• Leszek Swirski's avatar
    Revert "[regexp] Better quick checks on loop entry nodes" · 51afbd1a
    Leszek Swirski authored
    This reverts commit 4b15b984.
    
    Reason for revert: UBSan failure (https://logs.chromium.org/logs/v8/buildbucket/cr-buildbucket.appspot.com/8906578530303352544/+/steps/Check/0/logs/regress-126412/0).
    
    Original change's description:
    > [regexp] Better quick checks on loop entry nodes
    > 
    > Like the predecessor change https://crrev.com/c/v8/v8/+/1702125 , this
    > change is inspired by attempting to exit earlier from generated RegExp
    > code, when no further matches are possible because any match would be
    > too long. The motivating example this time is the following expression,
    > which tests whether a string of Unicode playing cards has five of the
    > same suit in a row:
    > 
    > /([🂡-🂮]{5})|([🂱-🂾]{5})|([🃁-🃎]{5})|([🃑-🃞]{5})/u
    > 
    > A human reading this expression can readily see that any match requires
    > at least 10 characters (5 surrogate pairs), but the LoopChoiceNode for
    > each repeated option reports its minimum distance to the end of a match
    > as zero. This is correct, because the LoopChoiceNode's behavior depends
    > on additional state (the loop counter). However, the preceding node, a
    > SET_REGISTER action that initializes the loop counter, could confidently
    > state that it consumes at least 10 characters. Furthermore, when we try
    > to emit a quick check for that action, we could follow only paths from
    > the LoopChoiceNode that are possible based on the minimum iteration
    > count. This change implements both of those "could"s.
    > 
    > I expect this improvement to apply pretty broadly to expressions that
    > use minimum repetition counts and that don't meet the criteria for
    > unrolling. In this particular case, I get about 12% improvement on the
    > overall UniPoker test, due to reducing the execution time of this
    > expression by 85% and the execution time of another similar expression
    > that checks for n-of-a-kind by 20%.
    > 
    > Bug: v8:9305
    > 
    > Change-Id: I319e381743967bdf83324be75bae943fbb5dd496
    > Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1704941
    > Commit-Queue: Seth Brenith <seth.brenith@microsoft.com>
    > Reviewed-by: Jakob Gruber <jgruber@chromium.org>
    > Cr-Commit-Position: refs/heads/master@{#62963}
    
    TBR=jgruber@chromium.org,seth.brenith@microsoft.com
    
    Change-Id: Iac085b75e054fdf0d218987cfe449be1f1630545
    No-Presubmit: true
    No-Tree-Checks: true
    No-Try: true
    Bug: v8:9305
    Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1725621Reviewed-by: 's avatarLeszek Swirski <leszeks@chromium.org>
    Commit-Queue: Leszek Swirski <leszeks@chromium.org>
    Cr-Commit-Position: refs/heads/master@{#62977}
    51afbd1a
Name
Last commit
Last update
..
api Loading commit data...
asmjs Loading commit data...
ast Loading commit data...
base Loading commit data...
builtins Loading commit data...
codegen Loading commit data...
common Loading commit data...
compiler Loading commit data...
compiler-dispatcher Loading commit data...
d8 Loading commit data...
date Loading commit data...
debug Loading commit data...
deoptimizer Loading commit data...
diagnostics Loading commit data...
execution Loading commit data...
extensions Loading commit data...
flags Loading commit data...
handles Loading commit data...
heap Loading commit data...
ic Loading commit data...
init Loading commit data...
inspector Loading commit data...
interpreter Loading commit data...
json Loading commit data...
libplatform Loading commit data...
libsampler Loading commit data...
logging Loading commit data...
numbers Loading commit data...
objects Loading commit data...
parsing Loading commit data...
profiler Loading commit data...
protobuf Loading commit data...
regexp Loading commit data...
roots Loading commit data...
runtime Loading commit data...
sanitizer Loading commit data...
snapshot Loading commit data...
strings Loading commit data...
tasks Loading commit data...
third_party Loading commit data...
torque Loading commit data...
tracing Loading commit data...
trap-handler Loading commit data...
utils Loading commit data...
wasm Loading commit data...
zone Loading commit data...
DEPS Loading commit data...
OWNERS Loading commit data...