//
// The LLVM Compiler Infrastructure
//
-// This file was developed by the LLVM research group and is distributed under
-// the University of Illinois Open Source License. See LICENSE.TXT for details.
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
#include "llvm/Constants.h"
#include "llvm/DerivedTypes.h"
#include "llvm/Function.h"
-#include "llvm/ParameterAttributes.h"
#include "llvm/GlobalVariable.h"
#include "llvm/Instructions.h"
+#include "llvm/IntrinsicInst.h"
#include "llvm/Pass.h"
#include "llvm/Target/TargetData.h"
#include "llvm/ADT/SmallVector.h"
+#include "llvm/ADT/STLExtras.h"
#include "llvm/Support/Compiler.h"
#include "llvm/Support/GetElementPtrTypeIterator.h"
#include "llvm/Support/ManagedStatic.h"
#include <algorithm>
using namespace llvm;
+//===----------------------------------------------------------------------===//
+// Useful predicates
+//===----------------------------------------------------------------------===//
+
+// Determine if an AllocationInst instruction escapes from the function it is
+// contained in. If it does not escape, there is no way for another function to
+// mod/ref it. We do this by looking at its uses and determining if the uses
+// can escape (recursively).
+static bool AddressMightEscape(const Value *V) {
+ for (Value::use_const_iterator UI = V->use_begin(), E = V->use_end();
+ UI != E; ++UI) {
+ const Instruction *I = cast<Instruction>(*UI);
+ switch (I->getOpcode()) {
+ case Instruction::Load:
+ break; //next use.
+ case Instruction::Store:
+ if (I->getOperand(0) == V)
+ return true; // Escapes if the pointer is stored.
+ break; // next use.
+ case Instruction::GetElementPtr:
+ if (AddressMightEscape(I))
+ return true;
+ break; // next use.
+ case Instruction::BitCast:
+ if (AddressMightEscape(I))
+ return true;
+ break; // next use
+ case Instruction::Ret:
+ // If returned, the address will escape to calling functions, but no
+ // callees could modify it.
+ break; // next use
+ case Instruction::Call:
+ // If the call is to a few known safe intrinsics, we know that it does
+ // not escape.
+ // TODO: Eventually just check the 'nocapture' attribute.
+ if (!isa<MemIntrinsic>(I))
+ return true;
+ break; // next use
+ default:
+ return true;
+ }
+ }
+ return false;
+}
+
+static const User *isGEP(const Value *V) {
+ if (isa<GetElementPtrInst>(V) ||
+ (isa<ConstantExpr>(V) &&
+ cast<ConstantExpr>(V)->getOpcode() == Instruction::GetElementPtr))
+ return cast<User>(V);
+ return 0;
+}
+
+static const Value *GetGEPOperands(const Value *V,
+ SmallVector<Value*, 16> &GEPOps){
+ assert(GEPOps.empty() && "Expect empty list to populate!");
+ GEPOps.insert(GEPOps.end(), cast<User>(V)->op_begin()+1,
+ cast<User>(V)->op_end());
+
+ // Accumulate all of the chained indexes into the operand array
+ V = cast<User>(V)->getOperand(0);
+
+ while (const User *G = isGEP(V)) {
+ if (!isa<Constant>(GEPOps[0]) || isa<GlobalValue>(GEPOps[0]) ||
+ !cast<Constant>(GEPOps[0])->isNullValue())
+ break; // Don't handle folding arbitrary pointer offsets yet...
+ GEPOps.erase(GEPOps.begin()); // Drop the zero index
+ GEPOps.insert(GEPOps.begin(), G->op_begin()+1, G->op_end());
+ V = G->getOperand(0);
+ }
+ return V;
+}
+
+/// isNoAliasCall - Return true if this pointer is returned by a noalias
+/// function.
+static bool isNoAliasCall(const Value *V) {
+ if (isa<CallInst>(V) || isa<InvokeInst>(V))
+ return CallSite(const_cast<Instruction*>(cast<Instruction>(V)))
+ .paramHasAttr(0, Attribute::NoAlias);
+ return false;
+}
+
+/// isIdentifiedObject - Return true if this pointer refers to a distinct and
+/// identifiable object. This returns true for:
+/// Global Variables and Functions
+/// Allocas and Mallocs
+/// ByVal and NoAlias Arguments
+/// NoAlias returns
+///
+static bool isIdentifiedObject(const Value *V) {
+ if (isa<GlobalValue>(V) || isa<AllocationInst>(V) || isNoAliasCall(V))
+ return true;
+ if (const Argument *A = dyn_cast<Argument>(V))
+ return A->hasNoAliasAttr() || A->hasByValAttr();
+ return false;
+}
+
+/// isKnownNonNull - Return true if we know that the specified value is never
+/// null.
+static bool isKnownNonNull(const Value *V) {
+ // Alloca never returns null, malloc might.
+ if (isa<AllocaInst>(V)) return true;
+
+ // A byval argument is never null.
+ if (const Argument *A = dyn_cast<Argument>(V))
+ return A->hasByValAttr();
+
+ // Global values are not null unless extern weak.
+ if (const GlobalValue *GV = dyn_cast<GlobalValue>(V))
+ return !GV->hasExternalWeakLinkage();
+ return false;
+}
+
+/// isNonEscapingLocalObject - Return true if the pointer is to a function-local
+/// object that never escapes from the function.
+static bool isNonEscapingLocalObject(const Value *V) {
+ // If this is a local allocation, check to see if it escapes.
+ if (isa<AllocationInst>(V) || isNoAliasCall(V))
+ return !AddressMightEscape(V);
+
+ // If this is an argument that corresponds to a byval or noalias argument,
+ // it can't escape either.
+ if (const Argument *A = dyn_cast<Argument>(V))
+ if (A->hasByValAttr() || A->hasNoAliasAttr())
+ return !AddressMightEscape(V);
+ return false;
+}
+
+
+/// isObjectSmallerThan - Return true if we can prove that the object specified
+/// by V is smaller than Size.
+static bool isObjectSmallerThan(const Value *V, unsigned Size,
+ const TargetData &TD) {
+ const Type *AccessTy;
+ if (const GlobalVariable *GV = dyn_cast<GlobalVariable>(V)) {
+ AccessTy = GV->getType()->getElementType();
+ } else if (const AllocationInst *AI = dyn_cast<AllocationInst>(V)) {
+ if (!AI->isArrayAllocation())
+ AccessTy = AI->getType()->getElementType();
+ else
+ return false;
+ } else if (const Argument *A = dyn_cast<Argument>(V)) {
+ if (A->hasByValAttr())
+ AccessTy = cast<PointerType>(A->getType())->getElementType();
+ else
+ return false;
+ } else {
+ return false;
+ }
+
+ if (AccessTy->isSized())
+ return TD.getABITypeSize(AccessTy) < Size;
+ return false;
+}
+
+//===----------------------------------------------------------------------===//
+// NoAA Pass
+//===----------------------------------------------------------------------===//
+
namespace {
/// NoAA - This class implements the -no-aa pass, which always returns "I
/// don't know" for alias queries. NoAA is unlike other alias analysis
///
struct VISIBILITY_HIDDEN NoAA : public ImmutablePass, public AliasAnalysis {
static char ID; // Class identification, replacement for typeinfo
- NoAA() : ImmutablePass((intptr_t)&ID) {}
- explicit NoAA(intptr_t PID) : ImmutablePass(PID) { }
+ NoAA() : ImmutablePass(&ID) {}
+ explicit NoAA(void *PID) : ImmutablePass(PID) { }
virtual void getAnalysisUsage(AnalysisUsage &AU) const {
AU.addRequired<TargetData>();
virtual void deleteValue(Value *V) {}
virtual void copyValue(Value *From, Value *To) {}
};
+} // End of anonymous namespace
- // Register this pass...
- char NoAA::ID = 0;
- RegisterPass<NoAA>
- U("no-aa", "No Alias Analysis (always returns 'may' alias)");
+// Register this pass...
+char NoAA::ID = 0;
+static RegisterPass<NoAA>
+U("no-aa", "No Alias Analysis (always returns 'may' alias)", true, true);
- // Declare that we implement the AliasAnalysis interface
- RegisterAnalysisGroup<AliasAnalysis> V(U);
-} // End of anonymous namespace
+// Declare that we implement the AliasAnalysis interface
+static RegisterAnalysisGroup<AliasAnalysis> V(U);
ImmutablePass *llvm::createNoAAPass() { return new NoAA(); }
+//===----------------------------------------------------------------------===//
+// BasicAA Pass
+//===----------------------------------------------------------------------===//
+
namespace {
/// BasicAliasAnalysis - This is the default alias analysis implementation.
/// Because it doesn't chain to a previous alias analysis (like -no-aa), it
/// derives from the NoAA class.
struct VISIBILITY_HIDDEN BasicAliasAnalysis : public NoAA {
static char ID; // Class identification, replacement for typeinfo
- BasicAliasAnalysis() : NoAA((intptr_t)&ID) { }
+ BasicAliasAnalysis() : NoAA(&ID) {}
AliasResult alias(const Value *V1, unsigned V1Size,
const Value *V2, unsigned V2Size);
ModRefResult getModRefInfo(CallSite CS, Value *P, unsigned Size);
- ModRefResult getModRefInfo(CallSite CS1, CallSite CS2) {
- return NoAA::getModRefInfo(CS1,CS2);
- }
-
+ ModRefResult getModRefInfo(CallSite CS1, CallSite CS2);
+
/// hasNoModRefInfoForCalls - We can provide mod/ref information against
/// non-escaping allocations.
virtual bool hasNoModRefInfoForCalls() const { return false; }
/// global) or not.
bool pointsToConstantMemory(const Value *P);
- virtual ModRefBehavior getModRefBehavior(Function *F, CallSite CS,
- std::vector<PointerAccessInfo> *Info);
-
private:
// CheckGEPInstructions - Check two GEP instructions with known
// must-aliasing base pointers. This checks to see if the index expressions
const Type *BasePtr2Ty,
Value **GEP2Ops, unsigned NumGEP2Ops, unsigned G2Size);
};
+} // End of anonymous namespace
- // Register this pass...
- char BasicAliasAnalysis::ID = 0;
- RegisterPass<BasicAliasAnalysis>
- X("basicaa", "Basic Alias Analysis (default AA impl)");
+// Register this pass...
+char BasicAliasAnalysis::ID = 0;
+static RegisterPass<BasicAliasAnalysis>
+X("basicaa", "Basic Alias Analysis (default AA impl)", false, true);
- // Declare that we implement the AliasAnalysis interface
- RegisterAnalysisGroup<AliasAnalysis, true> Y(X);
-} // End of anonymous namespace
+// Declare that we implement the AliasAnalysis interface
+static RegisterAnalysisGroup<AliasAnalysis, true> Y(X);
ImmutablePass *llvm::createBasicAliasAnalysisPass() {
return new BasicAliasAnalysis();
}
-// getUnderlyingObject - This traverses the use chain to figure out what object
-// the specified value points to. If the value points to, or is derived from, a
-// unique object or an argument, return it.
-static const Value *getUnderlyingObject(const Value *V) {
- if (!isa<PointerType>(V->getType())) return 0;
-
- // If we are at some type of object, return it. GlobalValues and Allocations
- // have unique addresses.
- if (isa<GlobalValue>(V) || isa<AllocationInst>(V) || isa<Argument>(V))
- return V;
-
- // Traverse through different addressing mechanisms...
- if (const Instruction *I = dyn_cast<Instruction>(V)) {
- if (isa<BitCastInst>(I) || isa<GetElementPtrInst>(I))
- return getUnderlyingObject(I->getOperand(0));
- } else if (const ConstantExpr *CE = dyn_cast<ConstantExpr>(V)) {
- if (CE->getOpcode() == Instruction::BitCast ||
- CE->getOpcode() == Instruction::GetElementPtr)
- return getUnderlyingObject(CE->getOperand(0));
- }
- return 0;
-}
-
-static const User *isGEP(const Value *V) {
- if (isa<GetElementPtrInst>(V) ||
- (isa<ConstantExpr>(V) &&
- cast<ConstantExpr>(V)->getOpcode() == Instruction::GetElementPtr))
- return cast<User>(V);
- return 0;
-}
-
-static const Value *GetGEPOperands(const Value *V,
- SmallVector<Value*, 16> &GEPOps){
- assert(GEPOps.empty() && "Expect empty list to populate!");
- GEPOps.insert(GEPOps.end(), cast<User>(V)->op_begin()+1,
- cast<User>(V)->op_end());
-
- // Accumulate all of the chained indexes into the operand array
- V = cast<User>(V)->getOperand(0);
-
- while (const User *G = isGEP(V)) {
- if (!isa<Constant>(GEPOps[0]) || isa<GlobalValue>(GEPOps[0]) ||
- !cast<Constant>(GEPOps[0])->isNullValue())
- break; // Don't handle folding arbitrary pointer offsets yet...
- GEPOps.erase(GEPOps.begin()); // Drop the zero index
- GEPOps.insert(GEPOps.begin(), G->op_begin()+1, G->op_end());
- V = G->getOperand(0);
- }
- return V;
-}
/// pointsToConstantMemory - Chase pointers until we find a (constant
/// global) or not.
bool BasicAliasAnalysis::pointsToConstantMemory(const Value *P) {
- if (const Value *V = getUnderlyingObject(P))
- if (const GlobalVariable *GV = dyn_cast<GlobalVariable>(V))
- return GV->isConstant();
- return false;
-}
-
-// Determine if an AllocationInst instruction escapes from the function it is
-// contained in. If it does not escape, there is no way for another function to
-// mod/ref it. We do this by looking at its uses and determining if the uses
-// can escape (recursively).
-static bool AddressMightEscape(const Value *V) {
- for (Value::use_const_iterator UI = V->use_begin(), E = V->use_end();
- UI != E; ++UI) {
- const Instruction *I = cast<Instruction>(*UI);
- switch (I->getOpcode()) {
- case Instruction::Load:
- break; //next use.
- case Instruction::Store:
- if (I->getOperand(0) == V)
- return true; // Escapes if the pointer is stored.
- break; // next use.
- case Instruction::GetElementPtr:
- if (AddressMightEscape(I))
- return true;
- case Instruction::BitCast:
- if (!isa<PointerType>(I->getType()))
- return true;
- if (AddressMightEscape(I))
- return true;
- break; // next use
- case Instruction::Ret:
- // If returned, the address will escape to calling functions, but no
- // callees could modify it.
- break; // next use
- default:
- return true;
- }
- }
+ if (const GlobalVariable *GV =
+ dyn_cast<GlobalVariable>(P->getUnderlyingObject()))
+ return GV->isConstant();
return false;
}
//
AliasAnalysis::ModRefResult
BasicAliasAnalysis::getModRefInfo(CallSite CS, Value *P, unsigned Size) {
- if (!isa<Constant>(P))
- if (const AllocationInst *AI =
- dyn_cast_or_null<AllocationInst>(getUnderlyingObject(P))) {
- // Okay, the pointer is to a stack allocated object. If we can prove that
- // the pointer never "escapes", then we know the call cannot clobber it,
- // because it simply can't get its address.
- if (!AddressMightEscape(AI))
- return NoModRef;
-
- // If this is a tail call and P points to a stack location, we know that
- // the tail call cannot access or modify the local stack.
+ if (!isa<Constant>(P)) {
+ const Value *Object = P->getUnderlyingObject();
+
+ // If this is a tail call and P points to a stack location, we know that
+ // the tail call cannot access or modify the local stack.
+ // We cannot exclude byval arguments here; these belong to the caller of
+ // the current function not to the current function, and a tail callee
+ // may reference them.
+ if (isa<AllocaInst>(Object))
if (CallInst *CI = dyn_cast<CallInst>(CS.getInstruction()))
- if (CI->isTailCall() && isa<AllocaInst>(AI))
+ if (CI->isTailCall())
return NoModRef;
+
+ // If the pointer is to a locally allocated object that does not escape,
+ // then the call can not mod/ref the pointer unless the call takes the
+ // argument without capturing it.
+ if (isNonEscapingLocalObject(Object)) {
+ bool passedAsArg = false;
+ // TODO: Eventually only check 'nocapture' arguments.
+ for (CallSite::arg_iterator CI = CS.arg_begin(), CE = CS.arg_end();
+ CI != CE; ++CI)
+ if (isa<PointerType>((*CI)->getType()) &&
+ alias(cast<Value>(CI), ~0U, P, ~0U) != NoAlias)
+ passedAsArg = true;
+
+ if (!passedAsArg)
+ return NoModRef;
}
+ }
// The AliasAnalysis base class has some smarts, lets use them.
return AliasAnalysis::getModRefInfo(CS, P, Size);
}
-static bool isNoAliasArgument(const Argument *Arg) {
- const Function *Func = Arg->getParent();
- const ParamAttrsList *Attr = Func->getFunctionType()->getParamAttrs();
- if (Attr) {
- unsigned Idx = 1;
- for (Function::const_arg_iterator I = Func->arg_begin(),
- E = Func->arg_end(); I != E; ++I, ++Idx) {
- if (&(*I) == Arg &&
- Attr->paramHasAttr(Idx, ParamAttr::NoAlias))
- return true;
- }
- }
- return false;
+
+AliasAnalysis::ModRefResult
+BasicAliasAnalysis::getModRefInfo(CallSite CS1, CallSite CS2) {
+ // If CS1 or CS2 are readnone, they don't interact.
+ ModRefBehavior CS1B = AliasAnalysis::getModRefBehavior(CS1);
+ if (CS1B == DoesNotAccessMemory) return NoModRef;
+
+ ModRefBehavior CS2B = AliasAnalysis::getModRefBehavior(CS2);
+ if (CS2B == DoesNotAccessMemory) return NoModRef;
+
+ // If they both only read from memory, just return ref.
+ if (CS1B == OnlyReadsMemory && CS2B == OnlyReadsMemory)
+ return Ref;
+
+ // Otherwise, fall back to NoAA (mod+ref).
+ return NoAA::getModRefInfo(CS1, CS2);
}
+
// alias - Provide a bunch of ad-hoc rules to disambiguate in common cases, such
// as array references. Note that this function is heavily tail recursive.
// Hopefully we have a smart C++ compiler. :)
// Are we checking for alias of the same value?
if (V1 == V2) return MustAlias;
- if ((!isa<PointerType>(V1->getType()) || !isa<PointerType>(V2->getType())) &&
- V1->getType() != Type::Int64Ty && V2->getType() != Type::Int64Ty)
+ if (!isa<PointerType>(V1->getType()) || !isa<PointerType>(V2->getType()))
return NoAlias; // Scalars cannot alias each other
// Strip off cast instructions...
return alias(V1, V1Size, I->getOperand(0), V2Size);
// Figure out what objects these things are pointing to if we can...
- const Value *O1 = getUnderlyingObject(V1);
- const Value *O2 = getUnderlyingObject(V2);
-
- // Pointing at a discernible object?
- if (O1) {
- if (O2) {
- if (isa<Argument>(O1)) {
- // Incoming argument cannot alias locally allocated object!
- if (isa<AllocationInst>(O2)) return NoAlias;
-
- // If they are two different objects, and one is a noalias argument
- // then they do not alias.
- if (O1 != O2 && isNoAliasArgument(cast<Argument>(O1)))
- return NoAlias;
-
- // Otherwise, nothing is known...
- }
-
- if (isa<Argument>(O2)) {
- // Incoming argument cannot alias locally allocated object!
- if (isa<AllocationInst>(O1)) return NoAlias;
-
- // If they are two different objects, and one is a noalias argument
- // then they do not alias.
- if (O1 != O2 && isNoAliasArgument(cast<Argument>(O2)))
- return NoAlias;
-
- // Otherwise, nothing is known...
- } else if (O1 != O2) {
- // If they are two different objects, we know that we have no alias...
- return NoAlias;
- }
+ const Value *O1 = V1->getUnderlyingObject();
+ const Value *O2 = V2->getUnderlyingObject();
- // If they are the same object, they we can look at the indexes. If they
- // index off of the object is the same for both pointers, they must alias.
- // If they are provably different, they must not alias. Otherwise, we
- // can't tell anything.
- }
-
-
- if (!isa<Argument>(O1) && isa<ConstantPointerNull>(V2))
- return NoAlias; // Unique values don't alias null
-
- if (isa<GlobalVariable>(O1) ||
- (isa<AllocationInst>(O1) &&
- !cast<AllocationInst>(O1)->isArrayAllocation()))
- if (cast<PointerType>(O1->getType())->getElementType()->isSized()) {
- // If the size of the other access is larger than the total size of the
- // global/alloca/malloc, it cannot be accessing the global (it's
- // undefined to load or store bytes before or after an object).
- const Type *ElTy = cast<PointerType>(O1->getType())->getElementType();
- unsigned GlobalSize = getTargetData().getTypeSize(ElTy);
- if (GlobalSize < V2Size && V2Size != ~0U)
- return NoAlias;
- }
- }
+ if (O1 != O2) {
+ // If V1/V2 point to two different objects we know that we have no alias.
+ if (isIdentifiedObject(O1) && isIdentifiedObject(O2))
+ return NoAlias;
+
+ // Arguments can't alias with local allocations or noalias calls.
+ if ((isa<Argument>(O1) && (isa<AllocationInst>(O2) || isNoAliasCall(O2))) ||
+ (isa<Argument>(O2) && (isa<AllocationInst>(O1) || isNoAliasCall(O1))))
+ return NoAlias;
- if (O2) {
- if (!isa<Argument>(O2) && isa<ConstantPointerNull>(V1))
- return NoAlias; // Unique values don't alias null
-
- if (isa<GlobalVariable>(O2) ||
- (isa<AllocationInst>(O2) &&
- !cast<AllocationInst>(O2)->isArrayAllocation()))
- if (cast<PointerType>(O2->getType())->getElementType()->isSized()) {
- // If the size of the other access is larger than the total size of the
- // global/alloca/malloc, it cannot be accessing the object (it's
- // undefined to load or store bytes before or after an object).
- const Type *ElTy = cast<PointerType>(O2->getType())->getElementType();
- unsigned GlobalSize = getTargetData().getTypeSize(ElTy);
- if (GlobalSize < V1Size && V1Size != ~0U)
- return NoAlias;
- }
+ // Most objects can't alias null.
+ if ((isa<ConstantPointerNull>(V2) && isKnownNonNull(O1)) ||
+ (isa<ConstantPointerNull>(V1) && isKnownNonNull(O2)))
+ return NoAlias;
}
-
+
+ // If the size of one access is larger than the entire object on the other
+ // side, then we know such behavior is undefined and can assume no alias.
+ const TargetData &TD = getTargetData();
+ if ((V1Size != ~0U && isObjectSmallerThan(O2, V1Size, TD)) ||
+ (V2Size != ~0U && isObjectSmallerThan(O1, V2Size, TD)))
+ return NoAlias;
+
+ // If one pointer is the result of a call/invoke and the other is a
+ // non-escaping local object, then we know the object couldn't escape to a
+ // point where the call could return it.
+ if ((isa<CallInst>(O1) || isa<InvokeInst>(O1)) &&
+ isNonEscapingLocalObject(O2))
+ return NoAlias;
+ if ((isa<CallInst>(O2) || isa<InvokeInst>(O2)) &&
+ isNonEscapingLocalObject(O1))
+ return NoAlias;
+
// If we have two gep instructions with must-alias'ing base pointers, figure
// out if the indexes to the GEP tell us anything about the derived pointer.
// Note that we also handle chains of getelementptr instructions as well as
if (isGEP(V1) && isGEP(V2)) {
// Drill down into the first non-gep value, to test for must-aliasing of
// the base pointers.
- const Value *BasePtr1 = V1, *BasePtr2 = V2;
- do {
- BasePtr1 = cast<User>(BasePtr1)->getOperand(0);
- } while (isGEP(BasePtr1) &&
- cast<User>(BasePtr1)->getOperand(1) ==
- Constant::getNullValue(cast<User>(BasePtr1)->getOperand(1)->getType()));
- do {
- BasePtr2 = cast<User>(BasePtr2)->getOperand(0);
- } while (isGEP(BasePtr2) &&
- cast<User>(BasePtr2)->getOperand(1) ==
- Constant::getNullValue(cast<User>(BasePtr2)->getOperand(1)->getType()));
+ const User *G = cast<User>(V1);
+ while (isGEP(G->getOperand(0)) &&
+ G->getOperand(1) ==
+ Constant::getNullValue(G->getOperand(1)->getType()))
+ G = cast<User>(G->getOperand(0));
+ const Value *BasePtr1 = G->getOperand(0);
+
+ G = cast<User>(V2);
+ while (isGEP(G->getOperand(0)) &&
+ G->getOperand(1) ==
+ Constant::getNullValue(G->getOperand(1)->getType()))
+ G = cast<User>(G->getOperand(0));
+ const Value *BasePtr2 = G->getOperand(0);
// Do the base pointers alias?
AliasResult BaseAlias = alias(BasePtr1, ~0U, BasePtr2, ~0U);
return MayAlias;
}
-// This function is used to determin if the indices of two GEP instructions are
+// This function is used to determine if the indices of two GEP instructions are
// equal. V1 and V2 are the indices.
static bool IndexOperandsEqual(Value *V1, Value *V2) {
if (V1->getType() == V2->getType())
if (isa<ConstantInt>(GEP1Ops[i]) &&
!cast<ConstantInt>(GEP1Ops[i])->isZero()) {
// Yup, there's a constant in the tail. Set all variables to
- // constants in the GEP instruction to make it suiteable for
+ // constants in the GEP instruction to make it suitable for
// TargetData::getIndexedOffset.
for (i = 0; i != MaxOperands; ++i)
if (!isa<ConstantInt>(GEP1Ops[i]))
int64_t Offset2 = TD.getIndexedOffset(GEPPointerTy, GEP1Ops,
MinOperands);
+ // Make sure we compare the absolute difference.
+ if (Offset1 > Offset2)
+ std::swap(Offset1, Offset2);
+
// If the tail provided a bit enough offset, return noalias!
if ((uint64_t)(Offset2-Offset1) >= SizeMax)
return NoAlias;
+ // Otherwise break - we don't look for another constant in the tail.
+ break;
}
}
if (const ArrayType *AT = dyn_cast<ArrayType>(BasePtr1Ty)) {
if (Op1C->getZExtValue() >= AT->getNumElements())
return MayAlias; // Be conservative with out-of-range accesses
- } else if (const VectorType *PT = dyn_cast<VectorType>(BasePtr1Ty)) {
- if (Op1C->getZExtValue() >= PT->getNumElements())
+ } else if (const VectorType *VT = dyn_cast<VectorType>(BasePtr1Ty)) {
+ if (Op1C->getZExtValue() >= VT->getNumElements())
return MayAlias; // Be conservative with out-of-range accesses
}
//
if (const ArrayType *AT = dyn_cast<ArrayType>(BasePtr1Ty))
GEP1Ops[i] = ConstantInt::get(Type::Int64Ty,AT->getNumElements()-1);
- else if (const VectorType *PT = dyn_cast<VectorType>(BasePtr1Ty))
- GEP1Ops[i] = ConstantInt::get(Type::Int64Ty,PT->getNumElements()-1);
-
+ else if (const VectorType *VT = dyn_cast<VectorType>(BasePtr1Ty))
+ GEP1Ops[i] = ConstantInt::get(Type::Int64Ty,VT->getNumElements()-1);
}
}
if (Op2) {
if (const ConstantInt *Op2C = dyn_cast<ConstantInt>(Op2)) {
// If this is an array index, make sure the array element is in range.
- if (const ArrayType *AT = dyn_cast<ArrayType>(BasePtr1Ty)) {
+ if (const ArrayType *AT = dyn_cast<ArrayType>(BasePtr2Ty)) {
if (Op2C->getZExtValue() >= AT->getNumElements())
return MayAlias; // Be conservative with out-of-range accesses
- } else if (const VectorType *PT = dyn_cast<VectorType>(BasePtr1Ty)) {
- if (Op2C->getZExtValue() >= PT->getNumElements())
+ } else if (const VectorType *VT = dyn_cast<VectorType>(BasePtr2Ty)) {
+ if (Op2C->getZExtValue() >= VT->getNumElements())
return MayAlias; // Be conservative with out-of-range accesses
}
} else { // Conservatively assume the minimum value for this index
getTargetData().getIndexedOffset(GEPPointerTy, GEP1Ops, NumGEP1Ops);
int64_t Offset2 =
getTargetData().getIndexedOffset(GEPPointerTy, GEP2Ops, NumGEP2Ops);
- assert(Offset1<Offset2 && "There is at least one different constant here!");
-
+ assert(Offset1 != Offset2 &&
+ "There is at least one different constant here!");
+
+ // Make sure we compare the absolute difference.
+ if (Offset1 > Offset2)
+ std::swap(Offset1, Offset2);
+
if ((uint64_t)(Offset2-Offset1) >= SizeMax) {
//cerr << "Determined that these two GEP's don't alias ["
// << SizeMax << " bytes]: \n" << *GEP1 << *GEP2;
return MayAlias;
}
-namespace {
- struct VISIBILITY_HIDDEN StringCompare {
- bool operator()(const char *LHS, const char *RHS) {
- return strcmp(LHS, RHS) < 0;
- }
- };
-}
-
-// Note that this list cannot contain libm functions (such as acos and sqrt)
-// that set errno on a domain or other error.
-static const char *DoesntAccessMemoryFns[] = {
- "abs", "labs", "llabs", "imaxabs", "fabs", "fabsf", "fabsl",
- "trunc", "truncf", "truncl", "ldexp",
-
- "atan", "atanf", "atanl", "atan2", "atan2f", "atan2l",
- "cbrt",
- "cos", "cosf", "cosl",
- "exp", "expf", "expl",
- "hypot",
- "sin", "sinf", "sinl",
- "tan", "tanf", "tanl", "tanh", "tanhf", "tanhl",
-
- "floor", "floorf", "floorl", "ceil", "ceilf", "ceill",
-
- // ctype.h
- "isalnum", "isalpha", "iscntrl", "isdigit", "isgraph", "islower", "isprint"
- "ispunct", "isspace", "isupper", "isxdigit", "tolower", "toupper",
-
- // wctype.h"
- "iswalnum", "iswalpha", "iswcntrl", "iswdigit", "iswgraph", "iswlower",
- "iswprint", "iswpunct", "iswspace", "iswupper", "iswxdigit",
-
- "iswctype", "towctrans", "towlower", "towupper",
-
- "btowc", "wctob",
-
- "isinf", "isnan", "finite",
-
- // C99 math functions
- "copysign", "copysignf", "copysignd",
- "nexttoward", "nexttowardf", "nexttowardd",
- "nextafter", "nextafterf", "nextafterd",
-
- // ISO C99:
- "__signbit", "__signbitf", "__signbitl",
-};
-
-
-static const char *OnlyReadsMemoryFns[] = {
- "atoi", "atol", "atof", "atoll", "atoq", "a64l",
- "bcmp", "memcmp", "memchr", "memrchr", "wmemcmp", "wmemchr",
-
- // Strings
- "strcmp", "strcasecmp", "strcoll", "strncmp", "strncasecmp",
- "strchr", "strcspn", "strlen", "strpbrk", "strrchr", "strspn", "strstr",
- "index", "rindex",
-
- // Wide char strings
- "wcschr", "wcscmp", "wcscoll", "wcscspn", "wcslen", "wcsncmp", "wcspbrk",
- "wcsrchr", "wcsspn", "wcsstr",
-
- // glibc
- "alphasort", "alphasort64", "versionsort", "versionsort64",
-
- // C99
- "nan", "nanf", "nand",
-
- // File I/O
- "feof", "ferror", "fileno",
- "feof_unlocked", "ferror_unlocked", "fileno_unlocked"
-};
-
-static ManagedStatic<std::vector<const char*> > NoMemoryTable;
-static ManagedStatic<std::vector<const char*> > OnlyReadsMemoryTable;
-
-
-AliasAnalysis::ModRefBehavior
-BasicAliasAnalysis::getModRefBehavior(Function *F, CallSite CS,
- std::vector<PointerAccessInfo> *Info) {
- if (!F->isDeclaration()) return UnknownModRefBehavior;
-
- static bool Initialized = false;
- if (!Initialized) {
- NoMemoryTable->insert(NoMemoryTable->end(),
- DoesntAccessMemoryFns,
- DoesntAccessMemoryFns+
- sizeof(DoesntAccessMemoryFns)/sizeof(DoesntAccessMemoryFns[0]));
-
- OnlyReadsMemoryTable->insert(OnlyReadsMemoryTable->end(),
- OnlyReadsMemoryFns,
- OnlyReadsMemoryFns+
- sizeof(OnlyReadsMemoryFns)/sizeof(OnlyReadsMemoryFns[0]));
-#define GET_MODREF_BEHAVIOR
-#include "llvm/Intrinsics.gen"
-#undef GET_MODREF_BEHAVIOR
-
- // Sort the table the first time through.
- std::sort(NoMemoryTable->begin(), NoMemoryTable->end(), StringCompare());
- std::sort(OnlyReadsMemoryTable->begin(), OnlyReadsMemoryTable->end(),
- StringCompare());
- Initialized = true;
- }
-
- std::vector<const char*>::iterator Ptr =
- std::lower_bound(NoMemoryTable->begin(), NoMemoryTable->end(),
- F->getName().c_str(), StringCompare());
- if (Ptr != NoMemoryTable->end() && *Ptr == F->getName())
- return DoesNotAccessMemory;
-
- Ptr = std::lower_bound(OnlyReadsMemoryTable->begin(),
- OnlyReadsMemoryTable->end(),
- F->getName().c_str(), StringCompare());
- if (Ptr != OnlyReadsMemoryTable->end() && *Ptr == F->getName())
- return OnlyReadsMemory;
-
- return UnknownModRefBehavior;
-}
-
// Make sure that anything that uses AliasAnalysis pulls in this file...
DEFINING_FILE_FOR(BasicAliasAnalysis)
projects / oota-llvm.git / blobdiff