Re: Query regarding expression evaluation.

[Andreas Schwab <schwab@suse.de>]

Ramana Radhakrishnan <ramana.radhakrishnan@codito.com> writes:

> Look at PR1978 . The discrepancy is because in valarith.c , GDB takes
> the operation to be unsigned depending only on the operand types. In the
> case described in the PR this seems alright with respect to the C
> standard since the result is implementation dependent. 

Here is a fix:

2005-08-11  Andreas Schwab  <schwab@suse.de>

	PR exp/1978
	* valarith.c (value_binop): Fix result type for the shift
	operators.

--- gdb/valarith.c.~1.41.~	2005-07-07 11:12:12.000000000 +0200
+++ gdb/valarith.c	2005-08-10 18:22:48.000000000 +0200
@@ -883,7 +883,14 @@ value_binop (struct value *arg1, struct 
          Use the signedness of the operand with the greater length.
          If both operands are of equal length, use unsigned operation
          if one of the operands is unsigned.  */
-      if (promoted_len1 > promoted_len2)
+      if (op == BINOP_RSH || op == BINOP_LSH)
+	{
+	  /* In case of the shift operators the type of the result only
+	     depends on the type of the left operand.  */
+	  unsigned_operation = is_unsigned1;
+	  result_len = promoted_len1;
+	}
+      else if (promoted_len1 > promoted_len2)
 	{
 	  unsigned_operation = is_unsigned1;
 	  result_len = promoted_len1;

Andreas.

-- 
Andreas Schwab, SuSE Labs, schwab@suse.de
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