[Bug target/20614] PowerPC - inefficient use of condition register

[dje at gcc dot gnu dot org]

------- Additional Comments From dje at gcc dot gnu dot org  2005-09-18 15:57 -------
Generating cmpw to different CRs instead of a sequence operating on GPRs does
not help unless bool variables can be assigned to CRs.  Using cmpw currently
causes GCC to move the result from a CR to a GPR using mfcr and a shift -- the
same number of instructions as the GPR sequence (now using cntlzw).  Without
bools assigned to CRs and using crand instruction, cmpw is not a win for
performance or code size by itself.  Using CRs to store bool user variables is
on the list of useful enhancements.

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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=20614