InstCombine: Turn _chk functions into the "unsafe" variant if length and max langth are equal.
This happens when we take the (non-constant) length from a malloc.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@122961 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Transforms/InstCombine/InstCombineCalls.cpp b/lib/Transforms/InstCombine/InstCombineCalls.cpp
index 603a010..ecd2243 100644
--- a/lib/Transforms/InstCombine/InstCombineCalls.cpp
+++ b/lib/Transforms/InstCombine/InstCombineCalls.cpp
@@ -722,6 +722,8 @@
NewInstruction = IC->ReplaceInstUsesWith(*CI, With);
}
bool isFoldable(unsigned SizeCIOp, unsigned SizeArgOp, bool isString) const {
+ if (CI->getArgOperand(SizeCIOp) == CI->getArgOperand(SizeArgOp))
+ return true;
if (ConstantInt *SizeCI =
dyn_cast<ConstantInt>(CI->getArgOperand(SizeCIOp))) {
if (SizeCI->isAllOnesValue())
diff --git a/test/Transforms/InstCombine/objsize.ll b/test/Transforms/InstCombine/objsize.ll
index 9950e5f..4154ea0 100644
--- a/test/Transforms/InstCombine/objsize.ll
+++ b/test/Transforms/InstCombine/objsize.ll
@@ -176,3 +176,14 @@
; CHECK-NOT: ret i32 %x
ret i32 %objsize
}
+
+define i8* @test10(i32 %x) {
+; CHECK: @test10
+ %alloc = call noalias i8* @malloc(i32 %x) nounwind
+ %objsize = call i32 @llvm.objectsize.i32(i8* %alloc, i1 false) nounwind readonly
+ tail call i8* @__memset_chk(i8* %alloc, i32 0, i32 %x, i32 %objsize) nounwind
+; CHECK-NOT: @llvm.objectsize
+; CHECK: @llvm.memset
+ ret i8* %alloc
+; CHECK: ret i8*
+}