#include "llvm/ADT/SetVector.h"
#include "llvm/ADT/SmallSet.h"
#include "llvm/ADT/Statistic.h"
+#include "llvm/ADT/StringSwitch.h"
#include "llvm/Analysis/AliasAnalysis.h"
#include "llvm/Analysis/AssumptionCache.h"
#include "llvm/Analysis/BasicAliasAnalysis.h"
STATISTIC(NumNoAlias, "Number of function returns marked noalias");
STATISTIC(NumNonNullReturn, "Number of function returns marked nonnull");
STATISTIC(NumAnnotated, "Number of attributes added to library functions");
+STATISTIC(NumNoRecurse, "Number of functions marked as norecurse");
+
+static cl::list<std::string>
+ForceAttributes("force-attribute", cl::Hidden,
+ cl::desc("Add an attribute to a function. This should be a "
+ "pair of 'function-name:attribute-name', for "
+ "example -force-add-attribute=foo:noinline. This "
+ "option can be specified multiple times."));
+
+namespace {
+typedef SmallSetVector<Function *, 8> SCCNodeSet;
+}
namespace {
struct FunctionAttrs : public CallGraphSCCPass {
}
bool runOnSCC(CallGraphSCC &SCC) override;
-
+ bool doInitialization(CallGraph &CG) override {
+ Revisit.clear();
+ return false;
+ }
+ bool doFinalization(CallGraph &CG) override;
+
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 IsFunctionMallocLike(Function *F, SmallPtrSet<Function *, 8> &) const;
- bool AddNoAliasAttrs(const CallGraphSCC &SCC);
- bool ReturnsNonNull(Function *F, SmallPtrSet<Function *, 8> &,
- bool &Speculative) const;
- bool AddNonNullAttrs(const CallGraphSCC &SCC);
- bool inferPrototypeAttributes(Function &F);
- bool annotateLibraryCalls(const CallGraphSCC &SCC);
+ SmallVector<WeakVH,16> Revisit;
};
}
Pass *llvm::createFunctionAttrsPass() { return new FunctionAttrs(); }
-/// Deduce readonly/readnone attributes for the SCC.
-bool FunctionAttrs::AddReadAttrs(const CallGraphSCC &SCC) {
- SmallPtrSet<Function *, 8> SCCNodes;
+namespace {
+/// The three kinds of memory access relevant to 'readonly' and
+/// 'readnone' attributes.
+enum MemoryAccessKind {
+ MAK_ReadNone = 0,
+ MAK_ReadOnly = 1,
+ MAK_MayWrite = 2
+};
+}
- // Fill SCCNodes with the elements of the SCC. Used for quickly
- // looking up whether a given CallGraphNode is in this SCC.
- for (CallGraphSCC::iterator I = SCC.begin(), E = SCC.end(); I != E; ++I)
- SCCNodes.insert((*I)->getFunction());
+static MemoryAccessKind checkFunctionMemoryAccess(Function &F, AAResults &AAR,
+ const SCCNodeSet &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;
+ }
- // Check if any of the functions in the SCC read or write memory. If they
- // write memory then they can't be marked readnone or readonly.
+ // Scan the function body for instructions that may read or write memory.
bool ReadsMemory = false;
- for (CallGraphSCC::iterator I = SCC.begin(), E = SCC.end(); I != E; ++I) {
- Function *F = (*I)->getFunction();
-
- if (!F || F->hasFnAttribute(Attribute::OptimizeNone))
- // External node or node we don't want to optimize - assume it may write
- // memory and give up.
- return false;
-
- // We need to manually construct BasicAA directly in order to disable its
- // use of other function analyses.
- BasicAAResult BAR(createLegacyPMBasicAAResult(*this, *F));
-
- // Construct our own AA results for this function. We do this manually to
- // work around the limitations of the legacy pass manager.
- AAResults AAR(createLegacyPMAAResults(*this, *F, BAR));
+ 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);
- FunctionModRefBehavior MRB = AAR.getModRefBehavior(F);
- if (MRB == FMRB_DoesNotAccessMemory)
- // Already perfect!
- continue;
+ // If the call doesn't access memory, we're done.
+ if (!(MRB & MRI_ModRef))
+ 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;
+ 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;
+ }
- 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()->isPtrOrPtrVectorTy())
+ 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;
+ AAMDNodes AAInfo;
+ I->getAAMetadata(AAInfo);
+ MemoryLocation Loc(Arg, MemoryLocation::UnknownSize, AAInfo);
- // 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;
- }
- }
- }
+ // 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;
- }
- // The call could access any memory. If that includes writes, give up.
+
if (MRB & MRI_Mod)
- return false;
- // If it reads, note it.
+ // 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);
+ }
+ 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;
+ // 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.
+template <typename AARGetterT>
+static bool addReadAttrs(const SCCNodeSet &SCCNodes, AARGetterT AARGetter) {
+ // Check if any of the functions in the SCC read or write memory. If they
+ // write memory then they can't be marked readnone or readonly.
+ bool ReadsMemory = false;
+ for (Function *F : SCCNodes) {
+ // Call the callable parameter to look up AA results for this function.
+ AAResults &AAR = AARGetter(*F);
- // If this instruction may read memory, remember that.
- ReadsMemory |= I->mayReadFromMemory();
+ switch (checkFunctionMemoryAccess(*F, AAR, SCCNodes)) {
+ case MAK_MayWrite:
+ return false;
+ case MAK_ReadOnly:
+ ReadsMemory = true;
+ break;
+ case MAK_ReadNone:
+ // Nothing to do!
+ break;
}
}
// Success! Functions in this SCC do not access memory, or only read memory.
// Give them the appropriate attribute.
bool MadeChange = false;
- for (CallGraphSCC::iterator I = SCC.begin(), E = SCC.end(); I != E; ++I) {
- Function *F = (*I)->getFunction();
-
+ for (Function *F : SCCNodes) {
if (F->doesNotAccessMemory())
// Already perfect!
continue;
/// 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)
+ ArgumentUsesTracker(const SCCNodeSet &SCCNodes)
: Captured(false), SCCNodes(SCCNodes) {}
void tooManyUses() override { Captured = true; }
}
Function *F = CS.getCalledFunction();
- if (!F || !SCCNodes.count(F)) {
+ if (!F || F->isDeclaration() || F->mayBeOverridden() ||
+ !SCCNodes.count(F)) {
Captured = true;
return true;
}
- bool Found = false;
- Function::arg_iterator AI = F->arg_begin(), AE = F->arg_end();
- for (CallSite::arg_iterator PI = CS.arg_begin(), PE = CS.arg_end();
- PI != PE; ++PI, ++AI) {
- if (AI == AE) {
- assert(F->isVarArg() && "More params than args in non-varargs call");
- Captured = true;
- return true;
- }
- if (PI == U) {
- Uses.push_back(AI);
- Found = true;
- break;
- }
+ // Note: the callee and the two successor blocks *follow* the argument
+ // operands. This means there is no need to adjust UseIndex to account for
+ // these.
+
+ unsigned UseIndex =
+ std::distance(const_cast<const Use *>(CS.arg_begin()), U);
+
+ assert(UseIndex < CS.data_operands_size() &&
+ "Indirect function calls should have been filtered above!");
+
+ if (UseIndex >= CS.getNumArgOperands()) {
+ // Data operand, but not a argument operand -- must be a bundle operand
+ assert(CS.hasOperandBundles() && "Must be!");
+
+ // CaptureTracking told us that we're being captured by an operand bundle
+ // use. In this case it does not matter if the callee is within our SCC
+ // or not -- we've been captured in some unknown way, and we have to be
+ // conservative.
+ Captured = true;
+ return true;
+ }
+
+ if (UseIndex >= F->arg_size()) {
+ assert(F->isVarArg() && "More params than args in non-varargs call");
+ Captured = true;
+ return true;
}
- assert(Found && "Capturing call-site captured nothing?");
- (void)Found;
+
+ Uses.push_back(&*std::next(F->arg_begin(), UseIndex));
return false;
}
bool Captured; // True only if certainly captured (used outside our SCC).
SmallVector<Argument *, 4> Uses; // Uses within our SCC.
- const SmallPtrSet<Function *, 8> &SCCNodes;
+ const SCCNodeSet &SCCNodes;
};
}
while (!Worklist.empty()) {
Use *U = Worklist.pop_back_val();
Instruction *I = cast<Instruction>(U->getUser());
- Value *V = U->get();
switch (I->getOpcode()) {
case Instruction::BitCast:
return Attribute::None;
}
- Function::arg_iterator AI = F->arg_begin(), AE = F->arg_end();
- CallSite::arg_iterator B = CS.arg_begin(), E = CS.arg_end();
- for (CallSite::arg_iterator A = B; A != E; ++A, ++AI) {
- if (A->get() == V) {
- if (AI == AE) {
- assert(F->isVarArg() &&
- "More params than args in non-varargs call.");
- return Attribute::None;
- }
- Captures &= !CS.doesNotCapture(A - B);
- if (SCCNodes.count(AI))
- continue;
- if (!CS.onlyReadsMemory() && !CS.onlyReadsMemory(A - B))
- return Attribute::None;
- if (!CS.doesNotAccessMemory(A - B))
- IsRead = true;
- }
+ // Note: the callee and the two successor blocks *follow* the argument
+ // operands. This means there is no need to adjust UseIndex to account
+ // for these.
+
+ unsigned UseIndex = std::distance(CS.arg_begin(), U);
+
+ // U cannot be the callee operand use: since we're exploring the
+ // transitive uses of an Argument, having such a use be a callee would
+ // imply the CallSite is an indirect call or invoke; and we'd take the
+ // early exit above.
+ assert(UseIndex < CS.data_operands_size() &&
+ "Data operand use expected!");
+
+ bool IsOperandBundleUse = UseIndex >= CS.getNumArgOperands();
+
+ if (UseIndex >= F->arg_size() && !IsOperandBundleUse) {
+ assert(F->isVarArg() && "More params than args in non-varargs call");
+ return Attribute::None;
+ }
+
+ Captures &= !CS.doesNotCapture(UseIndex);
+
+ // Since the optimizer (by design) cannot see the data flow corresponding
+ // to a operand bundle use, these cannot participate in the optimistic SCC
+ // analysis. Instead, we model the operand bundle uses as arguments in
+ // call to a function external to the SCC.
+ if (!SCCNodes.count(&*std::next(F->arg_begin(), UseIndex)) ||
+ IsOperandBundleUse) {
+
+ // The accessors used on CallSite here do the right thing for calls and
+ // invokes with operand bundles.
+
+ if (!CS.onlyReadsMemory() && !CS.onlyReadsMemory(UseIndex))
+ return Attribute::None;
+ if (!CS.doesNotAccessMemory(UseIndex))
+ IsRead = true;
}
+
AddUsersToWorklistIfCapturing();
break;
}
}
/// Deduce nocapture attributes for the SCC.
-bool FunctionAttrs::AddArgumentAttrs(const CallGraphSCC &SCC) {
+static bool addArgumentAttrs(const SCCNodeSet &SCCNodes) {
bool Changed = false;
- SmallPtrSet<Function *, 8> SCCNodes;
-
- // Fill SCCNodes with the elements of the SCC. Used for quickly
- // looking up whether a given CallGraphNode is in this SCC.
- for (CallGraphSCC::iterator I = SCC.begin(), E = SCC.end(); I != E; ++I) {
- Function *F = (*I)->getFunction();
- if (F && !F->isDeclaration() && !F->mayBeOverridden() &&
- !F->hasFnAttribute(Attribute::OptimizeNone))
- SCCNodes.insert(F);
- }
-
ArgumentGraph AG;
AttrBuilder B;
// Check each function in turn, determining which pointer arguments are not
// captured.
- for (CallGraphSCC::iterator I = SCC.begin(), E = SCC.end(); I != E; ++I) {
- Function *F = (*I)->getFunction();
-
- if (!F || F->hasFnAttribute(Attribute::OptimizeNone))
- // External node or function we're trying not to optimize - only a problem
- // for arguments that we pass to it.
- continue;
-
+ for (Function *F : SCCNodes) {
// Definitions with weak linkage may be overridden at linktime with
// something that captures pointers, so treat them like declarations.
if (F->isDeclaration() || F->mayBeOverridden())
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);
///
/// 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 {
+static bool isFunctionMallocLike(Function *F, const SCCNodeSet &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()))
}
/// Deduce noalias attributes for the SCC.
-bool FunctionAttrs::AddNoAliasAttrs(const CallGraphSCC &SCC) {
- SmallPtrSet<Function *, 8> SCCNodes;
-
- // Fill SCCNodes with the elements of the SCC. Used for quickly
- // looking up whether a given CallGraphNode is in this SCC.
- for (CallGraphSCC::iterator I = SCC.begin(), E = SCC.end(); I != E; ++I)
- SCCNodes.insert((*I)->getFunction());
-
+static bool addNoAliasAttrs(const SCCNodeSet &SCCNodes) {
// Check each function in turn, determining which functions return noalias
// pointers.
- for (CallGraphSCC::iterator I = SCC.begin(), E = SCC.end(); I != E; ++I) {
- Function *F = (*I)->getFunction();
-
- if (!F || F->hasFnAttribute(Attribute::OptimizeNone))
- // External node or node we don't want to optimize - skip it;
- return false;
-
+ for (Function *F : SCCNodes) {
// Already noalias.
if (F->doesNotAlias(0))
continue;
if (!F->getReturnType()->isPointerTy())
continue;
- if (!IsFunctionMallocLike(F, SCCNodes))
+ if (!isFunctionMallocLike(F, SCCNodes))
return false;
}
bool MadeChange = false;
- for (CallGraphSCC::iterator I = SCC.begin(), E = SCC.end(); I != E; ++I) {
- Function *F = (*I)->getFunction();
+ for (Function *F : SCCNodes) {
if (F->doesNotAlias(0) || !F->getReturnType()->isPointerTy())
continue;
}
/// Tests whether this function is known to not return null.
-bool FunctionAttrs::ReturnsNonNull(Function *F,
- SmallPtrSet<Function *, 8> &SCCNodes,
- bool &Speculative) const {
+///
+/// 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, const SCCNodeSet &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
}
/// Deduce nonnull attributes for the SCC.
-bool FunctionAttrs::AddNonNullAttrs(const CallGraphSCC &SCC) {
- SmallPtrSet<Function *, 8> SCCNodes;
-
- // Fill SCCNodes with the elements of the SCC. Used for quickly
- // looking up whether a given CallGraphNode is in this SCC.
- for (CallGraphSCC::iterator I = SCC.begin(), E = SCC.end(); I != E; ++I)
- SCCNodes.insert((*I)->getFunction());
-
+static bool addNonNullAttrs(const SCCNodeSet &SCCNodes,
+ const TargetLibraryInfo &TLI) {
// Speculative that all functions in the SCC return only nonnull
// pointers. We may refute this as we analyze functions.
bool SCCReturnsNonNull = true;
// Check each function in turn, determining which functions return nonnull
// pointers.
- for (CallGraphSCC::iterator I = SCC.begin(), E = SCC.end(); I != E; ++I) {
- Function *F = (*I)->getFunction();
-
- if (!F || F->hasFnAttribute(Attribute::OptimizeNone))
- // External node or node we don't want to optimize - skip it;
- return false;
-
+ for (Function *F : SCCNodes) {
// Already nonnull.
if (F->getAttributes().hasAttribute(AttributeSet::ReturnIndex,
Attribute::NonNull))
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
}
if (SCCReturnsNonNull) {
- for (CallGraphSCC::iterator I = SCC.begin(), E = SCC.end(); I != E; ++I) {
- Function *F = (*I)->getFunction();
+ for (Function *F : SCCNodes) {
if (F->getAttributes().hasAttribute(AttributeSet::ReturnIndex,
Attribute::NonNull) ||
!F->getReturnType()->isPointerTy())
}
}
+static bool setDoesNotRecurse(Function &F) {
+ if (F.doesNotRecurse())
+ return false;
+ F.setDoesNotRecurse();
+ ++NumNoRecurse;
+ return true;
+}
+
/// 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 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;
}
-/// Adds attributes to well-known standard library call declarations.
-bool FunctionAttrs::annotateLibraryCalls(const CallGraphSCC &SCC) {
- bool MadeChange = false;
+static bool addNoRecurseAttrs(const CallGraphSCC &SCC,
+ SmallVectorImpl<WeakVH> &Revisit) {
+ // Try and identify functions that do not recurse.
- // Check each function in turn annotating well-known library function
- // declarations with attributes.
- for (CallGraphSCC::iterator I = SCC.begin(), E = SCC.end(); I != E; ++I) {
- Function *F = (*I)->getFunction();
+ // If the SCC contains multiple nodes we know for sure there is recursion.
+ if (!SCC.isSingular())
+ return false;
+
+ const CallGraphNode *CGN = *SCC.begin();
+ Function *F = CGN->getFunction();
+ if (!F || F->isDeclaration() || F->doesNotRecurse())
+ return false;
+
+ // If all of the calls in F are identifiable and are to norecurse functions, F
+ // is norecurse. This check also detects self-recursion as F is not currently
+ // marked norecurse, so any called from F to F will not be marked norecurse.
+ if (std::all_of(CGN->begin(), CGN->end(),
+ [](const CallGraphNode::CallRecord &CR) {
+ Function *F = CR.second->getFunction();
+ return F && F->doesNotRecurse();
+ }))
+ // Function calls a potentially recursive function.
+ return setDoesNotRecurse(*F);
+
+ // We know that F is not obviously recursive, but we haven't been able to
+ // prove that it doesn't actually recurse. Add it to the Revisit list to try
+ // again top-down later.
+ Revisit.push_back(F);
+ return false;
+}
- if (F && F->isDeclaration())
- MadeChange |= inferPrototypeAttributes(*F);
+static bool addNoRecurseAttrsTopDownOnly(Function *F) {
+ // If F is internal and all uses are in norecurse functions, then F is also
+ // norecurse.
+ if (F->doesNotRecurse())
+ return false;
+ if (F->hasInternalLinkage()) {
+ for (auto *U : F->users())
+ if (auto *I = dyn_cast<Instruction>(U)) {
+ if (!I->getParent()->getParent()->doesNotRecurse())
+ return false;
+ } else {
+ return false;
+ }
+ return setDoesNotRecurse(*F);
}
+ return false;
+}
- return MadeChange;
+static Attribute::AttrKind parseAttrKind(StringRef Kind) {
+ return StringSwitch<Attribute::AttrKind>(Kind)
+ .Case("alwaysinline", Attribute::AlwaysInline)
+ .Case("builtin", Attribute::Builtin)
+ .Case("cold", Attribute::Cold)
+ .Case("convergent", Attribute::Convergent)
+ .Case("inlinehint", Attribute::InlineHint)
+ .Case("jumptable", Attribute::JumpTable)
+ .Case("minsize", Attribute::MinSize)
+ .Case("naked", Attribute::Naked)
+ .Case("nobuiltin", Attribute::NoBuiltin)
+ .Case("noduplicate", Attribute::NoDuplicate)
+ .Case("noimplicitfloat", Attribute::NoImplicitFloat)
+ .Case("noinline", Attribute::NoInline)
+ .Case("nonlazybind", Attribute::NonLazyBind)
+ .Case("noredzone", Attribute::NoRedZone)
+ .Case("noreturn", Attribute::NoReturn)
+ .Case("norecurse", Attribute::NoRecurse)
+ .Case("nounwind", Attribute::NoUnwind)
+ .Case("optnone", Attribute::OptimizeNone)
+ .Case("optsize", Attribute::OptimizeForSize)
+ .Case("readnone", Attribute::ReadNone)
+ .Case("readonly", Attribute::ReadOnly)
+ .Case("argmemonly", Attribute::ArgMemOnly)
+ .Case("returns_twice", Attribute::ReturnsTwice)
+ .Case("safestack", Attribute::SafeStack)
+ .Case("sanitize_address", Attribute::SanitizeAddress)
+ .Case("sanitize_memory", Attribute::SanitizeMemory)
+ .Case("sanitize_thread", Attribute::SanitizeThread)
+ .Case("ssp", Attribute::StackProtect)
+ .Case("sspreq", Attribute::StackProtectReq)
+ .Case("sspstrong", Attribute::StackProtectStrong)
+ .Case("uwtable", Attribute::UWTable)
+ .Default(Attribute::None);
+}
+
+/// If F has any forced attributes given on the command line, add them.
+static bool addForcedAttributes(Function *F) {
+ bool Changed = false;
+ for (auto &S : ForceAttributes) {
+ auto KV = StringRef(S).split(':');
+ if (KV.first != F->getName())
+ continue;
+
+ auto Kind = parseAttrKind(KV.second);
+ if (Kind == Attribute::None) {
+ DEBUG(dbgs() << "ForcedAttribute: " << KV.second
+ << " unknown or not handled!\n");
+ continue;
+ }
+ if (F->hasFnAttribute(Kind))
+ continue;
+ Changed = true;
+ F->addFnAttr(Kind);
+ }
+ return Changed;
}
bool FunctionAttrs::runOnSCC(CallGraphSCC &SCC) {
TLI = &getAnalysis<TargetLibraryInfoWrapperPass>().getTLI();
+ bool Changed = false;
- bool Changed = annotateLibraryCalls(SCC);
- Changed |= AddReadAttrs(SCC);
- Changed |= AddArgumentAttrs(SCC);
- Changed |= AddNoAliasAttrs(SCC);
- Changed |= AddNonNullAttrs(SCC);
+ // We compute dedicated AA results for each function in the SCC as needed. We
+ // use a lambda referencing external objects so that they live long enough to
+ // be queried, but we re-use them each time.
+ Optional<BasicAAResult> BAR;
+ Optional<AAResults> AAR;
+ auto AARGetter = [&](Function &F) -> AAResults & {
+ BAR.emplace(createLegacyPMBasicAAResult(*this, F));
+ AAR.emplace(createLegacyPMAAResults(*this, F, *BAR));
+ return *AAR;
+ };
+
+ // Fill SCCNodes with the elements of the SCC. Used for quickly looking up
+ // whether a given CallGraphNode is in this SCC. Also track whether there are
+ // any external or opt-none nodes that will prevent us from optimizing any
+ // part of the SCC.
+ SCCNodeSet SCCNodes;
+ bool ExternalNode = false;
+ for (CallGraphSCC::iterator I = SCC.begin(), E = SCC.end(); I != E; ++I) {
+ Function *F = (*I)->getFunction();
+ if (!F || F->hasFnAttribute(Attribute::OptimizeNone)) {
+ // External node or function we're trying not to optimize - we both avoid
+ // transform them and avoid leveraging information they provide.
+ ExternalNode = true;
+ continue;
+ }
+
+ // When initially processing functions, also infer their prototype
+ // attributes if they are declarations.
+ if (F->isDeclaration())
+ Changed |= inferPrototypeAttributes(*F, *TLI);
+
+ Changed |= addForcedAttributes(F);
+ SCCNodes.insert(F);
+ }
+
+ Changed |= addReadAttrs(SCCNodes, AARGetter);
+ Changed |= addArgumentAttrs(SCCNodes);
+
+ // If we have no external nodes participating in the SCC, we can infer some
+ // more precise attributes as well.
+ if (!ExternalNode) {
+ Changed |= addNoAliasAttrs(SCCNodes);
+ Changed |= addNonNullAttrs(SCCNodes, *TLI);
+ }
+
+ Changed |= addNoRecurseAttrs(SCC, Revisit);
+ return Changed;
+}
+
+bool FunctionAttrs::doFinalization(CallGraph &CG) {
+ bool Changed = false;
+ // When iterating over SCCs we visit functions in a bottom-up fashion. Some of
+ // the rules we have for identifying norecurse functions work best with a
+ // top-down walk, so look again at all the functions we previously marked as
+ // worth revisiting, in top-down order.
+ for (auto &F : reverse(Revisit))
+ if (F)
+ Changed |= addNoRecurseAttrsTopDownOnly(cast<Function>((Value*)F));
return Changed;
}
projects / oota-llvm.git / blobdiff