[PATCH] D16835: InstCombine: Restrict computeKnownBits() on everyValue to OptLevel > 2
Matthias Braun via llvm-commits
llvm-commits at lists.llvm.org
Tue Feb 2 18:14:48 PST 2016
MatzeB created this revision.
MatzeB added a reviewer: hfinkel.
MatzeB added subscribers: sanjoy, llvm-commits.
MatzeB set the repository for this revision to rL LLVM.
Herald added subscribers: mcrosier, joker.eph.
As part of r251146 InstCombine was extended to call computeKnownBits on
every value in the function to determine whether it happens to be
constant. This increases typical compiletime by 1-3% (5% in irgen+opt
time) in my measurements. On the other hand this case did not trigger
once in the whole llvm-testsuite.
This patch introduces the notion of ExpensiveCombines which are only
enabled for OptLevel > 2. I removed the check in InstructionSimplify as
that is called from various places where the OptLevel is not known but
given the rarity of the situation I think a check in InstCombine is
-------------- next part --------------
A non-text attachment was scrubbed...
Size: 13562 bytes
Desc: not available
More information about the llvm-commits