Re: [PATCH 1/2] gimplefe: Add support for REF_REVERSE_STORAGE_ORDER on mem

On Sun, Aug 9, 2026 at 12:20 AM Andrea Pinski
<[email protected]> wrote:
>
> While fixing PR 126729 and PR 126570, I found it was hard
> to figure out if REF_REVERSE_STORAGE_ORDER was set on a MEM_REF.
> Even for the gimple fe was able to set it.
> This adds support to the gimple fe and also outputs
> REF_REVERSE_STORAGE_ORDER for MEM_REF in gimple mode.
>
> Bootstrapped and tested on x84_64-linux-gnu.
>
> gcc/c/ChangeLog:
>
>         * gimple-parser.cc (c_parser_gimple_postfix_expression):
>         Allow for an optional `, 1/0` in front of the cb pair
>         for MEM_REF.
>
> gcc/ChangeLog:
>
>         * tree-pretty-print.cc (dump_mem_ref): Dump REF_REVERSE_STORAGE_ORDER
>         if it was set.
>
> gcc/testsuite/ChangeLog:
>
>         * gcc.dg/gimplefe-59.c: New test.
>
> Signed-off-by: Andrea Pinski <[email protected]>
> ---
>  gcc/c/gimple-parser.cc             | 34 ++++++++++++++++++++++++++++--
>  gcc/testsuite/gcc.dg/gimplefe-59.c | 16 ++++++++++++++
>  gcc/tree-pretty-print.cc           |  6 ++++++
>  3 files changed, 54 insertions(+), 2 deletions(-)
>  create mode 100644 gcc/testsuite/gcc.dg/gimplefe-59.c
>
> diff --git a/gcc/c/gimple-parser.cc b/gcc/c/gimple-parser.cc
> index 0fcb9ead83d..59cb29f420c 100644
> --- a/gcc/c/gimple-parser.cc
> +++ b/gcc/c/gimple-parser.cc
> @@ -1530,6 +1530,7 @@ c_parser_gimple_postfix_expression (gimple_parser &parser)
>               /* __MEM '<' type-name [ ',' number ] '>'
>                        '(' [ '(' type-name ')' ] unary-expression
>                            [ '+' number ]
> +                          [ ',' number ]

But this breaks existing IL, no?  Also, why a number ... and why in
the deref part?
I'd have expected this to be part of the <type-name ...> part,
alongside the alignment
specification?

>                            [ ',' number ':' number ] ')'  */
>               location_t loc = c_parser_peek_token (parser)->location;
>               c_parser_consume_token (parser);
> @@ -1542,6 +1543,8 @@ c_parser_gimple_postfix_expression (gimple_parser &parser)
>               index2.value = NULL_TREE;
>               unsigned short clique = 0;
>               unsigned short base = 0;
> +             bool reverse_order = false;
> +             struct c_expr ro;
>               if (c_parser_require (parser, CPP_OPEN_PAREN, "expected %<(%>"))
>                 {
>                   tree alias_type = NULL_TREE;
> @@ -1626,10 +1629,29 @@ c_parser_gimple_postfix_expression (gimple_parser &parser)
>                   if (c_parser_next_token_is (parser, CPP_COMMA))
>                     {
>                       struct c_expr cl, ba;
> +                     bool has_clb = true;
>                       c_parser_consume_token (parser);
>                       cl = c_parser_gimple_postfix_expression (parser);
> -                     if (c_parser_require (parser,
> -                                           CPP_COLON, "expected %<:%>"))
> +                     if (!c_parser_next_token_is (parser, CPP_COLON))
> +                       {
> +                         ro = cl;
> +                         unsigned HOST_WIDE_INT tmp = 0;
> +                         if (!tree_fits_uhwi_p (ro.value)
> +                             || (tmp = tree_to_uhwi (ro.value)) > 1)
> +                           error_at (ro.get_start (),
> +                                     "invalid reverse order value");
> +                         reverse_order = tmp;
> +                         has_clb = false;
> +                         if (c_parser_next_token_is (parser, CPP_COMMA))
> +                           {
> +                             c_parser_consume_token (parser);
> +                             cl = c_parser_gimple_postfix_expression (parser);
> +                             has_clb = true;
> +                           }
> +                       }
> +                     if (has_clb
> +                         && c_parser_require (parser,
> +                                              CPP_COLON, "expected %<:%>"))
>                         {
>                           ba = c_parser_gimple_postfix_expression (parser);
>                           if (!tree_fits_uhwi_p (cl.value)
> @@ -1665,6 +1687,14 @@ c_parser_gimple_postfix_expression (gimple_parser &parser)
>                   MR_DEPENDENCE_CLIQUE (expr.value) = clique;
>                   MR_DEPENDENCE_BASE (expr.value) = base;
>                 }
> +             if (reverse_order)
> +               {
> +                 if (TREE_CODE (expr.value) == MEM_REF)
> +                   REF_REVERSE_STORAGE_ORDER (expr.value) = reverse_order;
> +                 else
> +                   error_at (ro.get_start (),
> +                             "target mem ref cannot have reverse order");
> +               }
>               break;
>             }
>           else if (strcmp (IDENTIFIER_POINTER (id), "__VIEW_CONVERT") == 0)
> diff --git a/gcc/testsuite/gcc.dg/gimplefe-59.c b/gcc/testsuite/gcc.dg/gimplefe-59.c
> new file mode 100644
> index 00000000000..296c088a2a0
> --- /dev/null
> +++ b/gcc/testsuite/gcc.dg/gimplefe-59.c
> @@ -0,0 +1,16 @@
> +/* { dg-do compile } */
> +/* { dg-options "-fgimple" } */
> +
> +/* test REF_REVERSE_STORAGE_ORDER parsing of gimple fe. */
> +
> +int __GIMPLE (ssa,guessed_local(1073741824))
> +f2 (void * a, bool b, bool bb)
> +{
> +  int _1;
> +
> +  __BB(2,guessed_local(1073741824)):
> +  _1 = __MEM <int> (a_5(D), 1);
> +  return _1;
> +
> +}
> +
> diff --git a/gcc/tree-pretty-print.cc b/gcc/tree-pretty-print.cc
> index bd60e5c15c1..316945c00ed 100644
> --- a/gcc/tree-pretty-print.cc
> +++ b/gcc/tree-pretty-print.cc
> @@ -2075,6 +2075,12 @@ dump_mem_ref (pretty_printer *pp, tree node, int spc, dump_flags_t flags)
>                                  spc, flags | TDF_SLIM, false);
>             }
>         }
> +      if (TREE_CODE (node) == MEM_REF
> +         && REF_REVERSE_STORAGE_ORDER (node))
> +       {
> +         pp_string (pp, ", ");
> +         pp_decimal_int (pp, REF_REVERSE_STORAGE_ORDER (node));
> +       }
>        if (MR_DEPENDENCE_CLIQUE (node) != 0)
>         {
>           pp_string (pp, ", ");
> --
> 2.43.0
>