md.texi (msub@var{m}@var{n}4, [...]): Document.

md.texi (msub@var{m}@var{n}4, [...]): Document.

* doc/md.texi (msub@var{m}@var{n}4, usub@var{m}@var{n}4): Document.
* optabs.h (OTI_smsub_widen, OTI_umsub_widen): New optab_indexes.
(smsub_widen_optab, umsub_widen_optab): Define.
* optabs.c (init_optabs): Initialize smsub_widen_optab and
umsub_widen_optab.
* genopinit.c (optabs): Fill in smsub_widen_optab and
umsub_widen_optab.
* expr.c (expand_expr_real_1): Try to use smsub_widen_optab
and umsub_widen_optab to implement multiply-subtract sequences.
* config/mips/mips.md (*msac<u>_di): Rename to...
(<u>msubsidi4): ...this.  Extend condition to include
GENERATE_MADD_MSUB and TARGET_DSPR2.  Change the constraint
of operand 0 to "ka" and use the three-operand form of msub<u>
for TARGET_DSPR2.
* config/mips/mips-dspr2.md (mips_msub, mips_msubu): Convert
to define_expands.

From-SVN: r124558