[committed] d: Fix gdc -O2 -mavx generates misaligned vmovdqa instruction [PR114171]

[Iain Buclaw]

Hi,

This patch fixes a wrong code issue in the D front-end where lowered
struct comparisons would reinterpret fields with a different (usually
bigger) alignment than the original.  Use `build_aligned_type' to
preserve the alignment when casting away for such comparisons.

Bootstrapped and regression tested on x86_64-linux-gnu/-m32, committed
to mainline, and backported to releases/gcc-13, releases/gcc-12, and
releases/gcc-11.

Regards,
Iain.
---
        PR d/114171

gcc/d/ChangeLog:

        * d-codegen.cc (lower_struct_comparison): Keep alignment of original
        type in reinterpret cast for comparison.

gcc/testsuite/ChangeLog:

        * gdc.dg/torture/pr114171.d: New test.
---
 gcc/d/d-codegen.cc                      |  1 +
 gcc/testsuite/gdc.dg/torture/pr114171.d | 29 +++++++++++++++++++++++++
 2 files changed, 30 insertions(+)
 create mode 100644 gcc/testsuite/gdc.dg/torture/pr114171.d

diff --git a/gcc/d/d-codegen.cc b/gcc/d/d-codegen.cc
index 5bc233928aa..43d7739f8fc 100644
--- a/gcc/d/d-codegen.cc
+++ b/gcc/d/d-codegen.cc
@@ -1006,6 +1006,7 @@ lower_struct_comparison (tree_code code, 
StructDeclaration *sd,
              if (tmode == NULL_TREE)
                tmode = make_unsigned_type (GET_MODE_BITSIZE (mode.require ()));
 
+             tmode = build_aligned_type (tmode, TYPE_ALIGN (stype));
              t1ref = build_vconvert (tmode, t1ref);
              t2ref = build_vconvert (tmode, t2ref);
 
diff --git a/gcc/testsuite/gdc.dg/torture/pr114171.d 
b/gcc/testsuite/gdc.dg/torture/pr114171.d
new file mode 100644
index 00000000000..0f9ffcab916
--- /dev/null
+++ b/gcc/testsuite/gdc.dg/torture/pr114171.d
@@ -0,0 +1,29 @@
+// { dg-do run }
+// { dg-additional-options "-mavx" { target avx_runtime } }
+// { dg-skip-if "needs gcc/config.d" { ! d_runtime } }
+import gcc.builtins;
+
+struct S1
+{
+    string label;
+}
+
+struct S2
+{
+    ulong pad;
+    S1 label;
+}
+
+pragma(inline, false)
+auto newitem()
+{
+    void *p = __builtin_malloc(S2.sizeof);
+    __builtin_memset(p, 0, S2.sizeof);
+    return cast(S2*) p;
+}
+
+int main()
+{
+    auto bn = newitem();
+    return bn.label is S1.init ? 0 : 1;
+}
-- 
2.40.1