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Re-commit "Properly handle multi-element and dynamically sized allocas in getPointerDereferenceableBytes()""

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llvm-clang-x86_64-expensive-checks-win is still broken, so the failure
seems unrelated.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@320953 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Bjorn Steinbrink 2017-12-17 21:20:16 +00:00
parent 89e3680254
commit 53f8289df4
3 changed files with 24 additions and 5 deletions
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2
include/llvm/IR/Value.h
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@ -570,7 +570,7 @@ public:
///
/// If CanBeNull is set by this function the pointer can either be null or be
/// dereferenceable up to the returned number of bytes.
unsigned getPointerDereferenceableBytes(const DataLayout &DL,
uint64_t getPointerDereferenceableBytes(const DataLayout &DL,
bool &CanBeNull) const;
/// \brief Returns an alignment of the pointer value.

10
lib/IR/Value.cpp
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@ -619,11 +619,11 @@ const Value *Value::stripInBoundsOffsets() const {
return stripPointerCastsAndOffsets<PSK_InBounds>(this);
}
unsigned Value::getPointerDereferenceableBytes(const DataLayout &DL,
uint64_t Value::getPointerDereferenceableBytes(const DataLayout &DL,
bool &CanBeNull) const {
assert(getType()->isPointerTy() && "must be pointer");
unsigned DerefBytes = 0;
uint64_t DerefBytes = 0;
CanBeNull = false;
if (const Argument *A = dyn_cast<Argument>(this)) {
DerefBytes = A->getDereferenceableBytes();
@ -655,8 +655,10 @@ unsigned Value::getPointerDereferenceableBytes(const DataLayout &DL,
CanBeNull = true;
}
} else if (auto *AI = dyn_cast<AllocaInst>(this)) {
if (AI->getAllocatedType()->isSized()) {
DerefBytes = DL.getTypeStoreSize(AI->getAllocatedType());
const ConstantInt *ArraySize = dyn_cast<ConstantInt>(AI->getArraySize());
if (ArraySize && AI->getAllocatedType()->isSized()) {
DerefBytes = DL.getTypeStoreSize(AI->getAllocatedType()) *
ArraySize->getZExtValue();
CanBeNull = false;
}
} else if (auto *GV = dyn_cast<GlobalVariable>(this)) {

17
test/Analysis/ValueTracking/memory-dereferenceable.ll
View File

@ -36,6 +36,23 @@ entry:
%alloca = alloca i1
%load2 = load i1, i1* %alloca
; Load from empty array alloca
; CHECK-NOT: %empty_alloca
%empty_alloca = alloca i8, i64 0
%empty_load = load i8, i8* %empty_alloca
; Load from too small array alloca
; CHECK-NOT: %small_array_alloca
%small_array_alloca = alloca i8, i64 2
%saa_cast = bitcast i8* %small_array_alloca to i32*
%saa_load = load i32, i32* %saa_cast
; Load from array alloca
; CHECK: %big_array_alloca{{.*}}(unaligned)
%big_array_alloca = alloca i8, i64 4
%baa_cast = bitcast i8* %big_array_alloca to i32*
%baa_load = load i32, i32* %baa_cast
; CHECK: %dparam{{.*}}(aligned)
%load3 = load i32, i32 addrspace(1)* %dparam