2006-04-05 Richard Guenther <rguenther@suse.de>

	PR tree-optimization/26763
	* fold-const.c (fold_comparison): Move folding of
	PTR + CST CMP PTR + CST ...
	(fold_binary): ... here.  Fold only for EQ_EXPR and NE_EXPR.

	* gcc.dg/torture/pr26763-1.c: New testcase.
	* gcc.dg/torture/pr26763-2.c: Likewise.

git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@112697 138bc75d-0d04-0410-961f-82ee72b054a4

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index fa7f412..5c3f251 100644 (file)
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,10 @@
+2006-04-05  Richard Guenther  <rguenther@suse.de>
+
+       PR tree-optimization/26763
+       * fold-const.c (fold_comparison): Move folding of
+       PTR + CST CMP PTR + CST ...
+       (fold_binary): ... here.  Fold only for EQ_EXPR and NE_EXPR.
+
 2006-04-05  Gerald Pfeifer  <gerald@pfeifer.com>
 
        * doc/install.texi (Prerequisites): Refine some wording on

diff --git a/gcc/fold-const.c b/gcc/fold-const.c
index aa710b1..d8f7efc 100644 (file)
--- a/gcc/fold-const.c
+++ b/gcc/fold-const.c
@@ -7305,33 +7305,6 @@ fold_comparison (enum tree_code code, tree type, tree op0, tree op1)
   if (tree_swap_operands_p (arg0, arg1, true))
     return fold_build2 (swap_tree_comparison (code), type, op1, op0);
 
-  /* If this is a comparison of two exprs that look like an
-     ARRAY_REF of the same object, then we can fold this to a
-     comparison of the two offsets.  */
-  {
-    tree base0, offset0, base1, offset1;
-
-    if (extract_array_ref (arg0, &base0, &offset0)
-       && extract_array_ref (arg1, &base1, &offset1)
-       && operand_equal_p (base0, base1, 0))
-      {
-       /* Handle no offsets on both sides specially.  */
-       if (offset0 == NULL_TREE && offset1 == NULL_TREE)
-         return fold_build2 (code, type, integer_zero_node,
-                             integer_zero_node);
-
-       if (!offset0 || !offset1
-           || TREE_TYPE (offset0) == TREE_TYPE (offset1))
-         {
-           if (offset0 == NULL_TREE)
-             offset0 = build_int_cst (TREE_TYPE (offset1), 0);
-           if (offset1 == NULL_TREE)
-             offset1 = build_int_cst (TREE_TYPE (offset0), 0);
-           return fold_build2 (code, type, offset0, offset1);
-         }
-      }
-  }
-
   /* Transform comparisons of the form X +- C1 CMP C2 to X CMP C2 +- C1.  */
   if ((TREE_CODE (arg0) == PLUS_EXPR || TREE_CODE (arg0) == MINUS_EXPR)
       && (TREE_CODE (TREE_OPERAND (arg0, 1)) == INTEGER_CST
@@ -10062,6 +10035,34 @@ fold_binary (enum tree_code code, tree type, tree op0, tree op1)
                              tem, build_int_cst (TREE_TYPE (tem), 0));
        }
 
+      /* If this is a comparison of two exprs that look like an
+        ARRAY_REF of the same object, then we can fold this to a
+        comparison of the two offsets.  This is only safe for
+        EQ_EXPR and NE_EXPR because of overflow issues.  */
+      {
+       tree base0, offset0, base1, offset1;
+
+       if (extract_array_ref (arg0, &base0, &offset0)
+           && extract_array_ref (arg1, &base1, &offset1)
+           && operand_equal_p (base0, base1, 0))
+          {
+           /* Handle no offsets on both sides specially.  */
+           if (offset0 == NULL_TREE && offset1 == NULL_TREE)
+             return fold_build2 (code, type, integer_zero_node,
+                                 integer_zero_node);
+
+           if (!offset0 || !offset1
+               || TREE_TYPE (offset0) == TREE_TYPE (offset1))
+             {
+               if (offset0 == NULL_TREE)
+                 offset0 = build_int_cst (TREE_TYPE (offset1), 0);
+               if (offset1 == NULL_TREE)
+                 offset1 = build_int_cst (TREE_TYPE (offset0), 0);
+               return fold_build2 (code, type, offset0, offset1);
+             }
+         }
+      }
+
       if (integer_zerop (arg1)
          && tree_expr_nonzero_p (arg0))
         {

diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index da9fedb..8c32d4e 100644 (file)
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,9 @@
+2006-04-05  Richard Guenther  <rguenther@suse.de>
+
+       PR tree-optimization/26763
+       * gcc.dg/torture/pr26763-1.c: New testcase.
+       * gcc.dg/torture/pr26763-2.c: Likewise.
+
 2006-04-04  Paul Thomas  <pault@gcc.gnu.org>
 
        PR fortran/23634

diff --git a/gcc/testsuite/gcc.dg/torture/pr26763-1.c b/gcc/testsuite/gcc.dg/torture/pr26763-1.c
new file mode 100644 (file)
index 0000000..37054e7
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/torture/pr26763-1.c
@@ -0,0 +1,18 @@
+/* { dg-do run } */
+
+extern void abort(void);
+
+int try (int *a)
+{
+  return a + -1 > a;
+}
+
+int main(void)
+{
+  int bla[100];
+
+  if (try (bla + 50))
+    abort ();
+
+  return 0;
+}

diff --git a/gcc/testsuite/gcc.dg/torture/pr26763-2.c b/gcc/testsuite/gcc.dg/torture/pr26763-2.c
new file mode 100644 (file)
index 0000000..d8155fb
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/torture/pr26763-2.c
@@ -0,0 +1,18 @@
+/* { dg-do run } */
+
+extern void abort(void);
+
+int try (char *a, int d)
+{
+  return a + d > a;
+}
+
+int main(void)
+{
+  char bla[100];
+
+  if (try (bla + 50, -1))
+    abort ();
+
+  return 0;
+}