1 //===- FunctionAttrs.cpp - Pass which marks functions attributes ----------===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file implements a simple interprocedural pass which walks the
11 // call-graph, looking for functions which do not access or only read
12 // non-local memory, and marking them readnone/readonly. It does the
13 // same with function arguments independently, marking them readonly/
14 // readnone/nocapture. Finally, well-known library call declarations
15 // are marked with all attributes that are consistent with the
16 // function's standard definition. This pass is implemented as a
17 // bottom-up traversal of the call-graph.
19 //===----------------------------------------------------------------------===//
21 #include "llvm/Transforms/IPO.h"
22 #include "llvm/ADT/SCCIterator.h"
23 #include "llvm/ADT/SetVector.h"
24 #include "llvm/ADT/SmallSet.h"
25 #include "llvm/ADT/Statistic.h"
26 #include "llvm/Analysis/AliasAnalysis.h"
27 #include "llvm/Analysis/AssumptionCache.h"
28 #include "llvm/Analysis/BasicAliasAnalysis.h"
29 #include "llvm/Analysis/CallGraph.h"
30 #include "llvm/Analysis/CallGraphSCCPass.h"
31 #include "llvm/Analysis/CaptureTracking.h"
32 #include "llvm/Analysis/TargetLibraryInfo.h"
33 #include "llvm/Analysis/ValueTracking.h"
34 #include "llvm/IR/GlobalVariable.h"
35 #include "llvm/IR/InstIterator.h"
36 #include "llvm/IR/IntrinsicInst.h"
37 #include "llvm/IR/LLVMContext.h"
38 #include "llvm/Support/Debug.h"
39 #include "llvm/Support/raw_ostream.h"
40 #include "llvm/Analysis/TargetLibraryInfo.h"
43 #define DEBUG_TYPE "functionattrs"
45 STATISTIC(NumReadNone, "Number of functions marked readnone");
46 STATISTIC(NumReadOnly, "Number of functions marked readonly");
47 STATISTIC(NumNoCapture, "Number of arguments marked nocapture");
48 STATISTIC(NumReadNoneArg, "Number of arguments marked readnone");
49 STATISTIC(NumReadOnlyArg, "Number of arguments marked readonly");
50 STATISTIC(NumNoAlias, "Number of function returns marked noalias");
51 STATISTIC(NumNonNullReturn, "Number of function returns marked nonnull");
52 STATISTIC(NumAnnotated, "Number of attributes added to library functions");
55 typedef SmallSetVector<Function *, 8> SCCNodeSet;
59 struct FunctionAttrs : public CallGraphSCCPass {
60 static char ID; // Pass identification, replacement for typeid
61 FunctionAttrs() : CallGraphSCCPass(ID) {
62 initializeFunctionAttrsPass(*PassRegistry::getPassRegistry());
65 bool runOnSCC(CallGraphSCC &SCC) override;
67 void getAnalysisUsage(AnalysisUsage &AU) const override {
69 AU.addRequired<AssumptionCacheTracker>();
70 AU.addRequired<TargetLibraryInfoWrapperPass>();
71 CallGraphSCCPass::getAnalysisUsage(AU);
75 TargetLibraryInfo *TLI;
79 char FunctionAttrs::ID = 0;
80 INITIALIZE_PASS_BEGIN(FunctionAttrs, "functionattrs",
81 "Deduce function attributes", false, false)
82 INITIALIZE_PASS_DEPENDENCY(AssumptionCacheTracker)
83 INITIALIZE_PASS_DEPENDENCY(CallGraphWrapperPass)
84 INITIALIZE_PASS_DEPENDENCY(TargetLibraryInfoWrapperPass)
85 INITIALIZE_PASS_END(FunctionAttrs, "functionattrs",
86 "Deduce function attributes", false, false)
88 Pass *llvm::createFunctionAttrsPass() { return new FunctionAttrs(); }
91 /// The three kinds of memory access relevant to 'readonly' and
92 /// 'readnone' attributes.
93 enum MemoryAccessKind {
100 static MemoryAccessKind checkFunctionMemoryAccess(Function &F, AAResults &AAR,
101 const SCCNodeSet &SCCNodes) {
102 FunctionModRefBehavior MRB = AAR.getModRefBehavior(&F);
103 if (MRB == FMRB_DoesNotAccessMemory)
107 // Definitions with weak linkage may be overridden at linktime with
108 // something that writes memory, so treat them like declarations.
109 if (F.isDeclaration() || F.mayBeOverridden()) {
110 if (AliasAnalysis::onlyReadsMemory(MRB))
113 // Conservatively assume it writes to memory.
117 // Scan the function body for instructions that may read or write memory.
118 bool ReadsMemory = false;
119 for (inst_iterator II = inst_begin(F), E = inst_end(F); II != E; ++II) {
120 Instruction *I = &*II;
122 // Some instructions can be ignored even if they read or write memory.
123 // Detect these now, skipping to the next instruction if one is found.
124 CallSite CS(cast<Value>(I));
126 // Ignore calls to functions in the same SCC.
127 if (CS.getCalledFunction() && SCCNodes.count(CS.getCalledFunction()))
129 FunctionModRefBehavior MRB = AAR.getModRefBehavior(CS);
131 // If the call doesn't access memory, we're done.
132 if (!(MRB & MRI_ModRef))
135 if (!AliasAnalysis::onlyAccessesArgPointees(MRB)) {
136 // The call could access any memory. If that includes writes, give up.
139 // If it reads, note it.
145 // Check whether all pointer arguments point to local memory, and
146 // ignore calls that only access local memory.
147 for (CallSite::arg_iterator CI = CS.arg_begin(), CE = CS.arg_end();
150 if (!Arg->getType()->isPointerTy())
154 I->getAAMetadata(AAInfo);
155 MemoryLocation Loc(Arg, MemoryLocation::UnknownSize, AAInfo);
157 // Skip accesses to local or constant memory as they don't impact the
158 // externally visible mod/ref behavior.
159 if (AAR.pointsToConstantMemory(Loc, /*OrLocal=*/true))
163 // Writes non-local memory. Give up.
166 // Ok, it reads non-local memory.
170 } else if (LoadInst *LI = dyn_cast<LoadInst>(I)) {
171 // Ignore non-volatile loads from local memory. (Atomic is okay here.)
172 if (!LI->isVolatile()) {
173 MemoryLocation Loc = MemoryLocation::get(LI);
174 if (AAR.pointsToConstantMemory(Loc, /*OrLocal=*/true))
177 } else if (StoreInst *SI = dyn_cast<StoreInst>(I)) {
178 // Ignore non-volatile stores to local memory. (Atomic is okay here.)
179 if (!SI->isVolatile()) {
180 MemoryLocation Loc = MemoryLocation::get(SI);
181 if (AAR.pointsToConstantMemory(Loc, /*OrLocal=*/true))
184 } else if (VAArgInst *VI = dyn_cast<VAArgInst>(I)) {
185 // Ignore vaargs on local memory.
186 MemoryLocation Loc = MemoryLocation::get(VI);
187 if (AAR.pointsToConstantMemory(Loc, /*OrLocal=*/true))
191 // Any remaining instructions need to be taken seriously! Check if they
192 // read or write memory.
193 if (I->mayWriteToMemory())
194 // Writes memory. Just give up.
197 // If this instruction may read memory, remember that.
198 ReadsMemory |= I->mayReadFromMemory();
201 return ReadsMemory ? MAK_ReadOnly : MAK_ReadNone;
204 /// Deduce readonly/readnone attributes for the SCC.
205 template <typename AARGetterT>
206 static bool addReadAttrs(const SCCNodeSet &SCCNodes, AARGetterT AARGetter) {
207 // Check if any of the functions in the SCC read or write memory. If they
208 // write memory then they can't be marked readnone or readonly.
209 bool ReadsMemory = false;
210 for (Function *F : SCCNodes) {
211 // Call the callable parameter to look up AA results for this function.
212 AAResults &AAR = AARGetter(*F);
214 switch (checkFunctionMemoryAccess(*F, AAR, SCCNodes)) {
226 // Success! Functions in this SCC do not access memory, or only read memory.
227 // Give them the appropriate attribute.
228 bool MadeChange = false;
229 for (Function *F : SCCNodes) {
230 if (F->doesNotAccessMemory())
234 if (F->onlyReadsMemory() && ReadsMemory)
240 // Clear out any existing attributes.
242 B.addAttribute(Attribute::ReadOnly).addAttribute(Attribute::ReadNone);
244 AttributeSet::FunctionIndex,
245 AttributeSet::get(F->getContext(), AttributeSet::FunctionIndex, B));
247 // Add in the new attribute.
248 F->addAttribute(AttributeSet::FunctionIndex,
249 ReadsMemory ? Attribute::ReadOnly : Attribute::ReadNone);
261 /// For a given pointer Argument, this retains a list of Arguments of functions
262 /// in the same SCC that the pointer data flows into. We use this to build an
263 /// SCC of the arguments.
264 struct ArgumentGraphNode {
265 Argument *Definition;
266 SmallVector<ArgumentGraphNode *, 4> Uses;
269 class ArgumentGraph {
270 // We store pointers to ArgumentGraphNode objects, so it's important that
271 // that they not move around upon insert.
272 typedef std::map<Argument *, ArgumentGraphNode> ArgumentMapTy;
274 ArgumentMapTy ArgumentMap;
276 // There is no root node for the argument graph, in fact:
277 // void f(int *x, int *y) { if (...) f(x, y); }
278 // is an example where the graph is disconnected. The SCCIterator requires a
279 // single entry point, so we maintain a fake ("synthetic") root node that
280 // uses every node. Because the graph is directed and nothing points into
281 // the root, it will not participate in any SCCs (except for its own).
282 ArgumentGraphNode SyntheticRoot;
285 ArgumentGraph() { SyntheticRoot.Definition = nullptr; }
287 typedef SmallVectorImpl<ArgumentGraphNode *>::iterator iterator;
289 iterator begin() { return SyntheticRoot.Uses.begin(); }
290 iterator end() { return SyntheticRoot.Uses.end(); }
291 ArgumentGraphNode *getEntryNode() { return &SyntheticRoot; }
293 ArgumentGraphNode *operator[](Argument *A) {
294 ArgumentGraphNode &Node = ArgumentMap[A];
296 SyntheticRoot.Uses.push_back(&Node);
301 /// This tracker checks whether callees are in the SCC, and if so it does not
302 /// consider that a capture, instead adding it to the "Uses" list and
303 /// continuing with the analysis.
304 struct ArgumentUsesTracker : public CaptureTracker {
305 ArgumentUsesTracker(const SCCNodeSet &SCCNodes)
306 : Captured(false), SCCNodes(SCCNodes) {}
308 void tooManyUses() override { Captured = true; }
310 bool captured(const Use *U) override {
311 CallSite CS(U->getUser());
312 if (!CS.getInstruction()) {
317 Function *F = CS.getCalledFunction();
318 if (!F || F->isDeclaration() || F->mayBeOverridden() ||
319 !SCCNodes.count(F)) {
324 // Note: the callee and the two successor blocks *follow* the argument
325 // operands. This means there is no need to adjust UseIndex to account for
329 std::distance(const_cast<const Use *>(CS.arg_begin()), U);
331 assert(UseIndex < CS.arg_size() && "Non-argument use?");
332 if (UseIndex >= F->arg_size()) {
333 assert(F->isVarArg() && "More params than args in non-varargs call");
338 Uses.push_back(&*std::next(F->arg_begin(), UseIndex));
342 bool Captured; // True only if certainly captured (used outside our SCC).
343 SmallVector<Argument *, 4> Uses; // Uses within our SCC.
345 const SCCNodeSet &SCCNodes;
350 template <> struct GraphTraits<ArgumentGraphNode *> {
351 typedef ArgumentGraphNode NodeType;
352 typedef SmallVectorImpl<ArgumentGraphNode *>::iterator ChildIteratorType;
354 static inline NodeType *getEntryNode(NodeType *A) { return A; }
355 static inline ChildIteratorType child_begin(NodeType *N) {
356 return N->Uses.begin();
358 static inline ChildIteratorType child_end(NodeType *N) {
359 return N->Uses.end();
363 struct GraphTraits<ArgumentGraph *> : public GraphTraits<ArgumentGraphNode *> {
364 static NodeType *getEntryNode(ArgumentGraph *AG) {
365 return AG->getEntryNode();
367 static ChildIteratorType nodes_begin(ArgumentGraph *AG) {
370 static ChildIteratorType nodes_end(ArgumentGraph *AG) { return AG->end(); }
374 /// Returns Attribute::None, Attribute::ReadOnly or Attribute::ReadNone.
375 static Attribute::AttrKind
376 determinePointerReadAttrs(Argument *A,
377 const SmallPtrSet<Argument *, 8> &SCCNodes) {
379 SmallVector<Use *, 32> Worklist;
380 SmallSet<Use *, 32> Visited;
382 // inalloca arguments are always clobbered by the call.
383 if (A->hasInAllocaAttr())
384 return Attribute::None;
387 // We don't need to track IsWritten. If A is written to, return immediately.
389 for (Use &U : A->uses()) {
391 Worklist.push_back(&U);
394 while (!Worklist.empty()) {
395 Use *U = Worklist.pop_back_val();
396 Instruction *I = cast<Instruction>(U->getUser());
399 switch (I->getOpcode()) {
400 case Instruction::BitCast:
401 case Instruction::GetElementPtr:
402 case Instruction::PHI:
403 case Instruction::Select:
404 case Instruction::AddrSpaceCast:
405 // The original value is not read/written via this if the new value isn't.
406 for (Use &UU : I->uses())
407 if (Visited.insert(&UU).second)
408 Worklist.push_back(&UU);
411 case Instruction::Call:
412 case Instruction::Invoke: {
413 bool Captures = true;
415 if (I->getType()->isVoidTy())
418 auto AddUsersToWorklistIfCapturing = [&] {
420 for (Use &UU : I->uses())
421 if (Visited.insert(&UU).second)
422 Worklist.push_back(&UU);
426 if (CS.doesNotAccessMemory()) {
427 AddUsersToWorklistIfCapturing();
431 Function *F = CS.getCalledFunction();
433 if (CS.onlyReadsMemory()) {
435 AddUsersToWorklistIfCapturing();
438 return Attribute::None;
441 Function::arg_iterator AI = F->arg_begin(), AE = F->arg_end();
442 CallSite::arg_iterator B = CS.arg_begin(), E = CS.arg_end();
443 for (CallSite::arg_iterator A = B; A != E; ++A, ++AI) {
446 assert(F->isVarArg() &&
447 "More params than args in non-varargs call.");
448 return Attribute::None;
450 Captures &= !CS.doesNotCapture(A - B);
451 if (SCCNodes.count(&*AI))
453 if (!CS.onlyReadsMemory() && !CS.onlyReadsMemory(A - B))
454 return Attribute::None;
455 if (!CS.doesNotAccessMemory(A - B))
459 AddUsersToWorklistIfCapturing();
463 case Instruction::Load:
467 case Instruction::ICmp:
468 case Instruction::Ret:
472 return Attribute::None;
476 return IsRead ? Attribute::ReadOnly : Attribute::ReadNone;
479 /// Deduce nocapture attributes for the SCC.
480 static bool addArgumentAttrs(const SCCNodeSet &SCCNodes) {
481 bool Changed = false;
486 B.addAttribute(Attribute::NoCapture);
488 // Check each function in turn, determining which pointer arguments are not
490 for (Function *F : SCCNodes) {
491 // Definitions with weak linkage may be overridden at linktime with
492 // something that captures pointers, so treat them like declarations.
493 if (F->isDeclaration() || F->mayBeOverridden())
496 // Functions that are readonly (or readnone) and nounwind and don't return
497 // a value can't capture arguments. Don't analyze them.
498 if (F->onlyReadsMemory() && F->doesNotThrow() &&
499 F->getReturnType()->isVoidTy()) {
500 for (Function::arg_iterator A = F->arg_begin(), E = F->arg_end(); A != E;
502 if (A->getType()->isPointerTy() && !A->hasNoCaptureAttr()) {
503 A->addAttr(AttributeSet::get(F->getContext(), A->getArgNo() + 1, B));
511 for (Function::arg_iterator A = F->arg_begin(), E = F->arg_end(); A != E;
513 if (!A->getType()->isPointerTy())
515 bool HasNonLocalUses = false;
516 if (!A->hasNoCaptureAttr()) {
517 ArgumentUsesTracker Tracker(SCCNodes);
518 PointerMayBeCaptured(&*A, &Tracker);
519 if (!Tracker.Captured) {
520 if (Tracker.Uses.empty()) {
521 // If it's trivially not captured, mark it nocapture now.
523 AttributeSet::get(F->getContext(), A->getArgNo() + 1, B));
527 // If it's not trivially captured and not trivially not captured,
528 // then it must be calling into another function in our SCC. Save
529 // its particulars for Argument-SCC analysis later.
530 ArgumentGraphNode *Node = AG[&*A];
531 for (SmallVectorImpl<Argument *>::iterator
532 UI = Tracker.Uses.begin(),
533 UE = Tracker.Uses.end();
535 Node->Uses.push_back(AG[*UI]);
537 HasNonLocalUses = true;
541 // Otherwise, it's captured. Don't bother doing SCC analysis on it.
543 if (!HasNonLocalUses && !A->onlyReadsMemory()) {
544 // Can we determine that it's readonly/readnone without doing an SCC?
545 // Note that we don't allow any calls at all here, or else our result
546 // will be dependent on the iteration order through the functions in the
548 SmallPtrSet<Argument *, 8> Self;
550 Attribute::AttrKind R = determinePointerReadAttrs(&*A, Self);
551 if (R != Attribute::None) {
554 A->addAttr(AttributeSet::get(A->getContext(), A->getArgNo() + 1, B));
556 R == Attribute::ReadOnly ? ++NumReadOnlyArg : ++NumReadNoneArg;
562 // The graph we've collected is partial because we stopped scanning for
563 // argument uses once we solved the argument trivially. These partial nodes
564 // show up as ArgumentGraphNode objects with an empty Uses list, and for
565 // these nodes the final decision about whether they capture has already been
566 // made. If the definition doesn't have a 'nocapture' attribute by now, it
569 for (scc_iterator<ArgumentGraph *> I = scc_begin(&AG); !I.isAtEnd(); ++I) {
570 const std::vector<ArgumentGraphNode *> &ArgumentSCC = *I;
571 if (ArgumentSCC.size() == 1) {
572 if (!ArgumentSCC[0]->Definition)
573 continue; // synthetic root node
575 // eg. "void f(int* x) { if (...) f(x); }"
576 if (ArgumentSCC[0]->Uses.size() == 1 &&
577 ArgumentSCC[0]->Uses[0] == ArgumentSCC[0]) {
578 Argument *A = ArgumentSCC[0]->Definition;
579 A->addAttr(AttributeSet::get(A->getContext(), A->getArgNo() + 1, B));
586 bool SCCCaptured = false;
587 for (auto I = ArgumentSCC.begin(), E = ArgumentSCC.end();
588 I != E && !SCCCaptured; ++I) {
589 ArgumentGraphNode *Node = *I;
590 if (Node->Uses.empty()) {
591 if (!Node->Definition->hasNoCaptureAttr())
598 SmallPtrSet<Argument *, 8> ArgumentSCCNodes;
599 // Fill ArgumentSCCNodes with the elements of the ArgumentSCC. Used for
600 // quickly looking up whether a given Argument is in this ArgumentSCC.
601 for (auto I = ArgumentSCC.begin(), E = ArgumentSCC.end(); I != E; ++I) {
602 ArgumentSCCNodes.insert((*I)->Definition);
605 for (auto I = ArgumentSCC.begin(), E = ArgumentSCC.end();
606 I != E && !SCCCaptured; ++I) {
607 ArgumentGraphNode *N = *I;
608 for (SmallVectorImpl<ArgumentGraphNode *>::iterator UI = N->Uses.begin(),
611 Argument *A = (*UI)->Definition;
612 if (A->hasNoCaptureAttr() || ArgumentSCCNodes.count(A))
621 for (unsigned i = 0, e = ArgumentSCC.size(); i != e; ++i) {
622 Argument *A = ArgumentSCC[i]->Definition;
623 A->addAttr(AttributeSet::get(A->getContext(), A->getArgNo() + 1, B));
628 // We also want to compute readonly/readnone. With a small number of false
629 // negatives, we can assume that any pointer which is captured isn't going
630 // to be provably readonly or readnone, since by definition we can't
631 // analyze all uses of a captured pointer.
633 // The false negatives happen when the pointer is captured by a function
634 // that promises readonly/readnone behaviour on the pointer, then the
635 // pointer's lifetime ends before anything that writes to arbitrary memory.
636 // Also, a readonly/readnone pointer may be returned, but returning a
637 // pointer is capturing it.
639 Attribute::AttrKind ReadAttr = Attribute::ReadNone;
640 for (unsigned i = 0, e = ArgumentSCC.size(); i != e; ++i) {
641 Argument *A = ArgumentSCC[i]->Definition;
642 Attribute::AttrKind K = determinePointerReadAttrs(A, ArgumentSCCNodes);
643 if (K == Attribute::ReadNone)
645 if (K == Attribute::ReadOnly) {
646 ReadAttr = Attribute::ReadOnly;
653 if (ReadAttr != Attribute::None) {
655 B.addAttribute(ReadAttr);
656 R.addAttribute(Attribute::ReadOnly).addAttribute(Attribute::ReadNone);
657 for (unsigned i = 0, e = ArgumentSCC.size(); i != e; ++i) {
658 Argument *A = ArgumentSCC[i]->Definition;
659 // Clear out existing readonly/readnone attributes
660 A->removeAttr(AttributeSet::get(A->getContext(), A->getArgNo() + 1, R));
661 A->addAttr(AttributeSet::get(A->getContext(), A->getArgNo() + 1, B));
662 ReadAttr == Attribute::ReadOnly ? ++NumReadOnlyArg : ++NumReadNoneArg;
671 /// Tests whether a function is "malloc-like".
673 /// A function is "malloc-like" if it returns either null or a pointer that
674 /// doesn't alias any other pointer visible to the caller.
675 static bool isFunctionMallocLike(Function *F, const SCCNodeSet &SCCNodes) {
676 SmallSetVector<Value *, 8> FlowsToReturn;
677 for (Function::iterator I = F->begin(), E = F->end(); I != E; ++I)
678 if (ReturnInst *Ret = dyn_cast<ReturnInst>(I->getTerminator()))
679 FlowsToReturn.insert(Ret->getReturnValue());
681 for (unsigned i = 0; i != FlowsToReturn.size(); ++i) {
682 Value *RetVal = FlowsToReturn[i];
684 if (Constant *C = dyn_cast<Constant>(RetVal)) {
685 if (!C->isNullValue() && !isa<UndefValue>(C))
691 if (isa<Argument>(RetVal))
694 if (Instruction *RVI = dyn_cast<Instruction>(RetVal))
695 switch (RVI->getOpcode()) {
696 // Extend the analysis by looking upwards.
697 case Instruction::BitCast:
698 case Instruction::GetElementPtr:
699 case Instruction::AddrSpaceCast:
700 FlowsToReturn.insert(RVI->getOperand(0));
702 case Instruction::Select: {
703 SelectInst *SI = cast<SelectInst>(RVI);
704 FlowsToReturn.insert(SI->getTrueValue());
705 FlowsToReturn.insert(SI->getFalseValue());
708 case Instruction::PHI: {
709 PHINode *PN = cast<PHINode>(RVI);
710 for (Value *IncValue : PN->incoming_values())
711 FlowsToReturn.insert(IncValue);
715 // Check whether the pointer came from an allocation.
716 case Instruction::Alloca:
718 case Instruction::Call:
719 case Instruction::Invoke: {
721 if (CS.paramHasAttr(0, Attribute::NoAlias))
723 if (CS.getCalledFunction() && SCCNodes.count(CS.getCalledFunction()))
727 return false; // Did not come from an allocation.
730 if (PointerMayBeCaptured(RetVal, false, /*StoreCaptures=*/false))
737 /// Deduce noalias attributes for the SCC.
738 static bool addNoAliasAttrs(const SCCNodeSet &SCCNodes) {
739 // Check each function in turn, determining which functions return noalias
741 for (Function *F : SCCNodes) {
743 if (F->doesNotAlias(0))
746 // Definitions with weak linkage may be overridden at linktime, so
747 // treat them like declarations.
748 if (F->isDeclaration() || F->mayBeOverridden())
751 // We annotate noalias return values, which are only applicable to
753 if (!F->getReturnType()->isPointerTy())
756 if (!isFunctionMallocLike(F, SCCNodes))
760 bool MadeChange = false;
761 for (Function *F : SCCNodes) {
762 if (F->doesNotAlias(0) || !F->getReturnType()->isPointerTy())
765 F->setDoesNotAlias(0);
773 /// Tests whether this function is known to not return null.
775 /// Requires that the function returns a pointer.
777 /// Returns true if it believes the function will not return a null, and sets
778 /// \p Speculative based on whether the returned conclusion is a speculative
779 /// conclusion due to SCC calls.
780 static bool isReturnNonNull(Function *F, const SCCNodeSet &SCCNodes,
781 const TargetLibraryInfo &TLI, bool &Speculative) {
782 assert(F->getReturnType()->isPointerTy() &&
783 "nonnull only meaningful on pointer types");
786 SmallSetVector<Value *, 8> FlowsToReturn;
787 for (BasicBlock &BB : *F)
788 if (auto *Ret = dyn_cast<ReturnInst>(BB.getTerminator()))
789 FlowsToReturn.insert(Ret->getReturnValue());
791 for (unsigned i = 0; i != FlowsToReturn.size(); ++i) {
792 Value *RetVal = FlowsToReturn[i];
794 // If this value is locally known to be non-null, we're good
795 if (isKnownNonNull(RetVal, &TLI))
798 // Otherwise, we need to look upwards since we can't make any local
800 Instruction *RVI = dyn_cast<Instruction>(RetVal);
803 switch (RVI->getOpcode()) {
804 // Extend the analysis by looking upwards.
805 case Instruction::BitCast:
806 case Instruction::GetElementPtr:
807 case Instruction::AddrSpaceCast:
808 FlowsToReturn.insert(RVI->getOperand(0));
810 case Instruction::Select: {
811 SelectInst *SI = cast<SelectInst>(RVI);
812 FlowsToReturn.insert(SI->getTrueValue());
813 FlowsToReturn.insert(SI->getFalseValue());
816 case Instruction::PHI: {
817 PHINode *PN = cast<PHINode>(RVI);
818 for (int i = 0, e = PN->getNumIncomingValues(); i != e; ++i)
819 FlowsToReturn.insert(PN->getIncomingValue(i));
822 case Instruction::Call:
823 case Instruction::Invoke: {
825 Function *Callee = CS.getCalledFunction();
826 // A call to a node within the SCC is assumed to return null until
828 if (Callee && SCCNodes.count(Callee)) {
835 return false; // Unknown source, may be null
837 llvm_unreachable("should have either continued or returned");
843 /// Deduce nonnull attributes for the SCC.
844 static bool addNonNullAttrs(const SCCNodeSet &SCCNodes,
845 const TargetLibraryInfo &TLI) {
846 // Speculative that all functions in the SCC return only nonnull
847 // pointers. We may refute this as we analyze functions.
848 bool SCCReturnsNonNull = true;
850 bool MadeChange = false;
852 // Check each function in turn, determining which functions return nonnull
854 for (Function *F : SCCNodes) {
856 if (F->getAttributes().hasAttribute(AttributeSet::ReturnIndex,
860 // Definitions with weak linkage may be overridden at linktime, so
861 // treat them like declarations.
862 if (F->isDeclaration() || F->mayBeOverridden())
865 // We annotate nonnull return values, which are only applicable to
867 if (!F->getReturnType()->isPointerTy())
870 bool Speculative = false;
871 if (isReturnNonNull(F, SCCNodes, TLI, Speculative)) {
873 // Mark the function eagerly since we may discover a function
874 // which prevents us from speculating about the entire SCC
875 DEBUG(dbgs() << "Eagerly marking " << F->getName() << " as nonnull\n");
876 F->addAttribute(AttributeSet::ReturnIndex, Attribute::NonNull);
882 // At least one function returns something which could be null, can't
883 // speculate any more.
884 SCCReturnsNonNull = false;
887 if (SCCReturnsNonNull) {
888 for (Function *F : SCCNodes) {
889 if (F->getAttributes().hasAttribute(AttributeSet::ReturnIndex,
890 Attribute::NonNull) ||
891 !F->getReturnType()->isPointerTy())
894 DEBUG(dbgs() << "SCC marking " << F->getName() << " as nonnull\n");
895 F->addAttribute(AttributeSet::ReturnIndex, Attribute::NonNull);
904 static void setDoesNotAccessMemory(Function &F) {
905 if (!F.doesNotAccessMemory()) {
906 F.setDoesNotAccessMemory();
911 static void setOnlyReadsMemory(Function &F) {
912 if (!F.onlyReadsMemory()) {
913 F.setOnlyReadsMemory();
918 static void setDoesNotThrow(Function &F) {
919 if (!F.doesNotThrow()) {
925 static void setDoesNotCapture(Function &F, unsigned n) {
926 if (!F.doesNotCapture(n)) {
927 F.setDoesNotCapture(n);
932 static void setOnlyReadsMemory(Function &F, unsigned n) {
933 if (!F.onlyReadsMemory(n)) {
934 F.setOnlyReadsMemory(n);
939 static void setDoesNotAlias(Function &F, unsigned n) {
940 if (!F.doesNotAlias(n)) {
941 F.setDoesNotAlias(n);
946 /// Analyze the name and prototype of the given function and set any applicable
949 /// Returns true if any attributes were set and false otherwise.
950 static bool inferPrototypeAttributes(Function &F, const TargetLibraryInfo &TLI) {
951 if (F.hasFnAttribute(Attribute::OptimizeNone))
954 FunctionType *FTy = F.getFunctionType();
955 LibFunc::Func TheLibFunc;
956 if (!(TLI.getLibFunc(F.getName(), TheLibFunc) && TLI.has(TheLibFunc)))
959 switch (TheLibFunc) {
960 case LibFunc::strlen:
961 if (FTy->getNumParams() != 1 || !FTy->getParamType(0)->isPointerTy())
963 setOnlyReadsMemory(F);
965 setDoesNotCapture(F, 1);
967 case LibFunc::strchr:
968 case LibFunc::strrchr:
969 if (FTy->getNumParams() != 2 || !FTy->getParamType(0)->isPointerTy() ||
970 !FTy->getParamType(1)->isIntegerTy())
972 setOnlyReadsMemory(F);
975 case LibFunc::strtol:
976 case LibFunc::strtod:
977 case LibFunc::strtof:
978 case LibFunc::strtoul:
979 case LibFunc::strtoll:
980 case LibFunc::strtold:
981 case LibFunc::strtoull:
982 if (FTy->getNumParams() < 2 || !FTy->getParamType(1)->isPointerTy())
985 setDoesNotCapture(F, 2);
986 setOnlyReadsMemory(F, 1);
988 case LibFunc::strcpy:
989 case LibFunc::stpcpy:
990 case LibFunc::strcat:
991 case LibFunc::strncat:
992 case LibFunc::strncpy:
993 case LibFunc::stpncpy:
994 if (FTy->getNumParams() < 2 || !FTy->getParamType(1)->isPointerTy())
997 setDoesNotCapture(F, 2);
998 setOnlyReadsMemory(F, 2);
1000 case LibFunc::strxfrm:
1001 if (FTy->getNumParams() != 3 || !FTy->getParamType(0)->isPointerTy() ||
1002 !FTy->getParamType(1)->isPointerTy())
1005 setDoesNotCapture(F, 1);
1006 setDoesNotCapture(F, 2);
1007 setOnlyReadsMemory(F, 2);
1009 case LibFunc::strcmp: // 0,1
1010 case LibFunc::strspn: // 0,1
1011 case LibFunc::strncmp: // 0,1
1012 case LibFunc::strcspn: // 0,1
1013 case LibFunc::strcoll: // 0,1
1014 case LibFunc::strcasecmp: // 0,1
1015 case LibFunc::strncasecmp: //
1016 if (FTy->getNumParams() < 2 || !FTy->getParamType(0)->isPointerTy() ||
1017 !FTy->getParamType(1)->isPointerTy())
1019 setOnlyReadsMemory(F);
1021 setDoesNotCapture(F, 1);
1022 setDoesNotCapture(F, 2);
1024 case LibFunc::strstr:
1025 case LibFunc::strpbrk:
1026 if (FTy->getNumParams() != 2 || !FTy->getParamType(1)->isPointerTy())
1028 setOnlyReadsMemory(F);
1030 setDoesNotCapture(F, 2);
1032 case LibFunc::strtok:
1033 case LibFunc::strtok_r:
1034 if (FTy->getNumParams() < 2 || !FTy->getParamType(1)->isPointerTy())
1037 setDoesNotCapture(F, 2);
1038 setOnlyReadsMemory(F, 2);
1040 case LibFunc::scanf:
1041 if (FTy->getNumParams() < 1 || !FTy->getParamType(0)->isPointerTy())
1044 setDoesNotCapture(F, 1);
1045 setOnlyReadsMemory(F, 1);
1047 case LibFunc::setbuf:
1048 case LibFunc::setvbuf:
1049 if (FTy->getNumParams() < 1 || !FTy->getParamType(0)->isPointerTy())
1052 setDoesNotCapture(F, 1);
1054 case LibFunc::strdup:
1055 case LibFunc::strndup:
1056 if (FTy->getNumParams() < 1 || !FTy->getReturnType()->isPointerTy() ||
1057 !FTy->getParamType(0)->isPointerTy())
1060 setDoesNotAlias(F, 0);
1061 setDoesNotCapture(F, 1);
1062 setOnlyReadsMemory(F, 1);
1065 case LibFunc::statvfs:
1066 if (FTy->getNumParams() < 2 || !FTy->getParamType(0)->isPointerTy() ||
1067 !FTy->getParamType(1)->isPointerTy())
1070 setDoesNotCapture(F, 1);
1071 setDoesNotCapture(F, 2);
1072 setOnlyReadsMemory(F, 1);
1074 case LibFunc::sscanf:
1075 if (FTy->getNumParams() < 2 || !FTy->getParamType(0)->isPointerTy() ||
1076 !FTy->getParamType(1)->isPointerTy())
1079 setDoesNotCapture(F, 1);
1080 setDoesNotCapture(F, 2);
1081 setOnlyReadsMemory(F, 1);
1082 setOnlyReadsMemory(F, 2);
1084 case LibFunc::sprintf:
1085 if (FTy->getNumParams() < 2 || !FTy->getParamType(0)->isPointerTy() ||
1086 !FTy->getParamType(1)->isPointerTy())
1089 setDoesNotCapture(F, 1);
1090 setDoesNotCapture(F, 2);
1091 setOnlyReadsMemory(F, 2);
1093 case LibFunc::snprintf:
1094 if (FTy->getNumParams() != 3 || !FTy->getParamType(0)->isPointerTy() ||
1095 !FTy->getParamType(2)->isPointerTy())
1098 setDoesNotCapture(F, 1);
1099 setDoesNotCapture(F, 3);
1100 setOnlyReadsMemory(F, 3);
1102 case LibFunc::setitimer:
1103 if (FTy->getNumParams() != 3 || !FTy->getParamType(1)->isPointerTy() ||
1104 !FTy->getParamType(2)->isPointerTy())
1107 setDoesNotCapture(F, 2);
1108 setDoesNotCapture(F, 3);
1109 setOnlyReadsMemory(F, 2);
1111 case LibFunc::system:
1112 if (FTy->getNumParams() != 1 || !FTy->getParamType(0)->isPointerTy())
1114 // May throw; "system" is a valid pthread cancellation point.
1115 setDoesNotCapture(F, 1);
1116 setOnlyReadsMemory(F, 1);
1118 case LibFunc::malloc:
1119 if (FTy->getNumParams() != 1 || !FTy->getReturnType()->isPointerTy())
1122 setDoesNotAlias(F, 0);
1124 case LibFunc::memcmp:
1125 if (FTy->getNumParams() != 3 || !FTy->getParamType(0)->isPointerTy() ||
1126 !FTy->getParamType(1)->isPointerTy())
1128 setOnlyReadsMemory(F);
1130 setDoesNotCapture(F, 1);
1131 setDoesNotCapture(F, 2);
1133 case LibFunc::memchr:
1134 case LibFunc::memrchr:
1135 if (FTy->getNumParams() != 3)
1137 setOnlyReadsMemory(F);
1141 case LibFunc::modff:
1142 case LibFunc::modfl:
1143 if (FTy->getNumParams() < 2 || !FTy->getParamType(1)->isPointerTy())
1146 setDoesNotCapture(F, 2);
1148 case LibFunc::memcpy:
1149 case LibFunc::memccpy:
1150 case LibFunc::memmove:
1151 if (FTy->getNumParams() < 2 || !FTy->getParamType(1)->isPointerTy())
1154 setDoesNotCapture(F, 2);
1155 setOnlyReadsMemory(F, 2);
1157 case LibFunc::memalign:
1158 if (!FTy->getReturnType()->isPointerTy())
1160 setDoesNotAlias(F, 0);
1162 case LibFunc::mkdir:
1163 if (FTy->getNumParams() == 0 || !FTy->getParamType(0)->isPointerTy())
1166 setDoesNotCapture(F, 1);
1167 setOnlyReadsMemory(F, 1);
1169 case LibFunc::mktime:
1170 if (FTy->getNumParams() == 0 || !FTy->getParamType(0)->isPointerTy())
1173 setDoesNotCapture(F, 1);
1175 case LibFunc::realloc:
1176 if (FTy->getNumParams() != 2 || !FTy->getParamType(0)->isPointerTy() ||
1177 !FTy->getReturnType()->isPointerTy())
1180 setDoesNotAlias(F, 0);
1181 setDoesNotCapture(F, 1);
1184 if (FTy->getNumParams() != 3 || !FTy->getParamType(1)->isPointerTy())
1186 // May throw; "read" is a valid pthread cancellation point.
1187 setDoesNotCapture(F, 2);
1189 case LibFunc::rewind:
1190 if (FTy->getNumParams() < 1 || !FTy->getParamType(0)->isPointerTy())
1193 setDoesNotCapture(F, 1);
1195 case LibFunc::rmdir:
1196 case LibFunc::remove:
1197 case LibFunc::realpath:
1198 if (FTy->getNumParams() < 1 || !FTy->getParamType(0)->isPointerTy())
1201 setDoesNotCapture(F, 1);
1202 setOnlyReadsMemory(F, 1);
1204 case LibFunc::rename:
1205 if (FTy->getNumParams() < 2 || !FTy->getParamType(0)->isPointerTy() ||
1206 !FTy->getParamType(1)->isPointerTy())
1209 setDoesNotCapture(F, 1);
1210 setDoesNotCapture(F, 2);
1211 setOnlyReadsMemory(F, 1);
1212 setOnlyReadsMemory(F, 2);
1214 case LibFunc::readlink:
1215 if (FTy->getNumParams() < 2 || !FTy->getParamType(0)->isPointerTy() ||
1216 !FTy->getParamType(1)->isPointerTy())
1219 setDoesNotCapture(F, 1);
1220 setDoesNotCapture(F, 2);
1221 setOnlyReadsMemory(F, 1);
1223 case LibFunc::write:
1224 if (FTy->getNumParams() != 3 || !FTy->getParamType(1)->isPointerTy())
1226 // May throw; "write" is a valid pthread cancellation point.
1227 setDoesNotCapture(F, 2);
1228 setOnlyReadsMemory(F, 2);
1230 case LibFunc::bcopy:
1231 if (FTy->getNumParams() != 3 || !FTy->getParamType(0)->isPointerTy() ||
1232 !FTy->getParamType(1)->isPointerTy())
1235 setDoesNotCapture(F, 1);
1236 setDoesNotCapture(F, 2);
1237 setOnlyReadsMemory(F, 1);
1240 if (FTy->getNumParams() != 3 || !FTy->getParamType(0)->isPointerTy() ||
1241 !FTy->getParamType(1)->isPointerTy())
1244 setOnlyReadsMemory(F);
1245 setDoesNotCapture(F, 1);
1246 setDoesNotCapture(F, 2);
1248 case LibFunc::bzero:
1249 if (FTy->getNumParams() != 2 || !FTy->getParamType(0)->isPointerTy())
1252 setDoesNotCapture(F, 1);
1254 case LibFunc::calloc:
1255 if (FTy->getNumParams() != 2 || !FTy->getReturnType()->isPointerTy())
1258 setDoesNotAlias(F, 0);
1260 case LibFunc::chmod:
1261 case LibFunc::chown:
1262 if (FTy->getNumParams() == 0 || !FTy->getParamType(0)->isPointerTy())
1265 setDoesNotCapture(F, 1);
1266 setOnlyReadsMemory(F, 1);
1268 case LibFunc::ctermid:
1269 case LibFunc::clearerr:
1270 case LibFunc::closedir:
1271 if (FTy->getNumParams() == 0 || !FTy->getParamType(0)->isPointerTy())
1274 setDoesNotCapture(F, 1);
1279 case LibFunc::atoll:
1280 if (FTy->getNumParams() != 1 || !FTy->getParamType(0)->isPointerTy())
1283 setOnlyReadsMemory(F);
1284 setDoesNotCapture(F, 1);
1286 case LibFunc::access:
1287 if (FTy->getNumParams() != 2 || !FTy->getParamType(0)->isPointerTy())
1290 setDoesNotCapture(F, 1);
1291 setOnlyReadsMemory(F, 1);
1293 case LibFunc::fopen:
1294 if (FTy->getNumParams() != 2 || !FTy->getReturnType()->isPointerTy() ||
1295 !FTy->getParamType(0)->isPointerTy() ||
1296 !FTy->getParamType(1)->isPointerTy())
1299 setDoesNotAlias(F, 0);
1300 setDoesNotCapture(F, 1);
1301 setDoesNotCapture(F, 2);
1302 setOnlyReadsMemory(F, 1);
1303 setOnlyReadsMemory(F, 2);
1305 case LibFunc::fdopen:
1306 if (FTy->getNumParams() != 2 || !FTy->getReturnType()->isPointerTy() ||
1307 !FTy->getParamType(1)->isPointerTy())
1310 setDoesNotAlias(F, 0);
1311 setDoesNotCapture(F, 2);
1312 setOnlyReadsMemory(F, 2);
1316 case LibFunc::fseek:
1317 case LibFunc::ftell:
1318 case LibFunc::fgetc:
1319 case LibFunc::fseeko:
1320 case LibFunc::ftello:
1321 case LibFunc::fileno:
1322 case LibFunc::fflush:
1323 case LibFunc::fclose:
1324 case LibFunc::fsetpos:
1325 case LibFunc::flockfile:
1326 case LibFunc::funlockfile:
1327 case LibFunc::ftrylockfile:
1328 if (FTy->getNumParams() == 0 || !FTy->getParamType(0)->isPointerTy())
1331 setDoesNotCapture(F, 1);
1333 case LibFunc::ferror:
1334 if (FTy->getNumParams() != 1 || !FTy->getParamType(0)->isPointerTy())
1337 setDoesNotCapture(F, 1);
1338 setOnlyReadsMemory(F);
1340 case LibFunc::fputc:
1341 case LibFunc::fstat:
1342 case LibFunc::frexp:
1343 case LibFunc::frexpf:
1344 case LibFunc::frexpl:
1345 case LibFunc::fstatvfs:
1346 if (FTy->getNumParams() != 2 || !FTy->getParamType(1)->isPointerTy())
1349 setDoesNotCapture(F, 2);
1351 case LibFunc::fgets:
1352 if (FTy->getNumParams() != 3 || !FTy->getParamType(0)->isPointerTy() ||
1353 !FTy->getParamType(2)->isPointerTy())
1356 setDoesNotCapture(F, 3);
1358 case LibFunc::fread:
1359 if (FTy->getNumParams() != 4 || !FTy->getParamType(0)->isPointerTy() ||
1360 !FTy->getParamType(3)->isPointerTy())
1363 setDoesNotCapture(F, 1);
1364 setDoesNotCapture(F, 4);
1366 case LibFunc::fwrite:
1367 if (FTy->getNumParams() != 4 || !FTy->getParamType(0)->isPointerTy() ||
1368 !FTy->getParamType(3)->isPointerTy())
1371 setDoesNotCapture(F, 1);
1372 setDoesNotCapture(F, 4);
1374 case LibFunc::fputs:
1375 if (FTy->getNumParams() < 2 || !FTy->getParamType(0)->isPointerTy() ||
1376 !FTy->getParamType(1)->isPointerTy())
1379 setDoesNotCapture(F, 1);
1380 setDoesNotCapture(F, 2);
1381 setOnlyReadsMemory(F, 1);
1383 case LibFunc::fscanf:
1384 case LibFunc::fprintf:
1385 if (FTy->getNumParams() < 2 || !FTy->getParamType(0)->isPointerTy() ||
1386 !FTy->getParamType(1)->isPointerTy())
1389 setDoesNotCapture(F, 1);
1390 setDoesNotCapture(F, 2);
1391 setOnlyReadsMemory(F, 2);
1393 case LibFunc::fgetpos:
1394 if (FTy->getNumParams() < 2 || !FTy->getParamType(0)->isPointerTy() ||
1395 !FTy->getParamType(1)->isPointerTy())
1398 setDoesNotCapture(F, 1);
1399 setDoesNotCapture(F, 2);
1402 case LibFunc::getlogin_r:
1403 case LibFunc::getc_unlocked:
1404 if (FTy->getNumParams() == 0 || !FTy->getParamType(0)->isPointerTy())
1407 setDoesNotCapture(F, 1);
1409 case LibFunc::getenv:
1410 if (FTy->getNumParams() != 1 || !FTy->getParamType(0)->isPointerTy())
1413 setOnlyReadsMemory(F);
1414 setDoesNotCapture(F, 1);
1417 case LibFunc::getchar:
1420 case LibFunc::getitimer:
1421 if (FTy->getNumParams() != 2 || !FTy->getParamType(1)->isPointerTy())
1424 setDoesNotCapture(F, 2);
1426 case LibFunc::getpwnam:
1427 if (FTy->getNumParams() != 1 || !FTy->getParamType(0)->isPointerTy())
1430 setDoesNotCapture(F, 1);
1431 setOnlyReadsMemory(F, 1);
1433 case LibFunc::ungetc:
1434 if (FTy->getNumParams() != 2 || !FTy->getParamType(1)->isPointerTy())
1437 setDoesNotCapture(F, 2);
1439 case LibFunc::uname:
1440 if (FTy->getNumParams() != 1 || !FTy->getParamType(0)->isPointerTy())
1443 setDoesNotCapture(F, 1);
1445 case LibFunc::unlink:
1446 if (FTy->getNumParams() != 1 || !FTy->getParamType(0)->isPointerTy())
1449 setDoesNotCapture(F, 1);
1450 setOnlyReadsMemory(F, 1);
1452 case LibFunc::unsetenv:
1453 if (FTy->getNumParams() != 1 || !FTy->getParamType(0)->isPointerTy())
1456 setDoesNotCapture(F, 1);
1457 setOnlyReadsMemory(F, 1);
1459 case LibFunc::utime:
1460 case LibFunc::utimes:
1461 if (FTy->getNumParams() != 2 || !FTy->getParamType(0)->isPointerTy() ||
1462 !FTy->getParamType(1)->isPointerTy())
1465 setDoesNotCapture(F, 1);
1466 setDoesNotCapture(F, 2);
1467 setOnlyReadsMemory(F, 1);
1468 setOnlyReadsMemory(F, 2);
1471 if (FTy->getNumParams() != 2 || !FTy->getParamType(1)->isPointerTy())
1474 setDoesNotCapture(F, 2);
1477 case LibFunc::printf:
1478 case LibFunc::perror:
1479 if (FTy->getNumParams() != 1 || !FTy->getParamType(0)->isPointerTy())
1482 setDoesNotCapture(F, 1);
1483 setOnlyReadsMemory(F, 1);
1485 case LibFunc::pread:
1486 if (FTy->getNumParams() != 4 || !FTy->getParamType(1)->isPointerTy())
1488 // May throw; "pread" is a valid pthread cancellation point.
1489 setDoesNotCapture(F, 2);
1491 case LibFunc::pwrite:
1492 if (FTy->getNumParams() != 4 || !FTy->getParamType(1)->isPointerTy())
1494 // May throw; "pwrite" is a valid pthread cancellation point.
1495 setDoesNotCapture(F, 2);
1496 setOnlyReadsMemory(F, 2);
1498 case LibFunc::putchar:
1501 case LibFunc::popen:
1502 if (FTy->getNumParams() != 2 || !FTy->getReturnType()->isPointerTy() ||
1503 !FTy->getParamType(0)->isPointerTy() ||
1504 !FTy->getParamType(1)->isPointerTy())
1507 setDoesNotAlias(F, 0);
1508 setDoesNotCapture(F, 1);
1509 setDoesNotCapture(F, 2);
1510 setOnlyReadsMemory(F, 1);
1511 setOnlyReadsMemory(F, 2);
1513 case LibFunc::pclose:
1514 if (FTy->getNumParams() != 1 || !FTy->getParamType(0)->isPointerTy())
1517 setDoesNotCapture(F, 1);
1519 case LibFunc::vscanf:
1520 if (FTy->getNumParams() != 2 || !FTy->getParamType(1)->isPointerTy())
1523 setDoesNotCapture(F, 1);
1524 setOnlyReadsMemory(F, 1);
1526 case LibFunc::vsscanf:
1527 if (FTy->getNumParams() != 3 || !FTy->getParamType(1)->isPointerTy() ||
1528 !FTy->getParamType(2)->isPointerTy())
1531 setDoesNotCapture(F, 1);
1532 setDoesNotCapture(F, 2);
1533 setOnlyReadsMemory(F, 1);
1534 setOnlyReadsMemory(F, 2);
1536 case LibFunc::vfscanf:
1537 if (FTy->getNumParams() != 3 || !FTy->getParamType(1)->isPointerTy() ||
1538 !FTy->getParamType(2)->isPointerTy())
1541 setDoesNotCapture(F, 1);
1542 setDoesNotCapture(F, 2);
1543 setOnlyReadsMemory(F, 2);
1545 case LibFunc::valloc:
1546 if (!FTy->getReturnType()->isPointerTy())
1549 setDoesNotAlias(F, 0);
1551 case LibFunc::vprintf:
1552 if (FTy->getNumParams() != 2 || !FTy->getParamType(0)->isPointerTy())
1555 setDoesNotCapture(F, 1);
1556 setOnlyReadsMemory(F, 1);
1558 case LibFunc::vfprintf:
1559 case LibFunc::vsprintf:
1560 if (FTy->getNumParams() != 3 || !FTy->getParamType(0)->isPointerTy() ||
1561 !FTy->getParamType(1)->isPointerTy())
1564 setDoesNotCapture(F, 1);
1565 setDoesNotCapture(F, 2);
1566 setOnlyReadsMemory(F, 2);
1568 case LibFunc::vsnprintf:
1569 if (FTy->getNumParams() != 4 || !FTy->getParamType(0)->isPointerTy() ||
1570 !FTy->getParamType(2)->isPointerTy())
1573 setDoesNotCapture(F, 1);
1574 setDoesNotCapture(F, 3);
1575 setOnlyReadsMemory(F, 3);
1578 if (FTy->getNumParams() < 2 || !FTy->getParamType(0)->isPointerTy())
1580 // May throw; "open" is a valid pthread cancellation point.
1581 setDoesNotCapture(F, 1);
1582 setOnlyReadsMemory(F, 1);
1584 case LibFunc::opendir:
1585 if (FTy->getNumParams() != 1 || !FTy->getReturnType()->isPointerTy() ||
1586 !FTy->getParamType(0)->isPointerTy())
1589 setDoesNotAlias(F, 0);
1590 setDoesNotCapture(F, 1);
1591 setOnlyReadsMemory(F, 1);
1593 case LibFunc::tmpfile:
1594 if (!FTy->getReturnType()->isPointerTy())
1597 setDoesNotAlias(F, 0);
1599 case LibFunc::times:
1600 if (FTy->getNumParams() != 1 || !FTy->getParamType(0)->isPointerTy())
1603 setDoesNotCapture(F, 1);
1605 case LibFunc::htonl:
1606 case LibFunc::htons:
1607 case LibFunc::ntohl:
1608 case LibFunc::ntohs:
1610 setDoesNotAccessMemory(F);
1612 case LibFunc::lstat:
1613 if (FTy->getNumParams() != 2 || !FTy->getParamType(0)->isPointerTy() ||
1614 !FTy->getParamType(1)->isPointerTy())
1617 setDoesNotCapture(F, 1);
1618 setDoesNotCapture(F, 2);
1619 setOnlyReadsMemory(F, 1);
1621 case LibFunc::lchown:
1622 if (FTy->getNumParams() != 3 || !FTy->getParamType(0)->isPointerTy())
1625 setDoesNotCapture(F, 1);
1626 setOnlyReadsMemory(F, 1);
1628 case LibFunc::qsort:
1629 if (FTy->getNumParams() != 4 || !FTy->getParamType(3)->isPointerTy())
1631 // May throw; places call through function pointer.
1632 setDoesNotCapture(F, 4);
1634 case LibFunc::dunder_strdup:
1635 case LibFunc::dunder_strndup:
1636 if (FTy->getNumParams() < 1 || !FTy->getReturnType()->isPointerTy() ||
1637 !FTy->getParamType(0)->isPointerTy())
1640 setDoesNotAlias(F, 0);
1641 setDoesNotCapture(F, 1);
1642 setOnlyReadsMemory(F, 1);
1644 case LibFunc::dunder_strtok_r:
1645 if (FTy->getNumParams() != 3 || !FTy->getParamType(1)->isPointerTy())
1648 setDoesNotCapture(F, 2);
1649 setOnlyReadsMemory(F, 2);
1651 case LibFunc::under_IO_getc:
1652 if (FTy->getNumParams() != 1 || !FTy->getParamType(0)->isPointerTy())
1655 setDoesNotCapture(F, 1);
1657 case LibFunc::under_IO_putc:
1658 if (FTy->getNumParams() != 2 || !FTy->getParamType(1)->isPointerTy())
1661 setDoesNotCapture(F, 2);
1663 case LibFunc::dunder_isoc99_scanf:
1664 if (FTy->getNumParams() < 1 || !FTy->getParamType(0)->isPointerTy())
1667 setDoesNotCapture(F, 1);
1668 setOnlyReadsMemory(F, 1);
1670 case LibFunc::stat64:
1671 case LibFunc::lstat64:
1672 case LibFunc::statvfs64:
1673 if (FTy->getNumParams() < 1 || !FTy->getParamType(0)->isPointerTy() ||
1674 !FTy->getParamType(1)->isPointerTy())
1677 setDoesNotCapture(F, 1);
1678 setDoesNotCapture(F, 2);
1679 setOnlyReadsMemory(F, 1);
1681 case LibFunc::dunder_isoc99_sscanf:
1682 if (FTy->getNumParams() < 1 || !FTy->getParamType(0)->isPointerTy() ||
1683 !FTy->getParamType(1)->isPointerTy())
1686 setDoesNotCapture(F, 1);
1687 setDoesNotCapture(F, 2);
1688 setOnlyReadsMemory(F, 1);
1689 setOnlyReadsMemory(F, 2);
1691 case LibFunc::fopen64:
1692 if (FTy->getNumParams() != 2 || !FTy->getReturnType()->isPointerTy() ||
1693 !FTy->getParamType(0)->isPointerTy() ||
1694 !FTy->getParamType(1)->isPointerTy())
1697 setDoesNotAlias(F, 0);
1698 setDoesNotCapture(F, 1);
1699 setDoesNotCapture(F, 2);
1700 setOnlyReadsMemory(F, 1);
1701 setOnlyReadsMemory(F, 2);
1703 case LibFunc::fseeko64:
1704 case LibFunc::ftello64:
1705 if (FTy->getNumParams() == 0 || !FTy->getParamType(0)->isPointerTy())
1708 setDoesNotCapture(F, 1);
1710 case LibFunc::tmpfile64:
1711 if (!FTy->getReturnType()->isPointerTy())
1714 setDoesNotAlias(F, 0);
1716 case LibFunc::fstat64:
1717 case LibFunc::fstatvfs64:
1718 if (FTy->getNumParams() != 2 || !FTy->getParamType(1)->isPointerTy())
1721 setDoesNotCapture(F, 2);
1723 case LibFunc::open64:
1724 if (FTy->getNumParams() < 2 || !FTy->getParamType(0)->isPointerTy())
1726 // May throw; "open" is a valid pthread cancellation point.
1727 setDoesNotCapture(F, 1);
1728 setOnlyReadsMemory(F, 1);
1730 case LibFunc::gettimeofday:
1731 if (FTy->getNumParams() != 2 || !FTy->getParamType(0)->isPointerTy() ||
1732 !FTy->getParamType(1)->isPointerTy())
1734 // Currently some platforms have the restrict keyword on the arguments to
1735 // gettimeofday. To be conservative, do not add noalias to gettimeofday's
1738 setDoesNotCapture(F, 1);
1739 setDoesNotCapture(F, 2);
1742 // Didn't mark any attributes.
1749 bool FunctionAttrs::runOnSCC(CallGraphSCC &SCC) {
1750 TLI = &getAnalysis<TargetLibraryInfoWrapperPass>().getTLI();
1751 bool Changed = false;
1753 // We compute dedicated AA results for each function in the SCC as needed. We
1754 // use a lambda referencing external objects so that they live long enough to
1755 // be queried, but we re-use them each time.
1756 Optional<BasicAAResult> BAR;
1757 Optional<AAResults> AAR;
1758 auto AARGetter = [&](Function &F) -> AAResults & {
1759 BAR.emplace(createLegacyPMBasicAAResult(*this, F));
1760 AAR.emplace(createLegacyPMAAResults(*this, F, *BAR));
1764 // Fill SCCNodes with the elements of the SCC. Used for quickly looking up
1765 // whether a given CallGraphNode is in this SCC. Also track whether there are
1766 // any external or opt-none nodes that will prevent us from optimizing any
1768 SCCNodeSet SCCNodes;
1769 bool ExternalNode = false;
1770 for (CallGraphSCC::iterator I = SCC.begin(), E = SCC.end(); I != E; ++I) {
1771 Function *F = (*I)->getFunction();
1772 if (!F || F->hasFnAttribute(Attribute::OptimizeNone)) {
1773 // External node or function we're trying not to optimize - we both avoid
1774 // transform them and avoid leveraging information they provide.
1775 ExternalNode = true;
1779 // When initially processing functions, also infer their prototype
1780 // attributes if they are declarations.
1781 if (F->isDeclaration())
1782 Changed |= inferPrototypeAttributes(*F, *TLI);
1787 Changed |= addReadAttrs(SCCNodes, AARGetter);
1788 Changed |= addArgumentAttrs(SCCNodes);
1790 // If we have no external nodes participating in the SCC, we can infer some
1791 // more precise attributes as well.
1792 if (!ExternalNode) {
1793 Changed |= addNoAliasAttrs(SCCNodes);
1794 Changed |= addNonNullAttrs(SCCNodes, *TLI);