[Bug target/32437] [4.3 Regression] MIPS: FAIL in gcc.dg/cleanup-[8|9|10|11].c

["rsandifo at gcc dot gnu dot org" <gcc-bugzilla at gcc dot gnu dot org>]

------- Comment #5 from rsandifo at gcc dot gnu dot org  2007-06-22 09:11 -------
I'm not surprised that converting it to an unspec_volatile stops
us from deleting the instruction, but that wasn't really my concern.

As I said earlier, several other ports use top-level unspecs (rather than
unspec_volatiles), and it appears that after the dataflow merge, that construct
is no longer allowed.  Thus I think we should first nail down whether this
is a deliberate change.  If it is (and I can see that it might be),
then I think we should change the RTL generators so that top-level
unspecs are not allowed in define_insns.  I do not think we should the
MIPS port until we have established what the new rules are.

(This isn't an issue about dataflow being more accurate per se;
the old code could also have deleted top-level unspecs with no
register dependencies, if it had thought that doing so was allowed.)


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=32437