Re: [PATCH] Fix removal of ifunc (PR ipa/81214).

[Jan Hubicka <hubicka@ucw.cz>]

> Hello.
> 
> Following patch fixes the issue where we do not emit ifunc and resolver
> for function that are not called in a compilation unit or and not
> referenced.
> 
> Patch can bootstrap on ppc64le-redhat-linux and survives regression tests.
> i386.exp tests work on x86_64-linux-gnu.

OK,
Honza
> 
> Ready to be installed?
> Martin
> 
> gcc/testsuite/ChangeLog:
> 
> 2017-06-29  Martin Liska  <mliska@suse.cz>
> 
> 	PR ipa/81214
> 	* gcc.target/i386/pr81214.c: New test.
> 
> gcc/ChangeLog:
> 
> 2017-06-29  Martin Liska  <mliska@suse.cz>
> 
> 	PR ipa/81214
> 	* multiple_target.c (create_dispatcher_calls): Make ifunc
> 	also for function that don't have calls or are not referenced.
> ---
>  gcc/multiple_target.c                   | 64 ++++++++++++++++-----------------
>  gcc/testsuite/gcc.target/i386/pr81214.c | 14 ++++++++
>  2 files changed, 46 insertions(+), 32 deletions(-)
>  create mode 100644 gcc/testsuite/gcc.target/i386/pr81214.c
> 
> 

> diff --git a/gcc/multiple_target.c b/gcc/multiple_target.c
> index eddc7d3744b..0d7cc3a2939 100644
> --- a/gcc/multiple_target.c
> +++ b/gcc/multiple_target.c
> @@ -68,6 +68,38 @@ create_dispatcher_calls (struct cgraph_node *node)
>        || !is_function_default_version (node->decl))
>      return;
>  
> +  if (!targetm.has_ifunc_p ())
> +    {
> +      error_at (DECL_SOURCE_LOCATION (node->decl),
> +		"the call requires ifunc, which is not"
> +		" supported by this target");
> +      return;
> +    }
> +  else if (!targetm.get_function_versions_dispatcher)
> +    {
> +      error_at (DECL_SOURCE_LOCATION (node->decl),
> +		"target does not support function version dispatcher");
> +      return;
> +    }
> +
> +  tree idecl = targetm.get_function_versions_dispatcher (node->decl);
> +  if (!idecl)
> +    {
> +      error_at (DECL_SOURCE_LOCATION (node->decl),
> +		"default target_clones attribute was not set");
> +      return;
> +    }
> +
> +  cgraph_node *inode = cgraph_node::get (idecl);
> +  gcc_assert (inode);
> +  tree resolver_decl = targetm.generate_version_dispatcher_body (inode);
> +
> +  /* Update aliases.  */
> +  inode->alias = true;
> +  inode->alias_target = resolver_decl;
> +  if (!inode->analyzed)
> +    inode->resolve_alias (cgraph_node::get (resolver_decl));
> +
>    auto_vec<cgraph_edge *> edges_to_redirect;
>    auto_vec<ipa_ref *> references_to_redirect;
>  
> @@ -80,38 +112,6 @@ create_dispatcher_calls (struct cgraph_node *node)
>  
>    if (!edges_to_redirect.is_empty () || !references_to_redirect.is_empty ())
>      {
> -      if (!targetm.has_ifunc_p ())
> -	{
> -	  error_at (DECL_SOURCE_LOCATION (node->decl),
> -		    "the call requires ifunc, which is not"
> -		    " supported by this target");
> -	  return;
> -	}
> -      else if (!targetm.get_function_versions_dispatcher)
> -	{
> -	  error_at (DECL_SOURCE_LOCATION (node->decl),
> -		    "target does not support function version dispatcher");
> -	  return;
> -	}
> -
> -      tree idecl = targetm.get_function_versions_dispatcher (node->decl);
> -      if (!idecl)
> -	{
> -	  error_at (DECL_SOURCE_LOCATION (node->decl),
> -		    "default target_clones attribute was not set");
> -	  return;
> -	}
> -
> -      cgraph_node *inode = cgraph_node::get (idecl);
> -      gcc_assert (inode);
> -      tree resolver_decl = targetm.generate_version_dispatcher_body (inode);
> -
> -      /* Update aliases.  */
> -      inode->alias = true;
> -      inode->alias_target = resolver_decl;
> -      if (!inode->analyzed)
> -	inode->resolve_alias (cgraph_node::get (resolver_decl));
> -
>        /* Redirect edges.  */
>        unsigned i;
>        cgraph_edge *e;
> diff --git a/gcc/testsuite/gcc.target/i386/pr81214.c b/gcc/testsuite/gcc.target/i386/pr81214.c
> new file mode 100644
> index 00000000000..2584decdb3c
> --- /dev/null
> +++ b/gcc/testsuite/gcc.target/i386/pr81214.c
> @@ -0,0 +1,14 @@
> +/* PR ipa/81214.  */
> +/* { dg-do compile } */
> +/* { dg-require-ifunc "" } */
> +
> +__attribute__((target_clones("avx","arch=slm","arch=core-avx2","default")))
> +int
> +foo ()
> +{
> +  return -2;
> +}
> +
> +/* { dg-final { scan-assembler "\t.globl\tfoo" } } */
> +/* { dg-final { scan-assembler "foo.resolver:" } } */
> +/* { dg-final { scan-assembler "foo, @gnu_indirect_function" } } */
>