Take alignment into account in isSafeToLoadUnconditionally

Reviewed By: hfinkel

Differential Revision: http://reviews.llvm.org/D10475

llvm-svn: 240636

1 files changed, 17 insertions, 0 deletions

diff --git a/llvm/test/Transforms/InstCombine/select.ll b/llvm/test/Transforms/InstCombine/select.ll
index 8be247228b8..fdf1199a66f 100644
--- a/llvm/test/Transforms/InstCombine/select.ll
+++ b/llvm/test/Transforms/InstCombine/select.ll
@@ -1296,6 +1296,23 @@ entry:
   ret i32 %v
 }
 
+define i32 @test78_neg(i1 %flag, i32* %x, i32* %y, i32* %z) {
+; The same as @test78 but we can't speculate the load because it can trap
+; if under-aligned.
+; CHECK-LABEL: @test78_neg(
+; CHECK: %p = select i1 %flag, i32* %x, i32* %y
+; CHECK-NEXT: %v = load i32, i32* %p, align 16
+; CHECK-NEXT: ret i32 %v
+entry:
+  store i32 0, i32* %x
+  store i32 0, i32* %y
+  ; Block forwarding by storing to %z which could alias either %x or %y.
+  store i32 42, i32* %z
+  %p = select i1 %flag, i32* %x, i32* %y
+  %v = load i32, i32* %p, align 16
+  ret i32 %v
+}
+
 define float @test79(i1 %flag, float* %x, i32* %y, i32* %z) {
 ; Test that we can speculate the loads around the select even when we can't
 ; fold the load completely away.