gas/

    * read.c (convert_to_bignum): Add sign parameter. Use it
    instead of X_unsigned to determine sign of resulting bignum.
    (emit_expr): Pass extra argument to convert_to_bignum.
    (emit_leb128_expr): Use X_extrabit instead of X_unsigned. Pass
    X_extrabit to convert_to_bignum.
    (parse_bitfield_cons): Set X_extrabit.
    * expr.c (make_expr_symbol, expr_build_uconstant, operand):
    Initialise X_extrabit field as appropriate.
    (add_to_result): New.
    (subtract_from_result): New.
    (expr): Use above.
    * expr.h (expressionS): Add X_extrabit field.

    gas/testsuite/
    * gas/all/sleb128-2.s: New test.
    * gas/all/sleb128-3.s: Likewise.
    * gas/all/sleb128-4.s: Likewise.
    * gas/all/sleb128-5.s: Likewise.
    * gas/all/sleb128-7.s: Likewise.
    * gas/all/sleb128-2.d: New.
    * gas/all/sleb128-3.d: New.
    * gas/all/sleb123-4.d: New.
    * gas/all/sleb123-5.d: New.
    * gas/all/sleb123-7.d: New.
    * gas/all/gas.exp (sleb128-2, sleb128-3, sleb128-4, sleb128-5)
    (sleb128-7): Run new tests.

1 files changed, 5 insertions, 0 deletions

diff --git a/gas/expr.h b/gas/expr.h
index cce932d..d2cb7fd 100644
--- a/gas/expr.h
+++ b/gas/expr.h
@@ -136,6 +136,11 @@ typedef struct expressionS {
      when performing arithmetic on these values).
      FIXME: This field is not set very reliably.  */
   unsigned int X_unsigned : 1;
+  /* This is used to implement "word size + 1 bit" arithmetic, so that e.g.
+     expressions used with .sleb128 directives can use the full range available
+     for an unsigned word, but can also properly represent all values of a
+     signed word.  */
+  unsigned int X_extrabit : 1;
 
   /* 7 additional bits can be defined if needed.  */