[Bug target/96827] [10/11 Regression] __m128i from _mm_set_epi32 is backwards with -O3

[joel.hutton at arm dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96827

--- Comment #8 from Joel Hutton <joel.hutton at arm dot com> ---
I'm working on this.

I believe this may have been introduced by my earlier SLP vector constructor
patch.(commit 10d1592)

What I believe to be the relevant section:

+  else if (constructor)
+    {
+      tree rhs = gimple_assign_rhs1 (stmt_info->stmt);
+      tree val;
+      FOR_EACH_CONSTRUCTOR_VALUE (CONSTRUCTOR_ELTS (rhs), i, val)
+       {
+         if (TREE_CODE (val) == SSA_NAME)
+           {
+             gimple* def = SSA_NAME_DEF_STMT (val);
+             stmt_vec_info def_info = vinfo->lookup_stmt (def);
+             /* Value is defined in another basic block.  */
+             if (!def_info)
+               return false;
+             scalar_stmts.safe_push (def_info);
+           }
+         else
+           return false;
+       }
+    }

I'm investigating, but I suspect pushing to a stack which is then popped from
later has created a reversal of element order.