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[PATCH] Fix PR54211


Fix a thinko in strength reduction.  I was checking the type of the
wrong operand to determine whether address arithmetic should be used in
replacing expressions.  This produced a spurious POINTER_PLUS_EXPR when
an address was converted to an unsigned long and back again.

Bootstrapped and tested on powerpc64-unknown-linux-gnu with no new
regressions.  Ok for trunk?

Thanks,
Bill


gcc:

2012-08-09  Bill Schmidt  <wschmidt@linux.vnet.ibm.com>

	PR middle-end/54211
	* gimple-ssa-strength-reduction.c (analyze_candidates_and_replace):
	Use cand_type to determine whether pointer arithmetic will be generated.

gcc/testsuite:

2012-08-09  Bill Schmidt  <wschmidt@linux.vnet.ibm.com>

	PR middle-end/54211
	* gcc.dg/tree-ssa/pr54211.c: New test.


Index: gcc/testsuite/gcc.dg/tree-ssa/pr54211.c
===================================================================
--- gcc/testsuite/gcc.dg/tree-ssa/pr54211.c	(revision 0)
+++ gcc/testsuite/gcc.dg/tree-ssa/pr54211.c	(revision 0)
@@ -0,0 +1,28 @@
+/* { dg-do compile } */
+/* { dg-options "-Os" } */
+
+int a, b;
+unsigned char e;
+void fn1 ()
+{
+    unsigned char *c=0;
+    for (;; a++)
+    {
+        unsigned char d = *(c + b);
+        for (; &e<&d; c++)
+            goto Found_Top;
+    }
+Found_Top:
+    if (0)
+        goto Empty_Bitmap;
+    for (;; a++)
+    {
+        unsigned char *e = c + b;
+        for (; c < e; c++)
+            goto Found_Bottom;
+        c -= b;
+    }
+Found_Bottom:
+Empty_Bitmap:
+    ;
+}
Index: gcc/gimple-ssa-strength-reduction.c
===================================================================
--- gcc/gimple-ssa-strength-reduction.c	(revision 190260)
+++ gcc/gimple-ssa-strength-reduction.c	(working copy)
@@ -2534,7 +2534,7 @@ analyze_candidates_and_replace (void)
 	  /* Determine whether we'll be generating pointer arithmetic
 	     when replacing candidates.  */
 	  address_arithmetic_p = (c->kind == CAND_ADD
-				  && POINTER_TYPE_P (TREE_TYPE (c->base_expr)));
+				  && POINTER_TYPE_P (c->cand_type));
 
 	  /* If all candidates have already been replaced under other
 	     interpretations, nothing remains to be done.  */



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