tree 5b50ddd666ece7e540abd5c2a3f18a9bc45cd137
parent eb9d9e319bde7cc98a433b0c145f2dab108eb8e9
author Benjamin Kramer <benny.kra@googlemail.com> 1516748704 +0000
committer Benjamin Kramer <benny.kra@googlemail.com> 1516748704 +0000

[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