From: Richard Guenther <rguenther@suse.de>
Date: Fri, 2 Sep 2011 11:53:55 +0000 (+0000)
Subject: tree-ssa-ccp.c (fold_builtin_alloca_for_var): Do not fold alloca (0).
X-Git-Tag: releases/gcc-4.7.0~4001
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=5d882cc1dafe2546b34f1845f943b91f024dbac4;p=thirdparty%2Fgcc.git

tree-ssa-ccp.c (fold_builtin_alloca_for_var): Do not fold alloca (0).

2011-09-02  Richard Guenther  <rguenther@suse.de>

	* tree-ssa-ccp.c (fold_builtin_alloca_for_var): Do not
	fold alloca (0).
	(ccp_fold_stmt): Continue replacing args when folding
	alloca fails.

From-SVN: r178465
---

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index ffd2855a31bd..e8cdf9e71f4f 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,10 @@
+2011-09-02  Richard Guenther  <rguenther@suse.de>
+
+	* tree-ssa-ccp.c (fold_builtin_alloca_for_var): Do not
+	fold alloca (0).
+	(ccp_fold_stmt): Continue replacing args when folding
+	alloca fails.
+
 2011-08-31  Richard Guenther  <rguenther@suse.de>
 
 	* expr.c (expand_expr_real_2): Move COND_EXPR and VEC_COND_EXPR
diff --git a/gcc/tree-ssa-ccp.c b/gcc/tree-ssa-ccp.c
index 007e17dd8b68..fc8d74780eaa 100644
--- a/gcc/tree-ssa-ccp.c
+++ b/gcc/tree-ssa-ccp.c
@@ -1702,10 +1702,14 @@ fold_builtin_alloca_for_var (gimple stmt)
 
   /* Detect constant argument.  */
   arg = get_constant_value (gimple_call_arg (stmt, 0));
-  if (arg == NULL_TREE || TREE_CODE (arg) != INTEGER_CST
+  if (arg == NULL_TREE
+      || TREE_CODE (arg) != INTEGER_CST
       || !host_integerp (arg, 1))
     return NULL_TREE;
+
   size = TREE_INT_CST_LOW (arg);
+  if (size == 0)
+    return NULL_TREE;
 
   /* Heuristic: don't fold large vlas.  */
   threshold = (unsigned HOST_WIDE_INT)PARAM_VALUE (PARAM_LARGE_STACK_FRAME);
@@ -1804,12 +1808,12 @@ ccp_fold_stmt (gimple_stmt_iterator *gsi)
         if (gimple_call_alloca_for_var_p (stmt))
           {
             tree new_rhs = fold_builtin_alloca_for_var (stmt);
-            bool res;
-            if (new_rhs == NULL_TREE)
-              return false;
-            res = update_call_from_tree (gsi, new_rhs);
-            gcc_assert (res);
-            return true;
+            if (new_rhs)
+	      {
+		bool res = update_call_from_tree (gsi, new_rhs);
+		gcc_assert (res);
+		return true;
+	      }
           }
 
 	/* Propagate into the call arguments.  Compared to replace_uses_in