Generate BFD_RELOC_MMIX_PUSHJ_STUBBABLE for PUSHJ when possible.

	* doc/c-mmix.texi (MMIX-Opts): Document --no-pushj-stubs and
	--no-stubs.
	* config/tc-mmix.c: Include limits.h.  Expand on mmix_relax_table
	comment.
	(expand_op, mmix_next_semicolon_is_eoln): Fix head comment.
	(pushj_stubs): New variable.
	(OPTION_NOPUSHJSTUBS, STATE_PUSHJSTUB, PUSHJSTUB_MIN)
	(PUSHJSTUB_MAX): New macros.
	(md_longopts): New options "--no-pushj-stubs" and synonym
	"--no-stubs".
	(mmix_relax_table): Handle new entry for STATE_PUSHJSTUB.
	(md_parse_option): Handle OPTION_NOPUSHJSTUBS.
	(md_estimate_size_before_relax): Modify STATE_PUSHJ state for
	PUSHJ stub relaxation.
	(md_convert_frag): Handle STATE_PUSHJSTUB.
	(md_apply_fix3): Handle BFD_RELOC_MMIX_PUSHJ_STUBBABLE.
	(tc_gen_reloc): Ditto.
	(mmix_md_relax_frag): Handle PUSHJ stub relaxation.
	* config/tc-mmix.h (TC_SEGMENT_INFO_TYPE): Define.
	(struct mmix_segment_info_type): New.

1 files changed, 15 insertions, 0 deletions

diff --git a/gas/doc/c-mmix.texi b/gas/doc/c-mmix.texi
index d1b3016..a5205b6 100644
--- a/gas/doc/c-mmix.texi
+++ b/gas/doc/c-mmix.texi
@@ -82,6 +82,21 @@ that at link stage can be contracted.  (Though linker relaxation isn't yet
 implemented in @code{@value{LD}}.)  The option @samp{-x} also imples
 @samp{--linker-allocated-gregs}.
 
+@cindex @samp{--no-pushj-stubs} command line option, MMIX
+@cindex @samp{--no-stubs} command line option, MMIX
+If instruction expansion is enabled, @code{@value{AS}} can expand a
+@samp{PUSHJ} instruction into a series of instructions.  The shortest
+expansion is to not expand it, but just mark the call as redirectable to a
+stub, which @code{@value{LD}} creates at link-time, but only if the
+original @samp{PUSHJ} instruction is found not to reach the target.  The
+stub consists of the necessary instructions to form a jump to the target.
+This happens if @code{@value{AS}} can assert that the @samp{PUSHJ}
+instruction can reach such a stub.  The option @samp{--no-pushj-stubs}
+disables this shorter expansion, and the longer series of instructions is
+then created at assembly-time.  The option @samp{--no-stubs} is a synonym,
+intended for compatibility with future releases, where generation of stubs
+for other instructions may be implemented.
+
 @cindex @samp{--linker-allocated-gregs} command line option, MMIX
 Usually a two-operand-expression (@pxref{GREG-base}) without a matching
 @samp{GREG} directive is treated as an error by @code{@value{AS}}.  When