gas: maintain O_constant signedness in more cases

Unary '~' doesn't really produce an unsigned result. Neither does
subtraction (unless taking operand values into consideration). And an
abstract operator applied to two operands which aren't both unsigned
can't be assumed to yield an unsigned result; exceptions are
- shifts, where only signedness of the left hand operand matters,
- comparisons, which - unlike unary '!' - produce signed results (they
  deliver 0 or ~0, as opposed to '!', which yields 0 or 1),
- logical operators (yielding 0 or 1 and hence treated like unary '!').

While doing this (specifically while extending the all/quad testcase),
update .quad and .8byte documentation: With 64-bit architectures now
being common, it is highly inappropriate to state that these directives
unconditionally require bignums.

1 files changed, 18 insertions, 10 deletions

diff --git a/gas/doc/as.texi b/gas/doc/as.texi
index ea18df2..10f9417 100644
--- a/gas/doc/as.texi
+++ b/gas/doc/as.texi
@@ -4631,7 +4631,7 @@ Some machine configurations provide additional directives.
 @end ifclear
 * 2byte::                       @code{.2byte @var{expressions}}
 * 4byte::                       @code{.4byte @var{expressions}}
-* 8byte::                       @code{.8byte @var{bignums}}
+* 8byte::                       @code{.8byte @var{expressions}}
 * Deprecated::                  Deprecated Directives
 @end menu
 
@@ -6579,14 +6579,16 @@ as in the @code{.section} (@pxref{Section}) directive.
 @end ifset
 
 @node Quad
-@section @code{.quad @var{bignums}}
+@section @code{.quad @var{expressions}}
 
 @cindex @code{quad} directive
-@code{.quad} expects zero or more bignums, separated by commas.  For
-each bignum, it emits
 @ifclear bignum-16
-an 8-byte integer.  If the bignum won't fit in 8 bytes, it prints a
-warning message; and just takes the lowest order 8 bytes of the bignum.
+For 64-bit architectures, or more generally with any GAS configured to support
+64-bit target virtual addresses, this is like @samp{.int}, but emitting 64-bit
+quantities.  Otherwise @code{.quad} expects zero or more bignums, separated by
+commas.  For each item, it emits an 8-byte integer.  If a bignum won't fit in
+8 bytes, a warning message is printed and just the lowest order 8 bytes of the
+bignum are taken.
 @cindex eight-byte integer
 @cindex integer, 8-byte
 
@@ -6594,8 +6596,11 @@ The term ``quad'' comes from contexts in which a ``word'' is two bytes;
 hence @emph{quad}-word for 8 bytes.
 @end ifclear
 @ifset bignum-16
-a 16-byte integer.  If the bignum won't fit in 16 bytes, it prints a
-warning message; and just takes the lowest order 16 bytes of the bignum.
+@code{.quad} expects zero or more bignums, separated by commas.  For
+each bignum, it emits a 16-byte integer.  If the bignum won't fit in 16
+bytes, it prints a warning message; and just takes the lowest order 16
+bytes of the bignum.
+@xref{Octa,,@code{.octa @var{bignums}}}.
 @cindex sixteen-byte integer
 @cindex integer, 16-byte
 @end ifset
@@ -7693,8 +7698,11 @@ long values into the output.
 @cindex eight-byte integer
 @cindex integer, 8-byte
 
-Like the @option{.2byte} directive, except that it inserts unaligned, eight
-byte long bignum values into the output.
+For 64-bit architectures, or more generally with any GAS configured to support
+64-bit target virtual addresses, this is like the @option{.2byte} directive,
+except that it inserts unaligned, eight byte long values into the output.
+Otherwise, like @ref{Quad,,@code{.quad @var{expressions}}}, it expects zero or
+more bignums, separated by commas.
 
 @node Deprecated
 @section Deprecated Directives