LICM: Do not loose alignment on promotion

The promotion code lost any alignment information, when hoisting loads and
stores out of the loop. This lead to incorrect aligned memory accesses. We now
use the largest alignment we can prove to be correct.

llvm-svn: 134520

1 files changed, 26 insertions, 0 deletions

diff --git a/llvm/test/Transforms/LICM/2011-07-06-Alignment.ll b/llvm/test/Transforms/LICM/2011-07-06-Alignment.ll
new file mode 100644
index 00000000000..f97b7010bc0
--- /dev/null
+++ b/llvm/test/Transforms/LICM/2011-07-06-Alignment.ll
@@ -0,0 +1,26 @@
+; RUN: opt -licm -S %s | FileCheck %s
+
+@A = common global [1024 x float] zeroinitializer, align 4
+
+define i32 @main() nounwind {
+entry:
+  br label %for.cond
+
+for.cond:
+  %indvar = phi i64 [ %indvar.next, %for.body ], [ 0, %entry ]
+  %arrayidx = getelementptr [1024 x float]* @A, i64 0, i64 3
+  %vecidx = bitcast float* %arrayidx to <4 x float>*
+  store <4 x float> zeroinitializer, <4 x float>* %vecidx, align 4
+  %indvar.next = add i64 %indvar, 1
+  %exitcond = icmp ne i64 %indvar, 1024
+  br i1 %exitcond, label %for.body, label %for.end
+
+for.body:
+  br label %for.cond
+
+for.end:
+  ret i32 0
+}
+
+;CHECK: store <4 x float> {{.*}} align 4
+