Re: [PATCH v2 RESEND] Document .Nbyte assembler directives

[Nick Clifton <nickc at redhat dot com>]

Hi Richard,

> Why zero or more?

No idea - maybe it was so that gcc could generate these directives without
having to check that there always was a value to be generated ?

> What happens if there are zero expressions?  Do I get
> a single entry inserted (with what), or nothing?
> 
> I think it's also worth pointing out that these:
> - Don't align (even if .short, .word, etc would)
> - Might affect the choice of relocation in a target-dependent manner.
> - Follow the natural endian model for the target (sort of expected, but
> probably worth stating anyway).
> 
> Given the above, it might be worth reworking this so that all three
> directives come in a single block with a common description; or put all
> the information in the first and reference it in the subsequent entries.

Is this what you had in mind:

Cheers
  Nick

diff --git a/gas/doc/as.texinfo b/gas/doc/as.texinfo
index 3b3e931..20791cc 100644
--- a/gas/doc/as.texinfo
+++ b/gas/doc/as.texinfo
@@ -7345,10 +7345,19 @@ instead of zero.  Using @samp{.zero} in this way would be confusing however.
 @cindex two-byte integer
 @cindex integer, 2-byte
 
-This directive expects zero or more expressions, separated by commas.  Each
-expression is evaluated and placed in the next two bytes of the current
-section.  If an expression will not fit in two bytes, a warning message
-is displayed and the lowest two bytes of the expression's value are used.
+This directive expects zero or more expressions, separated by commas.  If there
+are no expressions then the directive does nothing.  Otherwise each expression
+is evaluated in turn and placed in the next two bytes of the current output
+section, using the endian model of the target.  If an expression will not fit
+in two bytes, a warning message is displayed and the lowest two bytes of the
+expression's value are used.  If an expression cannot be evaluated at assembly
+time then relocations will be generated in order to compute the value at link
+time.  
+
+This directive does not apply any alignment before or after inserting the
+values.  As a result of this, if relocations are generated, they may be
+different from those used for inserting values with a guaranteed alignment.
+
 This directive is only available for ELF targets,
 
 @node 4byte
@@ -7357,11 +7366,8 @@ This directive is only available for ELF targets,
 @cindex four-byte integer
 @cindex integer, 4-byte
 
-This directive expects zero or more expressions, separated by commas.  Each
-expression is evaluated and placed in the next four bytes of the current
-section.  If an expression will not fit in four bytes, a warning message
-is displayed and the lowest four bytes of the expression's value are used.
-This directive is only available for ELF targets,
+Like the @option{.2byte} directive, except that it inserts unaligned, four byte
+long values into the output.
 
 @node 8byte
 @section @code{.8byte @var{expression} [, @var{expression}]*}
@@ -7369,11 +7375,9 @@ This directive is only available for ELF targets,
 @cindex eight-byte integer
 @cindex integer, 8-byte
 
-This directive expects zero or more expressions, separated by commas.  Each
-expression is evaluated and the resulting bignum is placed in the next eight
-bytes of the current section.  If an expression will not fit in eight bytes, a
-warning message is displayed and the lowest eight bytes of the expression's
-value are used.  This directive is only available for ELF targets,
+Like the @option{.8byte} directive, except that it inserts unaligned, eight
+byte long bignum values into the output.
+
 @end ifset
 
 @node Deprecated