re PR middle-end/32244 (bit-field: optimization BUG)

2008-01-25  Richard Guenther  <rguenther@suse.de>

	PR middle-end/32244
	* expr.c (expand_expr_real_1): Reduce result of LSHIFT_EXPR
	to its bitfield precision if required.

	* gcc.c-torture/execute/pr32244-1.c: New testcase.

From-SVN: r131828

gcc/ChangeLog

@@ -1,3 +1,9 @@
+2008-01-25  Richard Guenther  <rguenther@suse.de>
+
+	PR middle-end/32244
+	* expr.c (expand_expr_real_1): Reduce result of LSHIFT_EXPR
+	to its bitfield precision if required.
+
 2008-01-25  Jakub Jelinek  <jakub@redhat.com>
 
 	PR middle-end/33880

gcc/expr.c

@@ -8920,8 +8920,11 @@ expand_expr_real_1 (tree exp, rtx target, enum machine_mode tmode,
 	target = 0;
       op0 = expand_expr (TREE_OPERAND (exp, 0), subtarget,
 			 VOIDmode, EXPAND_NORMAL);
-      return expand_shift (code, mode, op0, TREE_OPERAND (exp, 1), target,
+      temp = expand_shift (code, mode, op0, TREE_OPERAND (exp, 1), target,
 			   unsignedp);
+      if (code == LSHIFT_EXPR)
+	temp = REDUCE_BIT_FIELD (temp);
+      return temp;
 
       /* Could determine the answer when only additive constants differ.  Also,
 	 the addition of one can be handled by changing the condition.  */

gcc/testsuite/ChangeLog

@@ -1,3 +1,8 @@
+2008-01-25  Richard Guenther  <rguenther@suse.de>
+
+	PR middle-end/32244
+	* gcc.c-torture/execute/pr32244-1.c: New testcase.
+
 2008-01-25  Richard Guenther  <rguenther@suse.de>
 
 	PR tree-optimization/34966

gcc/testsuite/gcc.c-torture/execute/pr32244-1.c

@@ -0,0 +1,20 @@
+struct foo
+{
+  unsigned long long b:40;
+} x;
+
+extern void abort (void);
+
+void test1(unsigned long long res)
+{
+  /* The shift is carried out in 40 bit precision.  */
+  if (x.b<<32 != res)
+    abort ();
+}
+
+int main()
+{
+  x.b = 0x0100;
+  test1(0);
+  return 0;
+}