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From: "crazylht at gmail dot com" <gcc-bugzilla@gcc.gnu.org>
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Subject: [Bug target/98442] [X86] suboptimal for memset with CLEAR_BY_PIECES
Date: Thu, 31 Dec 2020 03:38:54 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D98442

--- Comment #1 from Hongtao.liu <crazylht at gmail dot com> ---
>=20
> Define TARGET_USE_BY_PIECES_INFRASTRUCTURE_P for i386?

It's actually determined by MOV_MAX_PIECES and related to MAX_FIXED_MODE_SI=
ZE

   ??? We should use TImode in 32-bit mode and use OImode or XImode
   if they are available.  But since by_pieces_ninsns determines the
   widest mode with MAX_FIXED_MODE_SIZE, we can only use TImode in
   64-bit mode.  */
#define MOVE_MAX_PIECES \
  ((TARGET_64BIT \
    && TARGET_SSE2 \
    && TARGET_SSE_UNALIGNED_LOAD_OPTIMAL \
    && TARGET_SSE_UNALIGNED_STORE_OPTIMAL) \
   ? GET_MODE_SIZE (OImode) : UNITS_PER_WORD)=