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From: "rguenth at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org> To: gcc-bugs@gcc.gnu.org Subject: [Bug rtl-optimization/95102] New: missed if-conversion Date: Wed, 13 May 2020 08:58:43 +0000 [thread overview] Message-ID: <bug-95102-4@http.gcc.gnu.org/bugzilla/> (raw) https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95102 Bug ID: 95102 Summary: missed if-conversion Product: gcc Version: 11.0 Status: UNCONFIRMED Severity: normal Priority: P3 Component: rtl-optimization Assignee: unassigned at gcc dot gnu.org Reporter: rguenth at gcc dot gnu.org Target Milestone: --- If you rewrite gcc.target/i386/pr54855-9.c to a form GIMPLE looks like after some PRE you end up with typedef float vec __attribute__((vector_size(16))); vec foo (vec x, float a) { if (!(x[0] < a)) x[0] = a; return x; } which is no longer recognized as the same and emits foo: .LFB0: .cfi_startproc comiss %xmm0, %xmm1 ja .L2 movss %xmm1, %xmm0 .L2: ret instead of foo: .LFB1: .cfi_startproc minss %xmm1, %xmm0 ret this is because RTL if-conversion does not recognize 7: r86:SF=vec_select(r84:V4SF,parallel) 8: flags:CCFP=cmp(r85:SF,r86:SF) REG_DEAD r86:SF 9: pc={(flags:CCFP>0)?L14:pc} REG_DEAD flags:CCFP REG_BR_PROB 536870916 10: NOTE_INSN_BASIC_BLOCK 3 12: r84:V4SF=vec_merge(vec_duplicate(r85:SF),r84:V4SF,0x1) REG_DEAD r85:SF 14: L14: 15: NOTE_INSN_BASIC_BLOCK 4 20: xmm0:V4SF=r84:V4SF the form it does recognize is 8: r82:SF=vec_select(r84:V4SF,parallel) 9: flags:CCFP=cmp(r85:SF,r82:SF) 10: pc={(flags:CCFP>0)?L28:pc} REG_DEAD flags:CCFP REG_BR_PROB 536870916 28: L28: 14: NOTE_INSN_BASIC_BLOCK 3 5: r85:SF=r82:SF REG_DEAD r82:SF 15: L15: 16: NOTE_INSN_BASIC_BLOCK 4 18: r87:V4SF=vec_merge(vec_duplicate(r85:SF),r84:V4SF,0x1)
next reply other threads:[~2020-05-13 8:58 UTC|newest] Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top 2020-05-13 8:58 rguenth at gcc dot gnu.org [this message] 2020-05-13 9:11 ` [Bug rtl-optimization/95102] " rguenth at gcc dot gnu.org 2021-07-20 1:05 ` pinskia at gcc dot gnu.org 2021-07-20 1:08 ` pinskia at gcc dot gnu.org 2021-07-20 7:27 ` rguenth at gcc dot gnu.org
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