//===----------------------------------------------------------------------===//
#include "llvm/Analysis/ValueTracking.h"
+#include "llvm/ADT/SmallPtrSet.h"
#include "llvm/Analysis/InstructionSimplify.h"
#include "llvm/Constants.h"
-#include "llvm/Instructions.h"
-#include "llvm/GlobalVariable.h"
+#include "llvm/DataLayout.h"
#include "llvm/GlobalAlias.h"
+#include "llvm/GlobalVariable.h"
+#include "llvm/Instructions.h"
#include "llvm/IntrinsicInst.h"
#include "llvm/LLVMContext.h"
#include "llvm/Metadata.h"
#include "llvm/Operator.h"
-#include "llvm/DataLayout.h"
#include "llvm/Support/ConstantRange.h"
#include "llvm/Support/GetElementPtrTypeIterator.h"
#include "llvm/Support/MathExtras.h"
#include "llvm/Support/PatternMatch.h"
-#include "llvm/ADT/SmallPtrSet.h"
#include <cstring>
using namespace llvm;
using namespace llvm::PatternMatch;
if (unsigned BitWidth = Ty->getScalarSizeInBits())
return BitWidth;
assert(isa<PointerType>(Ty) && "Expected a pointer type!");
- return TD ?
- TD->getPointerSizeInBits(cast<PointerType>(Ty)->getAddressSpace()) : 0;
+ return TD ? TD->getPointerSizeInBits() : 0;
}
static void ComputeMaskedBitsAddSub(bool Add, Value *Op0, Value *Op1, bool NSW,
case Instruction::ZExt:
case Instruction::Trunc: {
Type *SrcTy = I->getOperand(0)->getType();
-
+
unsigned SrcBitWidth;
// Note that we handle pointer operands here because of inttoptr/ptrtoint
// which fall through here.
- if (SrcTy->isPointerTy())
- SrcBitWidth = TD->getTypeSizeInBits(SrcTy);
- else
- SrcBitWidth = SrcTy->getScalarSizeInBits();
-
+ SrcBitWidth = TD->getTypeSizeInBits(SrcTy->getScalarType());
+
+ assert(SrcBitWidth && "SrcBitWidth can't be zero");
KnownZero = KnownZero.zextOrTrunc(SrcBitWidth);
KnownOne = KnownOne.zextOrTrunc(SrcBitWidth);
ComputeMaskedBits(I->getOperand(0), KnownZero, KnownOne, TD, Depth+1);
return false;
}
+/// \brief Test whether a GEP's result is known to be non-null.
+///
+/// Uses properties inherent in a GEP to try to determine whether it is known
+/// to be non-null.
+///
+/// Currently this routine does not support vector GEPs.
+static bool isGEPKnownNonNull(GEPOperator *GEP, const DataLayout *DL,
+ unsigned Depth) {
+ if (!GEP->isInBounds() || GEP->getPointerAddressSpace() != 0)
+ return false;
+
+ // FIXME: Support vector-GEPs.
+ assert(GEP->getType()->isPointerTy() && "We only support plain pointer GEP");
+
+ // If the base pointer is non-null, we cannot walk to a null address with an
+ // inbounds GEP in address space zero.
+ if (isKnownNonZero(GEP->getPointerOperand(), DL, Depth))
+ return true;
+
+ // Past this, if we don't have DataLayout, we can't do much.
+ if (!DL)
+ return false;
+
+ // Walk the GEP operands and see if any operand introduces a non-zero offset.
+ // If so, then the GEP cannot produce a null pointer, as doing so would
+ // inherently violate the inbounds contract within address space zero.
+ for (gep_type_iterator GTI = gep_type_begin(GEP), GTE = gep_type_end(GEP);
+ GTI != GTE; ++GTI) {
+ // Struct types are easy -- they must always be indexed by a constant.
+ if (StructType *STy = dyn_cast<StructType>(*GTI)) {
+ ConstantInt *OpC = cast<ConstantInt>(GTI.getOperand());
+ unsigned ElementIdx = OpC->getZExtValue();
+ const StructLayout *SL = DL->getStructLayout(STy);
+ uint64_t ElementOffset = SL->getElementOffset(ElementIdx);
+ if (ElementOffset > 0)
+ return true;
+ continue;
+ }
+
+ // If we have a zero-sized type, the index doesn't matter. Keep looping.
+ if (DL->getTypeAllocSize(GTI.getIndexedType()) == 0)
+ continue;
+
+ // Fast path the constant operand case both for efficiency and so we don't
+ // increment Depth when just zipping down an all-constant GEP.
+ if (ConstantInt *OpC = dyn_cast<ConstantInt>(GTI.getOperand())) {
+ if (!OpC->isZero())
+ return true;
+ continue;
+ }
+
+ // We post-increment Depth here because while isKnownNonZero increments it
+ // as well, when we pop back up that increment won't persist. We don't want
+ // to recurse 10k times just because we have 10k GEP operands. We don't
+ // bail completely out because we want to handle constant GEPs regardless
+ // of depth.
+ if (Depth++ >= MaxDepth)
+ continue;
+
+ if (isKnownNonZero(GTI.getOperand(), DL, Depth))
+ return true;
+ }
+
+ return false;
+}
+
/// isKnownNonZero - Return true if the given value is known to be non-zero
/// when defined. For vectors return true if every element is known to be
/// non-zero when defined. Supports values with integer or pointer type and
if (Depth++ >= MaxDepth)
return false;
+ // Check for pointer simplifications.
+ if (V->getType()->isPointerTy()) {
+ if (GEPOperator *GEP = dyn_cast<GEPOperator>(V))
+ if (isGEPKnownNonNull(GEP, TD, Depth))
+ return true;
+ }
+
unsigned BitWidth = getBitWidth(V->getType(), TD);
// X | Y != 0 if X != 0 or Y != 0.
const Operator *I = dyn_cast<Operator>(V);
if (I == 0) return false;
-
+
+ // Check if the nsz fast-math flag is set
+ if (const FPMathOperator *FPO = dyn_cast<FPMathOperator>(I))
+ if (FPO->hasNoSignedZeros())
+ return true;
+
// (add x, 0.0) is guaranteed to return +0.0, not -0.0.
if (I->getOpcode() == Instruction::FAdd &&
isa<ConstantFP>(I->getOperand(1)) &&
// Re-sign extend from the pointer size if needed to get overflow edge cases
// right.
- unsigned AS = GEP->getPointerAddressSpace();
- unsigned PtrSize = TD.getPointerSizeInBits(AS);
+ unsigned PtrSize = TD.getPointerSizeInBits();
if (PtrSize < 64)
Offset = SignExtend64(Offset, PtrSize);
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