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Make check-llvm run 50% faster on macOS, 18% faster on Windows.

Authored by thakis on Jan 6 2020, 7:54 AM.

Description

Make check-llvm run 50% faster on macOS, 18% faster on Windows.

While looking at cycle time graphs of some of my bots, I noticed
that 327894859cc made check-llvm noticeably slower on macOS and
Windows.

As it turns out, the 5 substitutions added in that change were
enough to cause lit to thrash the build-in cache in re.compile()
(re.sub() is implemented as re.compile().sub()), and apparently
applySubstitutions() is on the cricital path and slow when all
regexes need to compile all the time.

(See _MAXCACHE = 512 in cpython/Lib/re.py)

Supporting full regexes for lit substitutions seems a bit like
overkill, but for now add a simple unbounded cache to recover
the lost performance.

No intended behavior change.

Details

Committed
thakisJan 6 2020, 9:57 AM
Parents
rG3abc2927cb23: [lldb/Test] Move @skipIfAsan from test class to test methods.
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