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From: "lis8215 at gmail dot com" <gcc-bugzilla@gcc.gnu.org> To: gcc-bugs@gcc.gnu.org Subject: [Bug rtl-optimization/111376] New: missed optimization of one bit test on MIPS32r1 Date: Mon, 11 Sep 2023 18:24:57 +0000 [thread overview] Message-ID: <bug-111376-4@http.gcc.gnu.org/bugzilla/> (raw) https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111376 Bug ID: 111376 Summary: missed optimization of one bit test on MIPS32r1 Product: gcc Version: unknown Status: UNCONFIRMED Severity: normal Priority: P3 Component: rtl-optimization Assignee: unassigned at gcc dot gnu.org Reporter: lis8215 at gmail dot com Target Milestone: --- Created attachment 55879 --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=55879&action=edit Silly patch to enable SLL+BLTZ/BGEZ Currently for testing bits above 14-th the following instructions emitted: LUI $t1, 0x1000 # 0x10000000 AND $t0, $t1, $t0 BEQ/BNE $t0, $Lxx However there's shorter & faster alternative, just need to shift the bit of interest to the sign bit and jump with BLTZ/BGEZ. The code above can be replaced with: SLL $t0, $0, 3 BGEZ/BLTZ $t0, $Lxx Not sure if it can be applied to MIPS64 without EXT/INS instructions and to older MIPS revisions (I..V). But for MIPS32 it helps reduce code size by removing 1 insn per ~700. evaluated on linux kernel and python3.11.
next reply other threads:[~2023-09-11 18:24 UTC|newest] Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top 2023-09-11 18:24 lis8215 at gmail dot com [this message] 2024-06-04 6:55 ` [Bug target/111376] " syq at gcc dot gnu.org 2024-06-04 7:00 ` syq at gcc dot gnu.org 2024-06-04 7:06 ` lis8215 at gmail dot com 2024-06-05 11:02 ` syq at gcc dot gnu.org 2024-06-05 16:56 ` syq at gcc dot gnu.org 2024-06-06 9:45 ` lis8215 at gmail dot com 2024-06-06 22:16 ` syq at gcc dot gnu.org 2024-06-07 8:25 ` lis8215 at gmail dot com 2024-06-13 4:50 ` syq at gcc dot gnu.org 2024-06-15 3:22 ` syq at gcc dot gnu.org 2024-06-15 3:24 ` syq at gcc dot gnu.org 2024-06-15 5:24 ` lis8215 at gmail dot com 2024-06-15 6:47 ` syq at gcc dot gnu.org 2024-06-15 7:18 ` syq at gcc dot gnu.org 2024-06-15 8:13 ` lis8215 at gmail dot com 2024-06-15 8:35 ` lis8215 at gmail dot com 2024-06-18 8:06 ` syq at gcc dot gnu.org 2024-06-19 14:18 ` syq at gcc dot gnu.org
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