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From: "jens.seifert at de dot ibm.com" <gcc-bugzilla@gcc.gnu.org> To: gcc-bugs@gcc.gnu.org Subject: [Bug target/103743] New: PPC: Inefficient equality compare for large 64-bit constants having only 16-bit relevant bits in high part Date: Thu, 16 Dec 2021 06:46:20 +0000 [thread overview] Message-ID: <bug-103743-4@http.gcc.gnu.org/bugzilla/> (raw) https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103743 Bug ID: 103743 Summary: PPC: Inefficient equality compare for large 64-bit constants having only 16-bit relevant bits in high part Product: gcc Version: 8.3.1 Status: UNCONFIRMED Severity: normal Priority: P3 Component: target Assignee: unassigned at gcc dot gnu.org Reporter: jens.seifert at de dot ibm.com Target Milestone: --- int overflow(); int negOverflow(long long in) { if (in == 0x8000000000000000LL) { return overflow(); } return 0; } Generates: negOverflow(long long): .quad .L.negOverflow(long long),.TOC.@tocbase,0 .L.negOverflow(long long): li 9,-1 rldicr 9,9,0,0 cmpd 0,3,9 beq 0,.L10 li 3,0 blr .L10: mflr 0 std 0,16(1) stdu 1,-112(1) bl overflow() nop addi 1,1,112 ld 0,16(1) mtlr 0 blr .long 0 .byte 0,9,0,1,128,0,0,0 Instead of: li 9,-1 rldicr 9,9,0,0 cmpd 0,3,9 Expected output: rotldi 3,3,1 cmpdi 0,3,1 This should be only applied if constant fits into 16-bit and if those 16-bit are in the first 32-bit.
next reply other threads:[~2021-12-16 6:46 UTC|newest] Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top 2021-12-16 6:46 jens.seifert at de dot ibm.com [this message] 2021-12-16 6:49 ` [Bug target/103743] " pinskia at gcc dot gnu.org 2021-12-16 15:06 ` bergner at gcc dot gnu.org 2021-12-16 22:14 ` pthaugen at gcc dot gnu.org 2022-03-15 2:06 ` guojiufu at gcc dot gnu.org 2022-03-15 7:32 ` guojiufu at gcc dot gnu.org 2022-03-16 9:48 ` guojiufu at gcc dot gnu.org 2022-05-16 1:59 ` guojiufu at gcc dot gnu.org 2022-12-20 3:59 ` cvs-commit at gcc dot gnu.org 2023-01-09 5:29 ` guojiufu at gcc dot gnu.org
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