert G -> FN
792 FNodesInTree.erase(I);
793 FNodesInTree.insert({G, IterToFNInFnTree});
794 // Replace F with G in FN, which is stored inside the FnTree.
795 FN.replaceBy(G);
796}
797
798// Insert a ComparableFunction into the FnTree, or merge it away if equal to one
799// that was already inserted.
800bool MergeFunctions::insert(Function *NewFunction) {
801 std::pair<FnTreeType::iterator, bool> Result =
802 FnTree.insert(FunctionNode(NewFunction));
803
804 if (Result.second) {
805 assert(FNodesInTree.count(NewFunction) == 0)((FNodesInTree.count(NewFunction) == 0) ? static_cast<void
> (0) : __assert_fail ("FNodesInTree.count(NewFunction) == 0"
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn301389/lib/Transforms/IPO/MergeFunctions.cpp"
, 805, __PRETTY_FUNCTION__))
;
806 FNodesInTree.insert({NewFunction, Result.first});
807 DEBUG(dbgs() << "Inserting as unique: " << NewFunction->getName() << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("mergefunc")) { dbgs() << "Inserting as unique: " <<
NewFunction->getName() << '\n'; } } while (false)
;
808 return false;
809 }
810
811 const FunctionNode &OldF = *Result.first;
812
813 // Don't merge tiny functions, since it can just end up making the function
814 // larger.
815 // FIXME: Should still merge them if they are unnamed_addr and produce an
816 // alias.
817 if (NewFunction->size() == 1) {
818 if (NewFunction->front().size() <= 2) {
819 DEBUG(dbgs() << NewFunction->getName()do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("mergefunc")) { dbgs() << NewFunction->getName() <<
" is to small to bother merging\n"; } } while (false)
820 << " is to small to bother merging\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("mergefunc")) { dbgs() << NewFunction->getName() <<
" is to small to bother merging\n"; } } while (false)
;
821 return false;
822 }
823 }
824
825 // Impose a total order (by name) on the replacement of functions. This is
826 // important when operating on more than one module independently to prevent
827 // cycles of thunks calling each other when the modules are linked together.
828 //
829 // First of all, we process strong functions before weak functions.
830 if ((OldF.getFunc()->isInterposable() && !NewFunction->isInterposable()) ||
831 (OldF.getFunc()->isInterposable() == NewFunction->isInterposable() &&
832 OldF.getFunc()->getName() > NewFunction->getName())) {
833 // Swap the two functions.
834 Function *F = OldF.getFunc();
835 replaceFunctionInTree(*Result.first, NewFunction);
836 NewFunction = F;
837 assert(OldF.getFunc() != F && "Must have swapped the functions.")((OldF.getFunc() != F && "Must have swapped the functions."
) ? static_cast<void> (0) : __assert_fail ("OldF.getFunc() != F && \"Must have swapped the functions.\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn301389/lib/Transforms/IPO/MergeFunctions.cpp"
, 837, __PRETTY_FUNCTION__))
;
838 }
839
840 DEBUG(dbgs() << " " << OldF.getFunc()->getName()do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("mergefunc")) { dbgs() << " " << OldF.getFunc()
->getName() << " == " << NewFunction->getName
() << '\n'; } } while (false)
841 << " == " << NewFunction->getName() << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("mergefunc")) { dbgs() << " " << OldF.getFunc()
->getName() << " == " << NewFunction->getName
() << '\n'; } } while (false)
;
842
843 Function *DeleteF = NewFunction;
844 mergeTwoFunctions(OldF.getFunc(), DeleteF);
845 return true;
846}
847
848// Remove a function from FnTree. If it was already in FnTree, add
849// it to Deferred so that we'll look at it in the next round.
850void MergeFunctions::remove(Function *F) {
851 auto I = FNodesInTree.find(F);
852 if (I != FNodesInTree.end()) {
853 DEBUG(dbgs() << "Deferred " << F->getName()<< ".\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("mergefunc")) { dbgs() << "Deferred " << F->getName
()<< ".\n"; } } while (false)
;
854 FnTree.erase(I->second);
855 // I->second has been invalidated, remove it from the FNodesInTree map to
856 // preserve the invariant.
857 FNodesInTree.erase(I);
858 Deferred.emplace_back(F);
859 }
860}
861
862// For each instruction used by the value, remove() the function that contains
863// the instruction. This should happen right before a call to RAUW.
864void MergeFunctions::removeUsers(Value *V) {
865 std::vector<Value *> Worklist;
866 Worklist.push_back(V);
867 SmallSet<Value*, 8> Visited;
868 Visited.insert(V);
869 while (!Worklist.empty()) {
870 Value *V = Worklist.back();
871 Worklist.pop_back();
872
873 for (User *U : V->users()) {
874 if (Instruction *I = dyn_cast<Instruction>(U)) {
875 remove(I->getParent()->getParent());
876 } else if (isa<GlobalValue>(U)) {
877 // do nothing
878 } else if (Constant *C = dyn_cast<Constant>(U)) {
879 for (User *UU : C->users()) {
880 if (!Visited.insert(UU).second)
881 Worklist.push_back(UU);
882 }
883 }
884 }
885 }
886}