[TableGen] Optimize the regex search.
llvm::Regex is still the slowest regex engine on earth, running it over
all instructions on X86 takes a while. Extract a prefix and use a binary
search to reduce the search space before we resort to regex matching.
There are a couple of caveats here:
- The generic opcodes are outside of the sorted enum. They're handled in an extra loop.
- If there's a top-level bar we can't use the prefix trick.
- We bail on top-level ?. This could be handled, but it's rare.
This brings the time to generate X86GenInstrInfo.inc from 21s to 4.7s on
my machine.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@323277 91177308-0d34-0410-b5e6-96231b3b80d8
1 file changed