> -----Original Message-----
> From: H.J. Lu <hjl.to...@gmail.com>
> Sent: Wednesday, July 30, 2025 9:17 PM
> To: Hongtao Liu <crazy...@gmail.com>
> Cc: gcc-patches@gcc.gnu.org; ubiz...@gmail.com; Liu, Hongtao
> <hongtao....@intel.com>
> Subject: Re: [PATCH] x86: Transform to "pushq $-1; popq reg" for -Oz
>
> On Tue, Jul 29, 2025 at 11:37 PM Hongtao Liu <crazy...@gmail.com> wrote:
> >
> > On Wed, Jul 30, 2025 at 11:45 AM H.J. Lu <hjl.to...@gmail.com> wrote:
> > >
> > > commit 4c80062d7b8c272e2e193b8074a8440dbb4fe588
> > > Author: H.J. Lu <hjl.to...@gmail.com>
> > > Date: Sun May 25 07:40:29 2025 +0800
> > >
> > > x86: Enable *mov<mode>_(and|or) only for -Oz
> > >
> > > disabled transformation from "movq $-1,reg" to "pushq $-1; popq reg"
> > > for -Oz. But for legacy integer registers, the former is 4 bytes
> > > and the latter is 3 bytes. Enable such transformation for -Oz.
> > Ok.
>
> Pushed. OK to backport to release branches?
Ok.
>
> > >
> > > gcc/
> > >
> > > PR target/120427
> > > * config/i386/i386.md (peephole2): Transform "movq $-1,reg" to
> > > "pushq $-1; popq reg" for -Oz if reg is a legacy integer register.
> > >
> > > gcc/testsuite/
> > >
> > > PR target/120427
> > > * gcc.target/i386/pr120427-5.c: New test.
> > >
> > > Signed-off-by: H.J. Lu <hjl.to...@gmail.com>
> > > ---
> > > gcc/config/i386/i386.md | 3 ++-
> > > gcc/testsuite/gcc.target/i386/pr120427-5.c | 10 ++++++++++
> > > 2 files changed, 12 insertions(+), 1 deletion(-) create mode
> > > 100644 gcc/testsuite/gcc.target/i386/pr120427-5.c
> > >
> > > diff --git a/gcc/config/i386/i386.md b/gcc/config/i386/i386.md index
> > > eb526997584..a50475bdaf4 100644
> > > --- a/gcc/config/i386/i386.md
> > > +++ b/gcc/config/i386/i386.md
> > > @@ -2968,7 +2968,8 @@ (define_peephole2
> > > (match_operand:SWI248 1 "const_int_operand"))]
> > > "optimize_insn_for_size_p () && optimize_size > 1
> > > && operands[1] != const0_rtx
> > > - && operands[1] != constm1_rtx
> > > + && (operands[1] != constm1_rtx
> > > + || (<MODE>mode == DImode && LEGACY_INT_REG_P (operands[0])))
> > > && IN_RANGE (INTVAL (operands[1]), -128, 127)
> > > && !ix86_red_zone_used
> > > && REGNO (operands[0]) != SP_REG"
> > > diff --git a/gcc/testsuite/gcc.target/i386/pr120427-5.c
> > > b/gcc/testsuite/gcc.target/i386/pr120427-5.c
> > > new file mode 100644
> > > index 00000000000..7199aef7924
> > > --- /dev/null
> > > +++ b/gcc/testsuite/gcc.target/i386/pr120427-5.c
> > > @@ -0,0 +1,10 @@
> > > +/* { dg-do compile { target { ! ia32 } } } */
> > > +/* { dg-options "-Oz" } */
> > > +
> > > +long long
> > > +func1 (void)
> > > +{
> > > + return -1;
> > > +}
> > > +/* { dg-final { scan-assembler-times "pushq\[ \\t\]+\\\$-1" 1 } }
> > > +*/
> > > +/* { dg-final { scan-assembler-times "popq\[ \\t\]+%rax" 1 } } */
> > > --
> > > 2.50.1
> > >
> >
> >
> > --
> > BR,
> > Hongtao
>
>
>
> --
> H.J.
