Bug Summary

File:lib/Transforms/Scalar/LoopRerollPass.cpp
Warning:line 476, column 18
Called C++ object pointer is null

Annotated Source Code

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clang -cc1 -triple x86_64-pc-linux-gnu -analyze -disable-free -disable-llvm-verifier -discard-value-names -main-file-name LoopRerollPass.cpp -analyzer-store=region -analyzer-opt-analyze-nested-blocks -analyzer-eagerly-assume -analyzer-checker=core -analyzer-checker=apiModeling -analyzer-checker=unix -analyzer-checker=deadcode -analyzer-checker=cplusplus -analyzer-checker=security.insecureAPI.UncheckedReturn -analyzer-checker=security.insecureAPI.getpw -analyzer-checker=security.insecureAPI.gets -analyzer-checker=security.insecureAPI.mktemp -analyzer-checker=security.insecureAPI.mkstemp -analyzer-checker=security.insecureAPI.vfork -analyzer-checker=nullability.NullPassedToNonnull -analyzer-checker=nullability.NullReturnedFromNonnull -analyzer-output plist -w -mrelocation-model pic -pic-level 2 -mthread-model posix -fmath-errno -masm-verbose -mconstructor-aliases -munwind-tables -fuse-init-array -target-cpu x86-64 -dwarf-column-info -debugger-tuning=gdb -momit-leaf-frame-pointer -ffunction-sections -fdata-sections -resource-dir /usr/lib/llvm-7/lib/clang/7.0.0 -D _DEBUG -D _GNU_SOURCE -D __STDC_CONSTANT_MACROS -D __STDC_FORMAT_MACROS -D __STDC_LIMIT_MACROS -I /build/llvm-toolchain-snapshot-7~svn329677/build-llvm/lib/Transforms/Scalar -I /build/llvm-toolchain-snapshot-7~svn329677/lib/Transforms/Scalar -I /build/llvm-toolchain-snapshot-7~svn329677/build-llvm/include -I /build/llvm-toolchain-snapshot-7~svn329677/include -U NDEBUG -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/7.3.0/../../../../include/c++/7.3.0 -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/7.3.0/../../../../include/x86_64-linux-gnu/c++/7.3.0 -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/7.3.0/../../../../include/x86_64-linux-gnu/c++/7.3.0 -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/7.3.0/../../../../include/c++/7.3.0/backward -internal-isystem /usr/include/clang/7.0.0/include/ -internal-isystem /usr/local/include -internal-isystem /usr/lib/llvm-7/lib/clang/7.0.0/include -internal-externc-isystem /usr/include/x86_64-linux-gnu -internal-externc-isystem /include -internal-externc-isystem /usr/include -O2 -Wno-unused-parameter -Wwrite-strings -Wno-missing-field-initializers -Wno-long-long -Wno-maybe-uninitialized -Wno-comment -std=c++11 -fdeprecated-macro -fdebug-compilation-dir /build/llvm-toolchain-snapshot-7~svn329677/build-llvm/lib/Transforms/Scalar -ferror-limit 19 -fmessage-length 0 -fvisibility-inlines-hidden -fobjc-runtime=gcc -fdiagnostics-show-option -vectorize-loops -vectorize-slp -analyzer-checker optin.performance.Padding -analyzer-output=html -analyzer-config stable-report-filename=true -o /tmp/scan-build-2018-04-11-031539-24776-1 -x c++ /build/llvm-toolchain-snapshot-7~svn329677/lib/Transforms/Scalar/LoopRerollPass.cpp

/build/llvm-toolchain-snapshot-7~svn329677/lib/Transforms/Scalar/LoopRerollPass.cpp

→
1//===- LoopReroll.cpp - Loop rerolling pass -------------------------------===//
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 implements a simple loop reroller.
11//
12//===----------------------------------------------------------------------===//
13
14#include "llvm/ADT/APInt.h"
15#include "llvm/ADT/BitVector.h"
16#include "llvm/ADT/DenseMap.h"
17#include "llvm/ADT/DenseSet.h"
18#include "llvm/ADT/MapVector.h"
19#include "llvm/ADT/STLExtras.h"
20#include "llvm/ADT/SmallSet.h"
21#include "llvm/ADT/SmallVector.h"
22#include "llvm/ADT/Statistic.h"
23#include "llvm/Analysis/AliasAnalysis.h"
24#include "llvm/Analysis/AliasSetTracker.h"
25#include "llvm/Analysis/LoopInfo.h"
26#include "llvm/Analysis/LoopPass.h"
27#include "llvm/Analysis/ScalarEvolution.h"
28#include "llvm/Analysis/ScalarEvolutionExpander.h"
29#include "llvm/Analysis/ScalarEvolutionExpressions.h"
30#include "llvm/Analysis/TargetLibraryInfo.h"
31#include "llvm/Analysis/Utils/Local.h"
32#include "llvm/Analysis/ValueTracking.h"
33#include "llvm/IR/BasicBlock.h"
34#include "llvm/IR/Constants.h"
35#include "llvm/IR/DataLayout.h"
36#include "llvm/IR/DerivedTypes.h"
37#include "llvm/IR/Dominators.h"
38#include "llvm/IR/IRBuilder.h"
39#include "llvm/IR/InstrTypes.h"
40#include "llvm/IR/Instruction.h"
41#include "llvm/IR/Instructions.h"
42#include "llvm/IR/IntrinsicInst.h"
43#include "llvm/IR/Intrinsics.h"
44#include "llvm/IR/Module.h"
45#include "llvm/IR/Type.h"
46#include "llvm/IR/Use.h"
47#include "llvm/IR/User.h"
48#include "llvm/IR/Value.h"
49#include "llvm/Pass.h"
50#include "llvm/Support/Casting.h"
51#include "llvm/Support/CommandLine.h"
52#include "llvm/Support/Debug.h"
53#include "llvm/Support/raw_ostream.h"
54#include "llvm/Transforms/Scalar.h"
55#include "llvm/Transforms/Utils.h"
56#include "llvm/Transforms/Utils/BasicBlockUtils.h"
57#include "llvm/Transforms/Utils/LoopUtils.h"
58#include <cassert>
59#include <cstddef>
60#include <cstdint>
61#include <cstdlib>
62#include <iterator>
63#include <map>
64#include <utility>
65
66using namespace llvm;
67
68#define DEBUG_TYPE"loop-reroll" "loop-reroll"
69
70STATISTIC(NumRerolledLoops, "Number of rerolled loops")static llvm::Statistic NumRerolledLoops = {"loop-reroll", "NumRerolledLoops"
, "Number of rerolled loops", {0}, {false}};
71
72static cl::opt<unsigned>
73MaxInc("max-reroll-increment", cl::init(2048), cl::Hidden,
74 cl::desc("The maximum increment for loop rerolling"));
75
76static cl::opt<unsigned>
77NumToleratedFailedMatches("reroll-num-tolerated-failed-matches", cl::init(400),
78 cl::Hidden,
79 cl::desc("The maximum number of failures to tolerate"
80 " during fuzzy matching. (default: 400)"));
81
82// This loop re-rolling transformation aims to transform loops like this:
83//
84// int foo(int a);
85// void bar(int *x) {
86// for (int i = 0; i < 500; i += 3) {
87// foo(i);
88// foo(i+1);
89// foo(i+2);
90// }
91// }
92//
93// into a loop like this:
94//
95// void bar(int *x) {
96// for (int i = 0; i < 500; ++i)
97// foo(i);
98// }
99//
100// It does this by looking for loops that, besides the latch code, are composed
101// of isomorphic DAGs of instructions, with each DAG rooted at some increment
102// to the induction variable, and where each DAG is isomorphic to the DAG
103// rooted at the induction variable (excepting the sub-DAGs which root the
104// other induction-variable increments). In other words, we're looking for loop
105// bodies of the form:
106//
107// %iv = phi [ (preheader, ...), (body, %iv.next) ]
108// f(%iv)
109// %iv.1 = add %iv, 1 <-- a root increment
110// f(%iv.1)
111// %iv.2 = add %iv, 2 <-- a root increment
112// f(%iv.2)
113// %iv.scale_m_1 = add %iv, scale-1 <-- a root increment
114// f(%iv.scale_m_1)
115// ...
116// %iv.next = add %iv, scale
117// %cmp = icmp(%iv, ...)
118// br %cmp, header, exit
119//
120// where each f(i) is a set of instructions that, collectively, are a function
121// only of i (and other loop-invariant values).
122//
123// As a special case, we can also reroll loops like this:
124//
125// int foo(int);
126// void bar(int *x) {
127// for (int i = 0; i < 500; ++i) {
128// x[3*i] = foo(0);
129// x[3*i+1] = foo(0);
130// x[3*i+2] = foo(0);
131// }
132// }
133//
134// into this:
135//
136// void bar(int *x) {
137// for (int i = 0; i < 1500; ++i)
138// x[i] = foo(0);
139// }
140//
141// in which case, we're looking for inputs like this:
142//
143// %iv = phi [ (preheader, ...), (body, %iv.next) ]
144// %scaled.iv = mul %iv, scale
145// f(%scaled.iv)
146// %scaled.iv.1 = add %scaled.iv, 1
147// f(%scaled.iv.1)
148// %scaled.iv.2 = add %scaled.iv, 2
149// f(%scaled.iv.2)
150// %scaled.iv.scale_m_1 = add %scaled.iv, scale-1
151// f(%scaled.iv.scale_m_1)
152// ...
153// %iv.next = add %iv, 1
154// %cmp = icmp(%iv, ...)
155// br %cmp, header, exit
156
157namespace {
158
159 enum IterationLimits {
160 /// The maximum number of iterations that we'll try and reroll.
161 IL_MaxRerollIterations = 32,
162 /// The bitvector index used by loop induction variables and other
163 /// instructions that belong to all iterations.
164 IL_All,
165 IL_End
166 };
167
168 class LoopReroll : public LoopPass {
169 public:
170 static char ID; // Pass ID, replacement for typeid
171
172 LoopReroll() : LoopPass(ID) {
173 initializeLoopRerollPass(*PassRegistry::getPassRegistry());
174 }
175
176 bool runOnLoop(Loop *L, LPPassManager &LPM) override;
177
178 void getAnalysisUsage(AnalysisUsage &AU) const override {
179 AU.addRequired<TargetLibraryInfoWrapperPass>();
180 getLoopAnalysisUsage(AU);
181 }
182
183 protected:
184 AliasAnalysis *AA;
185 LoopInfo *LI;
186 ScalarEvolution *SE;
187 TargetLibraryInfo *TLI;
188 DominatorTree *DT;
189 bool PreserveLCSSA;
190
191 using SmallInstructionVector = SmallVector<Instruction *, 16>;
192 using SmallInstructionSet = SmallSet<Instruction *, 16>;
193
194 // Map between induction variable and its increment
195 DenseMap<Instruction *, int64_t> IVToIncMap;
196
197 // For loop with multiple induction variable, remember the one used only to
198 // control the loop.
199 Instruction *LoopControlIV;
200
201 // A chain of isomorphic instructions, identified by a single-use PHI
202 // representing a reduction. Only the last value may be used outside the
203 // loop.
204 struct SimpleLoopReduction {
205 SimpleLoopReduction(Instruction *P, Loop *L) : Instructions(1, P) {
206 assert(isa<PHINode>(P) && "First reduction instruction must be a PHI")(static_cast <bool> (isa<PHINode>(P) && "First reduction instruction must be a PHI"
) ? void (0) : __assert_fail ("isa<PHINode>(P) && \"First reduction instruction must be a PHI\""
, "/build/llvm-toolchain-snapshot-7~svn329677/lib/Transforms/Scalar/LoopRerollPass.cpp"
, 206, __extension__ __PRETTY_FUNCTION__));
207 add(L);
208 }
209
210 bool valid() const {
211 return Valid;
212 }
213
214 Instruction *getPHI() const {
215 assert(Valid && "Using invalid reduction")(static_cast <bool> (Valid && "Using invalid reduction"
) ? void (0) : __assert_fail ("Valid && \"Using invalid reduction\""
, "/build/llvm-toolchain-snapshot-7~svn329677/lib/Transforms/Scalar/LoopRerollPass.cpp"
, 215, __extension__ __PRETTY_FUNCTION__));
216 return Instructions.front();
217 }
218
219 Instruction *getReducedValue() const {
220 assert(Valid && "Using invalid reduction")(static_cast <bool> (Valid && "Using invalid reduction"
) ? void (0) : __assert_fail ("Valid && \"Using invalid reduction\""
, "/build/llvm-toolchain-snapshot-7~svn329677/lib/Transforms/Scalar/LoopRerollPass.cpp"
, 220, __extension__ __PRETTY_FUNCTION__));
221 return Instructions.back();
222 }
223
224 Instruction *get(size_t i) const {
225 assert(Valid && "Using invalid reduction")(static_cast <bool> (Valid && "Using invalid reduction"
) ? void (0) : __assert_fail ("Valid && \"Using invalid reduction\""
, "/build/llvm-toolchain-snapshot-7~svn329677/lib/Transforms/Scalar/LoopRerollPass.cpp"
, 225, __extension__ __PRETTY_FUNCTION__));
226 return Instructions[i+1];
227 }
228
229 Instruction *operator [] (size_t i) const { return get(i); }
230
231 // The size, ignoring the initial PHI.
232 size_t size() const {
233 assert(Valid && "Using invalid reduction")(static_cast <bool> (Valid && "Using invalid reduction"
) ? void (0) : __assert_fail ("Valid && \"Using invalid reduction\""
, "/build/llvm-toolchain-snapshot-7~svn329677/lib/Transforms/Scalar/LoopRerollPass.cpp"
, 233, __extension__ __PRETTY_FUNCTION__));
234 return Instructions.size()-1;
235 }
236
237 using iterator = SmallInstructionVector::iterator;
238 using const_iterator = SmallInstructionVector::const_iterator;
239
240 iterator begin() {
241 assert(Valid && "Using invalid reduction")(static_cast <bool> (Valid && "Using invalid reduction"
) ? void (0) : __assert_fail ("Valid && \"Using invalid reduction\""
, "/build/llvm-toolchain-snapshot-7~svn329677/lib/Transforms/Scalar/LoopRerollPass.cpp"
, 241, __extension__ __PRETTY_FUNCTION__));
242 return std::next(Instructions.begin());
243 }
244
245 const_iterator begin() const {
246 assert(Valid && "Using invalid reduction")(static_cast <bool> (Valid && "Using invalid reduction"
) ? void (0) : __assert_fail ("Valid && \"Using invalid reduction\""
, "/build/llvm-toolchain-snapshot-7~svn329677/lib/Transforms/Scalar/LoopRerollPass.cpp"
, 246, __extension__ __PRETTY_FUNCTION__));
247 return std::next(Instructions.begin());
248 }
249
250 iterator end() { return Instructions.end(); }
251 const_iterator end() const { return Instructions.end(); }
252
253 protected:
254 bool Valid = false;
255 SmallInstructionVector Instructions;
256
257 void add(Loop *L);
258 };
259
260 // The set of all reductions, and state tracking of possible reductions
261 // during loop instruction processing.
262 struct ReductionTracker {
263 using SmallReductionVector = SmallVector<SimpleLoopReduction, 16>;
264
265 // Add a new possible reduction.
266 void addSLR(SimpleLoopReduction &SLR) { PossibleReds.push_back(SLR); }
267
268 // Setup to track possible reductions corresponding to the provided
269 // rerolling scale. Only reductions with a number of non-PHI instructions
270 // that is divisible by the scale are considered. Three instructions sets
271 // are filled in:
272 // - A set of all possible instructions in eligible reductions.
273 // - A set of all PHIs in eligible reductions
274 // - A set of all reduced values (last instructions) in eligible
275 // reductions.
276 void restrictToScale(uint64_t Scale,
277 SmallInstructionSet &PossibleRedSet,
278 SmallInstructionSet &PossibleRedPHISet,
279 SmallInstructionSet &PossibleRedLastSet) {
280 PossibleRedIdx.clear();
281 PossibleRedIter.clear();
282 Reds.clear();
283
284 for (unsigned i = 0, e = PossibleReds.size(); i != e; ++i)
285 if (PossibleReds[i].size() % Scale == 0) {
286 PossibleRedLastSet.insert(PossibleReds[i].getReducedValue());
287 PossibleRedPHISet.insert(PossibleReds[i].getPHI());
288
289 PossibleRedSet.insert(PossibleReds[i].getPHI());
290 PossibleRedIdx[PossibleReds[i].getPHI()] = i;
291 for (Instruction *J : PossibleReds[i]) {
292 PossibleRedSet.insert(J);
293 PossibleRedIdx[J] = i;
294 }
295 }
296 }
297
298 // The functions below are used while processing the loop instructions.
299
300 // Are the two instructions both from reductions, and furthermore, from
301 // the same reduction?
302 bool isPairInSame(Instruction *J1, Instruction *J2) {
303 DenseMap<Instruction *, int>::iterator J1I = PossibleRedIdx.find(J1);
304 if (J1I != PossibleRedIdx.end()) {
305 DenseMap<Instruction *, int>::iterator J2I = PossibleRedIdx.find(J2);
306 if (J2I != PossibleRedIdx.end() && J1I->second == J2I->second)
307 return true;
308 }
309
310 return false;
311 }
312
313 // The two provided instructions, the first from the base iteration, and
314 // the second from iteration i, form a matched pair. If these are part of
315 // a reduction, record that fact.
316 void recordPair(Instruction *J1, Instruction *J2, unsigned i) {
317 if (PossibleRedIdx.count(J1)) {
318 assert(PossibleRedIdx.count(J2) &&(static_cast <bool> (PossibleRedIdx.count(J2) &&
"Recording reduction vs. non-reduction instruction?") ? void
(0) : __assert_fail ("PossibleRedIdx.count(J2) && \"Recording reduction vs. non-reduction instruction?\""
, "/build/llvm-toolchain-snapshot-7~svn329677/lib/Transforms/Scalar/LoopRerollPass.cpp"
, 319, __extension__ __PRETTY_FUNCTION__))
319 "Recording reduction vs. non-reduction instruction?")(static_cast <bool> (PossibleRedIdx.count(J2) &&
"Recording reduction vs. non-reduction instruction?") ? void
(0) : __assert_fail ("PossibleRedIdx.count(J2) && \"Recording reduction vs. non-reduction instruction?\""
, "/build/llvm-toolchain-snapshot-7~svn329677/lib/Transforms/Scalar/LoopRerollPass.cpp"
, 319, __extension__ __PRETTY_FUNCTION__));
320
321 PossibleRedIter[J1] = 0;
322 PossibleRedIter[J2] = i;
323
324 int Idx = PossibleRedIdx[J1];
325 assert(Idx == PossibleRedIdx[J2] &&(static_cast <bool> (Idx == PossibleRedIdx[J2] &&
"Recording pair from different reductions?") ? void (0) : __assert_fail
("Idx == PossibleRedIdx[J2] && \"Recording pair from different reductions?\""
, "/build/llvm-toolchain-snapshot-7~svn329677/lib/Transforms/Scalar/LoopRerollPass.cpp"
, 326, __extension__ __PRETTY_FUNCTION__))
326 "Recording pair from different reductions?")(static_cast <bool> (Idx == PossibleRedIdx[J2] &&
"Recording pair from different reductions?") ? void (0) : __assert_fail
("Idx == PossibleRedIdx[J2] && \"Recording pair from different reductions?\""
, "/build/llvm-toolchain-snapshot-7~svn329677/lib/Transforms/Scalar/LoopRerollPass.cpp"
, 326, __extension__ __PRETTY_FUNCTION__));
327 Reds.insert(Idx);
328 }
329 }
330
331 // The functions below can be called after we've finished processing all
332 // instructions in the loop, and we know which reductions were selected.
333
334 bool validateSelected();
335 void replaceSelected();
336
337 protected:
338 // The vector of all possible reductions (for any scale).
339 SmallReductionVector PossibleReds;
340
341 DenseMap<Instruction *, int> PossibleRedIdx;
342 DenseMap<Instruction *, int> PossibleRedIter;
343 DenseSet<int> Reds;
344 };
345
346 // A DAGRootSet models an induction variable being used in a rerollable
347 // loop. For example,
348 //
349 // x[i*3+0] = y1
350 // x[i*3+1] = y2
351 // x[i*3+2] = y3
352 //
353 // Base instruction -> i*3
354 // +---+----+
355 // / | \
356 // ST[y1] +1 +2 <-- Roots
357 // | |
358 // ST[y2] ST[y3]
359 //
360 // There may be multiple DAGRoots, for example:
361 //
362 // x[i*2+0] = ... (1)
363 // x[i*2+1] = ... (1)
364 // x[i*2+4] = ... (2)
365 // x[i*2+5] = ... (2)
366 // x[(i+1234)*2+5678] = ... (3)
367 // x[(i+1234)*2+5679] = ... (3)
368 //
369 // The loop will be rerolled by adding a new loop induction variable,
370 // one for the Base instruction in each DAGRootSet.
371 //
372 struct DAGRootSet {
373 Instruction *BaseInst;
374 SmallInstructionVector Roots;
375
376 // The instructions between IV and BaseInst (but not including BaseInst).
377 SmallInstructionSet SubsumedInsts;
378 };
379
380 // The set of all DAG roots, and state tracking of all roots
381 // for a particular induction variable.
382 struct DAGRootTracker {
383 DAGRootTracker(LoopReroll *Parent, Loop *L, Instruction *IV,
384 ScalarEvolution *SE, AliasAnalysis *AA,
385 TargetLibraryInfo *TLI, DominatorTree *DT, LoopInfo *LI,
386 bool PreserveLCSSA,
387 DenseMap<Instruction *, int64_t> &IncrMap,
388 Instruction *LoopCtrlIV)
389 : Parent(Parent), L(L), SE(SE), AA(AA), TLI(TLI), DT(DT), LI(LI),
390 PreserveLCSSA(PreserveLCSSA), IV(IV), IVToIncMap(IncrMap),
391 LoopControlIV(LoopCtrlIV) {}
392
393 /// Stage 1: Find all the DAG roots for the induction variable.
394 bool findRoots();
395
396 /// Stage 2: Validate if the found roots are valid.
397 bool validate(ReductionTracker &Reductions);
398
399 /// Stage 3: Assuming validate() returned true, perform the
400 /// replacement.
401 /// @param IterCount The maximum iteration count of L.
402 void replace(const SCEV *IterCount);
403
404 protected:
405 using UsesTy = MapVector<Instruction *, BitVector>;
406
407 void findRootsRecursive(Instruction *IVU,
408 SmallInstructionSet SubsumedInsts);
409 bool findRootsBase(Instruction *IVU, SmallInstructionSet SubsumedInsts);
410 bool collectPossibleRoots(Instruction *Base,
411 std::map<int64_t,Instruction*> &Roots);
412 bool validateRootSet(DAGRootSet &DRS);
413
414 bool collectUsedInstructions(SmallInstructionSet &PossibleRedSet);
415 void collectInLoopUserSet(const SmallInstructionVector &Roots,
416 const SmallInstructionSet &Exclude,
417 const SmallInstructionSet &Final,
418 DenseSet<Instruction *> &Users);
419 void collectInLoopUserSet(Instruction *Root,
420 const SmallInstructionSet &Exclude,
421 const SmallInstructionSet &Final,
422 DenseSet<Instruction *> &Users);
423
424 UsesTy::iterator nextInstr(int Val, UsesTy &In,
425 const SmallInstructionSet &Exclude,
426 UsesTy::iterator *StartI=nullptr);
427 bool isBaseInst(Instruction *I);
428 bool isRootInst(Instruction *I);
429 bool instrDependsOn(Instruction *I,
430 UsesTy::iterator Start,
431 UsesTy::iterator End);
432 void replaceIV(Instruction *Inst, Instruction *IV, const SCEV *IterCount);
433 void updateNonLoopCtrlIncr();
434
435 LoopReroll *Parent;
436
437 // Members of Parent, replicated here for brevity.
438 Loop *L;
439 ScalarEvolution *SE;
440 AliasAnalysis *AA;
441 TargetLibraryInfo *TLI;
442 DominatorTree *DT;
443 LoopInfo *LI;
444 bool PreserveLCSSA;
445
446 // The loop induction variable.
447 Instruction *IV;
448
449 // Loop step amount.
450 int64_t Inc;
451
452 // Loop reroll count; if Inc == 1, this records the scaling applied
453 // to the indvar: a[i*2+0] = ...; a[i*2+1] = ... ;
454 // If Inc is not 1, Scale = Inc.
455 uint64_t Scale;
456
457 // The roots themselves.
458 SmallVector<DAGRootSet,16> RootSets;
459
460 // All increment instructions for IV.
461 SmallInstructionVector LoopIncs;
462
463 // Map of all instructions in the loop (in order) to the iterations
464 // they are used in (or specially, IL_All for instructions
465 // used in the loop increment mechanism).
466 UsesTy Uses;
467
468 // Map between induction variable and its increment
469 DenseMap<Instruction *, int64_t> &IVToIncMap;
470
471 Instruction *LoopControlIV;
472 };
473
474 // Check if it is a compare-like instruction whose user is a branch
475 bool isCompareUsedByBranch(Instruction *I) {
476 auto *TI = I->getParent()->getTerminator();
41
←
Called C++ object pointer is null
477 if (!isa<BranchInst>(TI) || !isa<CmpInst>(I))
478 return false;
479 return I->hasOneUse() && TI->getOperand(0) == I;
480 };
481
482 bool isLoopControlIV(Loop *L, Instruction *IV);
483 void collectPossibleIVs(Loop *L, SmallInstructionVector &PossibleIVs);
484 void collectPossibleReductions(Loop *L,
485 ReductionTracker &Reductions);
486 bool reroll(Instruction *IV, Loop *L, BasicBlock *Header, const SCEV *IterCount,
487 ReductionTracker &Reductions);
488 };
489
490} // end anonymous namespace
491
492char LoopReroll::ID = 0;
493
494INITIALIZE_PASS_BEGIN(LoopReroll, "loop-reroll", "Reroll loops", false, false)static void *initializeLoopRerollPassOnce(PassRegistry &Registry
) {
495INITIALIZE_PASS_DEPENDENCY(LoopPass)initializeLoopPassPass(Registry);
496INITIALIZE_PASS_DEPENDENCY(TargetLibraryInfoWrapperPass)initializeTargetLibraryInfoWrapperPassPass(Registry);
497INITIALIZE_PASS_END(LoopReroll, "loop-reroll", "Reroll loops", false, false)PassInfo *PI = new PassInfo( "Reroll loops", "loop-reroll", &
LoopReroll::ID, PassInfo::NormalCtor_t(callDefaultCtor<LoopReroll
>), false, false); Registry.registerPass(*PI, true); return
PI; } static llvm::once_flag InitializeLoopRerollPassFlag; void
llvm::initializeLoopRerollPass(PassRegistry &Registry) {
llvm::call_once(InitializeLoopRerollPassFlag, initializeLoopRerollPassOnce
, std::ref(Registry)); }
498
499Pass *llvm::createLoopRerollPass() {
500 return new LoopReroll;
501}
502
503// Returns true if the provided instruction is used outside the given loop.
504// This operates like Instruction::isUsedOutsideOfBlock, but considers PHIs in
505// non-loop blocks to be outside the loop.
506static bool hasUsesOutsideLoop(Instruction *I, Loop *L) {
507 for (User *U : I->users()) {
508 if (!L->contains(cast<Instruction>(U)))
509 return true;
510 }
511 return false;
512}
513
514static const SCEVConstant *getIncrmentFactorSCEV(ScalarEvolution *SE,
515 const SCEV *SCEVExpr,
516 Instruction &IV) {
517 const SCEVMulExpr *MulSCEV = dyn_cast<SCEVMulExpr>(SCEVExpr);
518
519 // If StepRecurrence of a SCEVExpr is a constant (c1 * c2, c2 = sizeof(ptr)),
520 // Return c1.
521 if (!MulSCEV && IV.getType()->isPointerTy())
522 if (const SCEVConstant *IncSCEV = dyn_cast<SCEVConstant>(SCEVExpr)) {
523 const PointerType *PTy = cast<PointerType>(IV.getType());
524 Type *ElTy = PTy->getElementType();
525 const SCEV *SizeOfExpr =
526 SE->getSizeOfExpr(SE->getEffectiveSCEVType(IV.getType()), ElTy);
527 if (IncSCEV->getValue()->getValue().isNegative()) {
528 const SCEV *NewSCEV =
529 SE->getUDivExpr(SE->getNegativeSCEV(SCEVExpr), SizeOfExpr);
530 return dyn_cast<SCEVConstant>(SE->getNegativeSCEV(NewSCEV));
531 } else {
532 return dyn_cast<SCEVConstant>(SE->getUDivExpr(SCEVExpr, SizeOfExpr));
533 }
534 }
535
536 if (!MulSCEV)
537 return nullptr;
538
539 // If StepRecurrence of a SCEVExpr is a c * sizeof(x), where c is constant,
540 // Return c.
541 const SCEVConstant *CIncSCEV = nullptr;
542 for (const SCEV *Operand : MulSCEV->operands()) {
543 if (const SCEVConstant *Constant = dyn_cast<SCEVConstant>(Operand)) {
544 CIncSCEV = Constant;
545 } else if (const SCEVUnknown *Unknown = dyn_cast<SCEVUnknown>(Operand)) {
546 Type *AllocTy;
547 if (!Unknown->isSizeOf(AllocTy))
548 break;
549 } else {
550 return nullptr;
551 }
552 }
553 return CIncSCEV;
554}
555
556// Check if an IV is only used to control the loop. There are two cases:
557// 1. It only has one use which is loop increment, and the increment is only
558// used by comparison and the PHI (could has sext with nsw in between), and the
559// comparison is only used by branch.
560// 2. It is used by loop increment and the comparison, the loop increment is
561// only used by the PHI, and the comparison is used only by the branch.
562bool LoopReroll::isLoopControlIV(Loop *L, Instruction *IV) {
563 unsigned IVUses = IV->getNumUses();
564 if (IVUses != 2 && IVUses != 1)
21
←
Assuming 'IVUses' is equal to 2
→
565 return false;
566
567 for (auto *User : IV->users()) {
568 int32_t IncOrCmpUses = User->getNumUses();
569 bool IsCompInst = isCompareUsedByBranch(cast<Instruction>(User));
570
571 // User can only have one or two uses.
572 if (IncOrCmpUses != 2 && IncOrCmpUses != 1)
22
←
Assuming 'IncOrCmpUses' is not equal to 2
→
23
←
Assuming 'IncOrCmpUses' is equal to 1
→
24
←
Taking false branch
→
573 return false;
574
575 // Case 1
576 if (IVUses == 1) {
25
←
Taking false branch
→
577 // The only user must be the loop increment.
578 // The loop increment must have two uses.
579 if (IsCompInst || IncOrCmpUses != 2)
580 return false;
581 }
582
583 // Case 2
584 if (IVUses == 2 && IncOrCmpUses != 1)
26
←
Taking false branch
→
585 return false;
586
587 // The users of the IV must be a binary operation or a comparison
588 if (auto *BO = dyn_cast<BinaryOperator>(User)) {
27
←
Assuming 'BO' is non-null
→
28
←
Taking true branch
→
589 if (BO->getOpcode() == Instruction::Add) {
29
←
Assuming the condition is true
→
30
←
Taking true branch
→
590 // Loop Increment
591 // User of Loop Increment should be either PHI or CMP
592 for (auto *UU : User->users()) {
593 if (PHINode *PN = dyn_cast<PHINode>(UU)) {
31
←
Taking false branch
→
594 if (PN != IV)
595 return false;
596 }
597 // Must be a CMP or an ext (of a value with nsw) then CMP
598 else {
599 Instruction *UUser = dyn_cast<Instruction>(UU);
32
←
Calling 'dyn_cast'
→
34
←
Returning from 'dyn_cast'
→
35
←
'UUser' initialized here
→
600 // Skip SExt if we are extending an nsw value
601 // TODO: Allow ZExt too
602 if (BO->hasNoSignedWrap() && UUser && UUser->hasOneUse() &&
36
←
Assuming the condition is true
→
37
←
Assuming pointer value is null
→
38
←
Assuming 'UUser' is null
→
603 isa<SExtInst>(UUser))
604 UUser = dyn_cast<Instruction>(*(UUser->user_begin()));
605 if (!isCompareUsedByBranch(UUser))
39
←
Passing null pointer value via 1st parameter 'I'
→
40
←
Calling 'LoopReroll::isCompareUsedByBranch'
→
606 return false;
607 }
608 }
609 } else
610 return false;
611 // Compare : can only have one use, and must be branch
612 } else if (!IsCompInst)
613 return false;
614 }
615 return true;
616}
617
618// Collect the list of loop induction variables with respect to which it might
619// be possible to reroll the loop.
620void LoopReroll::collectPossibleIVs(Loop *L,
621 SmallInstructionVector &PossibleIVs) {
622 BasicBlock *Header = L->getHeader();
623 for (BasicBlock::iterator I = Header->begin(),
8
←
Loop condition is true. Entering loop body
→
624 IE = Header->getFirstInsertionPt(); I != IE; ++I) {
625 if (!isa<PHINode>(I))
9
←
Taking false branch
→
626 continue;
627 if (!I->getType()->isIntegerTy() && !I->getType()->isPointerTy())
10
←
Taking false branch
→
628 continue;
629
630 if (const SCEVAddRecExpr *PHISCEV =
11
←
Assuming 'PHISCEV' is non-null
→
12
←
Taking true branch
→
631 dyn_cast<SCEVAddRecExpr>(SE->getSCEV(&*I))) {
632 if (PHISCEV->getLoop() != L)
13
←
Assuming the condition is false
→
14
←
Taking false branch
→
633 continue;
634 if (!PHISCEV->isAffine())
15
←
Taking false branch
→
635 continue;
636 const SCEVConstant *IncSCEV = nullptr;
637 if (I->getType()->isPointerTy())
16
←
Taking false branch
→
638 IncSCEV =
639 getIncrmentFactorSCEV(SE, PHISCEV->getStepRecurrence(*SE), *I);
640 else
641 IncSCEV = dyn_cast<SCEVConstant>(PHISCEV->getStepRecurrence(*SE));
642 if (IncSCEV) {
17
←
Assuming 'IncSCEV' is non-null
→
18
←
Taking true branch
→
643 const APInt &AInt = IncSCEV->getValue()->getValue().abs();
644 if (IncSCEV->getValue()->isZero() || AInt.uge(MaxInc))
19
←
Taking false branch
→
645 continue;
646 IVToIncMap[&*I] = IncSCEV->getValue()->getSExtValue();
647 DEBUG(dbgs() << "LRR: Possible IV: " << *I << " = " << *PHISCEVdo { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reroll")) { dbgs() << "LRR: Possible IV: " <<
*I << " = " << *PHISCEV << "\n"; } } while
(false)
648 << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reroll")) { dbgs() << "LRR: Possible IV: " <<
*I << " = " << *PHISCEV << "\n"; } } while
(false);
649
650 if (isLoopControlIV(L, &*I)) {
20
←
Calling 'LoopReroll::isLoopControlIV'
→
651 assert(!LoopControlIV && "Found two loop control only IV")(static_cast <bool> (!LoopControlIV && "Found two loop control only IV"
) ? void (0) : __assert_fail ("!LoopControlIV && \"Found two loop control only IV\""
, "/build/llvm-toolchain-snapshot-7~svn329677/lib/Transforms/Scalar/LoopRerollPass.cpp"
, 651, __extension__ __PRETTY_FUNCTION__));
652 LoopControlIV = &(*I);
653 DEBUG(dbgs() << "LRR: Possible loop control only IV: " << *I << " = "do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reroll")) { dbgs() << "LRR: Possible loop control only IV: "
<< *I << " = " << *PHISCEV << "\n"; }
} while (false)
654 << *PHISCEV << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reroll")) { dbgs() << "LRR: Possible loop control only IV: "
<< *I << " = " << *PHISCEV << "\n"; }
} while (false);
655 } else
656 PossibleIVs.push_back(&*I);
657 }
658 }
659 }
660}
661
662// Add the remainder of the reduction-variable chain to the instruction vector
663// (the initial PHINode has already been added). If successful, the object is
664// marked as valid.
665void LoopReroll::SimpleLoopReduction::add(Loop *L) {
666 assert(!Valid && "Cannot add to an already-valid chain")(static_cast <bool> (!Valid && "Cannot add to an already-valid chain"
) ? void (0) : __assert_fail ("!Valid && \"Cannot add to an already-valid chain\""
, "/build/llvm-toolchain-snapshot-7~svn329677/lib/Transforms/Scalar/LoopRerollPass.cpp"
, 666, __extension__ __PRETTY_FUNCTION__));
667
668 // The reduction variable must be a chain of single-use instructions
669 // (including the PHI), except for the last value (which is used by the PHI
670 // and also outside the loop).
671 Instruction *C = Instructions.front();
672 if (C->user_empty())
673 return;
674
675 do {
676 C = cast<Instruction>(*C->user_begin());
677 if (C->hasOneUse()) {
678 if (!C->isBinaryOp())
679 return;
680
681 if (!(isa<PHINode>(Instructions.back()) ||
682 C->isSameOperationAs(Instructions.back())))
683 return;
684
685 Instructions.push_back(C);
686 }
687 } while (C->hasOneUse());
688
689 if (Instructions.size() < 2 ||
690 !C->isSameOperationAs(Instructions.back()) ||
691 C->use_empty())
692 return;
693
694 // C is now the (potential) last instruction in the reduction chain.
695 for (User *U : C->users()) {
696 // The only in-loop user can be the initial PHI.
697 if (L->contains(cast<Instruction>(U)))
698 if (cast<Instruction>(U) != Instructions.front())
699 return;
700 }
701
702 Instructions.push_back(C);
703 Valid = true;
704}
705
706// Collect the vector of possible reduction variables.
707void LoopReroll::collectPossibleReductions(Loop *L,
708 ReductionTracker &Reductions) {
709 BasicBlock *Header = L->getHeader();
710 for (BasicBlock::iterator I = Header->begin(),
711 IE = Header->getFirstInsertionPt(); I != IE; ++I) {
712 if (!isa<PHINode>(I))
713 continue;
714 if (!I->getType()->isSingleValueType())
715 continue;
716
717 SimpleLoopReduction SLR(&*I, L);
718 if (!SLR.valid())
719 continue;
720
721 DEBUG(dbgs() << "LRR: Possible reduction: " << *I << " (with " <<do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reroll")) { dbgs() << "LRR: Possible reduction: "
<< *I << " (with " << SLR.size() << " chained instructions)\n"
; } } while (false)
722 SLR.size() << " chained instructions)\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reroll")) { dbgs() << "LRR: Possible reduction: "
<< *I << " (with " << SLR.size() << " chained instructions)\n"
; } } while (false);
723 Reductions.addSLR(SLR);
724 }
725}
726
727// Collect the set of all users of the provided root instruction. This set of
728// users contains not only the direct users of the root instruction, but also
729// all users of those users, and so on. There are two exceptions:
730//
731// 1. Instructions in the set of excluded instructions are never added to the
732// use set (even if they are users). This is used, for example, to exclude
733// including root increments in the use set of the primary IV.
734//
735// 2. Instructions in the set of final instructions are added to the use set
736// if they are users, but their users are not added. This is used, for
737// example, to prevent a reduction update from forcing all later reduction
738// updates into the use set.
739void LoopReroll::DAGRootTracker::collectInLoopUserSet(
740 Instruction *Root, const SmallInstructionSet &Exclude,
741 const SmallInstructionSet &Final,
742 DenseSet<Instruction *> &Users) {
743 SmallInstructionVector Queue(1, Root);
744 while (!Queue.empty()) {
745 Instruction *I = Queue.pop_back_val();
746 if (!Users.insert(I).second)
747 continue;
748
749 if (!Final.count(I))
750 for (Use &U : I->uses()) {
751 Instruction *User = cast<Instruction>(U.getUser());
752 if (PHINode *PN = dyn_cast<PHINode>(User)) {
753 // Ignore "wrap-around" uses to PHIs of this loop's header.
754 if (PN->getIncomingBlock(U) == L->getHeader())
755 continue;
756 }
757
758 if (L->contains(User) && !Exclude.count(User)) {
759 Queue.push_back(User);
760 }
761 }
762
763 // We also want to collect single-user "feeder" values.
764 for (User::op_iterator OI = I->op_begin(),
765 OIE = I->op_end(); OI != OIE; ++OI) {
766 if (Instruction *Op = dyn_cast<Instruction>(*OI))
767 if (Op->hasOneUse() && L->contains(Op) && !Exclude.count(Op) &&
768 !Final.count(Op))
769 Queue.push_back(Op);
770 }
771 }
772}
773
774// Collect all of the users of all of the provided root instructions (combined
775// into a single set).
776void LoopReroll::DAGRootTracker::collectInLoopUserSet(
777 const SmallInstructionVector &Roots,
778 const SmallInstructionSet &Exclude,
779 const SmallInstructionSet &Final,
780 DenseSet<Instruction *> &Users) {
781 for (Instruction *Root : Roots)
782 collectInLoopUserSet(Root, Exclude, Final, Users);
783}
784
785static bool isUnorderedLoadStore(Instruction *I) {
786 if (LoadInst *LI = dyn_cast<LoadInst>(I))
787 return LI->isUnordered();
788 if (StoreInst *SI = dyn_cast<StoreInst>(I))
789 return SI->isUnordered();
790 if (MemIntrinsic *MI = dyn_cast<MemIntrinsic>(I))
791 return !MI->isVolatile();
792 return false;
793}
794
795/// Return true if IVU is a "simple" arithmetic operation.
796/// This is used for narrowing the search space for DAGRoots; only arithmetic
797/// and GEPs can be part of a DAGRoot.
798static bool isSimpleArithmeticOp(User *IVU) {
799 if (Instruction *I = dyn_cast<Instruction>(IVU)) {
800 switch (I->getOpcode()) {
801 default: return false;
802 case Instruction::Add:
803 case Instruction::Sub:
804 case Instruction::Mul:
805 case Instruction::Shl:
806 case Instruction::AShr:
807 case Instruction::LShr:
808 case Instruction::GetElementPtr:
809 case Instruction::Trunc:
810 case Instruction::ZExt:
811 case Instruction::SExt:
812 return true;
813 }
814 }
815 return false;
816}
817
818static bool isLoopIncrement(User *U, Instruction *IV) {
819 BinaryOperator *BO = dyn_cast<BinaryOperator>(U);
820
821 if ((BO && BO->getOpcode() != Instruction::Add) ||
822 (!BO && !isa<GetElementPtrInst>(U)))
823 return false;
824
825 for (auto *UU : U->users()) {
826 PHINode *PN = dyn_cast<PHINode>(UU);
827 if (PN && PN == IV)
828 return true;
829 }
830 return false;
831}
832
833bool LoopReroll::DAGRootTracker::
834collectPossibleRoots(Instruction *Base, std::map<int64_t,Instruction*> &Roots) {
835 SmallInstructionVector BaseUsers;
836
837 for (auto *I : Base->users()) {
838 ConstantInt *CI = nullptr;
839
840 if (isLoopIncrement(I, IV)) {
841 LoopIncs.push_back(cast<Instruction>(I));
842 continue;
843 }
844
845 // The root nodes must be either GEPs, ORs or ADDs.
846 if (auto *BO = dyn_cast<BinaryOperator>(I)) {
847 if (BO->getOpcode() == Instruction::Add ||
848 BO->getOpcode() == Instruction::Or)
849 CI = dyn_cast<ConstantInt>(BO->getOperand(1));
850 } else if (auto *GEP = dyn_cast<GetElementPtrInst>(I)) {
851 Value *LastOperand = GEP->getOperand(GEP->getNumOperands()-1);
852 CI = dyn_cast<ConstantInt>(LastOperand);
853 }
854
855 if (!CI) {
856 if (Instruction *II = dyn_cast<Instruction>(I)) {
857 BaseUsers.push_back(II);
858 continue;
859 } else {
860 DEBUG(dbgs() << "LRR: Aborting due to non-instruction: " << *I << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reroll")) { dbgs() << "LRR: Aborting due to non-instruction: "
<< *I << "\n"; } } while (false);
861 return false;
862 }
863 }
864
865 int64_t V = std::abs(CI->getValue().getSExtValue());
866 if (Roots.find(V) != Roots.end())
867 // No duplicates, please.
868 return false;
869
870 Roots[V] = cast<Instruction>(I);
871 }
872
873 // Make sure we have at least two roots.
874 if (Roots.empty() || (Roots.size() == 1 && BaseUsers.empty()))
875 return false;
876
877 // If we found non-loop-inc, non-root users of Base, assume they are
878 // for the zeroth root index. This is because "add %a, 0" gets optimized
879 // away.
880 if (BaseUsers.size()) {
881 if (Roots.find(0) != Roots.end()) {
882 DEBUG(dbgs() << "LRR: Multiple roots found for base - aborting!\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reroll")) { dbgs() << "LRR: Multiple roots found for base - aborting!\n"
; } } while (false);
883 return false;
884 }
885 Roots[0] = Base;
886 }
887
888 // Calculate the number of users of the base, or lowest indexed, iteration.
889 unsigned NumBaseUses = BaseUsers.size();
890 if (NumBaseUses == 0)
891 NumBaseUses = Roots.begin()->second->getNumUses();
892
893 // Check that every node has the same number of users.
894 for (auto &KV : Roots) {
895 if (KV.first == 0)
896 continue;
897 if (!KV.second->hasNUses(NumBaseUses)) {
898 DEBUG(dbgs() << "LRR: Aborting - Root and Base #users not the same: "do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reroll")) { dbgs() << "LRR: Aborting - Root and Base #users not the same: "
<< "#Base=" << NumBaseUses << ", #Root=" <<
KV.second->getNumUses() << "\n"; } } while (false)
899 << "#Base=" << NumBaseUses << ", #Root=" <<do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reroll")) { dbgs() << "LRR: Aborting - Root and Base #users not the same: "
<< "#Base=" << NumBaseUses << ", #Root=" <<
KV.second->getNumUses() << "\n"; } } while (false)
900 KV.second->getNumUses() << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reroll")) { dbgs() << "LRR: Aborting - Root and Base #users not the same: "
<< "#Base=" << NumBaseUses << ", #Root=" <<
KV.second->getNumUses() << "\n"; } } while (false);
901 return false;
902 }
903 }
904
905 return true;
906}
907
908void LoopReroll::DAGRootTracker::
909findRootsRecursive(Instruction *I, SmallInstructionSet SubsumedInsts) {
910 // Does the user look like it could be part of a root set?
911 // All its users must be simple arithmetic ops.
912 if (I->hasNUsesOrMore(IL_MaxRerollIterations + 1))
913 return;
914
915 if (I != IV && findRootsBase(I, SubsumedInsts))
916 return;
917
918 SubsumedInsts.insert(I);
919
920 for (User *V : I->users()) {
921 Instruction *I = cast<Instruction>(V);
922 if (is_contained(LoopIncs, I))
923 continue;
924
925 if (!isSimpleArithmeticOp(I))
926 continue;
927
928 // The recursive call makes a copy of SubsumedInsts.
929 findRootsRecursive(I, SubsumedInsts);
930 }
931}
932
933bool LoopReroll::DAGRootTracker::validateRootSet(DAGRootSet &DRS) {
934 if (DRS.Roots.empty())
935 return false;
936
937 // Consider a DAGRootSet with N-1 roots (so N different values including
938 // BaseInst).
939 // Define d = Roots[0] - BaseInst, which should be the same as
940 // Roots[I] - Roots[I-1] for all I in [1..N).
941 // Define D = BaseInst@J - BaseInst@J-1, where "@J" means the value at the
942 // loop iteration J.
943 //
944 // Now, For the loop iterations to be consecutive:
945 // D = d * N
946 const auto *ADR = dyn_cast<SCEVAddRecExpr>(SE->getSCEV(DRS.BaseInst));
947 if (!ADR)
948 return false;
949 unsigned N = DRS.Roots.size() + 1;
950 const SCEV *StepSCEV = SE->getMinusSCEV(SE->getSCEV(DRS.Roots[0]), ADR);
951 const SCEV *ScaleSCEV = SE->getConstant(StepSCEV->getType(), N);
952 if (ADR->getStepRecurrence(*SE) != SE->getMulExpr(StepSCEV, ScaleSCEV))
953 return false;
954
955 return true;
956}
957
958bool LoopReroll::DAGRootTracker::
959findRootsBase(Instruction *IVU, SmallInstructionSet SubsumedInsts) {
960 // The base of a RootSet must be an AddRec, so it can be erased.
961 const auto *IVU_ADR = dyn_cast<SCEVAddRecExpr>(SE->getSCEV(IVU));
962 if (!IVU_ADR || IVU_ADR->getLoop() != L)
963 return false;
964
965 std::map<int64_t, Instruction*> V;
966 if (!collectPossibleRoots(IVU, V))
967 return false;
968
969 // If we didn't get a root for index zero, then IVU must be
970 // subsumed.
971 if (V.find(0) == V.end())
972 SubsumedInsts.insert(IVU);
973
974 // Partition the vector into monotonically increasing indexes.
975 DAGRootSet DRS;
976 DRS.BaseInst = nullptr;
977
978 SmallVector<DAGRootSet, 16> PotentialRootSets;
979
980 for (auto &KV : V) {
981 if (!DRS.BaseInst) {
982 DRS.BaseInst = KV.second;
983 DRS.SubsumedInsts = SubsumedInsts;
984 } else if (DRS.Roots.empty()) {
985 DRS.Roots.push_back(KV.second);
986 } else if (V.find(KV.first - 1) != V.end()) {
987 DRS.Roots.push_back(KV.second);
988 } else {
989 // Linear sequence terminated.
990 if (!validateRootSet(DRS))
991 return false;
992
993 // Construct a new DAGRootSet with the next sequence.
994 PotentialRootSets.push_back(DRS);
995 DRS.BaseInst = KV.second;
996 DRS.Roots.clear();
997 }
998 }
999
1000 if (!validateRootSet(DRS))
1001 return false;
1002
1003 PotentialRootSets.push_back(DRS);
1004
1005 RootSets.append(PotentialRootSets.begin(), PotentialRootSets.end());
1006
1007 return true;
1008}
1009
1010bool LoopReroll::DAGRootTracker::findRoots() {
1011 Inc = IVToIncMap[IV];
1012
1013 assert(RootSets.empty() && "Unclean state!")(static_cast <bool> (RootSets.empty() && "Unclean state!"
) ? void (0) : __assert_fail ("RootSets.empty() && \"Unclean state!\""
, "/build/llvm-toolchain-snapshot-7~svn329677/lib/Transforms/Scalar/LoopRerollPass.cpp"
, 1013, __extension__ __PRETTY_FUNCTION__));
1014 if (std::abs(Inc) == 1) {
1015 for (auto *IVU : IV->users()) {
1016 if (isLoopIncrement(IVU, IV))
1017 LoopIncs.push_back(cast<Instruction>(IVU));
1018 }
1019 findRootsRecursive(IV, SmallInstructionSet());
1020 LoopIncs.push_back(IV);
1021 } else {
1022 if (!findRootsBase(IV, SmallInstructionSet()))
1023 return false;
1024 }
1025
1026 // Ensure all sets have the same size.
1027 if (RootSets.empty()) {
1028 DEBUG(dbgs() << "LRR: Aborting because no root sets found!\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reroll")) { dbgs() << "LRR: Aborting because no root sets found!\n"
; } } while (false);
1029 return false;
1030 }
1031 for (auto &V : RootSets) {
1032 if (V.Roots.empty() || V.Roots.size() != RootSets[0].Roots.size()) {
1033 DEBUG(dbgs()do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reroll")) { dbgs() << "LRR: Aborting because not all root sets have the same size\n"
; } } while (false)
1034 << "LRR: Aborting because not all root sets have the same size\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reroll")) { dbgs() << "LRR: Aborting because not all root sets have the same size\n"
; } } while (false);
1035 return false;
1036 }
1037 }
1038
1039 Scale = RootSets[0].Roots.size() + 1;
1040
1041 if (Scale > IL_MaxRerollIterations) {
1042 DEBUG(dbgs() << "LRR: Aborting - too many iterations found. "do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reroll")) { dbgs() << "LRR: Aborting - too many iterations found. "
<< "#Found=" << Scale << ", #Max=" <<
IL_MaxRerollIterations << "\n"; } } while (false)
1043 << "#Found=" << Scale << ", #Max=" << IL_MaxRerollIterationsdo { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reroll")) { dbgs() << "LRR: Aborting - too many iterations found. "
<< "#Found=" << Scale << ", #Max=" <<
IL_MaxRerollIterations << "\n"; } } while (false)
1044 << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reroll")) { dbgs() << "LRR: Aborting - too many iterations found. "
<< "#Found=" << Scale << ", #Max=" <<
IL_MaxRerollIterations << "\n"; } } while (false);
1045 return false;
1046 }
1047
1048 DEBUG(dbgs() << "LRR: Successfully found roots: Scale=" << Scale << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reroll")) { dbgs() << "LRR: Successfully found roots: Scale="
<< Scale << "\n"; } } while (false);
1049
1050 return true;
1051}
1052
1053bool LoopReroll::DAGRootTracker::collectUsedInstructions(SmallInstructionSet &PossibleRedSet) {
1054 // Populate the MapVector with all instructions in the block, in order first,
1055 // so we can iterate over the contents later in perfect order.
1056 for (auto &I : *L->getHeader()) {
1057 Uses[&I].resize(IL_End);
1058 }
1059
1060 SmallInstructionSet Exclude;
1061 for (auto &DRS : RootSets) {
1062 Exclude.insert(DRS.Roots.begin(), DRS.Roots.end());
1063 Exclude.insert(DRS.SubsumedInsts.begin(), DRS.SubsumedInsts.end());
1064 Exclude.insert(DRS.BaseInst);
1065 }
1066 Exclude.insert(LoopIncs.begin(), LoopIncs.end());
1067
1068 for (auto &DRS : RootSets) {
1069 DenseSet<Instruction*> VBase;
1070 collectInLoopUserSet(DRS.BaseInst, Exclude, PossibleRedSet, VBase);
1071 for (auto *I : VBase) {
1072 Uses[I].set(0);
1073 }
1074
1075 unsigned Idx = 1;
1076 for (auto *Root : DRS.Roots) {
1077 DenseSet<Instruction*> V;
1078 collectInLoopUserSet(Root, Exclude, PossibleRedSet, V);
1079
1080 // While we're here, check the use sets are the same size.
1081 if (V.size() != VBase.size()) {
1082 DEBUG(dbgs() << "LRR: Aborting - use sets are different sizes\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reroll")) { dbgs() << "LRR: Aborting - use sets are different sizes\n"
; } } while (false);
1083 return false;
1084 }
1085
1086 for (auto *I : V) {
1087 Uses[I].set(Idx);
1088 }
1089 ++Idx;
1090 }
1091
1092 // Make sure our subsumed instructions are remembered too.
1093 for (auto *I : DRS.SubsumedInsts) {
1094 Uses[I].set(IL_All);
1095 }
1096 }
1097
1098 // Make sure the loop increments are also accounted for.
1099
1100 Exclude.clear();
1101 for (auto &DRS : RootSets) {
1102 Exclude.insert(DRS.Roots.begin(), DRS.Roots.end());
1103 Exclude.insert(DRS.SubsumedInsts.begin(), DRS.SubsumedInsts.end());
1104 Exclude.insert(DRS.BaseInst);
1105 }
1106
1107 DenseSet<Instruction*> V;
1108 collectInLoopUserSet(LoopIncs, Exclude, PossibleRedSet, V);
1109 for (auto *I : V) {
1110 Uses[I].set(IL_All);
1111 }
1112
1113 return true;
1114}
1115
1116/// Get the next instruction in "In" that is a member of set Val.
1117/// Start searching from StartI, and do not return anything in Exclude.
1118/// If StartI is not given, start from In.begin().
1119LoopReroll::DAGRootTracker::UsesTy::iterator
1120LoopReroll::DAGRootTracker::nextInstr(int Val, UsesTy &In,
1121 const SmallInstructionSet &Exclude,
1122 UsesTy::iterator *StartI) {
1123 UsesTy::iterator I = StartI ? *StartI : In.begin();
1124 while (I != In.end() && (I->second.test(Val) == 0 ||
1125 Exclude.count(I->first) != 0))
1126 ++I;
1127 return I;
1128}
1129
1130bool LoopReroll::DAGRootTracker::isBaseInst(Instruction *I) {
1131 for (auto &DRS : RootSets) {
1132 if (DRS.BaseInst == I)
1133 return true;
1134 }
1135 return false;
1136}
1137
1138bool LoopReroll::DAGRootTracker::isRootInst(Instruction *I) {
1139 for (auto &DRS : RootSets) {
1140 if (is_contained(DRS.Roots, I))
1141 return true;
1142 }
1143 return false;
1144}
1145
1146/// Return true if instruction I depends on any instruction between
1147/// Start and End.
1148bool LoopReroll::DAGRootTracker::instrDependsOn(Instruction *I,
1149 UsesTy::iterator Start,
1150 UsesTy::iterator End) {
1151 for (auto *U : I->users()) {
1152 for (auto It = Start; It != End; ++It)
1153 if (U == It->first)
1154 return true;
1155 }
1156 return false;
1157}
1158
1159static bool isIgnorableInst(const Instruction *I) {
1160 if (isa<DbgInfoIntrinsic>(I))
1161 return true;
1162 const IntrinsicInst* II = dyn_cast<IntrinsicInst>(I);
1163 if (!II)
1164 return false;
1165 switch (II->getIntrinsicID()) {
1166 default:
1167 return false;
1168 case Intrinsic::annotation:
1169 case Intrinsic::ptr_annotation:
1170 case Intrinsic::var_annotation:
1171 // TODO: the following intrinsics may also be whitelisted:
1172 // lifetime_start, lifetime_end, invariant_start, invariant_end
1173 return true;
1174 }
1175 return false;
1176}
1177
1178bool LoopReroll::DAGRootTracker::validate(ReductionTracker &Reductions) {
1179 // We now need to check for equivalence of the use graph of each root with
1180 // that of the primary induction variable (excluding the roots). Our goal
1181 // here is not to solve the full graph isomorphism problem, but rather to
1182 // catch common cases without a lot of work. As a result, we will assume
1183 // that the relative order of the instructions in each unrolled iteration
1184 // is the same (although we will not make an assumption about how the
1185 // different iterations are intermixed). Note that while the order must be
1186 // the same, the instructions may not be in the same basic block.
1187
1188 // An array of just the possible reductions for this scale factor. When we
1189 // collect the set of all users of some root instructions, these reduction
1190 // instructions are treated as 'final' (their uses are not considered).
1191 // This is important because we don't want the root use set to search down
1192 // the reduction chain.
1193 SmallInstructionSet PossibleRedSet;
1194 SmallInstructionSet PossibleRedLastSet;
1195 SmallInstructionSet PossibleRedPHISet;
1196 Reductions.restrictToScale(Scale, PossibleRedSet,
1197 PossibleRedPHISet, PossibleRedLastSet);
1198
1199 // Populate "Uses" with where each instruction is used.
1200 if (!collectUsedInstructions(PossibleRedSet))
1201 return false;
1202
1203 // Make sure we mark the reduction PHIs as used in all iterations.
1204 for (auto *I : PossibleRedPHISet) {
1205 Uses[I].set(IL_All);
1206 }
1207
1208 // Make sure we mark loop-control-only PHIs as used in all iterations. See
1209 // comment above LoopReroll::isLoopControlIV for more information.
1210 BasicBlock *Header = L->getHeader();
1211 if (LoopControlIV && LoopControlIV != IV) {
1212 for (auto *U : LoopControlIV->users()) {
1213 Instruction *IVUser = dyn_cast<Instruction>(U);
1214 // IVUser could be loop increment or compare
1215 Uses[IVUser].set(IL_All);
1216 for (auto *UU : IVUser->users()) {
1217 Instruction *UUser = dyn_cast<Instruction>(UU);
1218 // UUser could be compare, PHI or branch
1219 Uses[UUser].set(IL_All);
1220 // Skip SExt
1221 if (isa<SExtInst>(UUser)) {
1222 UUser = dyn_cast<Instruction>(*(UUser->user_begin()));
1223 Uses[UUser].set(IL_All);
1224 }
1225 // Is UUser a compare instruction?
1226 if (UU->hasOneUse()) {
1227 Instruction *BI = dyn_cast<BranchInst>(*UUser->user_begin());
1228 if (BI == cast<BranchInst>(Header->getTerminator()))
1229 Uses[BI].set(IL_All);
1230 }
1231 }
1232 }
1233 }
1234
1235 // Make sure all instructions in the loop are in one and only one
1236 // set.
1237 for (auto &KV : Uses) {
1238 if (KV.second.count() != 1 && !isIgnorableInst(KV.first)) {
1239 DEBUG(dbgs() << "LRR: Aborting - instruction is not used in 1 iteration: "do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reroll")) { dbgs() << "LRR: Aborting - instruction is not used in 1 iteration: "
<< *KV.first << " (#uses=" << KV.second.count
() << ")\n"; } } while (false)
1240 << *KV.first << " (#uses=" << KV.second.count() << ")\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reroll")) { dbgs() << "LRR: Aborting - instruction is not used in 1 iteration: "
<< *KV.first << " (#uses=" << KV.second.count
() << ")\n"; } } while (false);
1241 return false;
1242 }
1243 }
1244
1245 DEBUG(do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reroll")) { for (auto &KV : Uses) { dbgs() <<
"LRR: " << KV.second.find_first() << "\t" <<
*KV.first << "\n"; }; } } while (false)
1246 for (auto &KV : Uses) {do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reroll")) { for (auto &KV : Uses) { dbgs() <<
"LRR: " << KV.second.find_first() << "\t" <<
*KV.first << "\n"; }; } } while (false)
1247 dbgs() << "LRR: " << KV.second.find_first() << "\t" << *KV.first << "\n";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reroll")) { for (auto &KV : Uses) { dbgs() <<
"LRR: " << KV.second.find_first() << "\t" <<
*KV.first << "\n"; }; } } while (false)
1248 }do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reroll")) { for (auto &KV : Uses) { dbgs() <<
"LRR: " << KV.second.find_first() << "\t" <<
*KV.first << "\n"; }; } } while (false)
1249 )do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reroll")) { for (auto &KV : Uses) { dbgs() <<
"LRR: " << KV.second.find_first() << "\t" <<
*KV.first << "\n"; }; } } while (false);
1250
1251 for (unsigned Iter = 1; Iter < Scale; ++Iter) {
1252 // In addition to regular aliasing information, we need to look for
1253 // instructions from later (future) iterations that have side effects
1254 // preventing us from reordering them past other instructions with side
1255 // effects.
1256 bool FutureSideEffects = false;
1257 AliasSetTracker AST(*AA);
1258 // The map between instructions in f(%iv.(i+1)) and f(%iv).
1259 DenseMap<Value *, Value *> BaseMap;
1260
1261 // Compare iteration Iter to the base.
1262 SmallInstructionSet Visited;
1263 auto BaseIt = nextInstr(0, Uses, Visited);
1264 auto RootIt = nextInstr(Iter, Uses, Visited);
1265 auto LastRootIt = Uses.begin();
1266
1267 while (BaseIt != Uses.end() && RootIt != Uses.end()) {
1268 Instruction *BaseInst = BaseIt->first;
1269 Instruction *RootInst = RootIt->first;
1270
1271 // Skip over the IV or root instructions; only match their users.
1272 bool Continue = false;
1273 if (isBaseInst(BaseInst)) {
1274 Visited.insert(BaseInst);
1275 BaseIt = nextInstr(0, Uses, Visited);
1276 Continue = true;
1277 }
1278 if (isRootInst(RootInst)) {
1279 LastRootIt = RootIt;
1280 Visited.insert(RootInst);
1281 RootIt = nextInstr(Iter, Uses, Visited);
1282 Continue = true;
1283 }
1284 if (Continue) continue;
1285
1286 if (!BaseInst->isSameOperationAs(RootInst)) {
1287 // Last chance saloon. We don't try and solve the full isomorphism
1288 // problem, but try and at least catch the case where two instructions
1289 // *of different types* are round the wrong way. We won't be able to
1290 // efficiently tell, given two ADD instructions, which way around we
1291 // should match them, but given an ADD and a SUB, we can at least infer
1292 // which one is which.
1293 //
1294 // This should allow us to deal with a greater subset of the isomorphism
1295 // problem. It does however change a linear algorithm into a quadratic
1296 // one, so limit the number of probes we do.
1297 auto TryIt = RootIt;
1298 unsigned N = NumToleratedFailedMatches;
1299 while (TryIt != Uses.end() &&
1300 !BaseInst->isSameOperationAs(TryIt->first) &&
1301 N--) {
1302 ++TryIt;
1303 TryIt = nextInstr(Iter, Uses, Visited, &TryIt);
1304 }
1305
1306 if (TryIt == Uses.end() || TryIt == RootIt ||
1307 instrDependsOn(TryIt->first, RootIt, TryIt)) {
1308 DEBUG(dbgs() << "LRR: iteration root match failed at " << *BaseInst <<do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reroll")) { dbgs() << "LRR: iteration root match failed at "
<< *BaseInst << " vs. " << *RootInst <<
"\n"; } } while (false)
1309 " vs. " << *RootInst << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reroll")) { dbgs() << "LRR: iteration root match failed at "
<< *BaseInst << " vs. " << *RootInst <<
"\n"; } } while (false);
1310 return false;
1311 }
1312
1313 RootIt = TryIt;
1314 RootInst = TryIt->first;
1315 }
1316
1317 // All instructions between the last root and this root
1318 // may belong to some other iteration. If they belong to a
1319 // future iteration, then they're dangerous to alias with.
1320 //
1321 // Note that because we allow a limited amount of flexibility in the order
1322 // that we visit nodes, LastRootIt might be *before* RootIt, in which
1323 // case we've already checked this set of instructions so we shouldn't
1324 // do anything.
1325 for (; LastRootIt < RootIt; ++LastRootIt) {
1326 Instruction *I = LastRootIt->first;
1327 if (LastRootIt->second.find_first() < (int)Iter)
1328 continue;
1329 if (I->mayWriteToMemory())
1330 AST.add(I);
1331 // Note: This is specifically guarded by a check on isa<PHINode>,
1332 // which while a valid (somewhat arbitrary) micro-optimization, is
1333 // needed because otherwise isSafeToSpeculativelyExecute returns
1334 // false on PHI nodes.
1335 if (!isa<PHINode>(I) && !isUnorderedLoadStore(I) &&
1336 !isSafeToSpeculativelyExecute(I))
1337 // Intervening instructions cause side effects.
1338 FutureSideEffects = true;
1339 }
1340
1341 // Make sure that this instruction, which is in the use set of this
1342 // root instruction, does not also belong to the base set or the set of
1343 // some other root instruction.
1344 if (RootIt->second.count() > 1) {
1345 DEBUG(dbgs() << "LRR: iteration root match failed at " << *BaseInst <<do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reroll")) { dbgs() << "LRR: iteration root match failed at "
<< *BaseInst << " vs. " << *RootInst <<
" (prev. case overlap)\n"; } } while (false)
1346 " vs. " << *RootInst << " (prev. case overlap)\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reroll")) { dbgs() << "LRR: iteration root match failed at "
<< *BaseInst << " vs. " << *RootInst <<
" (prev. case overlap)\n"; } } while (false);
1347 return false;
1348 }
1349
1350 // Make sure that we don't alias with any instruction in the alias set
1351 // tracker. If we do, then we depend on a future iteration, and we
1352 // can't reroll.
1353 if (RootInst->mayReadFromMemory())
1354 for (auto &K : AST) {
1355 if (K.aliasesUnknownInst(RootInst, *AA)) {
1356 DEBUG(dbgs() << "LRR: iteration root match failed at " << *BaseInst <<do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reroll")) { dbgs() << "LRR: iteration root match failed at "
<< *BaseInst << " vs. " << *RootInst <<
" (depends on future store)\n"; } } while (false)
1357 " vs. " << *RootInst << " (depends on future store)\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reroll")) { dbgs() << "LRR: iteration root match failed at "
<< *BaseInst << " vs. " << *RootInst <<
" (depends on future store)\n"; } } while (false);
1358 return false;
1359 }
1360 }
1361
1362 // If we've past an instruction from a future iteration that may have
1363 // side effects, and this instruction might also, then we can't reorder
1364 // them, and this matching fails. As an exception, we allow the alias
1365 // set tracker to handle regular (unordered) load/store dependencies.
1366 if (FutureSideEffects && ((!isUnorderedLoadStore(BaseInst) &&
1367 !isSafeToSpeculativelyExecute(BaseInst)) ||
1368 (!isUnorderedLoadStore(RootInst) &&
1369 !isSafeToSpeculativelyExecute(RootInst)))) {
1370 DEBUG(dbgs() << "LRR: iteration root match failed at " << *BaseInst <<do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reroll")) { dbgs() << "LRR: iteration root match failed at "
<< *BaseInst << " vs. " << *RootInst <<
" (side effects prevent reordering)\n"; } } while (false)
1371 " vs. " << *RootInst <<do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reroll")) { dbgs() << "LRR: iteration root match failed at "
<< *BaseInst << " vs. " << *RootInst <<
" (side effects prevent reordering)\n"; } } while (false)
1372 " (side effects prevent reordering)\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reroll")) { dbgs() << "LRR: iteration root match failed at "
<< *BaseInst << " vs. " << *RootInst <<
" (side effects prevent reordering)\n"; } } while (false);
1373 return false;
1374 }
1375
1376 // For instructions that are part of a reduction, if the operation is
1377 // associative, then don't bother matching the operands (because we
1378 // already know that the instructions are isomorphic, and the order
1379 // within the iteration does not matter). For non-associative reductions,
1380 // we do need to match the operands, because we need to reject
1381 // out-of-order instructions within an iteration!
1382 // For example (assume floating-point addition), we need to reject this:
1383 // x += a[i]; x += b[i];
1384 // x += a[i+1]; x += b[i+1];
1385 // x += b[i+2]; x += a[i+2];
1386 bool InReduction = Reductions.isPairInSame(BaseInst, RootInst);
1387
1388 if (!(InReduction && BaseInst->isAssociative())) {
1389 bool Swapped = false, SomeOpMatched = false;
1390 for (unsigned j = 0; j < BaseInst->getNumOperands(); ++j) {
1391 Value *Op2 = RootInst->getOperand(j);
1392
1393 // If this is part of a reduction (and the operation is not
1394 // associatve), then we match all operands, but not those that are
1395 // part of the reduction.
1396 if (InReduction)
1397 if (Instruction *Op2I = dyn_cast<Instruction>(Op2))
1398 if (Reductions.isPairInSame(RootInst, Op2I))
1399 continue;
1400
1401 DenseMap<Value *, Value *>::iterator BMI = BaseMap.find(Op2);
1402 if (BMI != BaseMap.end()) {
1403 Op2 = BMI->second;
1404 } else {
1405 for (auto &DRS : RootSets) {
1406 if (DRS.Roots[Iter-1] == (Instruction*) Op2) {
1407 Op2 = DRS.BaseInst;
1408 break;
1409 }
1410 }
1411 }
1412
1413 if (BaseInst->getOperand(Swapped ? unsigned(!j) : j) != Op2) {
1414 // If we've not already decided to swap the matched operands, and
1415 // we've not already matched our first operand (note that we could
1416 // have skipped matching the first operand because it is part of a
1417 // reduction above), and the instruction is commutative, then try
1418 // the swapped match.
1419 if (!Swapped && BaseInst->isCommutative() && !SomeOpMatched &&
1420 BaseInst->getOperand(!j) == Op2) {
1421 Swapped = true;
1422 } else {
1423 DEBUG(dbgs() << "LRR: iteration root match failed at " << *BaseInstdo { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reroll")) { dbgs() << "LRR: iteration root match failed at "
<< *BaseInst << " vs. " << *RootInst <<
" (operand " << j << ")\n"; } } while (false)
1424 << " vs. " << *RootInst << " (operand " << j << ")\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reroll")) { dbgs() << "LRR: iteration root match failed at "
<< *BaseInst << " vs. " << *RootInst <<
" (operand " << j << ")\n"; } } while (false);
1425 return false;
1426 }
1427 }
1428
1429 SomeOpMatched = true;
1430 }
1431 }
1432
1433 if ((!PossibleRedLastSet.count(BaseInst) &&
1434 hasUsesOutsideLoop(BaseInst, L)) ||
1435 (!PossibleRedLastSet.count(RootInst) &&
1436 hasUsesOutsideLoop(RootInst, L))) {
1437 DEBUG(dbgs() << "LRR: iteration root match failed at " << *BaseInst <<do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reroll")) { dbgs() << "LRR: iteration root match failed at "
<< *BaseInst << " vs. " << *RootInst <<
" (uses outside loop)\n"; } } while (false)
1438 " vs. " << *RootInst << " (uses outside loop)\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reroll")) { dbgs() << "LRR: iteration root match failed at "
<< *BaseInst << " vs. " << *RootInst <<
" (uses outside loop)\n"; } } while (false);
1439 return false;
1440 }
1441
1442 Reductions.recordPair(BaseInst, RootInst, Iter);
1443 BaseMap.insert(std::make_pair(RootInst, BaseInst));
1444
1445 LastRootIt = RootIt;
1446 Visited.insert(BaseInst);
1447 Visited.insert(RootInst);
1448 BaseIt = nextInstr(0, Uses, Visited);
1449 RootIt = nextInstr(Iter, Uses, Visited);
1450 }
1451 assert(BaseIt == Uses.end() && RootIt == Uses.end() &&(static_cast <bool> (BaseIt == Uses.end() && RootIt
== Uses.end() && "Mismatched set sizes!") ? void (0)
: __assert_fail ("BaseIt == Uses.end() && RootIt == Uses.end() && \"Mismatched set sizes!\""
, "/build/llvm-toolchain-snapshot-7~svn329677/lib/Transforms/Scalar/LoopRerollPass.cpp"
, 1452, __extension__ __PRETTY_FUNCTION__))
1452 "Mismatched set sizes!")(static_cast <bool> (BaseIt == Uses.end() && RootIt
== Uses.end() && "Mismatched set sizes!") ? void (0)
: __assert_fail ("BaseIt == Uses.end() && RootIt == Uses.end() && \"Mismatched set sizes!\""
, "/build/llvm-toolchain-snapshot-7~svn329677/lib/Transforms/Scalar/LoopRerollPass.cpp"
, 1452, __extension__ __PRETTY_FUNCTION__));
1453 }
1454
1455 DEBUG(dbgs() << "LRR: Matched all iteration increments for " <<do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reroll")) { dbgs() << "LRR: Matched all iteration increments for "
<< *IV << "\n"; } } while (false)
1456 *IV << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reroll")) { dbgs() << "LRR: Matched all iteration increments for "
<< *IV << "\n"; } } while (false);
1457
1458 return true;
1459}
1460
1461void LoopReroll::DAGRootTracker::replace(const SCEV *IterCount) {
1462 BasicBlock *Header = L->getHeader();
1463 // Remove instructions associated with non-base iterations.
1464 for (BasicBlock::reverse_iterator J = Header->rbegin(), JE = Header->rend();
1465 J != JE;) {
1466 unsigned I = Uses[&*J].find_first();
1467 if (I > 0 && I < IL_All) {
1468 DEBUG(dbgs() << "LRR: removing: " << *J << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reroll")) { dbgs() << "LRR: removing: " <<
*J << "\n"; } } while (false);
1469 J++->eraseFromParent();
1470 continue;
1471 }
1472
1473 ++J;
1474 }
1475
1476 bool HasTwoIVs = LoopControlIV && LoopControlIV != IV;
1477
1478 if (HasTwoIVs) {
1479 updateNonLoopCtrlIncr();
1480 replaceIV(LoopControlIV, LoopControlIV, IterCount);
1481 } else
1482 // We need to create a new induction variable for each different BaseInst.
1483 for (auto &DRS : RootSets)
1484 // Insert the new induction variable.
1485 replaceIV(DRS.BaseInst, IV, IterCount);
1486
1487 SimplifyInstructionsInBlock(Header, TLI);
1488 DeleteDeadPHIs(Header, TLI);
1489}
1490
1491// For non-loop-control IVs, we only need to update the last increment
1492// with right amount, then we are done.
1493void LoopReroll::DAGRootTracker::updateNonLoopCtrlIncr() {
1494 const SCEV *NewInc = nullptr;
1495 for (auto *LoopInc : LoopIncs) {
1496 GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(LoopInc);
1497 const SCEVConstant *COp = nullptr;
1498 if (GEP && LoopInc->getOperand(0)->getType()->isPointerTy()) {
1499 COp = dyn_cast<SCEVConstant>(SE->getSCEV(LoopInc->getOperand(1)));
1500 } else {
1501 COp = dyn_cast<SCEVConstant>(SE->getSCEV(LoopInc->getOperand(0)));
1502 if (!COp)
1503 COp = dyn_cast<SCEVConstant>(SE->getSCEV(LoopInc->getOperand(1)));
1504 }
1505
1506 assert(COp && "Didn't find constant operand of LoopInc!\n")(static_cast <bool> (COp && "Didn't find constant operand of LoopInc!\n"
) ? void (0) : __assert_fail ("COp && \"Didn't find constant operand of LoopInc!\\n\""
, "/build/llvm-toolchain-snapshot-7~svn329677/lib/Transforms/Scalar/LoopRerollPass.cpp"
, 1506, __extension__ __PRETTY_FUNCTION__));
1507
1508 const APInt &AInt = COp->getValue()->getValue();
1509 const SCEV *ScaleSCEV = SE->getConstant(COp->getType(), Scale);
1510 if (AInt.isNegative()) {
1511 NewInc = SE->getNegativeSCEV(COp);
1512 NewInc = SE->getUDivExpr(NewInc, ScaleSCEV);
1513 NewInc = SE->getNegativeSCEV(NewInc);
1514 } else
1515 NewInc = SE->getUDivExpr(COp, ScaleSCEV);
1516
1517 LoopInc->setOperand(1, dyn_cast<SCEVConstant>(NewInc)->getValue());
1518 }
1519}
1520
1521void LoopReroll::DAGRootTracker::replaceIV(Instruction *Inst,
1522 Instruction *InstIV,
1523 const SCEV *IterCount) {
1524 BasicBlock *Header = L->getHeader();
1525 int64_t Inc = IVToIncMap[InstIV];
1526 bool NeedNewIV = InstIV == LoopControlIV;
1527 bool Negative = !NeedNewIV && Inc < 0;
1528
1529 const SCEVAddRecExpr *RealIVSCEV = cast<SCEVAddRecExpr>(SE->getSCEV(Inst));
1530 const SCEV *Start = RealIVSCEV->getStart();
1531
1532 if (NeedNewIV)
1533 Start = SE->getConstant(Start->getType(), 0);
1534
1535 const SCEV *SizeOfExpr = nullptr;
1536 const SCEV *IncrExpr =
1537 SE->getConstant(RealIVSCEV->getType(), Negative ? -1 : 1);
1538 if (auto *PTy = dyn_cast<PointerType>(Inst->getType())) {
1539 Type *ElTy = PTy->getElementType();
1540 SizeOfExpr =
1541 SE->getSizeOfExpr(SE->getEffectiveSCEVType(Inst->getType()), ElTy);
1542 IncrExpr = SE->getMulExpr(IncrExpr, SizeOfExpr);
1543 }
1544 const SCEV *NewIVSCEV =
1545 SE->getAddRecExpr(Start, IncrExpr, L, SCEV::FlagAnyWrap);
1546
1547 { // Limit the lifetime of SCEVExpander.
1548 const DataLayout &DL = Header->getModule()->getDataLayout();
1549 SCEVExpander Expander(*SE, DL, "reroll");
1550 Value *NewIV = Expander.expandCodeFor(NewIVSCEV, Inst->getType(),
1551 Header->getFirstNonPHIOrDbg());
1552
1553 for (auto &KV : Uses)
1554 if (KV.second.find_first() == 0)
1555 KV.first->replaceUsesOfWith(Inst, NewIV);
1556
1557 if (BranchInst *BI = dyn_cast<BranchInst>(Header->getTerminator())) {
1558 // FIXME: Why do we need this check?
1559 if (Uses[BI].find_first() == IL_All) {
1560 const SCEV *ICSCEV = RealIVSCEV->evaluateAtIteration(IterCount, *SE);
1561
1562 if (NeedNewIV)
1563 ICSCEV = SE->getMulExpr(IterCount,
1564 SE->getConstant(IterCount->getType(), Scale));
1565
1566 // Iteration count SCEV minus or plus 1
1567 const SCEV *MinusPlus1SCEV =
1568 SE->getConstant(ICSCEV->getType(), Negative ? -1 : 1);
1569 if (Inst->getType()->isPointerTy()) {
1570 assert(SizeOfExpr && "SizeOfExpr is not initialized")(static_cast <bool> (SizeOfExpr && "SizeOfExpr is not initialized"
) ? void (0) : __assert_fail ("SizeOfExpr && \"SizeOfExpr is not initialized\""
, "/build/llvm-toolchain-snapshot-7~svn329677/lib/Transforms/Scalar/LoopRerollPass.cpp"
, 1570, __extension__ __PRETTY_FUNCTION__));
1571 MinusPlus1SCEV = SE->getMulExpr(MinusPlus1SCEV, SizeOfExpr);
1572 }
1573
1574 const SCEV *ICMinusPlus1SCEV = SE->getMinusSCEV(ICSCEV, MinusPlus1SCEV);
1575 // Iteration count minus 1
1576 Instruction *InsertPtr = nullptr;
1577 if (isa<SCEVConstant>(ICMinusPlus1SCEV)) {
1578 InsertPtr = BI;
1579 } else {
1580 BasicBlock *Preheader = L->getLoopPreheader();
1581 if (!Preheader)
1582 Preheader = InsertPreheaderForLoop(L, DT, LI, PreserveLCSSA);
1583 InsertPtr = Preheader->getTerminator();
1584 }
1585
1586 if (!isa<PointerType>(NewIV->getType()) && NeedNewIV &&
1587 (SE->getTypeSizeInBits(NewIV->getType()) <
1588 SE->getTypeSizeInBits(ICMinusPlus1SCEV->getType()))) {
1589 IRBuilder<> Builder(BI);
1590 Builder.SetCurrentDebugLocation(BI->getDebugLoc());
1591 NewIV = Builder.CreateSExt(NewIV, ICMinusPlus1SCEV->getType());
1592 }
1593 Value *ICMinusPlus1 = Expander.expandCodeFor(
1594 ICMinusPlus1SCEV, NewIV->getType(), InsertPtr);
1595
1596 Value *Cond =
1597 new ICmpInst(BI, CmpInst::ICMP_EQ, NewIV, ICMinusPlus1, "exitcond");
1598 BI->setCondition(Cond);
1599
1600 if (BI->getSuccessor(1) != Header)
1601 BI->swapSuccessors();
1602 }
1603 }
1604 }
1605}
1606
1607// Validate the selected reductions. All iterations must have an isomorphic
1608// part of the reduction chain and, for non-associative reductions, the chain
1609// entries must appear in order.
1610bool LoopReroll::ReductionTracker::validateSelected() {
1611 // For a non-associative reduction, the chain entries must appear in order.
1612 for (int i : Reds) {
1613 int PrevIter = 0, BaseCount = 0, Count = 0;
1614 for (Instruction *J : PossibleReds[i]) {
1615 // Note that all instructions in the chain must have been found because
1616 // all instructions in the function must have been assigned to some
1617 // iteration.
1618 int Iter = PossibleRedIter[J];
1619 if (Iter != PrevIter && Iter != PrevIter + 1 &&
1620 !PossibleReds[i].getReducedValue()->isAssociative()) {
1621 DEBUG(dbgs() << "LRR: Out-of-order non-associative reduction: " <<do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reroll")) { dbgs() << "LRR: Out-of-order non-associative reduction: "
<< J << "\n"; } } while (false)
1622 J << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reroll")) { dbgs() << "LRR: Out-of-order non-associative reduction: "
<< J << "\n"; } } while (false);
1623 return false;
1624 }
1625
1626 if (Iter != PrevIter) {
1627 if (Count != BaseCount) {
1628 DEBUG(dbgs() << "LRR: Iteration " << PrevIter <<do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reroll")) { dbgs() << "LRR: Iteration " <<
PrevIter << " reduction use count " << Count <<
" is not equal to the base use count " << BaseCount <<
"\n"; } } while (false)
1629 " reduction use count " << Count <<do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reroll")) { dbgs() << "LRR: Iteration " <<
PrevIter << " reduction use count " << Count <<
" is not equal to the base use count " << BaseCount <<
"\n"; } } while (false)
1630 " is not equal to the base use count " <<do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reroll")) { dbgs() << "LRR: Iteration " <<
PrevIter << " reduction use count " << Count <<
" is not equal to the base use count " << BaseCount <<
"\n"; } } while (false)
1631 BaseCount << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reroll")) { dbgs() << "LRR: Iteration " <<
PrevIter << " reduction use count " << Count <<
" is not equal to the base use count " << BaseCount <<
"\n"; } } while (false);
1632 return false;
1633 }
1634
1635 Count = 0;
1636 }
1637
1638 ++Count;
1639 if (Iter == 0)
1640 ++BaseCount;
1641
1642 PrevIter = Iter;
1643 }
1644 }
1645
1646 return true;
1647}
1648
1649// For all selected reductions, remove all parts except those in the first
1650// iteration (and the PHI). Replace outside uses of the reduced value with uses
1651// of the first-iteration reduced value (in other words, reroll the selected
1652// reductions).
1653void LoopReroll::ReductionTracker::replaceSelected() {
1654 // Fixup reductions to refer to the last instruction associated with the
1655 // first iteration (not the last).
1656 for (int i : Reds) {
1657 int j = 0;
1658 for (int e = PossibleReds[i].size(); j != e; ++j)
1659 if (PossibleRedIter[PossibleReds[i][j]] != 0) {
1660 --j;
1661 break;
1662 }
1663
1664 // Replace users with the new end-of-chain value.
1665 SmallInstructionVector Users;
1666 for (User *U : PossibleReds[i].getReducedValue()->users()) {
1667 Users.push_back(cast<Instruction>(U));
1668 }
1669
1670 for (Instruction *User : Users)
1671 User->replaceUsesOfWith(PossibleReds[i].getReducedValue(),
1672 PossibleReds[i][j]);
1673 }
1674}
1675
1676// Reroll the provided loop with respect to the provided induction variable.
1677// Generally, we're looking for a loop like this:
1678//
1679// %iv = phi [ (preheader, ...), (body, %iv.next) ]
1680// f(%iv)
1681// %iv.1 = add %iv, 1 <-- a root increment
1682// f(%iv.1)
1683// %iv.2 = add %iv, 2 <-- a root increment
1684// f(%iv.2)
1685// %iv.scale_m_1 = add %iv, scale-1 <-- a root increment
1686// f(%iv.scale_m_1)
1687// ...
1688// %iv.next = add %iv, scale
1689// %cmp = icmp(%iv, ...)
1690// br %cmp, header, exit
1691//
1692// Notably, we do not require that f(%iv), f(%iv.1), etc. be isolated groups of
1693// instructions. In other words, the instructions in f(%iv), f(%iv.1), etc. can
1694// be intermixed with eachother. The restriction imposed by this algorithm is
1695// that the relative order of the isomorphic instructions in f(%iv), f(%iv.1),
1696// etc. be the same.
1697//
1698// First, we collect the use set of %iv, excluding the other increment roots.
1699// This gives us f(%iv). Then we iterate over the loop instructions (scale-1)
1700// times, having collected the use set of f(%iv.(i+1)), during which we:
1701// - Ensure that the next unmatched instruction in f(%iv) is isomorphic to
1702// the next unmatched instruction in f(%iv.(i+1)).
1703// - Ensure that both matched instructions don't have any external users
1704// (with the exception of last-in-chain reduction instructions).
1705// - Track the (aliasing) write set, and other side effects, of all
1706// instructions that belong to future iterations that come before the matched
1707// instructions. If the matched instructions read from that write set, then
1708// f(%iv) or f(%iv.(i+1)) has some dependency on instructions in
1709// f(%iv.(j+1)) for some j > i, and we cannot reroll the loop. Similarly,
1710// if any of these future instructions had side effects (could not be
1711// speculatively executed), and so do the matched instructions, when we
1712// cannot reorder those side-effect-producing instructions, and rerolling
1713// fails.
1714//
1715// Finally, we make sure that all loop instructions are either loop increment
1716// roots, belong to simple latch code, parts of validated reductions, part of
1717// f(%iv) or part of some f(%iv.i). If all of that is true (and all reductions
1718// have been validated), then we reroll the loop.
1719bool LoopReroll::reroll(Instruction *IV, Loop *L, BasicBlock *Header,
1720 const SCEV *IterCount,
1721 ReductionTracker &Reductions) {
1722 DAGRootTracker DAGRoots(this, L, IV, SE, AA, TLI, DT, LI, PreserveLCSSA,
1723 IVToIncMap, LoopControlIV);
1724
1725 if (!DAGRoots.findRoots())
1726 return false;
1727 DEBUG(dbgs() << "LRR: Found all root induction increments for: " <<do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reroll")) { dbgs() << "LRR: Found all root induction increments for: "
<< *IV << "\n"; } } while (false)
1728 *IV << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reroll")) { dbgs() << "LRR: Found all root induction increments for: "
<< *IV << "\n"; } } while (false);
1729
1730 if (!DAGRoots.validate(Reductions))
1731 return false;
1732 if (!Reductions.validateSelected())
1733 return false;
1734 // At this point, we've validated the rerolling, and we're committed to
1735 // making changes!
1736
1737 Reductions.replaceSelected();
1738 DAGRoots.replace(IterCount);
1739
1740 ++NumRerolledLoops;
1741 return true;
1742}
1743
1744bool LoopReroll::runOnLoop(Loop *L, LPPassManager &LPM) {
1745 if (skipLoop(L))
1
Assuming the condition is false
→
2
←
Taking false branch
→
1746 return false;
1747
1748 AA = &getAnalysis<AAResultsWrapperPass>().getAAResults();
1749 LI = &getAnalysis<LoopInfoWrapperPass>().getLoopInfo();
1750 SE = &getAnalysis<ScalarEvolutionWrapperPass>().getSE();
1751 TLI = &getAnalysis<TargetLibraryInfoWrapperPass>().getTLI();
1752 DT = &getAnalysis<DominatorTreeWrapperPass>().getDomTree();
1753 PreserveLCSSA = mustPreserveAnalysisID(LCSSAID);
1754
1755 BasicBlock *Header = L->getHeader();
1756 DEBUG(dbgs() << "LRR: F[" << Header->getParent()->getName() <<do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reroll")) { dbgs() << "LRR: F[" << Header->
getParent()->getName() << "] Loop %" << Header
->getName() << " (" << L->getNumBlocks() <<
" block(s))\n"; } } while (false)
1757 "] Loop %" << Header->getName() << " (" <<do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reroll")) { dbgs() << "LRR: F[" << Header->
getParent()->getName() << "] Loop %" << Header
->getName() << " (" << L->getNumBlocks() <<
" block(s))\n"; } } while (false)
1758 L->getNumBlocks() << " block(s))\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reroll")) { dbgs() << "LRR: F[" << Header->
getParent()->getName() << "] Loop %" << Header
->getName() << " (" << L->getNumBlocks() <<
" block(s))\n"; } } while (false);
1759
1760 // For now, we'll handle only single BB loops.
1761 if (L->getNumBlocks() > 1)
3
←
Assuming the condition is false
→
4
←
Taking false branch
→
1762 return false;
1763
1764 if (!SE->hasLoopInvariantBackedgeTakenCount(L))
5
←
Assuming the condition is false
→
6
←
Taking false branch
→
1765 return false;
1766
1767 const SCEV *LIBETC = SE->getBackedgeTakenCount(L);
1768 const SCEV *IterCount = SE->getAddExpr(LIBETC, SE->getOne(LIBETC->getType()));
1769 DEBUG(dbgs() << "\n Before Reroll:\n" << *(L->getHeader()) << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reroll")) { dbgs() << "\n Before Reroll:\n" <<
*(L->getHeader()) << "\n"; } } while (false);
1770 DEBUG(dbgs() << "LRR: iteration count = " << *IterCount << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reroll")) { dbgs() << "LRR: iteration count = " <<
*IterCount << "\n"; } } while (false);
1771
1772 // First, we need to find the induction variable with respect to which we can
1773 // reroll (there may be several possible options).
1774 SmallInstructionVector PossibleIVs;
1775 IVToIncMap.clear();
1776 LoopControlIV = nullptr;
1777 collectPossibleIVs(L, PossibleIVs);
7
←
Calling 'LoopReroll::collectPossibleIVs'
→
1778
1779 if (PossibleIVs.empty()) {
1780 DEBUG(dbgs() << "LRR: No possible IVs found\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reroll")) { dbgs() << "LRR: No possible IVs found\n"
; } } while (false);
1781 return false;
1782 }
1783
1784 ReductionTracker Reductions;
1785 collectPossibleReductions(L, Reductions);
1786 bool Changed = false;
1787
1788 // For each possible IV, collect the associated possible set of 'root' nodes
1789 // (i+1, i+2, etc.).
1790 for (Instruction *PossibleIV : PossibleIVs)
1791 if (reroll(PossibleIV, L, Header, IterCount, Reductions)) {
1792 Changed = true;
1793 break;
1794 }
1795 DEBUG(dbgs() << "\n After Reroll:\n" << *(L->getHeader()) << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reroll")) { dbgs() << "\n After Reroll:\n" <<
*(L->getHeader()) << "\n"; } } while (false);
1796
1797 // Trip count of L has changed so SE must be re-evaluated.
1798 if (Changed)
1799 SE->forgetLoop(L);
1800
1801 return Changed;
1802}
←

/build/llvm-toolchain-snapshot-7~svn329677/include/llvm/Support/Casting.h

1//===- llvm/Support/Casting.h - Allow flexible, checked, casts --*- C++ -*-===//
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 file defines the isa<X>(), cast<X>(), dyn_cast<X>(), cast_or_null<X>(),
11// and dyn_cast_or_null<X>() templates.
12//
13//===----------------------------------------------------------------------===//
14
15#ifndef LLVM_SUPPORT_CASTING_H
16#define LLVM_SUPPORT_CASTING_H
17
18#include "llvm/Support/Compiler.h"
19#include "llvm/Support/type_traits.h"
20#include <cassert>
21#include <memory>
22#include <type_traits>
23
24namespace llvm {
25
26//===----------------------------------------------------------------------===//
27// isa<x> Support Templates
28//===----------------------------------------------------------------------===//
29
30// Define a template that can be specialized by smart pointers to reflect the
31// fact that they are automatically dereferenced, and are not involved with the
32// template selection process... the default implementation is a noop.
33//
34template<typename From> struct simplify_type {
35 using SimpleType = From; // The real type this represents...
36
37 // An accessor to get the real value...
38 static SimpleType &getSimplifiedValue(From &Val) { return Val; }
39};
40
41template<typename From> struct simplify_type<const From> {
42 using NonConstSimpleType = typename simplify_type<From>::SimpleType;
43 using SimpleType =
44 typename add_const_past_pointer<NonConstSimpleType>::type;
45 using RetType =
46 typename add_lvalue_reference_if_not_pointer<SimpleType>::type;
47
48 static RetType getSimplifiedValue(const From& Val) {
49 return simplify_type<From>::getSimplifiedValue(const_cast<From&>(Val));
50 }
51};
52
53// The core of the implementation of isa<X> is here; To and From should be
54// the names of classes. This template can be specialized to customize the
55// implementation of isa<> without rewriting it from scratch.
56template <typename To, typename From, typename Enabler = void>
57struct isa_impl {
58 static inline bool doit(const From &Val) {
59 return To::classof(&Val);
60 }
61};
62
63/// \brief Always allow upcasts, and perform no dynamic check for them.
64template <typename To, typename From>
65struct isa_impl<
66 To, From, typename std::enable_if<std::is_base_of<To, From>::value>::type> {
67 static inline bool doit(const From &) { return true; }
68};
69
70template <typename To, typename From> struct isa_impl_cl {
71 static inline bool doit(const From &Val) {
72 return isa_impl<To, From>::doit(Val);
73 }
74};
75
76template <typename To, typename From> struct isa_impl_cl<To, const From> {
77 static inline bool doit(const From &Val) {
78 return isa_impl<To, From>::doit(Val);
79 }
80};
81
82template <typename To, typename From>
83struct isa_impl_cl<To, const std::unique_ptr<From>> {
84 static inline bool doit(const std::unique_ptr<From> &Val) {
85 assert(Val && "isa<> used on a null pointer")(static_cast <bool> (Val && "isa<> used on a null pointer"
) ? void (0) : __assert_fail ("Val && \"isa<> used on a null pointer\""
, "/build/llvm-toolchain-snapshot-7~svn329677/include/llvm/Support/Casting.h"
, 85, __extension__ __PRETTY_FUNCTION__));
86 return isa_impl_cl<To, From>::doit(*Val);
87 }
88};
89
90template <typename To, typename From> struct isa_impl_cl<To, From*> {
91 static inline bool doit(const From *Val) {
92 assert(Val && "isa<> used on a null pointer")(static_cast <bool> (Val && "isa<> used on a null pointer"
) ? void (0) : __assert_fail ("Val && \"isa<> used on a null pointer\""
, "/build/llvm-toolchain-snapshot-7~svn329677/include/llvm/Support/Casting.h"
, 92, __extension__ __PRETTY_FUNCTION__));
93 return isa_impl<To, From>::doit(*Val);
94 }
95};
96
97template <typename To, typename From> struct isa_impl_cl<To, From*const> {
98 static inline bool doit(const From *Val) {
99 assert(Val && "isa<> used on a null pointer")(static_cast <bool> (Val && "isa<> used on a null pointer"
) ? void (0) : __assert_fail ("Val && \"isa<> used on a null pointer\""
, "/build/llvm-toolchain-snapshot-7~svn329677/include/llvm/Support/Casting.h"
, 99, __extension__ __PRETTY_FUNCTION__));
100 return isa_impl<To, From>::doit(*Val);
101 }
102};
103
104template <typename To, typename From> struct isa_impl_cl<To, const From*> {
105 static inline bool doit(const From *Val) {
106 assert(Val && "isa<> used on a null pointer")(static_cast <bool> (Val && "isa<> used on a null pointer"
) ? void (0) : __assert_fail ("Val && \"isa<> used on a null pointer\""
, "/build/llvm-toolchain-snapshot-7~svn329677/include/llvm/Support/Casting.h"
, 106, __extension__ __PRETTY_FUNCTION__));
107 return isa_impl<To, From>::doit(*Val);
108 }
109};
110
111template <typename To, typename From> struct isa_impl_cl<To, const From*const> {
112 static inline bool doit(const From *Val) {
113 assert(Val && "isa<> used on a null pointer")(static_cast <bool> (Val && "isa<> used on a null pointer"
) ? void (0) : __assert_fail ("Val && \"isa<> used on a null pointer\""
, "/build/llvm-toolchain-snapshot-7~svn329677/include/llvm/Support/Casting.h"
, 113, __extension__ __PRETTY_FUNCTION__));
114 return isa_impl<To, From>::doit(*Val);
115 }
116};
117
118template<typename To, typename From, typename SimpleFrom>
119struct isa_impl_wrap {
120 // When From != SimplifiedType, we can simplify the type some more by using
121 // the simplify_type template.
122 static bool doit(const From &Val) {
123 return isa_impl_wrap<To, SimpleFrom,
124 typename simplify_type<SimpleFrom>::SimpleType>::doit(
125 simplify_type<const From>::getSimplifiedValue(Val));
126 }
127};
128
129template<typename To, typename FromTy>
130struct isa_impl_wrap<To, FromTy, FromTy> {
131 // When From == SimpleType, we are as simple as we are going to get.
132 static bool doit(const FromTy &Val) {
133 return isa_impl_cl<To,FromTy>::doit(Val);
134 }
135};
136
137// isa<X> - Return true if the parameter to the template is an instance of the
138// template type argument. Used like this:
139//
140// if (isa<Type>(myVal)) { ... }
141//
142template <class X, class Y> LLVM_NODISCARD[[clang::warn_unused_result]] inline bool isa(const Y &Val) {
143 return isa_impl_wrap<X, const Y,
144 typename simplify_type<const Y>::SimpleType>::doit(Val);
145}
146
147//===----------------------------------------------------------------------===//
148// cast<x> Support Templates
149//===----------------------------------------------------------------------===//
150
151template<class To, class From> struct cast_retty;
152
153// Calculate what type the 'cast' function should return, based on a requested
154// type of To and a source type of From.
155template<class To, class From> struct cast_retty_impl {
156 using ret_type = To &; // Normal case, return Ty&
157};
158template<class To, class From> struct cast_retty_impl<To, const From> {
159 using ret_type = const To &; // Normal case, return Ty&
160};
161
162template<class To, class From> struct cast_retty_impl<To, From*> {
163 using ret_type = To *; // Pointer arg case, return Ty*
164};
165
166template<class To, class From> struct cast_retty_impl<To, const From*> {
167 using ret_type = const To *; // Constant pointer arg case, return const Ty*
168};
169
170template<class To, class From> struct cast_retty_impl<To, const From*const> {
171 using ret_type = const To *; // Constant pointer arg case, return const Ty*
172};
173
174template <class To, class From>
175struct cast_retty_impl<To, std::unique_ptr<From>> {
176private:
177 using PointerType = typename cast_retty_impl<To, From *>::ret_type;
178 using ResultType = typename std::remove_pointer<PointerType>::type;
179
180public:
181 using ret_type = std::unique_ptr<ResultType>;
182};
183
184template<class To, class From, class SimpleFrom>
185struct cast_retty_wrap {
186 // When the simplified type and the from type are not the same, use the type
187 // simplifier to reduce the type, then reuse cast_retty_impl to get the
188 // resultant type.
189 using ret_type = typename cast_retty<To, SimpleFrom>::ret_type;
190};
191
192template<class To, class FromTy>
193struct cast_retty_wrap<To, FromTy, FromTy> {
194 // When the simplified type is equal to the from type, use it directly.
195 using ret_type = typename cast_retty_impl<To,FromTy>::ret_type;
196};
197
198template<class To, class From>
199struct cast_retty {
200 using ret_type = typename cast_retty_wrap<
201 To, From, typename simplify_type<From>::SimpleType>::ret_type;
202};
203
204// Ensure the non-simple values are converted using the simplify_type template
205// that may be specialized by smart pointers...
206//
207template<class To, class From, class SimpleFrom> struct cast_convert_val {
208 // This is not a simple type, use the template to simplify it...
209 static typename cast_retty<To, From>::ret_type doit(From &Val) {
210 return cast_convert_val<To, SimpleFrom,
211 typename simplify_type<SimpleFrom>::SimpleType>::doit(
212 simplify_type<From>::getSimplifiedValue(Val));
213 }
214};
215
216template<class To, class FromTy> struct cast_convert_val<To,FromTy,FromTy> {
217 // This _is_ a simple type, just cast it.
218 static typename cast_retty<To, FromTy>::ret_type doit(const FromTy &Val) {
219 typename cast_retty<To, FromTy>::ret_type Res2
220 = (typename cast_retty<To, FromTy>::ret_type)const_cast<FromTy&>(Val);
221 return Res2;
222 }
223};
224
225template <class X> struct is_simple_type {
226 static const bool value =
227 std::is_same<X, typename simplify_type<X>::SimpleType>::value;
228};
229
230// cast<X> - Return the argument parameter cast to the specified type. This
231// casting operator asserts that the type is correct, so it does not return null
232// on failure. It does not allow a null argument (use cast_or_null for that).
233// It is typically used like this:
234//
235// cast<Instruction>(myVal)->getParent()
236//
237template <class X, class Y>
238inline typename std::enable_if<!is_simple_type<Y>::value,
239 typename cast_retty<X, const Y>::ret_type>::type
240cast(const Y &Val) {
241 assert(isa<X>(Val) && "cast<Ty>() argument of incompatible type!")(static_cast <bool> (isa<X>(Val) && "cast<Ty>() argument of incompatible type!"
) ? void (0) : __assert_fail ("isa<X>(Val) && \"cast<Ty>() argument of incompatible type!\""
, "/build/llvm-toolchain-snapshot-7~svn329677/include/llvm/Support/Casting.h"
, 241, __extension__ __PRETTY_FUNCTION__));
242 return cast_convert_val<
243 X, const Y, typename simplify_type<const Y>::SimpleType>::doit(Val);
244}
245
246template <class X, class Y>
247inline typename cast_retty<X, Y>::ret_type cast(Y &Val) {
248 assert(isa<X>(Val) && "cast<Ty>() argument of incompatible type!")(static_cast <bool> (isa<X>(Val) && "cast<Ty>() argument of incompatible type!"
) ? void (0) : __assert_fail ("isa<X>(Val) && \"cast<Ty>() argument of incompatible type!\""
, "/build/llvm-toolchain-snapshot-7~svn329677/include/llvm/Support/Casting.h"
, 248, __extension__ __PRETTY_FUNCTION__));
249 return cast_convert_val<X, Y,
250 typename simplify_type<Y>::SimpleType>::doit(Val);
251}
252
253template <class X, class Y>
254inline typename cast_retty<X, Y *>::ret_type cast(Y *Val) {
255 assert(isa<X>(Val) && "cast<Ty>() argument of incompatible type!")(static_cast <bool> (isa<X>(Val) && "cast<Ty>() argument of incompatible type!"
) ? void (0) : __assert_fail ("isa<X>(Val) && \"cast<Ty>() argument of incompatible type!\""
, "/build/llvm-toolchain-snapshot-7~svn329677/include/llvm/Support/Casting.h"
, 255, __extension__ __PRETTY_FUNCTION__));
256 return cast_convert_val<X, Y*,
257 typename simplify_type<Y*>::SimpleType>::doit(Val);
258}
259
260template <class X, class Y>
261inline typename cast_retty<X, std::unique_ptr<Y>>::ret_type
262cast(std::unique_ptr<Y> &&Val) {
263 assert(isa<X>(Val.get()) && "cast<Ty>() argument of incompatible type!")(static_cast <bool> (isa<X>(Val.get()) &&
"cast<Ty>() argument of incompatible type!") ? void (0
) : __assert_fail ("isa<X>(Val.get()) && \"cast<Ty>() argument of incompatible type!\""
, "/build/llvm-toolchain-snapshot-7~svn329677/include/llvm/Support/Casting.h"
, 263, __extension__ __PRETTY_FUNCTION__));
264 using ret_type = typename cast_retty<X, std::unique_ptr<Y>>::ret_type;
265 return ret_type(
266 cast_convert_val<X, Y *, typename simplify_type<Y *>::SimpleType>::doit(
267 Val.release()));
268}
269
270// cast_or_null<X> - Functionally identical to cast, except that a null value is
271// accepted.
272//
273template <class X, class Y>
274LLVM_NODISCARD[[clang::warn_unused_result]] inline
275 typename std::enable_if<!is_simple_type<Y>::value,
276 typename cast_retty<X, const Y>::ret_type>::type
277 cast_or_null(const Y &Val) {
278 if (!Val)
279 return nullptr;
280 assert(isa<X>(Val) && "cast_or_null<Ty>() argument of incompatible type!")(static_cast <bool> (isa<X>(Val) && "cast_or_null<Ty>() argument of incompatible type!"
) ? void (0) : __assert_fail ("isa<X>(Val) && \"cast_or_null<Ty>() argument of incompatible type!\""
, "/build/llvm-toolchain-snapshot-7~svn329677/include/llvm/Support/Casting.h"
, 280, __extension__ __PRETTY_FUNCTION__));
281 return cast<X>(Val);
282}
283
284template <class X, class Y>
285LLVM_NODISCARD[[clang::warn_unused_result]] inline
286 typename std::enable_if<!is_simple_type<Y>::value,
287 typename cast_retty<X, Y>::ret_type>::type
288 cast_or_null(Y &Val) {
289 if (!Val)
290 return nullptr;
291 assert(isa<X>(Val) && "cast_or_null<Ty>() argument of incompatible type!")(static_cast <bool> (isa<X>(Val) && "cast_or_null<Ty>() argument of incompatible type!"
) ? void (0) : __assert_fail ("isa<X>(Val) && \"cast_or_null<Ty>() argument of incompatible type!\""
, "/build/llvm-toolchain-snapshot-7~svn329677/include/llvm/Support/Casting.h"
, 291, __extension__ __PRETTY_FUNCTION__));
292 return cast<X>(Val);
293}
294
295template <class X, class Y>
296LLVM_NODISCARD[[clang::warn_unused_result]] inline typename cast_retty<X, Y *>::ret_type
297cast_or_null(Y *Val) {
298 if (!Val) return nullptr;
299 assert(isa<X>(Val) && "cast_or_null<Ty>() argument of incompatible type!")(static_cast <bool> (isa<X>(Val) && "cast_or_null<Ty>() argument of incompatible type!"
) ? void (0) : __assert_fail ("isa<X>(Val) && \"cast_or_null<Ty>() argument of incompatible type!\""
, "/build/llvm-toolchain-snapshot-7~svn329677/include/llvm/Support/Casting.h"
, 299, __extension__ __PRETTY_FUNCTION__));
300 return cast<X>(Val);
301}
302
303template <class X, class Y>
304inline typename cast_retty<X, std::unique_ptr<Y>>::ret_type
305cast_or_null(std::unique_ptr<Y> &&Val) {
306 if (!Val)
307 return nullptr;
308 return cast<X>(std::move(Val));
309}
310
311// dyn_cast<X> - Return the argument parameter cast to the specified type. This
312// casting operator returns null if the argument is of the wrong type, so it can
313// be used to test for a type as well as cast if successful. This should be
314// used in the context of an if statement like this:
315//
316// if (const Instruction *I = dyn_cast<Instruction>(myVal)) { ... }
317//
318
319template <class X, class Y>
320LLVM_NODISCARD[[clang::warn_unused_result]] inline
321 typename std::enable_if<!is_simple_type<Y>::value,
322 typename cast_retty<X, const Y>::ret_type>::type
323 dyn_cast(const Y &Val) {
324 return isa<X>(Val) ? cast<X>(Val) : nullptr;
325}
326
327template <class X, class Y>
328LLVM_NODISCARD[[clang::warn_unused_result]] inline typename cast_retty<X, Y>::ret_type dyn_cast(Y &Val) {
329 return isa<X>(Val) ? cast<X>(Val) : nullptr;
330}
331
332template <class X, class Y>
333LLVM_NODISCARD[[clang::warn_unused_result]] inline typename cast_retty<X, Y *>::ret_type dyn_cast(Y *Val) {
334 return isa<X>(Val) ? cast<X>(Val) : nullptr;
33
←
'?' condition is true
→
335}
336
337// dyn_cast_or_null<X> - Functionally identical to dyn_cast, except that a null
338// value is accepted.
339//
340template <class X, class Y>
341LLVM_NODISCARD[[clang::warn_unused_result]] inline
342 typename std::enable_if<!is_simple_type<Y>::value,
343 typename cast_retty<X, const Y>::ret_type>::type
344 dyn_cast_or_null(const Y &Val) {
345 return (Val && isa<X>(Val)) ? cast<X>(Val) : nullptr;
346}
347
348template <class X, class Y>
349LLVM_NODISCARD[[clang::warn_unused_result]] inline
350 typename std::enable_if<!is_simple_type<Y>::value,
351 typename cast_retty<X, Y>::ret_type>::type
352 dyn_cast_or_null(Y &Val) {
353 return (Val && isa<X>(Val)) ? cast<X>(Val) : nullptr;
354}
355
356template <class X, class Y>
357LLVM_NODISCARD[[clang::warn_unused_result]] inline typename cast_retty<X, Y *>::ret_type
358dyn_cast_or_null(Y *Val) {
359 return (Val && isa<X>(Val)) ? cast<X>(Val) : nullptr;
360}
361
362// unique_dyn_cast<X> - Given a unique_ptr<Y>, try to return a unique_ptr<X>,
363// taking ownership of the input pointer iff isa<X>(Val) is true. If the
364// cast is successful, From refers to nullptr on exit and the casted value
365// is returned. If the cast is unsuccessful, the function returns nullptr
366// and From is unchanged.
367template <class X, class Y>
368LLVM_NODISCARD[[clang::warn_unused_result]] inline auto unique_dyn_cast(std::unique_ptr<Y> &Val)
369 -> decltype(cast<X>(Val)) {
370 if (!isa<X>(Val))
371 return nullptr;
372 return cast<X>(std::move(Val));
373}
374
375template <class X, class Y>
376LLVM_NODISCARD[[clang::warn_unused_result]] inline auto unique_dyn_cast(std::unique_ptr<Y> &&Val)
377 -> decltype(cast<X>(Val)) {
378 return unique_dyn_cast<X, Y>(Val);
379}
380
381// dyn_cast_or_null<X> - Functionally identical to unique_dyn_cast, except that
382// a null value is accepted.
383template <class X, class Y>
384LLVM_NODISCARD[[clang::warn_unused_result]] inline auto unique_dyn_cast_or_null(std::unique_ptr<Y> &Val)
385 -> decltype(cast<X>(Val)) {
386 if (!Val)
387 return nullptr;
388 return unique_dyn_cast<X, Y>(Val);
389}
390
391template <class X, class Y>
392LLVM_NODISCARD[[clang::warn_unused_result]] inline auto unique_dyn_cast_or_null(std::unique_ptr<Y> &&Val)
393 -> decltype(cast<X>(Val)) {
394 return unique_dyn_cast_or_null<X, Y>(Val);
395}
396
397} // end namespace llvm
398
399#endif // LLVM_SUPPORT_CASTING_H