tree-ssa-alias.c (ref_maybe_used_by_call_p_1): Handle BUILT_IN_REALLOC like BUILT_IN_STRDUP.

2014-05-22  Richard Biener  <rguenther@suse.de>

	* tree-ssa-alias.c (ref_maybe_used_by_call_p_1): Handle
	BUILT_IN_REALLOC like BUILT_IN_STRDUP.
	(call_may_clobber_ref_p_1): Handle BUILT_IN_REALLOC as allocation
	and deallocation site.
	* tree-ssa-structalias.c (find_func_aliases_for_builtin_call):
	Handle BUILT_IN_REALLOC similar to BUILT_IN_STRDUP with also
	passing through the incoming points-to set.
	(handle_lhs_call): Use flags argument instead of recomputing it.
	(find_func_aliases_for_call): Call handle_lhs_call with proper
	call return flags.

	* gcc.dg/tree-ssa/alias-33.c: New testcase.

From-SVN: r210802

gcc/ChangeLog

+2014-05-22  Richard Biener  <rguenther@suse.de>
+
+	* tree-ssa-alias.c (ref_maybe_used_by_call_p_1): Handle
+	BUILT_IN_REALLOC like BUILT_IN_STRDUP.
+	(call_may_clobber_ref_p_1): Handle BUILT_IN_REALLOC as allocation
+	and deallocation site.
+	* tree-ssa-structalias.c (find_func_aliases_for_builtin_call):
+	Handle BUILT_IN_REALLOC similar to BUILT_IN_STRDUP with also
+	passing through the incoming points-to set.
+	(handle_lhs_call): Use flags argument instead of recomputing it.
+	(find_func_aliases_for_call): Call handle_lhs_call with proper
+	call return flags.
+
 2014-05-22  Jakub Jelinek  <jakub@redhat.com>
 
 	* tree-streamer-in.c (unpack_ts_real_cst_value_fields): Make sure

gcc/testsuite/ChangeLog

+2014-05-22  Richard Biener  <rguenther@suse.de>
+
+	* gcc.dg/tree-ssa/alias-33.c: New testcase.
+
 2014-05-22  Kostya Serebryany  <kcc@google.com>
 
 	* c-c++-common/tsan/mutexset1.c: Update the test to match

gcc/testsuite/gcc.dg/tree-ssa/alias-33.c

+/* { dg-do run } */
+/* { dg-options "-O -fdump-tree-fre1-details" } */
+
+int j;
+int main ()
+{
+  int i = 1;
+  int **p;
+  j = 0;
+  p = __builtin_malloc (sizeof (int *));
+  *p = &i;
+  p = __builtin_realloc (p, 2 * sizeof (int *));
+  **p = 0;
+  if (i != 0)
+    __builtin_abort ();
+  return j;
+}
+
+/* { dg-final { scan-tree-dump "Replaced j with 0" "fre1" } } */
+/* { dg-final { cleanup-tree-dump "fre1" } } */

gcc/tree-ssa-alias.c

@@ -1594,6 +1594,7 @@ ref_maybe_used_by_call_p_1 (gimple call, ao_ref *ref)
 	/* These read memory pointed to by the first argument.  */
 	case BUILT_IN_STRDUP:
 	case BUILT_IN_STRNDUP:
+	case BUILT_IN_REALLOC:
 	  {
 	    ao_ref dref;
 	    tree size = NULL_TREE;
@@ -1991,6 +1992,15 @@ call_may_clobber_ref_p_1 (gimple call, ao_ref *ref)
 	    tree ptr = gimple_call_arg (call, 0);
 	    return ptr_deref_may_alias_ref_p_1 (ptr, ref);
 	  }
+	/* Realloc serves both as allocation point and deallocation point.  */
+	case BUILT_IN_REALLOC:
+	  {
+	    tree ptr = gimple_call_arg (call, 0);
+	    /* Unix98 specifies that errno is set on allocation failure.  */
+	    return ((flag_errno_math
+		     && targetm.ref_may_alias_errno (ref))
+		    || ptr_deref_may_alias_ref_p_1 (ptr, ref));
+	  }
 	case BUILT_IN_GAMMA_R:
 	case BUILT_IN_GAMMAF_R:
 	case BUILT_IN_GAMMAL_R:

gcc/tree-ssa-structalias.c

@@ -3974,7 +3974,6 @@ handle_lhs_call (gimple stmt, tree lhs, int flags, vec<ce_s> rhsc,
 
   /* If the call returns an argument unmodified override the rhs
      constraints.  */
-  flags = gimple_call_return_flags (stmt);
   if (flags & ERF_RETURNS_ARG
       && (flags & ERF_RETURN_ARG_MASK) < gimple_call_num_args (stmt))
     {
@@ -4299,9 +4298,11 @@ find_func_aliases_for_builtin_call (struct function *fn, gimple t)
 	return true;
       case BUILT_IN_STRDUP:
       case BUILT_IN_STRNDUP:
+      case BUILT_IN_REALLOC:
 	if (gimple_call_lhs (t))
 	  {
-	    handle_lhs_call (t, gimple_call_lhs (t), gimple_call_flags (t),
+	    handle_lhs_call (t, gimple_call_lhs (t),
+			     gimple_call_return_flags (t) | ERF_NOALIAS,
 			     vNULL, fndecl);
 	    get_constraint_for_ptr_offset (gimple_call_lhs (t),
 					   NULL_TREE, &lhsc);
@@ -4312,6 +4313,17 @@ find_func_aliases_for_builtin_call (struct function *fn, gimple t)
 	    process_all_all_constraints (lhsc, rhsc);
 	    lhsc.release ();
 	    rhsc.release ();
+	    /* For realloc the resulting pointer can be equal to the
+	       argument as well.  But only doing this wouldn't be
+	       correct because with ptr == 0 realloc behaves like malloc.  */
+	    if (DECL_FUNCTION_CODE (fndecl) == BUILT_IN_REALLOC)
+	      {
+		get_constraint_for (gimple_call_lhs (t), &lhsc);
+		get_constraint_for (gimple_call_arg (t, 0), &rhsc);
+		process_all_all_constraints (lhsc, rhsc);
+		lhsc.release ();
+		rhsc.release ();
+	      }
 	    return true;
 	  }
 	break;
@@ -4535,7 +4547,8 @@ find_func_aliases_for_call (struct function *fn, gimple t)
       else
 	handle_rhs_call (t, &rhsc);
       if (gimple_call_lhs (t))
-	handle_lhs_call (t, gimple_call_lhs (t), flags, rhsc, fndecl);
+	handle_lhs_call (t, gimple_call_lhs (t),
+			 gimple_call_return_flags (t), rhsc, fndecl);
       rhsc.release ();
     }
   else