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.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@134520 91177308-0d34-0410-b5e6-96231b3b80d8

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
+