On Mon, Dec 20, 2021 at 12:26 PM Roger Sayle <ro...@nextmovesoftware.com> wrote: > > > Hi Uros, > Many thanks for the review. Here's a revised patch incorporating your > suggestion to use a single define_insn with a mode iterator instead of two > new near identical define_insns for SImode and DImode. I initially tried > SWI48, but a testsuite failure of pr82418.c revealed that it's more > efficient on TARGET_64BIT to use a full width multiplication than a > SImode highpart multiplication, i.e. we only want ?mulsi3_highpart on > !TARGET_64BIT, so this revised patch uses a DWIH mode iterator. > > This patch has been tested on x86_64-pc-linux-gnu by make bootstrap and > make -k check (with and without RUNTESTFLAGS="--target_board='unix{-m32}'") > with no new failures. Ok for mainline? > > > 2021-12-20 Roger Sayle <ro...@nextmovesoftware.com> > Uroš Bizjak <ubiz...@gmail.com> > > gcc/ChangeLog > * config/i386/i386.md (any_mul_highpart): New code iterator. > (sgnprefix, s): Add attribute support for [su]mul_highpart. > (<s>mul<mode>3_highpart): Delete expander. > (<s>mul<mode>3_highpart, <s>mulsi32_highpart_zext): > New define_insn patterns. > (define_peephole2): Tweak the register allocation for the above > instructions after reload. > > gcc/testsuite/ChangeLog > * gcc.target/i386/smuldi3_highpart.c: New test case.
OK. Thanks, Uros. > > Thanks again, > Roger > -- > > > -----Original Message----- > > From: Uros Bizjak <ubiz...@gmail.com> > > Sent: 13 December 2021 11:53 > > To: Roger Sayle <ro...@nextmovesoftware.com> > > Cc: GCC Patches <gcc-patches@gcc.gnu.org> > > Subject: Re: [PATCH] x86_64: Improve code expanded for highpart > > multiplications. > > > > On Fri, Dec 10, 2021 at 12:58 PM Roger Sayle <ro...@nextmovesoftware.com> > > wrote: > > > > > > > > > While working on a middle-end patch to more aggressively use highpart > > > multiplications on targets that support them, I noticed that the RTL > > > expanded by the x86 backend interacts poorly with register allocation > > > leading to suboptimal code. > > > > > > For the testcase, > > > typedef int __attribute ((mode(TI))) ti_t; long foo(long x) { > > > return ((ti_t)x * 19065) >> 64; > > > } > > > > > > we'd like to avoid: > > > foo: movq %rdi, %rax > > > movl $19065, %edx > > > imulq %rdx > > > movq %rdx, %rax > > > ret > > > > > > and would prefer: > > > foo: movl $19065, %eax > > > imulq %rdi > > > movq %rdx, %rax > > > ret > > > > > > This patch provides a pair of peephole2 transformations to tweak the > > > spills generated by reload, and at the same time replaces the current > > > define_expand with define_insn patterns using the new [su]mul_highpart > > > RTX codes. I've left the old-style patterns in the machine > > > description for the time being, but plan to remove these once my > > > planned middle-end improvements make them obsolete. > > > > > > This patch has been tested on x86_64-pc-linux-gnu (both with and > > > without the middle-end changes) by make bootstrap and make -k check > > > with no new failures. The new test case, which currently passes, > > > ensures that the code we generate isn't adversely affected by changes > > > outside > > the backend. > > > Ok for mainline? > > > > > > > > > 2021-12-10 Roger Sayle <ro...@nextmovesoftware.com> > > > > > > gcc/ChangeLog > > > * config/i386/i386.md (any_mul_highpart): New code iterator. > > > (sgnprefix, s): Add attribute support for [su]mul_highpart. > > > (<s>mul<mode>3_highpart): Delete expander. > > > (<s>muldi3_highpart, <s>mulsi3_highpart, > > > <s>mulsi32_highpart_zext): > > > New define_insn patterns. > > > (define_peephole2): Tweak the register allocation for the above > > > instructions after reload. > > > > > > gcc/testsuite/ChangeLog > > > * gcc.target/i386/smuldi3_highpart.c: New test case. > > > > Can you please merge <s>muldi3_highpart and *<s>mulsi3_highpart using > > SWI48 mode iterator? > > > > Uros. > > > > > > > > > > > Thanks in advance, > > > Roger > > > -- > > >