initializeFunctionAttrsPass(*PassRegistry::getPassRegistry());
}
- // runOnSCC - Analyze the SCC, performing the transformation if possible.
bool runOnSCC(CallGraphSCC &SCC) override;
- // AddReadAttrs - Deduce readonly/readnone attributes for the SCC.
- bool AddReadAttrs(const CallGraphSCC &SCC);
-
- // AddArgumentAttrs - Deduce nocapture attributes for the SCC.
- bool AddArgumentAttrs(const CallGraphSCC &SCC);
-
- // IsFunctionMallocLike - Does this function allocate new memory?
- bool IsFunctionMallocLike(Function *F, SmallPtrSet<Function *, 8> &) const;
-
- // AddNoAliasAttrs - Deduce noalias attributes for the SCC.
- bool AddNoAliasAttrs(const CallGraphSCC &SCC);
-
- /// \brief Does this function return null?
- bool ReturnsNonNull(Function *F, SmallPtrSet<Function *, 8> &,
- bool &Speculative) const;
-
- /// \brief Deduce nonnull attributes for the SCC.
- bool AddNonNullAttrs(const CallGraphSCC &SCC);
-
- // Utility methods used by inferPrototypeAttributes to add attributes
- // and maintain annotation statistics.
-
- void setDoesNotAccessMemory(Function &F) {
- if (!F.doesNotAccessMemory()) {
- F.setDoesNotAccessMemory();
- ++NumAnnotated;
- }
- }
-
- void setOnlyReadsMemory(Function &F) {
- if (!F.onlyReadsMemory()) {
- F.setOnlyReadsMemory();
- ++NumAnnotated;
- }
- }
-
- void setDoesNotThrow(Function &F) {
- if (!F.doesNotThrow()) {
- F.setDoesNotThrow();
- ++NumAnnotated;
- }
- }
-
- void setDoesNotCapture(Function &F, unsigned n) {
- if (!F.doesNotCapture(n)) {
- F.setDoesNotCapture(n);
- ++NumAnnotated;
- }
- }
-
- void setOnlyReadsMemory(Function &F, unsigned n) {
- if (!F.onlyReadsMemory(n)) {
- F.setOnlyReadsMemory(n);
- ++NumAnnotated;
- }
- }
-
- void setDoesNotAlias(Function &F, unsigned n) {
- if (!F.doesNotAlias(n)) {
- F.setDoesNotAlias(n);
- ++NumAnnotated;
- }
- }
-
- // inferPrototypeAttributes - Analyze the name and prototype of the
- // given function and set any applicable attributes. Returns true
- // if any attributes were set and false otherwise.
- bool inferPrototypeAttributes(Function &F);
-
- // annotateLibraryCalls - Adds attributes to well-known standard library
- // call declarations.
- bool annotateLibraryCalls(const CallGraphSCC &SCC);
-
void getAnalysisUsage(AnalysisUsage &AU) const override {
AU.setPreservesCFG();
AU.addRequired<AssumptionCacheTracker>();
private:
TargetLibraryInfo *TLI;
+
+ bool AddReadAttrs(const CallGraphSCC &SCC);
+ bool AddArgumentAttrs(const CallGraphSCC &SCC);
+ bool AddNoAliasAttrs(const CallGraphSCC &SCC);
+ bool AddNonNullAttrs(const CallGraphSCC &SCC);
+ bool annotateLibraryCalls(const CallGraphSCC &SCC);
};
}
Pass *llvm::createFunctionAttrsPass() { return new FunctionAttrs(); }
-/// AddReadAttrs - Deduce readonly/readnone attributes for the SCC.
+namespace {
+/// The three kinds of memory access relevant to 'readonly' and
+/// 'readnone' attributes.
+enum MemoryAccessKind {
+ MAK_ReadNone = 0,
+ MAK_ReadOnly = 1,
+ MAK_MayWrite = 2
+};
+}
+
+static MemoryAccessKind
+checkFunctionMemoryAccess(Function &F, AAResults &AAR,
+ const SmallPtrSetImpl<Function *> &SCCNodes) {
+ FunctionModRefBehavior MRB = AAR.getModRefBehavior(&F);
+ if (MRB == FMRB_DoesNotAccessMemory)
+ // Already perfect!
+ return MAK_ReadNone;
+
+ // Definitions with weak linkage may be overridden at linktime with
+ // something that writes memory, so treat them like declarations.
+ if (F.isDeclaration() || F.mayBeOverridden()) {
+ if (AliasAnalysis::onlyReadsMemory(MRB))
+ return MAK_ReadOnly;
+
+ // Conservatively assume it writes to memory.
+ return MAK_MayWrite;
+ }
+
+ // Scan the function body for instructions that may read or write memory.
+ bool ReadsMemory = false;
+ for (inst_iterator II = inst_begin(F), E = inst_end(F); II != E; ++II) {
+ Instruction *I = &*II;
+
+ // Some instructions can be ignored even if they read or write memory.
+ // Detect these now, skipping to the next instruction if one is found.
+ CallSite CS(cast<Value>(I));
+ if (CS) {
+ // Ignore calls to functions in the same SCC.
+ if (CS.getCalledFunction() && SCCNodes.count(CS.getCalledFunction()))
+ continue;
+ FunctionModRefBehavior MRB = AAR.getModRefBehavior(CS);
+
+ // If the call doesn't access memory, we're done.
+ if (!(MRB & MRI_ModRef))
+ continue;
+
+ if (!AliasAnalysis::onlyAccessesArgPointees(MRB)) {
+ // The call could access any memory. If that includes writes, give up.
+ if (MRB & MRI_Mod)
+ return MAK_MayWrite;
+ // If it reads, note it.
+ if (MRB & MRI_Ref)
+ ReadsMemory = true;
+ continue;
+ }
+
+ // Check whether all pointer arguments point to local memory, and
+ // ignore calls that only access local memory.
+ for (CallSite::arg_iterator CI = CS.arg_begin(), CE = CS.arg_end();
+ CI != CE; ++CI) {
+ Value *Arg = *CI;
+ if (!Arg->getType()->isPointerTy())
+ continue;
+
+ AAMDNodes AAInfo;
+ I->getAAMetadata(AAInfo);
+ MemoryLocation Loc(Arg, MemoryLocation::UnknownSize, AAInfo);
+
+ // Skip accesses to local or constant memory as they don't impact the
+ // externally visible mod/ref behavior.
+ if (AAR.pointsToConstantMemory(Loc, /*OrLocal=*/true))
+ continue;
+
+ if (MRB & MRI_Mod)
+ // Writes non-local memory. Give up.
+ return MAK_MayWrite;
+ if (MRB & MRI_Ref)
+ // Ok, it reads non-local memory.
+ ReadsMemory = true;
+ }
+ continue;
+ } else if (LoadInst *LI = dyn_cast<LoadInst>(I)) {
+ // Ignore non-volatile loads from local memory. (Atomic is okay here.)
+ if (!LI->isVolatile()) {
+ MemoryLocation Loc = MemoryLocation::get(LI);
+ if (AAR.pointsToConstantMemory(Loc, /*OrLocal=*/true))
+ continue;
+ }
+ } else if (StoreInst *SI = dyn_cast<StoreInst>(I)) {
+ // Ignore non-volatile stores to local memory. (Atomic is okay here.)
+ if (!SI->isVolatile()) {
+ MemoryLocation Loc = MemoryLocation::get(SI);
+ if (AAR.pointsToConstantMemory(Loc, /*OrLocal=*/true))
+ continue;
+ }
+ } else if (VAArgInst *VI = dyn_cast<VAArgInst>(I)) {
+ // Ignore vaargs on local memory.
+ MemoryLocation Loc = MemoryLocation::get(VI);
+ if (AAR.pointsToConstantMemory(Loc, /*OrLocal=*/true))
+ continue;
+ }
+
+ // Any remaining instructions need to be taken seriously! Check if they
+ // read or write memory.
+ if (I->mayWriteToMemory())
+ // Writes memory. Just give up.
+ return MAK_MayWrite;
+
+ // If this instruction may read memory, remember that.
+ ReadsMemory |= I->mayReadFromMemory();
+ }
+
+ return ReadsMemory ? MAK_ReadOnly : MAK_ReadNone;
+}
+
+/// Deduce readonly/readnone attributes for the SCC.
bool FunctionAttrs::AddReadAttrs(const CallGraphSCC &SCC) {
SmallPtrSet<Function *, 8> SCCNodes;
// work around the limitations of the legacy pass manager.
AAResults AAR(createLegacyPMAAResults(*this, *F, BAR));
- FunctionModRefBehavior MRB = AAR.getModRefBehavior(F);
- if (MRB == FMRB_DoesNotAccessMemory)
- // Already perfect!
- continue;
-
- // Definitions with weak linkage may be overridden at linktime with
- // something that writes memory, so treat them like declarations.
- if (F->isDeclaration() || F->mayBeOverridden()) {
- if (!AliasAnalysis::onlyReadsMemory(MRB))
- // May write memory. Just give up.
- return false;
-
+ switch (checkFunctionMemoryAccess(*F, AAR, SCCNodes)) {
+ case MAK_MayWrite:
+ return false;
+ case MAK_ReadOnly:
ReadsMemory = true;
- continue;
- }
-
- // Scan the function body for instructions that may read or write memory.
- for (inst_iterator II = inst_begin(F), E = inst_end(F); II != E; ++II) {
- Instruction *I = &*II;
-
- // Some instructions can be ignored even if they read or write memory.
- // Detect these now, skipping to the next instruction if one is found.
- CallSite CS(cast<Value>(I));
- if (CS) {
- // Ignore calls to functions in the same SCC.
- if (CS.getCalledFunction() && SCCNodes.count(CS.getCalledFunction()))
- continue;
- FunctionModRefBehavior MRB = AAR.getModRefBehavior(CS);
- // If the call doesn't access arbitrary memory, we may be able to
- // figure out something.
- if (AliasAnalysis::onlyAccessesArgPointees(MRB)) {
- // If the call does access argument pointees, check each argument.
- if (AliasAnalysis::doesAccessArgPointees(MRB))
- // Check whether all pointer arguments point to local memory, and
- // ignore calls that only access local memory.
- for (CallSite::arg_iterator CI = CS.arg_begin(), CE = CS.arg_end();
- CI != CE; ++CI) {
- Value *Arg = *CI;
- if (Arg->getType()->isPointerTy()) {
- AAMDNodes AAInfo;
- I->getAAMetadata(AAInfo);
-
- MemoryLocation Loc(Arg, MemoryLocation::UnknownSize, AAInfo);
- if (!AAR.pointsToConstantMemory(Loc, /*OrLocal=*/true)) {
- if (MRB & MRI_Mod)
- // Writes non-local memory. Give up.
- return false;
- if (MRB & MRI_Ref)
- // Ok, it reads non-local memory.
- ReadsMemory = true;
- }
- }
- }
- continue;
- }
- // The call could access any memory. If that includes writes, give up.
- if (MRB & MRI_Mod)
- return false;
- // If it reads, note it.
- if (MRB & MRI_Ref)
- ReadsMemory = true;
- continue;
- } else if (LoadInst *LI = dyn_cast<LoadInst>(I)) {
- // Ignore non-volatile loads from local memory. (Atomic is okay here.)
- if (!LI->isVolatile()) {
- MemoryLocation Loc = MemoryLocation::get(LI);
- if (AAR.pointsToConstantMemory(Loc, /*OrLocal=*/true))
- continue;
- }
- } else if (StoreInst *SI = dyn_cast<StoreInst>(I)) {
- // Ignore non-volatile stores to local memory. (Atomic is okay here.)
- if (!SI->isVolatile()) {
- MemoryLocation Loc = MemoryLocation::get(SI);
- if (AAR.pointsToConstantMemory(Loc, /*OrLocal=*/true))
- continue;
- }
- } else if (VAArgInst *VI = dyn_cast<VAArgInst>(I)) {
- // Ignore vaargs on local memory.
- MemoryLocation Loc = MemoryLocation::get(VI);
- if (AAR.pointsToConstantMemory(Loc, /*OrLocal=*/true))
- continue;
- }
-
- // Any remaining instructions need to be taken seriously! Check if they
- // read or write memory.
- if (I->mayWriteToMemory())
- // Writes memory. Just give up.
- return false;
-
- // If this instruction may read memory, remember that.
- ReadsMemory |= I->mayReadFromMemory();
+ break;
+ case MAK_ReadNone:
+ // Nothing to do!
+ break;
}
}
}
namespace {
-// For a given pointer Argument, this retains a list of Arguments of functions
-// in the same SCC that the pointer data flows into. We use this to build an
-// SCC of the arguments.
+/// For a given pointer Argument, this retains a list of Arguments of functions
+/// in the same SCC that the pointer data flows into. We use this to build an
+/// SCC of the arguments.
struct ArgumentGraphNode {
Argument *Definition;
SmallVector<ArgumentGraphNode *, 4> Uses;
}
};
-// This tracker checks whether callees are in the SCC, and if so it does not
-// consider that a capture, instead adding it to the "Uses" list and
-// continuing with the analysis.
+/// This tracker checks whether callees are in the SCC, and if so it does not
+/// consider that a capture, instead adding it to the "Uses" list and
+/// continuing with the analysis.
struct ArgumentUsesTracker : public CaptureTracker {
ArgumentUsesTracker(const SmallPtrSet<Function *, 8> &SCCNodes)
: Captured(false), SCCNodes(SCCNodes) {}
return true;
}
if (PI == U) {
- Uses.push_back(AI);
+ Uses.push_back(&*AI);
Found = true;
break;
}
};
}
-// Returns Attribute::None, Attribute::ReadOnly or Attribute::ReadNone.
+/// Returns Attribute::None, Attribute::ReadOnly or Attribute::ReadNone.
static Attribute::AttrKind
determinePointerReadAttrs(Argument *A,
const SmallPtrSet<Argument *, 8> &SCCNodes) {
return Attribute::None;
}
Captures &= !CS.doesNotCapture(A - B);
- if (SCCNodes.count(AI))
+ if (SCCNodes.count(&*AI))
continue;
if (!CS.onlyReadsMemory() && !CS.onlyReadsMemory(A - B))
return Attribute::None;
return IsRead ? Attribute::ReadOnly : Attribute::ReadNone;
}
-/// AddArgumentAttrs - Deduce nocapture attributes for the SCC.
+/// Deduce nocapture attributes for the SCC.
bool FunctionAttrs::AddArgumentAttrs(const CallGraphSCC &SCC) {
bool Changed = false;
bool HasNonLocalUses = false;
if (!A->hasNoCaptureAttr()) {
ArgumentUsesTracker Tracker(SCCNodes);
- PointerMayBeCaptured(A, &Tracker);
+ PointerMayBeCaptured(&*A, &Tracker);
if (!Tracker.Captured) {
if (Tracker.Uses.empty()) {
// If it's trivially not captured, mark it nocapture now.
// If it's not trivially captured and not trivially not captured,
// then it must be calling into another function in our SCC. Save
// its particulars for Argument-SCC analysis later.
- ArgumentGraphNode *Node = AG[A];
+ ArgumentGraphNode *Node = AG[&*A];
for (SmallVectorImpl<Argument *>::iterator
UI = Tracker.Uses.begin(),
UE = Tracker.Uses.end();
// will be dependent on the iteration order through the functions in the
// SCC.
SmallPtrSet<Argument *, 8> Self;
- Self.insert(A);
- Attribute::AttrKind R = determinePointerReadAttrs(A, Self);
+ Self.insert(&*A);
+ Attribute::AttrKind R = determinePointerReadAttrs(&*A, Self);
if (R != Attribute::None) {
AttrBuilder B;
B.addAttribute(R);
return Changed;
}
-/// IsFunctionMallocLike - A function is malloc-like if it returns either null
-/// or a pointer that doesn't alias any other pointer visible to the caller.
-bool FunctionAttrs::IsFunctionMallocLike(
- Function *F, SmallPtrSet<Function *, 8> &SCCNodes) const {
+/// Tests whether a function is "malloc-like".
+///
+/// A function is "malloc-like" if it returns either null or a pointer that
+/// doesn't alias any other pointer visible to the caller.
+static bool isFunctionMallocLike(Function *F,
+ SmallPtrSet<Function *, 8> &SCCNodes) {
SmallSetVector<Value *, 8> FlowsToReturn;
for (Function::iterator I = F->begin(), E = F->end(); I != E; ++I)
if (ReturnInst *Ret = dyn_cast<ReturnInst>(I->getTerminator()))
return true;
}
-/// AddNoAliasAttrs - Deduce noalias attributes for the SCC.
+/// Deduce noalias attributes for the SCC.
bool FunctionAttrs::AddNoAliasAttrs(const CallGraphSCC &SCC) {
SmallPtrSet<Function *, 8> SCCNodes;
if (!F->getReturnType()->isPointerTy())
continue;
- if (!IsFunctionMallocLike(F, SCCNodes))
+ if (!isFunctionMallocLike(F, SCCNodes))
return false;
}
return MadeChange;
}
-bool FunctionAttrs::ReturnsNonNull(Function *F,
- SmallPtrSet<Function *, 8> &SCCNodes,
- bool &Speculative) const {
+/// Tests whether this function is known to not return null.
+///
+/// Requires that the function returns a pointer.
+///
+/// Returns true if it believes the function will not return a null, and sets
+/// \p Speculative based on whether the returned conclusion is a speculative
+/// conclusion due to SCC calls.
+static bool isReturnNonNull(Function *F, SmallPtrSet<Function *, 8> &SCCNodes,
+ const TargetLibraryInfo &TLI, bool &Speculative) {
assert(F->getReturnType()->isPointerTy() &&
"nonnull only meaningful on pointer types");
Speculative = false;
Value *RetVal = FlowsToReturn[i];
// If this value is locally known to be non-null, we're good
- if (isKnownNonNull(RetVal, TLI))
+ if (isKnownNonNull(RetVal, &TLI))
continue;
// Otherwise, we need to look upwards since we can't make any local
return true;
}
+/// Deduce nonnull attributes for the SCC.
bool FunctionAttrs::AddNonNullAttrs(const CallGraphSCC &SCC) {
SmallPtrSet<Function *, 8> SCCNodes;
continue;
bool Speculative = false;
- if (ReturnsNonNull(F, SCCNodes, Speculative)) {
+ if (isReturnNonNull(F, SCCNodes, *TLI, Speculative)) {
if (!Speculative) {
// Mark the function eagerly since we may discover a function
// which prevents us from speculating about the entire SCC
return MadeChange;
}
-/// inferPrototypeAttributes - Analyze the name and prototype of the
-/// given function and set any applicable attributes. Returns true
-/// if any attributes were set and false otherwise.
-bool FunctionAttrs::inferPrototypeAttributes(Function &F) {
+static void setDoesNotAccessMemory(Function &F) {
+ if (!F.doesNotAccessMemory()) {
+ F.setDoesNotAccessMemory();
+ ++NumAnnotated;
+ }
+}
+
+static void setOnlyReadsMemory(Function &F) {
+ if (!F.onlyReadsMemory()) {
+ F.setOnlyReadsMemory();
+ ++NumAnnotated;
+ }
+}
+
+static void setDoesNotThrow(Function &F) {
+ if (!F.doesNotThrow()) {
+ F.setDoesNotThrow();
+ ++NumAnnotated;
+ }
+}
+
+static void setDoesNotCapture(Function &F, unsigned n) {
+ if (!F.doesNotCapture(n)) {
+ F.setDoesNotCapture(n);
+ ++NumAnnotated;
+ }
+}
+
+static void setOnlyReadsMemory(Function &F, unsigned n) {
+ if (!F.onlyReadsMemory(n)) {
+ F.setOnlyReadsMemory(n);
+ ++NumAnnotated;
+ }
+}
+
+static void setDoesNotAlias(Function &F, unsigned n) {
+ if (!F.doesNotAlias(n)) {
+ F.setDoesNotAlias(n);
+ ++NumAnnotated;
+ }
+}
+
+/// Analyze the name and prototype of the given function and set any applicable
+/// attributes.
+///
+/// Returns true if any attributes were set and false otherwise.
+static bool inferPrototypeAttributes(Function &F, const TargetLibraryInfo &TLI) {
if (F.hasFnAttribute(Attribute::OptimizeNone))
return false;
FunctionType *FTy = F.getFunctionType();
LibFunc::Func TheLibFunc;
- if (!(TLI->getLibFunc(F.getName(), TheLibFunc) && TLI->has(TheLibFunc)))
+ if (!(TLI.getLibFunc(F.getName(), TheLibFunc) && TLI.has(TheLibFunc)))
return false;
switch (TheLibFunc) {
return true;
}
-/// annotateLibraryCalls - Adds attributes to well-known standard library
-/// call declarations.
+/// Adds attributes to well-known standard library call declarations.
bool FunctionAttrs::annotateLibraryCalls(const CallGraphSCC &SCC) {
bool MadeChange = false;
Function *F = (*I)->getFunction();
if (F && F->isDeclaration())
- MadeChange |= inferPrototypeAttributes(*F);
+ MadeChange |= inferPrototypeAttributes(*F, *TLI);
}
return MadeChange;
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