[RFC] Fix unwind info for sparc -mflat

Richard Henderson rth@twiddle.net
Tue Jun 21 01:00:00 GMT 2011

The current code generation for -mflat uses 3 insn patterns
which emit up two three insns (sort of) emulating the save

The problem is that the unwind info is only produced at the
end of any pattern, leaving a 1 or 2 insn hole for which the
unwind info is not correct.

I tried to figure out why things had been done in this
slightly convoluted manner and failed.  It seems to me that
this is easily represented with the individual instructions.
A comment indicated that there had been problems with the
copy to %o7 being deleted.  Elsewhere we have successfully
used a naked USE pattern to keep such things from being

Unfortunately, I can't seem to get -mflat to bootstrap on
gcc62 (as sparc-linux, not sparc64) either before or after
this patch, so I'm not sure what sort of pre-requisite I'm
missing in order to be able to test it...


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