On Mon, May 26, 2025 at 2:30 PM H.J. Lu <hjl.to...@gmail.com> wrote:
>
> On Sun, May 25, 2025 at 7:02 PM H.J. Lu <hjl.to...@gmail.com> wrote:
> >
> > On Sun, May 25, 2025 at 8:12 AM H.J. Lu <hjl.to...@gmail.com> wrote:
> > >
> > > On Sun, May 25, 2025 at 7:47 AM H.J. Lu <hjl.to...@gmail.com> wrote:
> > > >
> > > > commit ef26c151c14a87177d46fd3d725e7f82e040e89f
> > > > Author: Roger Sayle <ro...@nextmovesoftware.com>
> > > > Date: Thu Dec 23 12:33:07 2021 +0000
> > > >
> > > > x86: PR target/103773: Fix wrong-code with -Oz from pop to memory.
> > > >
> > > > transformed "mov $0,mem" to the shorter and "$0,mem" for -Oz. But
> > > >
> > > > (define_insn "*mov<mode>_and"
> > > > [(set (match_operand:SWI248 0 "memory_operand" "=m")
> > > > (match_operand:SWI248 1 "const0_operand"))
> > > > (clobber (reg:CC FLAGS_REG))]
> > > > "reload_completed"
> > > > "and{<imodesuffix>}\t{%1, %0|%0, %1}"
> > > > [(set_attr "type" "alu1")
> > > > (set_attr "mode" "<MODE>")
> > > > (set_attr "length_immediate" "1")])
> > > >
> > > > isn't guarded for -Oz. As a result, "and $0,mem" is generated without
> > > > -Oz. Enable *mov<mode>_and only for -Oz.
> > > >
> > > > gcc/
> > > >
> > > > PR target/120427
> > > > * config/i386/i386.md (*mov<mode>_and): Enable only for -Oz.
> > > >
> > > > gcc/testsuite/
> > > >
> > > > PR target/120427
> > > > * gcc.target/i386/pr120427.c: New test.
> > > >
> > > > OK for master?
> > > >
> > >
> > > "mov $-1,mem" has the same issue. Here is the updated patch to also
> > > enable "or $-1,mem" only for -Oz.
> > >
> > > OK for master?
> >
> > It doesn't work since "*mov<mode>_or" was extended from load. Here is
> > the v2 patch:
> >
> > 1. Add "*mov<mode>_or_store" for "or $-1,mem".
> > 2. Rename "*mov<mode>_or" to "*mov<mode>_or_load", replacing
> > nonimmediate_operand with register_operand.
> > 3. Enable "*mov<mode>_and" and "*mov<mode>_or_store" only for -Oz.
> >
> > Tested on x86-64.
>
> Here is the v3 patch. Change "*mov<mode>_or" to define_insn_and_split
> and split it to "mov $-1,mem" if not -Oz. Don't transform "mov $-1,reg" to
> "push $-1; pop reg" for -Oz since it should be transformed to "or $-1,reg".
>
> Tested on x86-64. OK for master?
>@@ -2442,18 +2442,24 @@ (define_insn "*mov<mode>_and"
> [(set (match_operand:SWI248 0 "memory_operand" "=m")
> (match_operand:SWI248 1 "const0_operand"))
> (clobber (reg:CC FLAGS_REG))]
>- "reload_completed"
>+ "reload_completed
>+ && optimize_insn_for_size_p () && optimize_size > 1"
Can we also change *mov<mode>_and to define_insn_and_split similar as
you did for *mov<mode>_or?
>--- a/gcc/testsuite/gcc.target/i386/cold-attribute-4.c
>+++ b/gcc/testsuite/gcc.target/i386/cold-attribute-4.c
>@@ -1,5 +1,5 @@
> /* { dg-do compile } */
>-/* { dg-options "-O2" } */
>+/* { dg-options "-Oz" } */
> #include <string.h>
>
>int
>__attribute__ ((cold))
>t(int c)
>{
> return -1;
>}
There's a COLD attribute for the function, so I assume the function
will be compiled with Oz internally and no need to change the option?
>
> Thanks.
>
> --
> H.J.
--
BR,
Hongtao
