[PATCH] gas value truncation warning reports truncated values, doesn't look at signedness.

[Bart Samwel]

Hi guys,

We've had a discussion on the linux-kernel mailing list about a warning 
that was generated by gas. The warning was correct, but it reported the 
same value for the truncated and the original value. It turns out that 
the warning prints unsigned longs, while the truncated values were 
unsigned long longs. Then I found another issue: the warning is issued 
for ~0x80000000 (which is correct, because this yields 
0xffffffff7fffffff) but not for ~0x7fffffff (which is incorrect, because 
this yields 0xffffffff80000000). The problem: the warning code assumes 
that the value is signed, even if it is really unsigned (like ~0x7fffffff).

The attached patch (against binutils 2.14) fixes this by upgrading the 
warning's format string to %Lx, and by taking into account the 
(un)signedness of the truncated value (through exp->X_unsigned). I hope 
this helps you to fix the problem.

If you reply to this message, please send it to my personal address as 
well, as I'm not subscribed to the list. Thanks!

-- Bart

diff -aur binutils-2.14.orig/gas/read.c binutils-2.14/gas/read.c
--- binutils-2.14.orig/gas/read.c       2003-06-02 22:35:23.000000000 +0200
+++ binutils-2.14/gas/read.c    2004-01-11 15:03:33.000000000 +0100
@@ -3641,11 +3641,12 @@
       get = exp->X_add_number;
       use = get & unmask;
       if ((get & mask) != 0
-         && ((get & mask) != mask
+         && (exp->X_unsigned
+             || (get & mask) != mask
              || (get & hibit) == 0))
        {               /* Leading bits contain both 0s & 1s.  */
-         as_warn (_("value 0x%lx truncated to 0x%lx"),
-                  (unsigned long) get, (unsigned long) use);
+         as_warn (_("value 0x%Lx truncated to 0x%Lx"),
+                  (unsigned long long) get, (unsigned long long) use);
        }
       /* Put bytes in right order.  */
       md_number_to_chars (p, use, (int) nbytes);