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From: "liuhongt at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug target/112891] [10/11/12/13/14 Regression] Missing vzeroupper
 insert.
Date: Thu, 07 Dec 2023 05:04:27 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D112891

--- Comment #2 from Hongtao Liu <liuhongt at gcc dot gnu.org> ---
(In reply to Hongtao Liu from comment #1)
> Aaused by r10-3477-g2a2e3a0dfcbe08, Can be fixed by revert the patch.
>=20
> --- a/gcc/config/i386/i386.cc
> +++ b/gcc/config/i386/i386.cc
> @@ -15032,14 +15032,7 @@ ix86_avx_u128_mode_needed (rtx_insn *insn)
>        if (avx_upper_reg_found)
>         return AVX_U128_DIRTY;
>=20
> -      /* If the function is known to preserve some SSE registers,
> -        RA and previous passes can legitimately rely on that for
> -        modes wider than 256 bits.  It's only safe to issue a
> -        vzeroupper if all SSE registers are clobbered.  */
> -      const function_abi &abi =3D insn_callee_abi (insn);
> -      if (vzeroupper_pattern (PATTERN (insn), VOIDmode)
> -         || !hard_reg_set_subset_p (reg_class_contents[SSE_REGS],
> -                                    abi.mode_clobbers (V4DImode)))
> +      if (vzeroupper_pattern (PATTERN (insn), VOIDmode))
>         return AVX_U128_ANY;
>=20
>        return AVX_U128_CLEAN;
Remove this regressed many testcases

So it looks like we need to handle ix86_avx_u128_mode_after=20

--- a/gcc/config/i386/i386.cc
+++ b/gcc/config/i386/i386.cc
@@ -15177,7 +15177,14 @@ ix86_avx_u128_mode_after (int mode, rtx_insn *insn)
       bool avx_upper_reg_found =3D false;
       note_stores (insn, ix86_check_avx_upper_stores, &avx_upper_reg_found=
);

-      return avx_upper_reg_found ? AVX_U128_DIRTY : AVX_U128_CLEAN;
+      if (avx_upper_reg_found)
+       return AVX_U128_DIRTY;
+
+      const function_abi &abi =3D insn_callee_abi (insn);
+      if (!hard_reg_set_subset_p (reg_class_contents[SSE_REGS],
+                                 abi.mode_clobbers (V4DImode)))
+       return AVX_U128_ANY;
+      return  AVX_U128_CLEAN;
     }=