re PR c/39779 (ICE shifting byte to the right with constant > 7FFFFFFF)

	PR rtl-optimization/39779
	* expr.c (convert_modes): Return when mode == oldmode after
	CONST_INTs are processed.

testsuite/ChangeLog:

	PR rtl-optimization/39779
	* gcc.dg/pr39979.c: New test.

From-SVN: r151573

gcc/expr.c

@@ -761,9 +761,6 @@ convert_modes (enum machine_mode mode, enum machine_mode oldmode, rtx x, int uns
   if (GET_MODE (x) != VOIDmode)
     oldmode = GET_MODE (x);
 
-  if (mode == oldmode)
-    return x;
-
   /* There is one case that we must handle specially: If we are converting
      a CONST_INT into a mode whose size is twice HOST_BITS_PER_WIDE_INT and
      we are to interpret the constant as unsigned, gen_lowpart will do
@@ -829,6 +826,9 @@ convert_modes (enum machine_mode mode, enum machine_mode oldmode, rtx x, int uns
       return gen_lowpart (mode, x);
     }
 
+  if (mode == oldmode)
+    return x;
+
   /* Converting from integer constant into mode is always equivalent to an
      subreg operation.  */
   if (VECTOR_MODE_P (mode) && GET_MODE (x) == VOIDmode)

gcc/testsuite/ChangeLog

+2009-09-09 Uros Bizjak <ubizjak@gmail.com>
+
+	PR rtl-optimization/39779
+	* gcc.dg/pr39979.c: New test.
+
 2009-09-09  Richard Guenther  <rguenther@suse.de>
 
 	PR tree-optimization/41101

gcc/testsuite/gcc.dg/pr39779.c

+/* { dg-do compile } */
+/* { dg-options "-w" } */
+
+int test (char v1)
+{
+  v1 >>= 0xdebecced;
+  return v1;
+}