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From: "jakub at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug tree-optimization/109011] missed optimization in presence of
 __builtin_ctz
Date: Mon, 06 Mar 2023 09:22:50 +0000
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X-Bugzilla-Component: tree-optimization
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D109011

--- Comment #17 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Testcase for the normal SI -> SI stuff might be something like
with e.g.
-O3 -mavx512{bw,cd,vl,dq,bitalg,vpopcntdq} -mbmi -mlzcnt
options or so (the intent of the last 2 is to make clz/ctz defined at zero =
in
GIMPLE).
Plus similar testcase with long long * instead of int * and ll suffixed
builtins.
And also with unsigned char * and unsigned short * too eventually.

void
foo (int *p, int *q)
{
  for (int i =3D 0; i < 2048; ++i)
    p[i] =3D __builtin_popcount (q[i]);
}

void
bar (int *p, int *q)
{
  for (int i =3D 0; i < 2048; ++i)
    p[i] =3D __builtin_clz (q[i]);
}

void
baz (int *p, int *q)
{
  for (int i =3D 0; i < 2048; ++i)
    p[i] =3D __builtin_ffs (q[i]);
}

void
qux (int *p, int *q)
{
  for (int i =3D 0; i < 2048; ++i)
    p[i] =3D __builtin_ctz (q[i]);
}

void
corge (int *p, int *q)
{
  for (int i =3D 0; i < 2048; ++i)
    p[i] =3D q[i] ? __builtin_clz (q[i]) : 32;
}

void
grault (int *p, int *q)
{
  for (int i =3D 0; i < 2048; ++i)
    p[i] =3D q[i] ? __builtin_ctz (q[i]) : 32;
}=