//===----------------------------------------------------------------------===//
#include "llvm/Analysis/AliasAnalysis.h"
+#include "llvm/Analysis/CaptureTracking.h"
#include "llvm/Analysis/Passes.h"
#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/LLVMContext.h"
+#include "llvm/Operator.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/ErrorHandling.h"
#include "llvm/Support/GetElementPtrTypeIterator.h"
-#include "llvm/Support/ManagedStatic.h"
#include <algorithm>
using namespace llvm;
+//===----------------------------------------------------------------------===//
+// Useful predicates
+//===----------------------------------------------------------------------===//
+
+static const GEPOperator *isGEP(const Value *V) {
+ return dyn_cast<GEPOperator>(V);
+}
+
+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;
+}
+
+/// 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 !PointerMayBeCaptured(V, false);
+
+ // If this is an argument that corresponds to a byval or noalias argument,
+ // then it has not escaped before entering the function. Check if it escapes
+ // inside the function.
+ if (const Argument *A = dyn_cast<Argument>(V))
+ if (A->hasByValAttr() || A->hasNoAliasAttr()) {
+ // Don't bother analyzing arguments already known not to escape.
+ if (A->hasNoCaptureAttr())
+ return true;
+ return !PointerMayBeCaptured(V, false);
+ }
+ 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.getTypeAllocSize(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 initializePass() {
- TD = &getAnalysis<TargetData>();
+ TD = getAnalysisIfAvailable<TargetData>();
}
virtual AliasResult alias(const Value *V1, unsigned V1Size,
return MayAlias;
}
- virtual ModRefBehavior getModRefBehavior(Function *F, CallSite CS,
- std::vector<PointerAccessInfo> *Info) {
- return UnknownModRefBehavior;
- }
-
virtual void getArgumentAccesses(Function *F, CallSite CS,
std::vector<PointerAccessInfo> &Info) {
- assert(0 && "This method may not be called on this function!");
+ llvm_unreachable("This method may not be called on this function!");
}
virtual void getMustAliases(Value *P, std::vector<Value*> &RetVals) { }
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.
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. This returns:
-/// Arguments, GlobalVariables, Functions, Allocas, Mallocs.
-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();
+ if (const GlobalVariable *GV =
+ dyn_cast<GlobalVariable>(P->getUnderlyingObject()))
+ 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;
- 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
- if (!isa<MemIntrinsic>(I))
- return true;
- break; // next use
- default:
- return true;
- }
- }
- return false;
-}
// getModRefInfo - Check to see if the specified callsite can clobber the
// specified memory object. Since we only look at local properties of this
AliasAnalysis::ModRefResult
BasicAliasAnalysis::getModRefInfo(CallSite CS, Value *P, unsigned Size) {
if (!isa<Constant>(P)) {
- const Value *Object = getUnderlyingObject(P);
- // Allocations and byval arguments are "new" objects.
- if (Object &&
- (isa<AllocationInst>(Object) ||
- (isa<Argument>(Object) &&
- (cast<Argument>(Object)->hasByValAttr() ||
- cast<Argument>(Object)->hasNoAliasAttr())))) {
- // Okay, the pointer is to a stack allocated (or effectively so, for
- // for noalias parameters) 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(Object))
- 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.
+ 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<MallocInst>(Object))
+ 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) && CS.getInstruction() != 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;
}
}
return AliasAnalysis::getModRefInfo(CS, P, Size);
}
+
+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. :)
+// as array references.
//
AliasAnalysis::AliasResult
BasicAliasAnalysis::alias(const Value *V1, unsigned V1Size,
const Value *V2, unsigned V2Size) {
- // Strip off any constant expression casts if they exist
- if (const ConstantExpr *CE = dyn_cast<ConstantExpr>(V1))
- if (CE->isCast() && isa<PointerType>(CE->getOperand(0)->getType()))
- V1 = CE->getOperand(0);
- if (const ConstantExpr *CE = dyn_cast<ConstantExpr>(V2))
- if (CE->isCast() && isa<PointerType>(CE->getOperand(0)->getType()))
- V2 = CE->getOperand(0);
+ // Strip off any casts if they exist.
+ V1 = V1->stripPointerCasts();
+ V2 = V2->stripPointerCasts();
// 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...
- if (const BitCastInst *I = dyn_cast<BitCastInst>(V1))
- return alias(I->getOperand(0), V1Size, V2, V2Size);
- if (const BitCastInst *I = dyn_cast<BitCastInst>(V2))
- 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 (const Argument *O1Arg = dyn_cast<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 && O1Arg->hasNoAliasAttr())
- return NoAlias;
-
- // Byval arguments can't alias globals or other arguments.
- if (O1 != O2 && O1Arg->hasByValAttr()) return NoAlias;
-
- // Otherwise, nothing is known...
- }
-
- if (const Argument *O2Arg = dyn_cast<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 && O2Arg->hasNoAliasAttr())
- return NoAlias;
-
- // Byval arguments can't alias globals or other arguments.
- if (O1 != O2 && O2Arg->hasByValAttr()) return NoAlias;
-
- // Otherwise, nothing is known...
-
- } else if (O1 != O2 && !isa<Argument>(O1)) {
- // If they are two different objects, and neither is an argument,
- // we know that we have no alias.
- return NoAlias;
- }
-
- // 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.
- }
+ // Figure out what objects these things are pointing to if we can.
+ const Value *O1 = V1->getUnderlyingObject();
+ const Value *O2 = V2->getUnderlyingObject();
- // Unique values don't alias null, except non-byval arguments.
- if (isa<ConstantPointerNull>(V2)) {
- if (const Argument *O1Arg = dyn_cast<Argument>(O1)) {
- if (O1Arg->hasByValAttr())
- return NoAlias;
- } else {
- return NoAlias;
- }
- }
-
- 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().getABITypeSize(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().getABITypeSize(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.
+ if (TD)
+ 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) && O1 != O2)
+ return NoAlias;
+ if ((isa<CallInst>(O2) || isa<InvokeInst>(O2)) &&
+ isNonEscapingLocalObject(O1) && O1 != O2)
+ 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
// constant expression getelementptrs here.
//
if (isGEP(V1) && isGEP(V2)) {
+ const User *GEP1 = cast<User>(V1);
+ const User *GEP2 = cast<User>(V2);
+
+ // If V1 and V2 are identical GEPs, just recurse down on both of them.
+ // This allows us to analyze things like:
+ // P = gep A, 0, i, 1
+ // Q = gep B, 0, i, 1
+ // by just analyzing A and B. This is even safe for variable indices.
+ if (GEP1->getType() == GEP2->getType() &&
+ GEP1->getNumOperands() == GEP2->getNumOperands() &&
+ GEP1->getOperand(0)->getType() == GEP2->getOperand(0)->getType() &&
+ // All operands are the same, ignoring the base.
+ std::equal(GEP1->op_begin()+1, GEP1->op_end(), GEP2->op_begin()+1))
+ return alias(GEP1->getOperand(0), V1Size, GEP2->getOperand(0), V2Size);
+
+
// Drill down into the first non-gep value, to test for must-aliasing of
// the base pointers.
- 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);
+ while (isGEP(GEP1->getOperand(0)) &&
+ GEP1->getOperand(1) ==
+ Constant::getNullValue(GEP1->getOperand(1)->getType()))
+ GEP1 = cast<User>(GEP1->getOperand(0));
+ const Value *BasePtr1 = GEP1->getOperand(0);
+
+ while (isGEP(GEP2->getOperand(0)) &&
+ GEP2->getOperand(1) ==
+ Constant::getNullValue(GEP2->getOperand(1)->getType()))
+ GEP2 = cast<User>(GEP2->getOperand(0));
+ const Value *BasePtr2 = GEP2->getOperand(0);
// Do the base pointers alias?
AliasResult BaseAlias = alias(BasePtr1, ~0U, BasePtr2, ~0U);
// the size of the argument... build an index vector that is equal to
// the arguments provided, except substitute 0's for any variable
// indexes we find...
- if (cast<PointerType>(
+ if (
TD && cast<PointerType>(
BasePtr->getType())->getElementType()->isSized()) {
for (unsigned i = 0; i != GEPOperands.size(); ++i)
if (!isa<ConstantInt>(GEPOperands[i]))
GEPOperands[i] =
Constant::getNullValue(GEPOperands[i]->getType());
int64_t Offset =
- getTargetData().getIndexedOffset(BasePtr->getType(),
- &GEPOperands[0],
- GEPOperands.size());
+ TD->getIndexedOffset(BasePtr->getType(),
+ &GEPOperands[0],
+ GEPOperands.size());
if (Offset >= (int64_t)V2Size || Offset <= -(int64_t)V1Size)
return NoAlias;
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) {
+static bool IndexOperandsEqual(Value *V1, Value *V2, LLVMContext &Context) {
if (V1->getType() == V2->getType())
return V1 == V2;
if (Constant *C1 = dyn_cast<Constant>(V1))
if (Constant *C2 = dyn_cast<Constant>(V2)) {
// Sign extend the constants to long types, if necessary
- if (C1->getType() != Type::Int64Ty)
- C1 = ConstantExpr::getSExt(C1, Type::Int64Ty);
- if (C2->getType() != Type::Int64Ty)
- C2 = ConstantExpr::getSExt(C2, Type::Int64Ty);
+ if (C1->getType() != Type::getInt64Ty(Context))
+ C1 = ConstantExpr::getSExt(C1, Type::getInt64Ty(Context));
+ if (C2->getType() != Type::getInt64Ty(Context))
+ C2 = ConstantExpr::getSExt(C2, Type::getInt64Ty(Context));
return C1 == C2;
}
return false;
const PointerType *GEPPointerTy = cast<PointerType>(BasePtr1Ty);
+ LLVMContext &Context = GEPPointerTy->getContext();
+
// Find the (possibly empty) initial sequence of equal values... which are not
// necessarily constants.
unsigned NumGEP1Operands = NumGEP1Ops, NumGEP2Operands = NumGEP2Ops;
unsigned MaxOperands = std::max(NumGEP1Operands, NumGEP2Operands);
unsigned UnequalOper = 0;
while (UnequalOper != MinOperands &&
- IndexOperandsEqual(GEP1Ops[UnequalOper], GEP2Ops[UnequalOper])) {
+ IndexOperandsEqual(GEP1Ops[UnequalOper], GEP2Ops[UnequalOper],
+ Context)) {
// Advance through the type as we go...
++UnequalOper;
if (const CompositeType *CT = dyn_cast<CompositeType>(BasePtr1Ty))
if (Constant *G2OC = dyn_cast<ConstantInt>(const_cast<Value*>(G2Oper))){
if (G1OC->getType() != G2OC->getType()) {
// Sign extend both operands to long.
- if (G1OC->getType() != Type::Int64Ty)
- G1OC = ConstantExpr::getSExt(G1OC, Type::Int64Ty);
- if (G2OC->getType() != Type::Int64Ty)
- G2OC = ConstantExpr::getSExt(G2OC, Type::Int64Ty);
+ if (G1OC->getType() != Type::getInt64Ty(Context))
+ G1OC = ConstantExpr::getSExt(G1OC, Type::getInt64Ty(Context));
+ if (G2OC->getType() != Type::getInt64Ty(Context))
+ G2OC = ConstantExpr::getSExt(G2OC, Type::getInt64Ty(Context));
GEP1Ops[FirstConstantOper] = G1OC;
GEP2Ops[FirstConstantOper] = G2OC;
}
if (G1OC != G2OC) {
// Handle the "be careful" case above: if this is an array/vector
// subscript, scan for a subsequent variable array index.
- if (isa<SequentialType>(BasePtr1Ty)) {
- const Type *NextTy =
- cast<SequentialType>(BasePtr1Ty)->getElementType();
+ if (const SequentialType *STy =
+ dyn_cast<SequentialType>(BasePtr1Ty)) {
+ const Type *NextTy = STy;
bool isBadCase = false;
- for (unsigned Idx = FirstConstantOper+1;
+ for (unsigned Idx = FirstConstantOper;
Idx != MinOperands && isa<SequentialType>(NextTy); ++Idx) {
const Value *V1 = GEP1Ops[Idx], *V2 = GEP2Ops[Idx];
if (!isa<Constant>(V1) || !isa<Constant>(V2)) {
isBadCase = true;
break;
}
+ // If the array is indexed beyond the bounds of the static type
+ // at this level, it will also fall into the "be careful" case.
+ // It would theoretically be possible to analyze these cases,
+ // but for now just be conservatively correct.
+ if (const ArrayType *ATy = dyn_cast<ArrayType>(STy))
+ if (cast<ConstantInt>(G1OC)->getZExtValue() >=
+ ATy->getNumElements() ||
+ cast<ConstantInt>(G2OC)->getZExtValue() >=
+ ATy->getNumElements()) {
+ isBadCase = true;
+ break;
+ }
+ if (const VectorType *VTy = dyn_cast<VectorType>(STy))
+ if (cast<ConstantInt>(G1OC)->getZExtValue() >=
+ VTy->getNumElements() ||
+ cast<ConstantInt>(G2OC)->getZExtValue() >=
+ VTy->getNumElements()) {
+ isBadCase = true;
+ break;
+ }
+ STy = cast<SequentialType>(NextTy);
NextTy = cast<SequentialType>(NextTy)->getElementType();
}
// However, one GEP may have more operands than the other. If this is the
// case, there may still be hope. Check this now.
if (FirstConstantOper == MinOperands) {
+ // Without TargetData, we won't know what the offsets are.
+ if (!TD)
+ return MayAlias;
+
// Make GEP1Ops be the longer one if there is a longer one.
if (NumGEP1Ops < NumGEP2Ops) {
std::swap(GEP1Ops, GEP2Ops);
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]))
GEP1Ops[i] = Constant::getNullValue(GEP1Ops[i]->getType());
// Okay, now get the offset. This is the relative offset for the full
// instruction.
- const TargetData &TD = getTargetData();
- int64_t Offset1 = TD.getIndexedOffset(GEPPointerTy, GEP1Ops,
- NumGEP1Ops);
+ int64_t Offset1 = TD->getIndexedOffset(GEPPointerTy, GEP1Ops,
+ NumGEP1Ops);
// Now check without any constants at the end.
- int64_t Offset2 = TD.getIndexedOffset(GEPPointerTy, GEP1Ops,
- MinOperands);
+ 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;
}
}
const Type *ZeroIdxTy = GEPPointerTy;
for (unsigned i = 0; i != FirstConstantOper; ++i) {
if (!isa<StructType>(ZeroIdxTy))
- GEP1Ops[i] = GEP2Ops[i] = Constant::getNullValue(Type::Int32Ty);
+ GEP1Ops[i] = GEP2Ops[i] =
+ Constant::getNullValue(Type::getInt32Ty(Context));
if (const CompositeType *CT = dyn_cast<CompositeType>(ZeroIdxTy))
ZeroIdxTy = CT->getTypeAtIndex(GEP1Ops[i]);
// value possible.
//
if (const ArrayType *AT = dyn_cast<ArrayType>(BasePtr1Ty))
- GEP1Ops[i] = ConstantInt::get(Type::Int64Ty,AT->getNumElements()-1);
+ GEP1Ops[i] =
+ ConstantInt::get(Type::getInt64Ty(Context),
+ AT->getNumElements()-1);
else if (const VectorType *VT = dyn_cast<VectorType>(BasePtr1Ty))
- GEP1Ops[i] = ConstantInt::get(Type::Int64Ty,VT->getNumElements()-1);
+ GEP1Ops[i] =
+ ConstantInt::get(Type::getInt64Ty(Context),
+ VT->getNumElements()-1);
}
}
}
}
- if (GEPPointerTy->getElementType()->isSized()) {
+ if (TD && GEPPointerTy->getElementType()->isSized()) {
int64_t Offset1 =
- getTargetData().getIndexedOffset(GEPPointerTy, GEP1Ops, NumGEP1Ops);
+ TD->getIndexedOffset(GEPPointerTy, GEP1Ops, NumGEP1Ops);
int64_t Offset2 =
- getTargetData().getIndexedOffset(GEPPointerTy, GEP2Ops, NumGEP2Ops);
+ TD->getIndexedOffset(GEPPointerTy, GEP2Ops, NumGEP2Ops);
assert(Offset1 != Offset2 &&
"There is at least one different constant here!");
projects / oota-llvm.git / blobdiff