[MemCpyOpt] Do not exchange llvm.lifetime.start and llvm.memcpy

Reviewers: iteratee

Subscribers: llvm-commits

Differential Revision: http://reviews.llvm.org/D21087

llvm-svn: 272192

1 files changed, 25 insertions, 0 deletions

diff --git a/llvm/test/Transforms/MemCpyOpt/lifetime.ll b/llvm/test/Transforms/MemCpyOpt/lifetime.ll
new file mode 100644
index 00000000000..6a7e44692da
--- /dev/null
+++ b/llvm/test/Transforms/MemCpyOpt/lifetime.ll
@@ -0,0 +1,25 @@
+; RUN: opt < %s -O1 -S | FileCheck %s
+
+; performCallSlotOptzn in MemCpy should not exchange the calls to
+; @llvm.lifetime.start and @llvm.memcpy.
+
+declare void @llvm.memcpy.p0i8.p0i8.i64(i8* nocapture, i8* nocapture readonly, i64, i32, i1) #1
+declare void @llvm.lifetime.start(i64, i8* nocapture) #1
+declare void @llvm.lifetime.end(i64, i8* nocapture) #1
+
+define void @_ZN4CordC2EOS_(i8* nocapture dereferenceable(16) %arg1) {
+bb:
+; CHECK-LABEL: @_ZN4CordC2EOS_
+; CHECK-NOT: call void @llvm.lifetime.start
+; CHECK: ret void
+  %tmp = alloca [8 x i8], align 8
+  %tmp5 = bitcast [8 x i8]* %tmp to i8*
+  call void @llvm.lifetime.start(i64 16, i8* %tmp5)
+  %tmp10 = getelementptr inbounds i8, i8* %tmp5, i64 7
+  store i8 0, i8* %tmp10, align 1
+  call void @llvm.memcpy.p0i8.p0i8.i64(i8* %arg1, i8* %tmp5, i64 16, i32 8, i1 false)
+  call void @llvm.lifetime.end(i64 16, i8* %tmp5)
+  ret void
+}
+
+attributes #1 = { argmemonly nounwind }