attribs: Restrict decl_attributes DECL_FUNCTION_SPECIFIC_TARGET changes to targets that care about target attributes/pragmas [PR105234]

  Hi!

The following code is rejected e.g. on mips64el-linux (but I think many
other targets which don't support target attribute or pragma).
The problem is that the change to decl_attributes below is done
unconditionally and with just #pragma GCC push_options/pop_options pair
we have target_option_default_node NULL, but after popping options
target_option_current_node becomes non-NULL and this decl_attribute
spot fills in DECL_FUNCTION_SPECIFIC_TARGET of a subset of a functions.
Those appearing before push_options/pop_options will have it NULL and
as target_option_default_node is also NULL on those targets, the default
can_inline_p will refuse to inline any functions defined with NULL
DECL_FUNCTION_SPECIFIC_TARGET into any function with non-NULL
DECL_FUNCTION_SPECIFIC_TARGET (even when nothing in the options really
changed).

The following patch restricts that snippet to targets that care (initialize
target_option_default_node to non-NULL to the command line options early)
which include all targets that actually implement target attribute and/or
pragma.

Bootstrapped/regtested on x86_64-linux and i686-linux, tested on the
testcase with cross-compiler to mips64el-linux, ok for trunk?

2022-04-13  Jakub Jelinek  <jakub@redhat.com>

	PR target/105234
	* attribs.cc (decl_attributes): Don't set
	DECL_FUNCTION_SPECIFIC_TARGET if target_option_default_node is
	NULL.

	* gcc.c-torture/compile/pr105234.c: New test.


	Jakub
  

On Wed, 13 Apr 2022, Jakub Jelinek wrote:

> Hi!
> 
> The following code is rejected e.g. on mips64el-linux (but I think many
> other targets which don't support target attribute or pragma).
> The problem is that the change to decl_attributes below is done
> unconditionally and with just #pragma GCC push_options/pop_options pair
> we have target_option_default_node NULL, but after popping options
> target_option_current_node becomes non-NULL and this decl_attribute
> spot fills in DECL_FUNCTION_SPECIFIC_TARGET of a subset of a functions.
> Those appearing before push_options/pop_options will have it NULL and
> as target_option_default_node is also NULL on those targets, the default
> can_inline_p will refuse to inline any functions defined with NULL
> DECL_FUNCTION_SPECIFIC_TARGET into any function with non-NULL
> DECL_FUNCTION_SPECIFIC_TARGET (even when nothing in the options really
> changed).
> 
> The following patch restricts that snippet to targets that care (initialize
> target_option_default_node to non-NULL to the command line options early)
> which include all targets that actually implement target attribute and/or
> pragma.
> 
> Bootstrapped/regtested on x86_64-linux and i686-linux, tested on the
> testcase with cross-compiler to mips64el-linux, ok for trunk?

OK.

Thanks,
Richard.

> 2022-04-13  Jakub Jelinek  <jakub@redhat.com>
> 
> 	PR target/105234
> 	* attribs.cc (decl_attributes): Don't set
> 	DECL_FUNCTION_SPECIFIC_TARGET if target_option_default_node is
> 	NULL.
> 
> 	* gcc.c-torture/compile/pr105234.c: New test.
> 
> --- gcc/attribs.cc.jj	2022-02-04 14:36:53.947620076 +0100
> +++ gcc/attribs.cc	2022-04-12 12:52:36.630967329 +0200
> @@ -636,15 +636,20 @@ decl_attributes (tree *node, tree attrib
>        && !DECL_FUNCTION_SPECIFIC_OPTIMIZATION (*node))
>      {
>        DECL_FUNCTION_SPECIFIC_OPTIMIZATION (*node) = optimization_current_node;
> -      tree cur_tree
> -	= build_target_option_node (&global_options, &global_options_set);
> -      tree old_tree = DECL_FUNCTION_SPECIFIC_TARGET (*node);
> -      if (!old_tree)
> -	old_tree = target_option_default_node;
> -      /* The changes on optimization options can cause the changes in
> -	 target options, update it accordingly if it's changed.  */
> -      if (old_tree != cur_tree)
> -	DECL_FUNCTION_SPECIFIC_TARGET (*node) = cur_tree;
> +      /* Don't set DECL_FUNCTION_SPECIFIC_TARGET for targets that don't
> +	 support #pragma GCC target or target attribute.  */
> +      if (target_option_default_node)
> +	{
> +	  tree cur_tree
> +	    = build_target_option_node (&global_options, &global_options_set);
> +	  tree old_tree = DECL_FUNCTION_SPECIFIC_TARGET (*node);
> +	  if (!old_tree)
> +	    old_tree = target_option_default_node;
> +	  /* The changes on optimization options can cause the changes in
> +	     target options, update it accordingly if it's changed.  */
> +	  if (old_tree != cur_tree)
> +	    DECL_FUNCTION_SPECIFIC_TARGET (*node) = cur_tree;
> +	}
>      }
>  
>    /* If this is a function and the user used #pragma GCC target, add the
> --- gcc/testsuite/gcc.c-torture/compile/pr105234.c.jj	2022-04-12 13:07:55.021142913 +0200
> +++ gcc/testsuite/gcc.c-torture/compile/pr105234.c	2022-04-12 13:07:43.596302442 +0200
> @@ -0,0 +1,14 @@
> +/* PR target/105234 */
> +/* { dg-do compile } */
> +
> +static inline __attribute__((always_inline)) int foo (int x) { return x + 1; }
> +#pragma GCC push_options
> +static inline __attribute__((always_inline)) int bar (int x) { return x + 2; }
> +#pragma GCC pop_options
> +static inline __attribute__((always_inline)) int baz (int x) { return x + 3; }
> +
> +int
> +qux (void)
> +{
> +  return foo (bar (baz (42)));
> +}
> 
> 	Jakub
> 
>