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b73bf8a14d
Enables the use of btst / btstq for a single bit (at other bits
than 0, including as indicated by a variable) to set
condition-codes. There's also a bug-fix for the bit-0-btstq
pattern; it shouldn't generate CCmode as only the Z flag is
valid, still using CC_NZmode is ok, as only equality-tests are
generated. The cris_rtx_costs tweak is necessary or else
combine will consider the btst not preferable. It reduces the
difference to cc0-costs beyond the threshold to the
transformation being seen as profitable, but there's still a
difference in values for the pre-split-time btst+branch as
opposed to the cc0 btst and branch, with both appearing to be
the cost of several insns (18 and 22).
gcc:
* config/cris/cris-modes.def (CC_ZnN): New CC_MODE.
* config/cris/cris.c (cris_rtx_costs): Handle pre-split bit-test
* config/cris/cris.md (ZnNNZSET, ZnNNZUSE): New mode_iterators.
(znnCC, rznnCC): New code_attrs.
("*btst<mode>"): Iterator over ZnNNZSET instead of NZVCSET. Remove
obseolete comment. Add belt-and-suspenders mode-test to condition.
Add fixme regarding remaining matched-but-not-generated case.
("*cbranch<mode>4_btstrq1_<CC>"): New insn_and_split.
("*cbranch<mode>4_btstqb0_<CC>"): Rename from
"*cbranch<mode>4_btstq<CC>". Split to CC_NZ instead of CC.
("*b<zcond:code><mode>"): Iterate over ZnNNZUSE instead of NZUSE.
Handle output of CC_ZnNmode.
("*b<nzcond:code>_reversed<mode>"): Ditto.
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