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From: "crazylht at gmail dot com" <gcc-bugzilla@gcc.gnu.org>
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Subject: [Bug target/104371] [x86] Failure to use optimize
 pxor+pcmpeqb+pmovmskb+cmp 0xFFFF pattern to ptest
Date: Mon, 07 Feb 2022 05:41:22 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D104371

--- Comment #5 from Hongtao.liu <crazylht at gmail dot com> ---
(In reply to Richard Biener from comment #1)
>   <bb 2> [local count: 1073741824]:
>   _2 =3D VIEW_CONVERT_EXPR<__v16qi>(x_3(D));
>   _6 =3D _2 =3D=3D { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 };
>   _7 =3D VIEW_CONVERT_EXPR<vector(16) signed char>(_6);
>   _4 =3D __builtin_ia32_pmovmskb128 (_7);
>   _5 =3D _4 =3D=3D 65535;
>   return _5;
>=20
> so likely one reason is the builtin and later UNSPEC for the movemask
> operation.
>=20

Under AVX512BW & AVX512VL we can fold __builtin_ia32_pmovmskb128 to=20

vector(16) <signed-boolean:1> temp_1 =3D _7 < { 0, 0, 0, 0, 0, 0, 0, 0, 0, =
0, 0,
0, 0, 0, 0, 0 }
temp_2 =3D VIEW_CONVERT_EXPR<unsigned short> temp_1; ----- ????
_4 =3D zero_extend temp_2;

but I'm not sure if VIEW_CONVERT_EXPR can be used between vector and integer
type.=