From: rguenth <rguenth@138bc75d-0d04-0410-961f-82ee72b054a4>
Date: Wed, 4 Jan 2012 13:25:28 +0000 (+0000)
Subject: 2012-01-04  Richard Guenther  <rguenther@suse.de>
X-Git-Url: http://git.sourceforge.jp/view?p=pf3gnuchains%2Fgcc-fork.git;a=commitdiff_plain;h=a6c23958b0f999e3d48b0679e263be234368dc99;hp=f48068845f391e30be9c0962ab50f70d8c7a4f4d

2012-01-04  Richard Guenther  <rguenther@suse.de>

	PR middle-end/51750
	* tree.c (size_low_cst): New function.
	* tree.h (size_low_cst): Declare.
	* fold-const.c (fold_comparison): Use it to extract the low
	part of the POINTER_PLUS_EXPR offset.


git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@182872 138bc75d-0d04-0410-961f-82ee72b054a4
---

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index e34cfa07d30..33caab17d6a 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,11 @@
+2012-01-04  Richard Guenther  <rguenther@suse.de>
+
+	PR middle-end/51750
+	* tree.c (size_low_cst): New function.
+	* tree.h (size_low_cst): Declare.
+	* fold-const.c (fold_comparison): Use it to extract the low
+	part of the POINTER_PLUS_EXPR offset.
+
 2012-01-04  Georg-Johann Lay  <avr@gjlay.de>
 
 	Fix clearing ZERO_REG
diff --git a/gcc/fold-const.c b/gcc/fold-const.c
index b88b5d72621..40a0986dda8 100644
--- a/gcc/fold-const.c
+++ b/gcc/fold-const.c
@@ -8886,13 +8886,16 @@ fold_comparison (location_t loc, enum tree_code code, tree type,
 	      indirect_base0 = true;
 	    }
 	  offset0 = TREE_OPERAND (arg0, 1);
-	  if (host_integerp (offset0, 0)
-	      && ((HOST_WIDE_INT) (TREE_INT_CST_LOW (offset0) * BITS_PER_UNIT)
-		  / BITS_PER_UNIT
-		  == (HOST_WIDE_INT) TREE_INT_CST_LOW (offset0)))
+	  if (host_integerp (offset0, 0))
 	    {
-	      bitpos0 = TREE_INT_CST_LOW (offset0) * BITS_PER_UNIT;
-	      offset0 = NULL_TREE;
+	      HOST_WIDE_INT off = size_low_cst (offset0);
+	      if ((HOST_WIDE_INT) (((unsigned HOST_WIDE_INT) off)
+				   * BITS_PER_UNIT)
+		  / BITS_PER_UNIT == (HOST_WIDE_INT) off)
+		{
+		  bitpos0 = off * BITS_PER_UNIT;
+		  offset0 = NULL_TREE;
+		}
 	    }
 	}
 
@@ -8917,13 +8920,16 @@ fold_comparison (location_t loc, enum tree_code code, tree type,
 	      indirect_base1 = true;
 	    }
 	  offset1 = TREE_OPERAND (arg1, 1);
-	  if (host_integerp (offset1, 0)
-	      && ((HOST_WIDE_INT) (TREE_INT_CST_LOW (offset1) * BITS_PER_UNIT)
-		  / BITS_PER_UNIT
-		  == (HOST_WIDE_INT) TREE_INT_CST_LOW (offset1)))
+	  if (host_integerp (offset1, 0))
 	    {
-	      bitpos1 = TREE_INT_CST_LOW (offset1) * BITS_PER_UNIT;
-	      offset1 = NULL_TREE;
+	      HOST_WIDE_INT off = size_low_cst (offset1);
+	      if ((HOST_WIDE_INT) (((unsigned HOST_WIDE_INT) off)
+				   * BITS_PER_UNIT)
+		  / BITS_PER_UNIT == (HOST_WIDE_INT) off)
+		{
+		  bitpos1 = off * BITS_PER_UNIT;
+		  offset1 = NULL_TREE;
+		}
 	    }
 	}
 
diff --git a/gcc/tree.c b/gcc/tree.c
index d7bbae3c675..76488f7528a 100644
--- a/gcc/tree.c
+++ b/gcc/tree.c
@@ -6509,6 +6509,17 @@ tree_low_cst (const_tree t, int pos)
   return TREE_INT_CST_LOW (t);
 }
 
+/* Return the HOST_WIDE_INT least significant bits of T, a sizetype
+   kind INTEGER_CST.  This makes sure to properly sign-extend the
+   constant.  */
+
+HOST_WIDE_INT
+size_low_cst (const_tree t)
+{
+  double_int d = tree_to_double_int (t);
+  return double_int_sext (d, TYPE_PRECISION (TREE_TYPE (t))).low;
+}
+
 /* Return the most significant (sign) bit of T.  */
 
 int
diff --git a/gcc/tree.h b/gcc/tree.h
index 7a0046b8260..2ea03a092f6 100644
--- a/gcc/tree.h
+++ b/gcc/tree.h
@@ -4428,6 +4428,7 @@ tree_low_cst (const_tree t, int pos)
   return TREE_INT_CST_LOW (t);
 }
 #endif
+extern HOST_WIDE_INT size_low_cst (const_tree);
 extern int tree_int_cst_sgn (const_tree);
 extern int tree_int_cst_sign_bit (const_tree);
 extern unsigned int tree_int_cst_min_precision (tree, bool);