[PATCH] Fix allocation of reg_known_value

[Paolo Bonzini <bonzini@gnu.org>]

When changing reg_known_value to a VEC, Steven sneaked in a small
semantic change.  That change has the advantage of improving compilation
time substantially on some testcases (including PR55489), but it is a
bit heavy-handed: it also makes set_known_reg_value a no-op, while
get_known_reg_value will always return NULL.

This patch fixes the VEC usage.  Bootstrap/regtest in progress, but I'm
going to commit this as obvious as soon as bootstrapping finishes.

Paolo

2012-11-26  Paolo Bonzini  <pbonzini@redhat.com>

	* alias.c (init_alias_analysis): Fix allocation of reg_known_value.

Index: ../../gcc/alias.c
===================================================================
--- ../../gcc/alias.c	(revisione 193853)
+++ ../../gcc/alias.c	(copia locale)
@@ -2808,7 +2808,7 @@ init_alias_analysis (void)
 
   timevar_push (TV_ALIAS_ANALYSIS);
 
-  vec_alloc (reg_known_value, maxreg - FIRST_PSEUDO_REGISTER);
+  vec_safe_grow_cleared (reg_known_value, maxreg - FIRST_PSEUDO_REGISTER);
   reg_known_equiv_p = sbitmap_alloc (maxreg - FIRST_PSEUDO_REGISTER);
 
   /* If we have memory allocated from the previous run, use it.  */