[Bug tree-optimization/94403] Missed optimization bswap

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94403

Jakub Jelinek <jakub at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
          Component|other                       |tree-optimization
   Last reconfirmed|                            |2020-03-30
     Ever confirmed|0                           |1
                 CC|                            |jakub at gcc dot gnu.org
         Resolution|DUPLICATE                   |---
             Status|RESOLVED                    |REOPENED

--- Comment #2 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
I don't see how it is similar except that it is about bswap detection.
Your comment is weird, because bswap is detected for int32_t and not for
int64_t, while the comment suggests otherwise.
And the reason this is optimized for int32_t only is that the loop is
completely unrolled in that case, but not for int64_t, where cunrolli punts on
it even with -O2 -funroll-loops or -O3.

And, the std::byte issue is unrelated to that.
--- gcc/gimple-ssa-store-merging.c.jj   2020-03-20 09:33:03.602112329 +0100
+++ gcc/gimple-ssa-store-merging.c      2020-03-30 18:30:31.723341519 +0200
@@ -315,7 +315,8 @@ verify_symbolic_number_p (struct symboli

   lhs_type = gimple_expr_type (stmt);

-  if (TREE_CODE (lhs_type) != INTEGER_TYPE)
+  if (TREE_CODE (lhs_type) != INTEGER_TYPE
+      && TREE_CODE (lhs_type) != ENUMERAL_TYPE)
     return false;

   if (TYPE_PRECISION (lhs_type) != TYPE_PRECISION (n->type))
can fix that one.