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From: "vineetg at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org> To: gcc-bugs@gcc.gnu.org Subject: [Bug target/109279] RISC-V: complex constants synthesized should be improved Date: Fri, 06 Oct 2023 19:37:53 +0000 [thread overview] Message-ID: <bug-109279-4-852TQeGLFS@http.gcc.gnu.org/bugzilla/> (raw) In-Reply-To: <bug-109279-4@http.gcc.gnu.org/bugzilla/> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109279 --- Comment #18 from Vineet Gupta <vineetg at gcc dot gnu.org> --- (In reply to Vineet Gupta from comment #17) > (In reply to Vineet Gupta from comment #16) > > > Which is what this produces: > > > ``` > > > long long f(void) > > > { > > > unsigned t = 16843009; > > > long long t1 = t; > > > long long t2 = ((unsigned long long )t) << 32; > > > asm("":"+r"(t1)); > > > return t1 | t2; > > > } > > > ``` > > li a0,16842752 > > addi a0,a0,257 > > li a5,16842752 > > slli a0,a0,32 > > addi a5,a5,257 > > or a0,a5,a0 > > ret > > This is again IRA inflicted pain (similar to [PR110748]). > IRA seems to be undoing split1 since we have 2 insn sequences to synthesize > the constant pieces. This explains why the problem got exacerbated with > commit 0530254413f8 ("riscv: relax splitter restrictions for creating > pseudos") since now different regs are used to create parts of const, vs 1 > reg being repeatedly used for assembling a const (fooling IRA's equivalent > replacement logic). After commit 2023-08-18 a047513c9222 RISC-V: Enable pressure-aware scheduling by default. the test above has improved. li a5,16842752 addi a5,a5,257 mv a0,a5 slli a5,a5,32 or a0,a0,a5 ret
next prev parent reply other threads:[~2023-10-06 19:37 UTC|newest] Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top 2023-03-24 22:04 [Bug target/109279] New: [13 Regression] RISC-V: complex constants synthesized vs. fetching from constant pool vineet.gupta at linux dot dev 2023-03-24 22:08 ` [Bug target/109279] " pinskia at gcc dot gnu.org 2023-03-24 22:08 ` pinskia at gcc dot gnu.org 2023-03-24 22:13 ` vineet.gupta at linux dot dev 2023-03-24 22:15 ` vineet.gupta at linux dot dev 2023-03-24 22:17 ` pinskia at gcc dot gnu.org 2023-03-24 22:29 ` [Bug target/109279] RISC-V: complex constants synthesized should be improved pinskia at gcc dot gnu.org 2023-03-24 22:33 ` pinskia at gcc dot gnu.org 2023-03-24 22:34 ` pinskia at gcc dot gnu.org 2023-03-24 23:33 ` pinskia at gcc dot gnu.org 2023-03-25 0:44 ` vineet.gupta at linux dot dev 2023-03-25 0:48 ` vineet.gupta at linux dot dev 2023-03-25 0:56 ` pinskia at gcc dot gnu.org 2023-03-25 1:12 ` vineet.gupta at linux dot dev 2023-03-30 18:40 ` vineet.gupta at linux dot dev 2023-05-19 17:31 ` vineetg at gcc dot gnu.org 2023-05-19 18:13 ` vineetg at gcc dot gnu.org 2023-08-15 17:37 ` vineetg at gcc dot gnu.org 2023-10-06 19:37 ` vineetg at gcc dot gnu.org [this message] 2023-10-06 19:38 ` vineetg at gcc dot gnu.org
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