Don't eliminate memcpy's when the address of the pointer may itself be relevant. Fixes PR18304. Patch by David Wiberg!

llvm-svn: 212970

1 files changed, 22 insertions, 0 deletions

diff --git a/llvm/test/Transforms/MemCpyOpt/capturing-func.ll b/llvm/test/Transforms/MemCpyOpt/capturing-func.ll
new file mode 100644
index 00000000000..17614fd181d
--- /dev/null
+++ b/llvm/test/Transforms/MemCpyOpt/capturing-func.ll
@@ -0,0 +1,22 @@
+; RUN: opt < %s -basicaa -memcpyopt -S | FileCheck %s
+
+target datalayout = "e"
+
+declare void @foo(i8*)
+declare void @llvm.memcpy.p0i8.p0i8.i32(i8* nocapture, i8* nocapture, i32, i32, i1) nounwind
+
+define void @test() {
+  %ptr1 = alloca i8
+  %ptr2 = alloca i8
+  call void @foo(i8* %ptr2)
+  call void @llvm.memcpy.p0i8.p0i8.i32(i8* %ptr1, i8* %ptr2, i32 1, i32 1, i1 false)
+  call void @foo(i8* %ptr1)
+  ret void
+
+  ; Check that the transformation isn't applied if the called function can
+  ; capture the pointer argument (i.e. the nocapture attribute isn't present)
+  ; CHECK-LABEL: @test(
+  ; CHECK: call void @foo(i8* %ptr2)
+  ; CHECK-NEXT: call void @llvm.memcpy
+  ; CHECK-NEXT: call void @foo(i8* %ptr1)
+}