On Thu, Apr 14, 2022 at 3:18 AM Hongyu Wang via Gcc-patches
<gcc-patches@gcc.gnu.org> wrote:
>
> Hi,
>
> From -Os point of view, stv converts scalar register to vector mode
> which introduces extra reg conversion and increase instruction size.
> Disabling stv under optimize_size would avoid such code size increment
> and no need to touch ix86_size_cost that has not been tuned for long
> time.
>
> Bootstrapped/regtested on x86_64-pc-linux-gnu{-m32,},
>
> Ok for master?
>
> gcc/ChangeLog:
>
> PR target/105034
> * config/i386/i386-features.cc (pass_stv::gate()): Block out
> optimize_size.
>
> gcc/testsuite/ChangeLog:
>
> PR target/105034
> * gcc.target/i386/pr105034.c: New test.
> ---
> gcc/config/i386/i386-features.cc | 3 ++-
> gcc/testsuite/gcc.target/i386/pr105034.c | 23 +++++++++++++++++++++++
> 2 files changed, 25 insertions(+), 1 deletion(-)
> create mode 100644 gcc/testsuite/gcc.target/i386/pr105034.c
>
> diff --git a/gcc/config/i386/i386-features.cc
> b/gcc/config/i386/i386-features.cc
> index 6fe41c3c24f..f57281e672f 100644
> --- a/gcc/config/i386/i386-features.cc
> +++ b/gcc/config/i386/i386-features.cc
> @@ -1911,7 +1911,8 @@ public:
> virtual bool gate (function *)
> {
> return ((!timode_p || TARGET_64BIT)
> - && TARGET_STV && TARGET_SSE2 && optimize > 1);
> + && TARGET_STV && TARGET_SSE2 && optimize > 1
> + && !optimize_size);
optimize_function_for_speed ()?
> }
>
> virtual unsigned int execute (function *)
> diff --git a/gcc/testsuite/gcc.target/i386/pr105034.c
> b/gcc/testsuite/gcc.target/i386/pr105034.c
> new file mode 100644
> index 00000000000..d997e26e9ed
> --- /dev/null
> +++ b/gcc/testsuite/gcc.target/i386/pr105034.c
> @@ -0,0 +1,23 @@
> +/* PR target/105034 */
> +/* { dg-do compile } */
> +/* { dg-options "-Os -msse4.1" } */
> +
> +#define max(a,b) (((a) > (b))? (a) : (b))
> +#define min(a,b) (((a) < (b))? (a) : (b))
> +
> +int foo(int x)
> +{
> + return max(x,0);
> +}
> +
> +int bar(int x)
> +{
> + return min(x,0);
> +}
> +
> +unsigned int baz(unsigned int x)
> +{
> + return min(x,1);
> +}
> +
> +/* { dg-final { scan-assembler-not "xmm" } } */
> --
> 2.18.1
>
