re PR middle-end/48590 (Alias analysis confused by builtin-stack-save/restore)

2011-04-14  Richard Guenther  <rguenther@suse.de>

	PR tree-optimization/48590
	* tree-ssa-alias.c (ref_maybe_used_by_call_p_1): Handle
	BUILT_IN_ALLOCA, BUILT_IN_STACK_SAVE and BUILT_IN_STACK_RESTORE.
	(call_may_clobber_ref_p_1): Handle BUILT_IN_ALLOCA and
	BUILT_IN_STACK_SAVE.
	* tree-ssa-dce.c (propagate_necessity): Handle
	BUILT_IN_ALLOCA, BUILT_IN_STACK_SAVE and BUILT_IN_STACK_RESTORE.

From-SVN: r172427

gcc/ChangeLog

+2011-04-14  Richard Guenther  <rguenther@suse.de>
+
+	PR tree-optimization/48590
+	* tree-ssa-alias.c (ref_maybe_used_by_call_p_1): Handle
+	BUILT_IN_ALLOCA, BUILT_IN_STACK_SAVE and BUILT_IN_STACK_RESTORE.
+	(call_may_clobber_ref_p_1): Handle BUILT_IN_ALLOCA and
+	BUILT_IN_STACK_SAVE.
+	* tree-ssa-dce.c (propagate_necessity): Handle
+	BUILT_IN_ALLOCA, BUILT_IN_STACK_SAVE and BUILT_IN_STACK_RESTORE.
+
 2011-04-14  Nicola Pero  <nicola.pero@meta-innovation.com>
 
 	* c-parser.c (c_parser_objc_class_declaration): Updated call to

gcc/tree-ssa-alias.c

@@ -1196,6 +1196,9 @@ ref_maybe_used_by_call_p_1 (gimple call, ao_ref *ref)
 	case BUILT_IN_FREE:
 	case BUILT_IN_MALLOC:
 	case BUILT_IN_CALLOC:
+	case BUILT_IN_ALLOCA:
+	case BUILT_IN_STACK_SAVE:
+	case BUILT_IN_STACK_RESTORE:
 	case BUILT_IN_MEMSET:
 	case BUILT_IN_FREXP:
 	case BUILT_IN_FREXPF:
@@ -1432,6 +1435,9 @@ call_may_clobber_ref_p_1 (gimple call, ao_ref *ref)
 	      && targetm.ref_may_alias_errno (ref))
 	    return true;
 	  return false;
+	case BUILT_IN_STACK_SAVE:
+	case BUILT_IN_ALLOCA:
+	  return false;
 	/* Freeing memory kills the pointed-to memory.  More importantly
 	   the call has to serve as a barrier for moving loads and stores
 	   across it.  */

gcc/tree-ssa-dce.c

@@ -824,7 +824,10 @@ propagate_necessity (struct edge_list *el)
 		  && DECL_BUILT_IN_CLASS (callee) == BUILT_IN_NORMAL
 		  && (DECL_FUNCTION_CODE (callee) == BUILT_IN_MEMSET
 		      || DECL_FUNCTION_CODE (callee) == BUILT_IN_MALLOC
-		      || DECL_FUNCTION_CODE (callee) == BUILT_IN_FREE))
+		      || DECL_FUNCTION_CODE (callee) == BUILT_IN_FREE
+		      || DECL_FUNCTION_CODE (callee) == BUILT_IN_ALLOCA
+		      || DECL_FUNCTION_CODE (callee) == BUILT_IN_STACK_SAVE
+		      || DECL_FUNCTION_CODE (callee) == BUILT_IN_STACK_RESTORE))
 		continue;
 
 	      /* Calls implicitly load from memory, their arguments