Fix PR47707

From-SVN: r170062

gcc/ChangeLog

+2011-02-11  Xinliang David Li  <davidxl@google.com>
+
+	PR tree-optimization/47707
+	* tree-chrec.c (convert_affine_scev): Keep type precision.
+
 2011-02-11  Eric Botcazou  <ebotcazou@adacore.com>
 
 	PR tree-optimization/47420

gcc/testsuite/ChangeLog

+2011-02-11  Xinliang David Li  <davidxl@google.com>
+
+	PR tree-optimization/47707
+	* g++.dg/tree-ssa/pr47707.C: New test.
+
 2011-02-11  Eric Botcazou  <ebotcazou@adacore.com>
 
 	* g++.dg/opt/inline17.C: New test.

gcc/testsuite/g++.dg/tree-ssa/pr47707.C

+/* { dg-do run } */
+/* { dg-options "-O2 -fno-tree-vrp" } */
+#include <assert.h>
+
+struct CH
+{
+  unsigned char ch : 3;
+} ch;
+
+__attribute__((noinline)) void MakeCheckOp (unsigned int *v1, unsigned int *v2)
+{
+ assert (*v1 == *v2);
+
+}
+
+int main (void)
+{
+
+  int len;
+
+  for (len = 4; len >= 1; len--)
+  {
+     unsigned v1, v2;
+     ch.ch = len;
+     v1 = ch.ch;
+     v2 = len;
+     MakeCheckOp (&v1, &v2);
+  }
+}

gcc/tree-chrec.c

@@ -1238,8 +1238,11 @@ convert_affine_scev (struct loop *loop, tree type,
      performed by default when CT is signed.  */
   new_step = *step;
   if (TYPE_PRECISION (step_type) > TYPE_PRECISION (ct) && TYPE_UNSIGNED (ct))
-    new_step = chrec_convert_1 (signed_type_for (ct), new_step, at_stmt,
-				use_overflow_semantics);
+    {
+      tree signed_ct = build_nonstandard_integer_type (TYPE_PRECISION (ct), 0);
+      new_step = chrec_convert_1 (signed_ct, new_step, at_stmt,
+                                  use_overflow_semantics);
+    }
   new_step = chrec_convert_1 (step_type, new_step, at_stmt, use_overflow_semantics);
 
   if (automatically_generated_chrec_p (new_base)
@@ -1579,4 +1582,3 @@ evolution_function_right_is_integer_cst (const_tree chrec)
       return false;
     }
 }
-