fix a bug noticed by inspection: when instcombine sinks loads through

phis, it didn't preserve the alignment of the load.  This is a missed
optimization of the alignment is high and a miscompilation when the
alignment is low.

llvm-svn: 85736

1 files changed, 21 insertions, 0 deletions

diff --git a/llvm/test/Transforms/InstCombine/phi.ll b/llvm/test/Transforms/InstCombine/phi.ll
index a5a535c6acf..08d28b4de7e 100644
--- a/llvm/test/Transforms/InstCombine/phi.ll
+++ b/llvm/test/Transforms/InstCombine/phi.ll
@@ -141,4 +141,25 @@ BB2:
 ; CHECK-NEXT: ret i32* %B
 }
 
+define i32 @test9(i32* %A, i32* %B) {
+entry:
+  %c = icmp eq i32* %A, null
+  br i1 %c, label %bb1, label %bb
+
+bb:
+  %C = load i32* %B, align 1
+  br label %bb2
+
+bb1:
+  %D = load i32* %A, align 1
+  br label %bb2
+
+bb2:
+  %E = phi i32 [ %C, %bb ], [ %D, %bb1 ]
+  ret i32 %E
+; CHECK:       bb2:
+; CHECK-NEXT:        phi i32* [ %B, %bb ], [ %A, %bb1 ]
+; CHECK-NEXT:   %E = load i32* %{{[^,]*}}, align 1
+; CHECK-NEXT:   ret i32 %E
 
+}