https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100738
Bug ID: 100738
Summary: Gimple failed to simplify ((v4si) ~a) < 0 ? c : d to
((v4si)a) >= 0 ? c : d
Product: gcc
Version: 12.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: middle-end
Assignee: unassigned at gcc dot gnu.org
Reporter: crazylht at gmail dot com
CC: hjl.tools at gmail dot com
Target Milestone: ---
Host: x86_64-pc-linux-gnu
Target: x86_64-*-* i?86-*-*
cat test.c
typedef int v4si __attribute__((vector_size (16)));
typedef char v16qi __attribute__((vector_size (16)));
v4si
foo (v16qi a, v4si b, v4si c, v4si d)
{
return ((v4si)~a) < 0 ? c : d;
}
gcc -Ofast -mavx2
foo(char __vector(16), int __vector(4), int __vector(4), int __vector(4)):
vpcmpeqd %xmm1, %xmm1, %xmm1
vpxor %xmm1, %xmm0, %xmm0
vblendvps %xmm0, %xmm2, %xmm3, %xmm0
ret
it can be better with
vblendvps xmm0, xmm3, xmm2, xmm0
gimple failed to simplify ((v4si)~a) < 0 ? c : d to ((v4si)a) >= 0 ? c : d
With https://gcc.gnu.org/pipermail/gcc-patches/2021-May/571056.html, i observe
rtl also won't simplify things like (vec_merge op1 op2 (lt (subreg （not op3) 0)
const0_rtx)) to (vec_merge op2 op1 (lt (subreg op3 0) const0_rtx))
