[gcc r14-9177] i386: Enable _BitInt support on ia32

[gcc r14-9177] i386: Enable _BitInt support on ia32

[Jakub Jelinek]

https://gcc.gnu.org/g:f12697f3298566412386e5d70dc48a431e09b75f

commit r14-9177-gf12697f3298566412386e5d70dc48a431e09b75f
Author: Jakub Jelinek <jakub@redhat.com>
Date:   Mon Feb 26 11:12:39 2024 +0100

    i386: Enable _BitInt support on ia32
    
    Given the https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113837#c9
    comment, the following patch just attempts to implement what I think
    is best for ia32.
    
    Compared to https://gitlab.com/x86-psABIs/i386-ABI/-/issues/5 ,
    like that patch for _BitInt(64) or smaller it uses the smallest containing
    {,un}signed {char,short,int,long long} for passing/returning and
    layout of variables including in structures for alignment/size, with any
    extra bits unspecified.
    Unlike the above proposal, for larger _BitInt (i.e. _BitInt(65)+), it uses
    passing/returning/layout/alignment of structure containing minimum needed
    number of 32-bit limbs, again with the extra bits unspecified.
    This is because most operations (except copy or bitwise ops) on _BitInts
    aren't really vectorizable and will be under the hood implemented in loops
    over 32-bit limbs anyway (using 64-bit limbs under the hood would mean
    often using library implementation for the basic operations) and because
    ia32 doesn't align even long long/double in structures to 64-bit I think
    it is better to just use 32-bit alignment for that.  And I don't see
    a reason to waste 32-bit bits say for _BitInt(224) or _BitInt(288) on ia32.
    
    So, effectively it is like the x86-64 _BitInt ABI with everything divided by
    2, the only exception is that in x86-64 psABI _BitInt(128) is said to be
    already a structure of 2 limbs, which happens to be passed mostly the same
    as __int128 (except for alignment).
    
    2024-02-26  Jakub Jelinek  <jakub@redhat.com>
    
            * config/i386/i386.cc (ix86_bitint_type_info): Add support for
            !TARGET_64BIT.

Diff:
---
 gcc/config/i386/i386.cc | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/gcc/config/i386/i386.cc b/gcc/config/i386/i386.cc
index 86381b050948..fc5068539c11 100644
--- a/gcc/config/i386/i386.cc
+++ b/gcc/config/i386/i386.cc
@@ -25777,13 +25777,11 @@ ix86_get_excess_precision (enum excess_precision_type type)
 bool
 ix86_bitint_type_info (int n, struct bitint_info *info)
 {
-  if (!TARGET_64BIT)
-    return false;
   if (n <= 8)
     info->limb_mode = QImode;
   else if (n <= 16)
     info->limb_mode = HImode;
-  else if (n <= 32)
+  else if (n <= 32 || (!TARGET_64BIT && n > 64))
     info->limb_mode = SImode;
   else
     info->limb_mode = DImode;