SOURCES (GCC_4_1): gcc-pr27364.patch (NEW) - fix detection of over...

[pluto]

Author: pluto                        Date: Tue May  2 21:00:43 2006 GMT
Module: SOURCES                       Tag: GCC_4_1
---- Log message:
- fix detection of overflow from multiply expressions.

---- Files affected:
SOURCES:
   gcc-pr27364.patch (NONE -> 1.1.2.1)  (NEW)

---- Diffs:

================================================================
Index: SOURCES/gcc-pr27364.patch
diff -u /dev/null SOURCES/gcc-pr27364.patch:1.1.2.1
--- /dev/null	Tue May  2 23:00:43 2006
+++ SOURCES/gcc-pr27364.patch	Tue May  2 23:00:38 2006
@@ -0,0 +1,47 @@
+	PR tree-optimization/27364
+	* tree-vrp.c (vrp_int_const_binop): Fix detection of overflow from
+	multiply expressions.
+
+--- gcc-4_1-branch/gcc/tree-vrp.c.orig	2006-02-10 09:46:43.000000000 +0100
++++ gcc-4_1-branch/gcc/tree-vrp.c	2006-05-02 22:59:17.000000000 +0200
+@@ -1101,17 +1101,39 @@
+   if (TYPE_UNSIGNED (TREE_TYPE (val1)))
+     {
+       int checkz = compare_values (res, val1);
++      bool overflow = false;
+ 
+       /* Ensure that res = val1 [+*] val2 >= val1
+          or that res = val1 - val2 <= val1.  */
+-      if (((code == PLUS_EXPR || code == MULT_EXPR)
++      if ((code == PLUS_EXPR
+ 	   && !(checkz == 1 || checkz == 0))
+           || (code == MINUS_EXPR
+ 	      && !(checkz == 0 || checkz == -1)))
+ 	{
++	  overflow = true;
++	}
++      /* Checking for multiplication overflow is done by dividing the
++	 output of the multiplication by the first input of the
++	 multiplication.  If the result of that division operation is
++	 not equal to the second input of the multiplication, then the
++	 multiplication overflowed.  */
++      else if (code == MULT_EXPR && !integer_zerop (val1))
++	{
++	  tree tmp = int_const_binop (TRUNC_DIV_EXPR,
++				      TYPE_MAX_VALUE (TREE_TYPE (val1)),
++				      val1, 0);
++	  int check = compare_values (tmp, val2);
++
++	  if (check != 0)
++	    overflow = true;
++	}
++
++      if (overflow)
++	{
+ 	  res = copy_node (res);
+ 	  TREE_OVERFLOW (res) = 1;
+ 	}
++
+     }
+   else if (TREE_OVERFLOW (res)
+ 	   && !TREE_OVERFLOW (val1)
================================================================