Committed: Document ARM's .syntax directive for GAS

[Nick Clifton <nickc at redhat dot com>]

Hi Guys,

  I am checking in the patch below to document the .syntax directive
  supported by the ARM port of GAS.  I noticed that the description
  was missing whilst investigating a different problem and I thought
  that it would be a good idea to make sure that it was documented.

Cheers
  Nick

gas/ChangeLog
2009-07-30  Nick Clifton  <nickc@redhat.com>

	* doc/c-arm.texi (ARM-Instruction-Set): New node.  Documents the
	different syntaxes support by the ARM port.
	(ARM Directives): Add entry for .syntax.

Index: gas/doc/c-arm.texi
===================================================================
RCS file: /cvs/src/src/gas/doc/c-arm.texi,v
retrieving revision 1.59
diff -c -3 -p -r1.59 c-arm.texi
*** gas/doc/c-arm.texi	15 Jul 2009 15:08:55 -0000	1.59
--- gas/doc/c-arm.texi	30 Jul 2009 08:46:23 -0000
*************** features.  The default is to warn.
*** 323,333 ****
--- 323,369 ----
  @node ARM Syntax
  @section Syntax
  @menu
+ * ARM-Instruction-Set::      Instruction Set
  * ARM-Chars::                Special Characters
  * ARM-Regs::                 Register Names
  * ARM-Relocations::	     Relocations
  @end menu
  
+ @node ARM-Instruction-Set
+ @subsection Instruction Set Syntax
+ Two slightly different syntaxes are support for ARM and THUMB
+ instructions.  The default, @code{divided}, uses the old style where
+ ARM and THUMB instructions had their own, separate syntaxes.  The new,
+ @code{unified} syntax, which can be selected via the @code{.syntax}
+ directive, and has the following main features:
+ 
+ @table @bullet
+ @item
+ Immediate operands do not require a @code{#} prefix.
+ 
+ @item
+ The @code{IT} instruction may appear, and if it does it is validated
+ against subsequent conditional affixes.  In ARM mode it does not
+ generate machine code, in THUMB mode it does.
+ 
+ @item
+ For ARM instructions the conditional affixes always appear at the end
+ of the instruction.  For THUMB instructions conditional affixes can be
+ used, but only inside the scope of an @code{IT} instruction.
+ 
+ @item
+ All of the instructions new to the V6T2 architecture (and later) are
+ available.  (Only a few such instructions can be written in the
+ @code{divided} syntax).
+ 
+ @item
+ The @code{.N} and @code{.W} suffixes are recognized and honored.
+ 
+ @item
+ All instructions set the flags if and only if they have an @code{s}
+ affix.
+ @end table
+ 
  @node ARM-Chars
  @subsection Special Characters
  
*************** This directive emits relocations that ev
*** 722,727 ****
--- 758,768 ----
  offset of each expression's symbol.  This directive is only supported
  for PE targets.
  
+ @cindex @code{.syntax} directive, ARM
+ @item .syntax [@code{unified} | @code{divided}]
+ This directive sets the Instruction Set Syntax as described in the
+ @ref{ARM-Instruction-Set} section.
+ 
  @c TTTTTTTTTTTTTTTTTTTTTTTTTT
  
  @cindex @code{.thumb} directive, ARM