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[PATCH] Fix PR51750
- From: Richard Guenther <rguenther at suse dot de>
- To: gcc-patches at gcc dot gnu dot org
- Date: Wed, 4 Jan 2012 14:22:09 +0100 (CET)
- Subject: [PATCH] Fix PR51750
Another manifestation about the issue we have wrt sizetypes
implicitly sign-extending but types-compatible types not.
Bootstrapped and tested on x86_64-unknown-linux-gnu, applied to trunk.
Richard.
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.
Index: gcc/tree.c
===================================================================
--- gcc/tree.c (revision 182867)
+++ gcc/tree.c (working copy)
@@ -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
Index: gcc/tree.h
===================================================================
--- gcc/tree.h (revision 182867)
+++ gcc/tree.h (working copy)
@@ -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);
Index: gcc/fold-const.c
===================================================================
--- gcc/fold-const.c (revision 182867)
+++ gcc/fold-const.c (working copy)
@@ -8886,13 +8886,16 @@ fold_comparison (location_t loc, enum tr
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 tr
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;
+ }
}
}