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From: "jakub at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org> To: gcc-bugs@gcc.gnu.org Subject: [Bug rtl-optimization/105338] [12 Regression] Regression: jump or cmove generated for pattern (x ? CST : 0) Date: Fri, 22 Apr 2022 11:00:56 +0000 [thread overview] Message-ID: <bug-105338-4-dkT1NvQhWo@http.gcc.gnu.org/bugzilla/> (raw) In-Reply-To: <bug-105338-4@http.gcc.gnu.org/bugzilla/> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105338 --- Comment #3 from Jakub Jelinek <jakub at gcc dot gnu.org> --- So, if I change passes.def NEXT_PASS (pass_sink_code, true /* unsplit edges */); line NEXT_PASS (pass_sink_code, false /* unsplit edges */); I get back the 11.x code. Before ce1 pass, in that case say f looks like: 8: flags:CCZ=cmp(r83:SI,0) 9: pc={(flags:CCZ!=0)?L22:pc} REG_DEAD flags:CCZ REG_BR_PROB 375809644 10: NOTE_INSN_BASIC_BLOCK 3 5: r82:SI=0 REG_DEAD r83:SI ; pc falls through to BB 5 22: L22: 21: NOTE_INSN_BASIC_BLOCK 4 4: r82:SI=0x5 15: L15: 18: NOTE_INSN_BASIC_BLOCK 5 use (r82) i.e. essentially if (tmp83 != 0) tmp82 = 5; else tmp82 = 0; But with vanilla trunk, it is instead: 7: flags:CCZ=cmp(r83:SI,0) 8: pc={(flags:CCZ==0)?L10:pc} REG_DEAD flags:CCZ REG_BR_PROB 697932188 9: NOTE_INSN_BASIC_BLOCK 4 4: r83:SI=0x5 10: L10: 11: NOTE_INSN_BASIC_BLOCK 5 use (r83) i.e. if (tmp83 != 0) tmp83 = 5; Before fwprop1, the code looks roughly the same except for the swapped branches, so in C if (tmp83 != 0) tmp82 = 5; else tmp82 = tmp83; vs. if (tmp83 == 0) tmp82 = tmp83; else tmp82 = 5; I think fwprop1 only works on extended basic blocks and therefore turns the latter into if (tmp83 == 0) tmp82 = 0; else tmp82 = 5; and not the former.
next prev parent reply other threads:[~2022-04-22 11:00 UTC|newest] Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top 2022-04-21 17:47 [Bug rtl-optimization/105338] New: " denis.campredon at gmail dot com 2022-04-22 6:13 ` [Bug rtl-optimization/105338] [12 Regression] " rguenth at gcc dot gnu.org 2022-04-22 9:17 ` jakub at gcc dot gnu.org 2022-04-22 9:48 ` pinskia at gcc dot gnu.org 2022-04-22 11:00 ` jakub at gcc dot gnu.org [this message] 2022-04-22 11:11 ` rguenth at gcc dot gnu.org 2022-04-22 11:14 ` rguenth at gcc dot gnu.org 2022-04-22 11:20 ` rguenth at gcc dot gnu.org 2022-04-22 12:28 ` jakub at gcc dot gnu.org 2022-04-22 13:59 ` jakub at gcc dot gnu.org 2022-04-22 14:11 ` jakub at gcc dot gnu.org 2022-04-22 14:24 ` [Bug target/105338] " jakub at gcc dot gnu.org 2022-04-23 8:26 ` cvs-commit at gcc dot gnu.org 2022-04-25 14:48 ` jakub at gcc dot gnu.org 2022-04-26 5:05 ` denis.campredon at gmail dot com 2022-04-26 8:21 ` jakub at gcc dot gnu.org
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