[gcc r13-1102] gen: Allow unspec numbers in .md attributes

[Richard Sandiford <rsandifo@gcc.gnu.org>]

https://gcc.gnu.org/g:183a4f3829243b43a28fc70e59129521033b8f8a

commit r13-1102-g183a4f3829243b43a28fc70e59129521033b8f8a
Author: Richard Sandiford <richard.sandiford@arm.com>
Date:   Wed Jun 15 11:12:51 2022 +0100

    gen: Allow unspec numbers in .md attributes
    
    Tamar pointed out that:
    
      (unspec:M ... <FOO>)
    
    didn't work when a value of attribute FOO was defined by
    define_constant, such as in:
    
      (define_int_attribute FOO [(UNSPEC_A "UNSPEC_B") ...])
    
    This is because symbolic constants are substituted during lexing
    and only apply to bare symbol names, not strings.
    
    One option would have been to extend this lexing substitution
    to define_*_attribute values as well.  However, that would replace
    symbolic names with integer constants in the generated .cc code,
    making it less readable.
    
    This patch goes for the more localised approach of only
    applying define_constants when we want their integer value.
    
    I don't think any changes to the docs are needed.  This isn't
    adding a new feature, it's just making an existing one work in
    the expected way.
    
    gcc/
            * read-rtl.cc (find_int): Substitute symbolic constants
            before converting the string to an integer.

Diff:
---
 gcc/read-rtl.cc | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/gcc/read-rtl.cc b/gcc/read-rtl.cc
index 798d2485991..62c7895af60 100644
--- a/gcc/read-rtl.cc
+++ b/gcc/read-rtl.cc
@@ -284,6 +284,12 @@ find_int (const char *name)
 {
   HOST_WIDE_INT tmp;
 
+  struct md_constant tmp_def;
+  tmp_def.name = const_cast<char *> (name);
+  auto htab = rtx_reader_ptr->get_md_constants ();
+  if (auto def = (struct md_constant *) htab_find (htab, &tmp_def))
+    name = def->value;
+
   validate_const_int (name);
 #if HOST_BITS_PER_WIDE_INT == HOST_BITS_PER_INT
   tmp = atoi (name);