https://gcc.gnu.org/bugzilla/show_bug.cgi?id=124138
Richard Biener <rguenth at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|ASSIGNED |NEW
Assignee|rguenth at gcc dot gnu.org |unassigned at gcc dot
gnu.org
Keywords| |needs-bisection
Known to work| |15.1.1
Priority|P3 |P1
--- Comment #2 from Richard Biener <rguenth at gcc dot gnu.org> ---
Hmm, V is vector(8) long long unsigned int, so we are correctly only using V.
Dump of assembler code for function foo:
=> 0x0000000000400566 <+0>: vpermilpd $0xba,%zmm1,%zmm0
0x000000000040056d <+7>: ret
(gdb) p $zmm1.v8_int64
$2 = {1, 2, 3, 4, 5, 6, 0, 0}
(gdb) si
0x000000000040056d 9 }
(gdb) p $zmm0.v8_int64
$3 = {1, 2, 3, 4, 6, 6, 0, 0}
so this looks like a backend problem? .final still has
(insn 8 4 15 2 (set (reg:V8DI 20 xmm0 [orig:103 _1 ] [103])
(vec_select:V8DI (reg:V8DI 21 xmm1 [orig:104 v ] [104])
(parallel [
(const_int 0 [0])
(const_int 1 [0x1])
(const_int 2 [0x2])
(const_int 5 [0x5])
(const_int 4 [0x4])
(const_int 5 [0x5])
(const_int 6 [0x6])
(const_int 7 [0x7])
]))) "t.c":7:9 9218 {*avx512f_vpermilpv8di}
(expr_list:REG_DEAD (reg:V8DI 21 xmm1 [orig:104 v ] [104])
(nil)))
I'll note that GCC 15 instead uses
(insn 8 4 9 2 (set (reg:V8DI 20 xmm0 [104])
(mem/u/c:V8DI (symbol_ref/u:DI ("*.LC0") [flags 0x2]) [0 S64 A512]))
"t.c":7:9 2404 {movv8di_internal}
(expr_list:REG_EQUIV (const_vector:V8DI [
(const_int 0 [0])
(const_int 1 [0x1])
(const_int 2 [0x2])
(const_int 5 [0x5])
(const_int 4 [0x4])
(const_int 5 [0x5])
(const_int 6 [0x6])
(const_int 7 [0x7])
])
(nil)))
(insn 9 8 16 2 (set (reg:V8DI 20 xmm0 [orig:103 _1 ] [103])
(unspec:V8DI [
(reg:V8DI 21 xmm1 [orig:105 v ] [105])
(reg:V8DI 20 xmm0 [104])
] UNSPEC_VPERMVAR)) "t.c":7:9 9049 {avx512f_permvarv8di}
thus
vmovdqa64 .LC0(%rip), %zmm0
vpermq %zmm1, %zmm0, %zmm0
