Don't drop the alignment on a memcpy intrinsic when producing a store. This is

only a missed optimization opportunity if the store is over-aligned, but a
miscompile if the store's new type has a higher natural alignment than the
memcpy did. Fixes PR13920!


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@164641 91177308-0d34-0410-b5e6-96231b3b80d8

test/Transforms/SROA/basictest.ll

@@ -863,6 +863,7 @@ define void @test22() {
 ; CHECK-NOT: alloca
 ; CHECK: ret void
 ; PR13916
+
 entry:
   %A = alloca %test22.struct
   br i1 undef, label %if.then, label %if.end
@@ -877,3 +878,18 @@ if.end:                                           ; preds = %entry
   %tmp2 = load %test22.struct* %A
   ret void
 }
+
+define void @test23(<2 x i64> %a, i16* %b) {
+; CHECK: @test23
+; CHECK: store {{.*}}, align 2
+; CHECK: ret void
+; PR13920
+
+entry:
+  %a.addr = alloca <2 x i64>, align 16
+  store <2 x i64> %a, <2 x i64>* %a.addr, align 16
+  %0 = bitcast i16* %b to i8*
+  %1 = bitcast <2 x i64>* %a.addr to i8*
+  call void @llvm.memcpy.p0i8.p0i8.i32(i8* %0, i8* %1, i32 16, i32 2, i1 false)
+  ret void
+}