On 9/2/20 3:34 AM, Hongtao Liu via Gcc-patches wrote:
> Hi:
> Add define_peephole2 to eliminate potential redundant conversion
> from mask to vector.
> Bootstrap is ok, regression test is ok for i386/x86-64 backend.
> Ok for trunk?
>
> gcc/ChangeLog:
> PR target/96891
> * config/i386/sse.md (VI_128_256): New mode iterator.
> (define_peephole2): Lower avx512 vector compare to avx version
> when dest is vector.
>
> gcc/testsuite/ChangeLog:
>
> * gcc.target/i386/avx512bw-pr96891-1.c: New test.
> * gcc.target/i386/avx512f-pr96891-1.c: New test.
> * gcc.target/i386/avx512f-pr96891-2.c: New test.
Aren't these the two insns in question:
(insn 7 4 8 2 (set (reg:QI 86)
(unspec:QI [
(reg:V8SF 90)
(reg:V8SF 89)
(const_int 2 [0x2])
] UNSPEC_PCMP)) "j.c":4:14 1911 {avx512vl_cmpv8sf3}
(expr_list:REG_DEAD (reg:V8SF 90)
(expr_list:REG_DEAD (reg:V8SF 89)
(nil))))
(note 8 7 9 2 NOTE_INSN_DELETED)
(insn 9 8 14 2 (set (reg:V8SI 82 [ _2 ])
(vec_merge:V8SI (const_vector:V8SI [
(const_int -1 [0xffffffffffffffff]) repeated x8
])
(const_vector:V8SI [
(const_int 0 [0]) repeated x8
])
(reg:QI 86))) "j.c":4:14 2705 {*avx512vl_cvtmask2dv8si}
(expr_list:REG_DEAD (reg:QI 86)
(nil)))
Note there's a data dependency between them. insn 7 feeds insn 9. When
there's a data dependency, combiner patterns are usually the better
choice than peepholes. I think you'd be looking to match something
likethis (from the . combine dump):
(set (reg:V8SI 82 [ _2 ])
(vec_merge:V8SI (const_vector:V8SI [
(const_int -1 [0xffffffffffffffff]) repeated x8
])
(const_vector:V8SI [
(const_int 0 [0]) repeated x8
])
(unspec:QI [
(reg:V8SF 90)
(reg:V8SF 89)
(const_int 2 [0x2])
] UNSPEC_PCMP)))
Jeff
