[PATCH] D41288: Properly handle multi-element and dynamically sized allocas in getPointerDereferenceableBytes()
Björn Steinbrink via Phabricator via llvm-commits
llvm-commits at lists.llvm.org
Fri Dec 15 06:06:15 PST 2017
dotdash created this revision.
dotdash added reviewers: hfinkel, rnk.
https://reviews.llvm.org/D41288
Files:
include/llvm/IR/Value.h
lib/IR/Value.cpp
test/Analysis/ValueTracking/memory-dereferenceable.ll
Index: test/Analysis/ValueTracking/memory-dereferenceable.ll
===================================================================
--- test/Analysis/ValueTracking/memory-dereferenceable.ll
+++ test/Analysis/ValueTracking/memory-dereferenceable.ll
@@ -34,6 +34,23 @@
%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
+ %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
Index: lib/IR/Value.cpp
===================================================================
--- lib/IR/Value.cpp
+++ lib/IR/Value.cpp
@@ -619,11 +619,11 @@
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 @@
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)) {
Index: include/llvm/IR/Value.h
===================================================================
--- include/llvm/IR/Value.h
+++ include/llvm/IR/Value.h
@@ -566,7 +566,7 @@
///
/// 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.
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