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[Xtensa] clarify GAS documentation
- From: Bob Wilson <bwilson at tensilica dot com>
- To: binutils at sources dot redhat dot com
- Date: Thu, 24 Jan 2008 17:09:36 -0800
- Subject: [Xtensa] clarify GAS documentation
I've committed this patch to clarify some issues in the Xtensa-specific portions
of the GAS documentation.
2008-01-24 Bob Wilson <bob.wilson@acm.org>
* doc/c-xtensa.texi (Xtensa Syntax): Clarify handling of opcodes that
can only be encoded in FLIX instructions but are not specified as such.
(Xtensa Automatic Alignment): Remove obsolete comment about debugging
labels.
Index: doc/c-xtensa.texi
===================================================================
RCS file: /cvs/src/src/gas/doc/c-xtensa.texi,v
retrieving revision 1.12
diff -u -r1.12 c-xtensa.texi
--- doc/c-xtensa.texi 19 Sep 2007 20:37:37 -0000 1.12
+++ doc/c-xtensa.texi 25 Jan 2008 00:56:23 -0000
@@ -144,10 +144,10 @@
@{ [@var{format};] @var{opcode0} [@var{operands}]; @var{opcode1} [@var{operands}]; @var{opcode2} [@var{operands}]; @dots{} @}
@end smallexample
-The assembler can automatically bundle opcodes into FLIX instructions.
-It encodes the opcodes in order, one at a time,
-choosing the smallest format where each opcode can be encoded and
-filling unused instruction slots with no-ops.
+If an opcode can only be encoded in a FLIX instruction but is not
+specified as part of a FLIX bundle, the assembler will choose the
+smallest format where the opcode can be encoded and
+will fill unused instruction slots with no-ops.
@menu
* Xtensa Opcodes:: Opcode Naming Conventions.
@@ -255,9 +255,7 @@
instruction immediately following a call is treated as a branch target
in this context, because it will be the target of a return from the
call. This alignment has the potential to reduce branch penalties at
-some expense in code size. The assembler will not attempt to align
-labels with the prefixes @code{.Ln} and @code{.LM}, since these labels
-are used for debugging information and are not typically branch targets.
+some expense in code size.
This optimization is enabled by default. You can disable it with the
@samp{--no-target-@-align} command-line option (@pxref{Xtensa Options,
,Command Line Options}).