[PATCH] Fix cgraph_node::rtl_info (PR target/77587)

[Jan Hubicka]

> Hi!
> 
> On the following testcase the weak alias can be overridden, so we shouldn't
> assume because we see bar to be alias to foo and have foo definition that
> call to bar will bind to the current TU's foo.
> cgraph_node::rtl_info calls ultimate_alias_target without checking if it can
> be overridden or not.
> The following patch fixes that, the decl != current_function_decl in there
> is there so that for the current function it always returns non-NULL,
> otherwise we ICE during bootstrap, and the node->decl != current_function_decl
> is there e.g. for the case where we'd call an alias ultimately pointing to
> the current function (TREE_ASM_WRITTEN would still not be set in that case).
> 
> The patch also removes extra calls to ultimate_alias_target, the function
> called it up to 4 times, while only one is enough.
> 
> Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?

OK, thanks.
It may make sense to backrport this eventually to release branches.

Honza
> 
> 2016-09-16  Jakub Jelinek  <jakub@redhat.com>
> 	    Jan Hubicka  <jh@suse.cz>
> 
> 	PR target/77587
> 	* cgraph.c (cgraph_node::rtl_info): Pass &avail to
> 	ultimate_alias_target call, return NULL if avail < AVAIL_AVAILABLE.
> 	Call ultimate_alias_target just once, not up to 4 times.
> 
> 	* gcc.dg/pr77587.c: New test.
> 	* gcc.dg/pr77587a.c: New file.
> 
> --- gcc/cgraph.c.jj	2016-08-06 12:11:49.000000000 +0200
> +++ gcc/cgraph.c	2016-09-16 14:19:31.553999007 +0200
> @@ -1955,14 +1955,17 @@ cgraph_node::rtl_info (tree decl)
>    cgraph_node *node = get (decl);
>    if (!node)
>      return NULL;
> -  node = node->ultimate_alias_target ();
> -  if (node->decl != current_function_decl
> -      && !TREE_ASM_WRITTEN (node->decl))
> +  enum availability avail;
> +  node = node->ultimate_alias_target (&avail);
> +  if (decl != current_function_decl
> +      && (avail < AVAIL_AVAILABLE
> +	  || (node->decl != current_function_decl
> +	      && !TREE_ASM_WRITTEN (node->decl))))
>      return NULL;
> -  /* Allocate if it doesnt exist.  */
> -  if (node->ultimate_alias_target ()->rtl == NULL)
> -    node->ultimate_alias_target ()->rtl = ggc_cleared_alloc<cgraph_rtl_info> ();
> -  return node->ultimate_alias_target ()->rtl;
> +  /* Allocate if it doesn't exist.  */
> +  if (node->rtl == NULL)
> +    node->rtl = ggc_cleared_alloc<cgraph_rtl_info> ();
> +  return node->rtl;
>  }
>  
>  /* Return a string describing the failure REASON.  */
> --- gcc/testsuite/gcc.dg/pr77587.c.jj	2016-09-15 14:06:09.449901026 +0200
> +++ gcc/testsuite/gcc.dg/pr77587.c	2016-09-15 14:18:53.615467361 +0200
> @@ -0,0 +1,14 @@
> +/* PR target/77587 */
> +/* { dg-do run } */
> +/* { dg-require-weak-override "" } */
> +/* { dg-additional-sources "pr77587a.c" } */
> +
> +void
> +bar (long x, long y, long z)
> +{
> +  struct __attribute__((aligned (16))) S { long a, b, c, d; } s;
> +  char *p = (char *) &s;
> +  __asm ("" : "+r" (p));
> +  if (((__UINTPTR_TYPE__) p) & 15)
> +    __builtin_abort ();
> +}
> --- gcc/testsuite/gcc.dg/pr77587a.c.jj	2016-09-15 14:05:58.873031952 +0200
> +++ gcc/testsuite/gcc.dg/pr77587a.c	2016-09-15 14:16:57.242903986 +0200
> @@ -0,0 +1,23 @@
> +/* PR target/77587 */
> +/* { dg-do compile } */
> +/* { dg-require-weak-override "" } */
> +
> +void
> +foo (long x, long y, long z)
> +{
> +}
> +
> +void bar (long x, long y, long z) __attribute__ ((weak, alias ("foo")));
> +
> +void
> +baz (long x, long y, long z)
> +{
> +  bar (0, 0, 0);
> +}
> +
> +int
> +main ()
> +{
> +  baz (0, 0, 0);
> +  return 0;
> +}
> 
> 	Jakub