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

On Mon, Aug 10, 2026 at 5:48 PM Richard Biener
<[email protected]> wrote:
>
>
>
> > Am 10.08.2026 um 17:45 schrieb Richard Biener <[email protected]>:
> >
> > 
> >
> >>> Am 10.08.2026 um 17:39 schrieb Andrea Pinski <[email protected]>:
> >>>
> >>> On Mon, Aug 10, 2026 at 1:58 AM Richard Biener
> >>> <[email protected]> wrote:
> >>>
> >>>> 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?
> >>
> >> No it does not break existing IL because the next part contains a `:`
> >> in its argument so it is easy to check.
> >> The reason for the number is it is easier to parse than anything else
> >
> > But a -GIMPLE dump should be as easy to parse than a regular one (did you adjust dumping)?  I don’t like a 0/1 here.
> >
> >>
> >>> I'd have expected this to be part of the <type-name ...> part,
> >>> alongside the alignment
> >>> specification?
> >>
> >> Alignment is part of the type while reverse is part of the mem_ref.
> >> I know it is a bit odd but that is the current situation we are in.
> >
> > Note that we do not have to match 1:1, but I see your point.
>
> IIRC it can also be on a CONPONENT_REF

BIT_FIELD_REF.  So I'm considering to allow "qualifiers" on tcc_reference nodes
given we also have TREE_READONLY, TREE_THIS_NOTRAP and TREE_THIS_VOLATILE
(and maybe more?).

So,

  _1 = __rev __MEM <int> (p_2);
  _1 = __rev __BIT_FIELD_REF <int> (...);

WDYT?

>
> >>
> >>>
> >>>>                          [ ',' 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
> >>>>