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

> 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.

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