Re: [PATCH] i386: Fix endless recursion in ix86_expand_vector_init_general with MMX [PR110152]

[Richard Biener via Gcc-patches]

> Am 07.06.2023 um 18:52 schrieb Jakub Jelinek via Gcc-patches 
> <gcc-patches@gcc.gnu.org>:
> 
> Hi!
> 
> I'm getting
> +FAIL: gcc.target/i386/3dnow-1.c (internal compiler error: Segmentation fault 
> signal terminated program cc1)
> +FAIL: gcc.target/i386/3dnow-1.c (test for excess errors)
> +FAIL: gcc.target/i386/3dnow-2.c (internal compiler error: Segmentation fault 
> signal terminated program cc1)
> +FAIL: gcc.target/i386/3dnow-2.c (test for excess errors)
> +FAIL: gcc.target/i386/mmx-1.c (internal compiler error: Segmentation fault 
> signal terminated program cc1)
> +FAIL: gcc.target/i386/mmx-1.c (test for excess errors)
> +FAIL: gcc.target/i386/mmx-2.c (internal compiler error: Segmentation fault 
> signal terminated program cc1)
> +FAIL: gcc.target/i386/mmx-2.c (test for excess errors)
> regressions on i686-linux since r14-1166.  The problem is when
> ix86_expand_vector_init_general is called with mmx_ok = true and
> mode = V4HImode, it newly recurses with mmx_ok = false and mode = V2SImode,
> but as mmx_ok is false and !TARGET_SSE, we recurse again with the same
> arguments (ok, fresh new tmp and vals) infinitely.
> The following patch fixes that by passing mmx_ok to that recursive call.
> For n_words == 4 it isn't needed, because we only care about mmx_ok for
> V2SImode or V2SFmode and no other modes.
> 
> Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?

Ok.

Richard 

> 2023-06-07  Jakub Jelinek  <ja...@redhat.com>
> 
>    PR target/110152
>    * config/i386/i386-expand.cc (ix86_expand_vector_init_general): For
>    n_words == 2 recurse with mmx_ok as first argument rather than false.
> 
> --- gcc/config/i386/i386-expand.cc.jj    2023-06-03 15:32:04.489410367 +0200
> +++ gcc/config/i386/i386-expand.cc    2023-06-07 10:31:34.715981752 +0200
> @@ -16371,7 +16371,7 @@ quarter:
>      machine_mode concat_mode = tmp_mode == DImode ? V2DImode : V2SImode;
>      rtx tmp = gen_reg_rtx (concat_mode);
>      vals = gen_rtx_PARALLEL (concat_mode, gen_rtvec_v (2, words));
> -      ix86_expand_vector_init_general (false, concat_mode, tmp, vals);
> +      ix86_expand_vector_init_general (mmx_ok, concat_mode, tmp, vals);
>      emit_move_insn (target, gen_lowpart (mode, tmp));
>    }
>       else if (n_words == 4)
> 
>    Jakub
>