1 //===-- LibCallsShrinkWrap.cpp ----------------------------------*- 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 pass shrink-wraps a call to function if the result is not used.
11 // The call can set errno but is otherwise side effect free. For example:
12 //    sqrt(val);
13 //  is transformed to
14 //    if (val < 0)
15 //      sqrt(val);
16 //  Even if the result of library call is not being used, the compiler cannot
17 //  safely delete the call because the function can set errno on error
18 //  conditions.
19 //  Note in many functions, the error condition solely depends on the incoming
20 //  parameter. In this optimization, we can generate the condition can lead to
21 //  the errno to shrink-wrap the call. Since the chances of hitting the error
22 //  condition is low, the runtime call is effectively eliminated.
23 //
24 //  These partially dead calls are usually results of C++ abstraction penalty
25 //  exposed by inlining.
26 //
27 //===----------------------------------------------------------------------===//
28 
29 #include "llvm/Transforms/Utils/LibCallsShrinkWrap.h"
30 #include "llvm/ADT/SmallVector.h"
31 #include "llvm/ADT/Statistic.h"
32 #include "llvm/Analysis/GlobalsModRef.h"
33 #include "llvm/Analysis/TargetLibraryInfo.h"
34 #include "llvm/IR/CFG.h"
35 #include "llvm/IR/Constants.h"
36 #include "llvm/IR/Function.h"
37 #include "llvm/IR/IRBuilder.h"
38 #include "llvm/IR/InstVisitor.h"
39 #include "llvm/IR/Instructions.h"
40 #include "llvm/IR/LLVMContext.h"
41 #include "llvm/IR/MDBuilder.h"
42 #include "llvm/Pass.h"
43 #include "llvm/Transforms/Utils/BasicBlockUtils.h"
44 using namespace llvm;
45 
46 #define DEBUG_TYPE "libcalls-shrinkwrap"
47 
48 STATISTIC(NumWrappedOneCond, "Number of One-Condition Wrappers Inserted");
49 STATISTIC(NumWrappedTwoCond, "Number of Two-Condition Wrappers Inserted");
50 
51 static cl::opt<bool> LibCallsShrinkWrapDoDomainError(
52     "libcalls-shrinkwrap-domain-error", cl::init(true), cl::Hidden,
53     cl::desc("Perform shrink-wrap on lib calls with domain errors"));
54 static cl::opt<bool> LibCallsShrinkWrapDoRangeError(
55     "libcalls-shrinkwrap-range-error", cl::init(true), cl::Hidden,
56     cl::desc("Perform shrink-wrap on lib calls with range errors"));
57 static cl::opt<bool> LibCallsShrinkWrapDoPoleError(
58     "libcalls-shrinkwrap-pole-error", cl::init(true), cl::Hidden,
59     cl::desc("Perform shrink-wrap on lib calls with pole errors"));
60 
61 namespace {
62 class LibCallsShrinkWrapLegacyPass : public FunctionPass {
63 public:
64   static char ID; // Pass identification, replacement for typeid
65   explicit LibCallsShrinkWrapLegacyPass() : FunctionPass(ID) {
66     initializeLibCallsShrinkWrapLegacyPassPass(
67         *PassRegistry::getPassRegistry());
68   }
69   void getAnalysisUsage(AnalysisUsage &AU) const override;
70   bool runOnFunction(Function &F) override;
71 };
72 }
73 
74 char LibCallsShrinkWrapLegacyPass::ID = 0;
75 INITIALIZE_PASS_BEGIN(LibCallsShrinkWrapLegacyPass, "libcalls-shrinkwrap",
76                       "Conditionally eliminate dead library calls", false,
77                       false)
78 INITIALIZE_PASS_DEPENDENCY(TargetLibraryInfoWrapperPass)
79 INITIALIZE_PASS_END(LibCallsShrinkWrapLegacyPass, "libcalls-shrinkwrap",
80                     "Conditionally eliminate dead library calls", false, false)
81 
82 class LibCallsShrinkWrap : public InstVisitor<LibCallsShrinkWrap> {
83 public:
84   LibCallsShrinkWrap(const TargetLibraryInfo &TLI) : TLI(TLI), Changed(false){};
85   bool isChanged() const { return Changed; }
86   void visitCallInst(CallInst &CI) { checkCandidate(CI); }
87   void perform() {
88     for (auto &CI : WorkList) {
89       DEBUG(dbgs() << "CDCE calls: " << CI->getCalledFunction()->getName()
90                    << "\n");
91       if (perform(CI)) {
92         Changed = true;
93         DEBUG(dbgs() << "Transformed\n");
94       }
95     }
96   }
97 
98 private:
99   bool perform(CallInst *CI);
100   void checkCandidate(CallInst &CI);
101   void shrinkWrapCI(CallInst *CI, Value *Cond);
102   bool performCallDomainErrorOnly(CallInst *CI, const LibFunc::Func &Func);
103   bool performCallErrors(CallInst *CI, const LibFunc::Func &Func);
104   bool performCallRangeErrorOnly(CallInst *CI, const LibFunc::Func &Func);
105   Value *generateOneRangeCond(CallInst *CI, const LibFunc::Func &Func);
106   Value *generateTwoRangeCond(CallInst *CI, const LibFunc::Func &Func);
107   Value *generateCondForPow(CallInst *CI, const LibFunc::Func &Func);
108 
109   // Create an OR of two conditions.
110   Value *createOrCond(CallInst *CI, CmpInst::Predicate Cmp, float Val,
111                       CmpInst::Predicate Cmp2, float Val2) {
112     IRBuilder<> BBBuilder(CI);
113     Value *Arg = CI->getArgOperand(0);
114     auto Cond2 = createCond(BBBuilder, Arg, Cmp2, Val2);
115     auto Cond1 = createCond(BBBuilder, Arg, Cmp, Val);
116     return BBBuilder.CreateOr(Cond1, Cond2);
117   }
118 
119   // Create a single condition using IRBuilder.
120   Value *createCond(IRBuilder<> &BBBuilder, Value *Arg, CmpInst::Predicate Cmp,
121                     float Val) {
122     Constant *V = ConstantFP::get(BBBuilder.getContext(), APFloat(Val));
123     if (!Arg->getType()->isFloatTy())
124       V = ConstantExpr::getFPExtend(V, Arg->getType());
125     return BBBuilder.CreateFCmp(Cmp, Arg, V);
126   }
127 
128   // Create a single condition.
129   Value *createCond(CallInst *CI, CmpInst::Predicate Cmp, float Val) {
130     IRBuilder<> BBBuilder(CI);
131     Value *Arg = CI->getArgOperand(0);
132     return createCond(BBBuilder, Arg, Cmp, Val);
133   }
134 
135   const TargetLibraryInfo &TLI;
136   SmallVector<CallInst *, 16> WorkList;
137   bool Changed;
138 };
139 
140 // Perform the transformation to calls with errno set by domain error.
141 bool LibCallsShrinkWrap::performCallDomainErrorOnly(CallInst *CI,
142                                                     const LibFunc::Func &Func) {
143   Value *Cond = nullptr;
144 
145   switch (Func) {
146   case LibFunc::acos:  // DomainError: (x < -1 || x > 1)
147   case LibFunc::acosf: // Same as acos
148   case LibFunc::acosl: // Same as acos
149   case LibFunc::asin:  // DomainError: (x < -1 || x > 1)
150   case LibFunc::asinf: // Same as asin
151   case LibFunc::asinl: // Same as asin
152   {
153     ++NumWrappedTwoCond;
154     Cond = createOrCond(CI, CmpInst::FCMP_OLT, -1.0f, CmpInst::FCMP_OGT, 1.0f);
155     break;
156   }
157   case LibFunc::cos:  // DomainError: (x == +inf || x == -inf)
158   case LibFunc::cosf: // Same as cos
159   case LibFunc::cosl: // Same as cos
160   case LibFunc::sin:  // DomainError: (x == +inf || x == -inf)
161   case LibFunc::sinf: // Same as sin
162   case LibFunc::sinl: // Same as sin
163   {
164     ++NumWrappedTwoCond;
165     Cond = createOrCond(CI, CmpInst::FCMP_OEQ, INFINITY, CmpInst::FCMP_OEQ,
166                         -INFINITY);
167     break;
168   }
169   case LibFunc::acosh:  // DomainError: (x < 1)
170   case LibFunc::acoshf: // Same as acosh
171   case LibFunc::acoshl: // Same as acosh
172   {
173     ++NumWrappedOneCond;
174     Cond = createCond(CI, CmpInst::FCMP_OLT, 1.0f);
175     break;
176   }
177   case LibFunc::sqrt:  // DomainError: (x < 0)
178   case LibFunc::sqrtf: // Same as sqrt
179   case LibFunc::sqrtl: // Same as sqrt
180   {
181     ++NumWrappedOneCond;
182     Cond = createCond(CI, CmpInst::FCMP_OLT, 0.0f);
183     break;
184   }
185   default:
186     return false;
187   }
188   shrinkWrapCI(CI, Cond);
189   return true;
190 }
191 
192 // Perform the transformation to calls with errno set by range error.
193 bool LibCallsShrinkWrap::performCallRangeErrorOnly(CallInst *CI,
194                                                    const LibFunc::Func &Func) {
195   Value *Cond = nullptr;
196 
197   switch (Func) {
198   case LibFunc::cosh:
199   case LibFunc::coshf:
200   case LibFunc::coshl:
201   case LibFunc::exp:
202   case LibFunc::expf:
203   case LibFunc::expl:
204   case LibFunc::exp10:
205   case LibFunc::exp10f:
206   case LibFunc::exp10l:
207   case LibFunc::exp2:
208   case LibFunc::exp2f:
209   case LibFunc::exp2l:
210   case LibFunc::sinh:
211   case LibFunc::sinhf:
212   case LibFunc::sinhl: {
213     Cond = generateTwoRangeCond(CI, Func);
214     break;
215   }
216   case LibFunc::expm1:  // RangeError: (709, inf)
217   case LibFunc::expm1f: // RangeError: (88, inf)
218   case LibFunc::expm1l: // RangeError: (11356, inf)
219   {
220     Cond = generateOneRangeCond(CI, Func);
221     break;
222   }
223   default:
224     return false;
225   }
226   shrinkWrapCI(CI, Cond);
227   return true;
228 }
229 
230 // Perform the transformation to calls with errno set by combination of errors.
231 bool LibCallsShrinkWrap::performCallErrors(CallInst *CI,
232                                            const LibFunc::Func &Func) {
233   Value *Cond = nullptr;
234 
235   switch (Func) {
236   case LibFunc::atanh:  // DomainError: (x < -1 || x > 1)
237                         // PoleError:   (x == -1 || x == 1)
238                         // Overall Cond: (x <= -1 || x >= 1)
239   case LibFunc::atanhf: // Same as atanh
240   case LibFunc::atanhl: // Same as atanh
241   {
242     if (!LibCallsShrinkWrapDoDomainError || !LibCallsShrinkWrapDoPoleError)
243       return false;
244     ++NumWrappedTwoCond;
245     Cond = createOrCond(CI, CmpInst::FCMP_OLE, -1.0f, CmpInst::FCMP_OGE, 1.0f);
246     break;
247   }
248   case LibFunc::log:    // DomainError: (x < 0)
249                         // PoleError:   (x == 0)
250                         // Overall Cond: (x <= 0)
251   case LibFunc::logf:   // Same as log
252   case LibFunc::logl:   // Same as log
253   case LibFunc::log10:  // Same as log
254   case LibFunc::log10f: // Same as log
255   case LibFunc::log10l: // Same as log
256   case LibFunc::log2:   // Same as log
257   case LibFunc::log2f:  // Same as log
258   case LibFunc::log2l:  // Same as log
259   case LibFunc::logb:   // Same as log
260   case LibFunc::logbf:  // Same as log
261   case LibFunc::logbl:  // Same as log
262   {
263     if (!LibCallsShrinkWrapDoDomainError || !LibCallsShrinkWrapDoPoleError)
264       return false;
265     ++NumWrappedOneCond;
266     Cond = createCond(CI, CmpInst::FCMP_OLE, 0.0f);
267     break;
268   }
269   case LibFunc::log1p:  // DomainError: (x < -1)
270                         // PoleError:   (x == -1)
271                         // Overall Cond: (x <= -1)
272   case LibFunc::log1pf: // Same as log1p
273   case LibFunc::log1pl: // Same as log1p
274   {
275     if (!LibCallsShrinkWrapDoDomainError || !LibCallsShrinkWrapDoPoleError)
276       return false;
277     ++NumWrappedOneCond;
278     Cond = createCond(CI, CmpInst::FCMP_OLE, -1.0f);
279     break;
280   }
281   case LibFunc::pow: // DomainError: x < 0 and y is noninteger
282                      // PoleError:   x == 0 and y < 0
283                      // RangeError:  overflow or underflow
284   case LibFunc::powf:
285   case LibFunc::powl: {
286     if (!LibCallsShrinkWrapDoDomainError || !LibCallsShrinkWrapDoPoleError ||
287         !LibCallsShrinkWrapDoRangeError)
288       return false;
289     Cond = generateCondForPow(CI, Func);
290     if (Cond == nullptr)
291       return false;
292     break;
293   }
294   default:
295     return false;
296   }
297   assert(Cond && "performCallErrors should not see an empty condition");
298   shrinkWrapCI(CI, Cond);
299   return true;
300 }
301 
302 // Checks if CI is a candidate for shrinkwrapping and put it into work list if
303 // true.
304 void LibCallsShrinkWrap::checkCandidate(CallInst &CI) {
305   if (CI.isNoBuiltin())
306     return;
307   // A possible improvement is to handle the calls with the return value being
308   // used. If there is API for fast libcall implementation without setting
309   // errno, we can use the same framework to direct/wrap the call to the fast
310   // API in the error free path, and leave the original call in the slow path.
311   if (!CI.use_empty())
312     return;
313 
314   LibFunc::Func Func;
315   Function *Callee = CI.getCalledFunction();
316   if (!Callee)
317     return;
318   if (!TLI.getLibFunc(*Callee, Func) || !TLI.has(Func))
319     return;
320 
321   if (CI.getNumArgOperands() == 0)
322     return;
323   // TODO: Handle long double in other formats.
324   Type *ArgType = CI.getArgOperand(0)->getType();
325   if (!(ArgType->isFloatTy() || ArgType->isDoubleTy() ||
326         ArgType->isX86_FP80Ty()))
327     return;
328 
329   WorkList.push_back(&CI);
330 }
331 
332 // Generate the upper bound condition for RangeError.
333 Value *LibCallsShrinkWrap::generateOneRangeCond(CallInst *CI,
334                                                 const LibFunc::Func &Func) {
335   float UpperBound;
336   switch (Func) {
337   case LibFunc::expm1: // RangeError: (709, inf)
338     UpperBound = 709.0f;
339     break;
340   case LibFunc::expm1f: // RangeError: (88, inf)
341     UpperBound = 88.0f;
342     break;
343   case LibFunc::expm1l: // RangeError: (11356, inf)
344     UpperBound = 11356.0f;
345     break;
346   default:
347     llvm_unreachable("Should be reach here");
348   }
349 
350   ++NumWrappedOneCond;
351   return createCond(CI, CmpInst::FCMP_OGT, UpperBound);
352 }
353 
354 // Generate the lower and upper bound condition for RangeError.
355 Value *LibCallsShrinkWrap::generateTwoRangeCond(CallInst *CI,
356                                                 const LibFunc::Func &Func) {
357   float UpperBound, LowerBound;
358   switch (Func) {
359   case LibFunc::cosh: // RangeError: (x < -710 || x > 710)
360   case LibFunc::sinh: // Same as cosh
361     LowerBound = -710.0f;
362     UpperBound = 710.0f;
363     break;
364   case LibFunc::coshf: // RangeError: (x < -89 || x > 89)
365   case LibFunc::sinhf: // Same as coshf
366     LowerBound = -89.0f;
367     UpperBound = 89.0f;
368     break;
369   case LibFunc::coshl: // RangeError: (x < -11357 || x > 11357)
370   case LibFunc::sinhl: // Same as coshl
371     LowerBound = -11357.0f;
372     UpperBound = 11357.0f;
373     break;
374   case LibFunc::exp: // RangeError: (x < -745 || x > 709)
375     LowerBound = -745.0f;
376     UpperBound = 709.0f;
377     break;
378   case LibFunc::expf: // RangeError: (x < -103 || x > 88)
379     LowerBound = -103.0f;
380     UpperBound = 88.0f;
381     break;
382   case LibFunc::expl: // RangeError: (x < -11399 || x > 11356)
383     LowerBound = -11399.0f;
384     UpperBound = 11356.0f;
385     break;
386   case LibFunc::exp10: // RangeError: (x < -323 || x > 308)
387     LowerBound = -323.0f;
388     UpperBound = 308.0f;
389     break;
390   case LibFunc::exp10f: // RangeError: (x < -45 || x > 38)
391     LowerBound = -45.0f;
392     UpperBound = 38.0f;
393     break;
394   case LibFunc::exp10l: // RangeError: (x < -4950 || x > 4932)
395     LowerBound = -4950.0f;
396     UpperBound = 4932.0f;
397     break;
398   case LibFunc::exp2: // RangeError: (x < -1074 || x > 1023)
399     LowerBound = -1074.0f;
400     UpperBound = 1023.0f;
401     break;
402   case LibFunc::exp2f: // RangeError: (x < -149 || x > 127)
403     LowerBound = -149.0f;
404     UpperBound = 127.0f;
405     break;
406   case LibFunc::exp2l: // RangeError: (x < -16445 || x > 11383)
407     LowerBound = -16445.0f;
408     UpperBound = 11383.0f;
409     break;
410   default:
411     llvm_unreachable("Should be reach here");
412   }
413 
414   ++NumWrappedTwoCond;
415   return createOrCond(CI, CmpInst::FCMP_OGT, UpperBound, CmpInst::FCMP_OLT,
416                       LowerBound);
417 }
418 
419 // For pow(x,y), We only handle the following cases:
420 // (1) x is a constant && (x >= 1) && (x < MaxUInt8)
421 //     Cond is: (y > 127)
422 // (2) x is a value coming from an integer type.
423 //   (2.1) if x's bit_size == 8
424 //         Cond: (x <= 0 || y > 128)
425 //   (2.2) if x's bit_size is 16
426 //         Cond: (x <= 0 || y > 64)
427 //   (2.3) if x's bit_size is 32
428 //         Cond: (x <= 0 || y > 32)
429 // Support for powl(x,y) and powf(x,y) are TBD.
430 //
431 // Note that condition can be more conservative than the actual condition
432 // (i.e. we might invoke the calls that will not set the errno.).
433 //
434 Value *LibCallsShrinkWrap::generateCondForPow(CallInst *CI,
435                                               const LibFunc::Func &Func) {
436   // FIXME: LibFunc::powf and powl TBD.
437   if (Func != LibFunc::pow) {
438     DEBUG(dbgs() << "Not handled powf() and powl()\n");
439     return nullptr;
440   }
441 
442   Value *Base = CI->getArgOperand(0);
443   Value *Exp = CI->getArgOperand(1);
444   IRBuilder<> BBBuilder(CI);
445 
446   // Constant Base case.
447   if (ConstantFP *CF = dyn_cast<ConstantFP>(Base)) {
448     double D = CF->getValueAPF().convertToDouble();
449     if (D < 1.0f || D > APInt::getMaxValue(8).getZExtValue()) {
450       DEBUG(dbgs() << "Not handled pow(): constant base out of range\n");
451       return nullptr;
452     }
453 
454     ++NumWrappedOneCond;
455     Constant *V = ConstantFP::get(CI->getContext(), APFloat(127.0f));
456     if (!Exp->getType()->isFloatTy())
457       V = ConstantExpr::getFPExtend(V, Exp->getType());
458     return BBBuilder.CreateFCmp(CmpInst::FCMP_OGT, Exp, V);
459   }
460 
461   // If the Base value coming from an integer type.
462   Instruction *I = dyn_cast<Instruction>(Base);
463   if (!I) {
464     DEBUG(dbgs() << "Not handled pow(): FP type base\n");
465     return nullptr;
466   }
467   unsigned Opcode = I->getOpcode();
468   if (Opcode == Instruction::UIToFP || Opcode == Instruction::SIToFP) {
469     unsigned BW = I->getOperand(0)->getType()->getPrimitiveSizeInBits();
470     float UpperV = 0.0f;
471     if (BW == 8)
472       UpperV = 128.0f;
473     else if (BW == 16)
474       UpperV = 64.0f;
475     else if (BW == 32)
476       UpperV = 32.0f;
477     else {
478       DEBUG(dbgs() << "Not handled pow(): type too wide\n");
479       return nullptr;
480     }
481 
482     ++NumWrappedTwoCond;
483     Constant *V = ConstantFP::get(CI->getContext(), APFloat(UpperV));
484     Constant *V0 = ConstantFP::get(CI->getContext(), APFloat(0.0f));
485     if (!Exp->getType()->isFloatTy())
486       V = ConstantExpr::getFPExtend(V, Exp->getType());
487     if (!Base->getType()->isFloatTy())
488       V0 = ConstantExpr::getFPExtend(V0, Exp->getType());
489 
490     Value *Cond = BBBuilder.CreateFCmp(CmpInst::FCMP_OGT, Exp, V);
491     Value *Cond0 = BBBuilder.CreateFCmp(CmpInst::FCMP_OLE, Base, V0);
492     return BBBuilder.CreateOr(Cond0, Cond);
493   }
494   DEBUG(dbgs() << "Not handled pow(): base not from integer convert\n");
495   return nullptr;
496 }
497 
498 // Wrap conditions that can potentially generate errno to the library call.
499 void LibCallsShrinkWrap::shrinkWrapCI(CallInst *CI, Value *Cond) {
500   assert(Cond != nullptr && "hrinkWrapCI is not expecting an empty call inst");
501   MDNode *BranchWeights =
502       MDBuilder(CI->getContext()).createBranchWeights(1, 2000);
503   TerminatorInst *NewInst =
504       SplitBlockAndInsertIfThen(Cond, CI, false, BranchWeights);
505   BasicBlock *CallBB = NewInst->getParent();
506   CallBB->setName("cdce.call");
507   CallBB->getSingleSuccessor()->setName("cdce.end");
508   CI->removeFromParent();
509   CallBB->getInstList().insert(CallBB->getFirstInsertionPt(), CI);
510   DEBUG(dbgs() << "== Basic Block After ==");
511   DEBUG(dbgs() << *CallBB->getSinglePredecessor() << *CallBB
512                << *CallBB->getSingleSuccessor() << "\n");
513 }
514 
515 // Perform the transformation to a single candidate.
516 bool LibCallsShrinkWrap::perform(CallInst *CI) {
517   LibFunc::Func Func;
518   Function *Callee = CI->getCalledFunction();
519   assert(Callee && "perform() should apply to a non-empty callee");
520   TLI.getLibFunc(*Callee, Func);
521   assert(Func && "perform() is not expecting an empty function");
522 
523   if (LibCallsShrinkWrapDoDomainError && performCallDomainErrorOnly(CI, Func))
524     return true;
525 
526   if (LibCallsShrinkWrapDoRangeError && performCallRangeErrorOnly(CI, Func))
527     return true;
528 
529   return performCallErrors(CI, Func);
530 }
531 
532 void LibCallsShrinkWrapLegacyPass::getAnalysisUsage(AnalysisUsage &AU) const {
533   AU.addPreserved<GlobalsAAWrapperPass>();
534   AU.addRequired<TargetLibraryInfoWrapperPass>();
535 }
536 
537 bool runImpl(Function &F, const TargetLibraryInfo &TLI) {
538   if (F.hasFnAttribute(Attribute::OptimizeForSize))
539     return false;
540   LibCallsShrinkWrap CCDCE(TLI);
541   CCDCE.visit(F);
542   CCDCE.perform();
543   return CCDCE.isChanged();
544 }
545 
546 bool LibCallsShrinkWrapLegacyPass::runOnFunction(Function &F) {
547   auto &TLI = getAnalysis<TargetLibraryInfoWrapperPass>().getTLI();
548   return runImpl(F, TLI);
549 }
550 
551 namespace llvm {
552 char &LibCallsShrinkWrapPassID = LibCallsShrinkWrapLegacyPass::ID;
553 
554 // Public interface to LibCallsShrinkWrap pass.
555 FunctionPass *createLibCallsShrinkWrapPass() {
556   return new LibCallsShrinkWrapLegacyPass();
557 }
558 
559 PreservedAnalyses LibCallsShrinkWrapPass::run(Function &F,
560                                               FunctionAnalysisManager &FAM) {
561   auto &TLI = FAM.getResult<TargetLibraryAnalysis>(F);
562   bool Changed = runImpl(F, TLI);
563   if (!Changed)
564     return PreservedAnalyses::all();
565   auto PA = PreservedAnalyses();
566   PA.preserve<GlobalsAA>();
567   return PA;
568 }
569 }
570