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[Bug bootstrap/52391] [4.7/4.8 regression] genattrtab almost 5X slower for m68k than in 4.6 and earlier releases


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52391

--- Comment #12 from Steven Bosscher <steven at gcc dot gnu.org> 2012-05-05 10:06:32 UTC ---
Created attachment 27315
  --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=27315
Avoid diving deep through generated IOR trees for EQ_ATTR

This patch tries to keep IOR-trees for EQ_ATTR tests together. This improves
genattrtab run time and also the generated code because more get_attr_* results
are cached.

On gcc110, the run time for genattrtab for m68k goes down from 9m3s to 4m15s.
The difference in insn-attrtab looks like an improvement at first glance, but I
could use some help interpreting the differences. (Will attach shortly.)

(The cf.md bit only sorts the attributes alphabetically but doesn't change the
genattrtab run time.)


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