[MemCpyOpt] Don't sink LoadInst below possible clobber.

Differential Revision: https://reviews.llvm.org/D26811

llvm-svn: 290611

1 files changed, 36 insertions, 0 deletions

diff --git a/llvm/test/Transforms/MemCpyOpt/load-store-to-memcpy.ll b/llvm/test/Transforms/MemCpyOpt/load-store-to-memcpy.ll
new file mode 100644
index 00000000000..f6b175e4171
--- /dev/null
+++ b/llvm/test/Transforms/MemCpyOpt/load-store-to-memcpy.ll
@@ -0,0 +1,36 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
+; RUN: opt -basicaa -scoped-noalias -memcpyopt -S %s | FileCheck %s
+
+%T = type { i8, i32 }
+
+; memcpy(%d, %a) should not be generated since store2 may-aliases load %a.
+define void @f(%T* %a, %T* %b, %T* %c, %T* %d) {
+; CHECK-LABEL: @f(
+; CHECK-NEXT:    [[VAL:%.*]] = load %T, %T* %a, !alias.scope !0
+; CHECK-NEXT:    store %T { i8 23, i32 23 }, %T* %b, !alias.scope !3
+; CHECK-NEXT:    store %T { i8 44, i32 44 }, %T* %c, !alias.scope !6, !noalias !3
+; CHECK-NEXT:    store %T [[VAL]], %T* %d, !alias.scope !9, !noalias !12
+; CHECK-NEXT:    ret void
+;
+  %val = load %T, %T* %a, !alias.scope !{!10}
+
+  ; store1 may-aliases the load
+  store %T { i8 23, i32 23 }, %T* %b, !alias.scope !{!11}
+
+  ; store2 may-aliases the load and store3
+  store %T { i8 44, i32 44 }, %T* %c, !alias.scope !{!12}, !noalias !{!11}
+
+  ; store3
+  store %T %val, %T* %d, !alias.scope !{!13}, !noalias !{!10, !11}
+  ret void
+}
+
+!0 = !{!0}
+!1 = !{!1}
+!2 = !{!2}
+!3 = !{!3}
+
+!10 = !{ !10, !0 }
+!11 = !{ !11, !1 }
+!12 = !{ !12, !2 }
+!13 = !{ !13, !3 }