Re: [PATCH] ipa-split: Don't split returns_twice functions [PR106923]

[Richard Biener via Gcc-patches]

> Am 07.02.2023 um 09:42 schrieb Jakub Jelinek via Gcc-patches 
> <gcc-patches@gcc.gnu.org>:
> 
> Hi!
> 
> As discussed in the PR, returns_twice functions are rare/special beasts
> that need special treatment in the cfg, and inside of their bodies
> we don't know which part actually works the weird returns twice way
> (either in the fork/vfork sense, or in the setjmp) and aren't updating
> ab edges to reflect that.
> 
> I think easiest is just to never split these, like we already never
> split noreturn or malloc functions.
> 
> Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?

Ok.

Richard 

> 2023-02-07  Jakub Jelinek  <ja...@redhat.com>
> 
>    PR tree-optimization/106923
>    * ipa-split.cc (execute_split_functions): Don't split returns_twice
>    functions.
> 
>    * gcc.dg/pr106923.c: New test.
> 
> --- gcc/ipa-split.cc.jj    2023-01-02 09:32:22.492283737 +0100
> +++ gcc/ipa-split.cc    2023-02-06 14:15:08.343271251 +0100
> @@ -1715,10 +1715,11 @@ execute_split_functions (void)
>   struct cgraph_node *node = cgraph_node::get (current_function_decl);
> 
>   if (flags_from_decl_or_type (current_function_decl)
> -      & (ECF_NORETURN|ECF_MALLOC))
> +      & (ECF_NORETURN|ECF_MALLOC|ECF_RETURNS_TWICE))
>     {
>       if (dump_file)
> -    fprintf (dump_file, "Not splitting: noreturn/malloc function.\n");
> +    fprintf (dump_file, "Not splitting: noreturn/malloc/returns_twice "
> +                "function.\n");
>       return 0;
>     }
>   if (MAIN_NAME_P (DECL_NAME (current_function_decl)))
> --- gcc/testsuite/gcc.dg/pr106923.c.jj    2023-02-06 14:19:33.464449400 +0100
> +++ gcc/testsuite/gcc.dg/pr106923.c    2023-02-06 14:18:25.498429162 +0100
> @@ -0,0 +1,23 @@
> +/* PR tree-optimization/106923 */
> +/* { dg-do compile } */
> +/* { dg-options "-O1 -finline-small-functions -fpartial-inlining --param 
> max-inline-insns-single=1 --param uninlined-function-insns=10000" } */
> +
> +int n;
> +
> +int
> +baz (void);
> +
> +__attribute__ ((returns_twice)) int
> +bar (void)
> +{
> +  if (baz ())
> +    ++n;
> +
> +  return 0;
> +}
> +
> +int
> +foo (void)
> +{
> +  return bar ();
> +}
> 
>    Jakub
>