Changeset 137094 in webkit for trunk/Source/JavaScriptCore/bytecode/ExecutionCounter.cpp

Timestamp:

Dec 9, 2012, 12:41:09 PM (13 years ago)

Author:

[email protected]

Message:

JSC should scale the optimization threshold for a code block according to the cost of compiling it
​https://bugs.webkit.org/show_bug.cgi?id=104406

Reviewed by Oliver Hunt.

We've long known that we want to scale the execution count threshold needed for the DFG
to kick in to scale according to some estimate of the cost of compiling that code block.
This institutes a relationship like this:

threshold = thresholdSetting * (a * sqrt(instructionCount + b) + abs(c * instructionCount) + d

Where a, b, c, d are coefficients derived from fitting the above expression to various
data points, which I chose based on looking at one benchmark (3d-cube) and from my
own intuitions.

Making this work well also required changing the thresholdForOptimizeAfterLongWarmUp
from 5000 to 1000.

This is a >1% speed-up on SunSpider, a >3% speed-up on V8Spider, ~1% speed-up on V8v7,
neutral on Octane, and neutral on Kraken.

I also out-of-lined a bunch of methods related to these heuristics, because I couldn't
stand having them defined in the header anymore. I also made improvements to debugging
code because I needed it for tuning this change.

• CMakeLists.txt:
• GNUmakefile.list.am:
• JavaScriptCore.vcproj/JavaScriptCore/JavaScriptCore.vcproj:
• JavaScriptCore.xcodeproj/project.pbxproj:
• Target.pri:
• bytecode/CodeBlock.cpp:

(JSC::CodeBlock::sourceCodeForTools):
(JSC::CodeBlock::sourceCodeOnOneLine):
(JSC::CodeBlock::dumpBytecode):
(JSC::CodeBlock::CodeBlock):
(JSC::CodeBlock::reoptimizationRetryCounter):
(JSC::CodeBlock::countReoptimization):
(JSC::CodeBlock::optimizationThresholdScalingFactor):
(JSC::clipThreshold):
(JSC::CodeBlock::counterValueForOptimizeAfterWarmUp):
(JSC::CodeBlock::counterValueForOptimizeAfterLongWarmUp):
(JSC::CodeBlock::counterValueForOptimizeSoon):
(JSC::CodeBlock::checkIfOptimizationThresholdReached):
(JSC::CodeBlock::optimizeNextInvocation):
(JSC::CodeBlock::dontOptimizeAnytimeSoon):
(JSC::CodeBlock::optimizeAfterWarmUp):
(JSC::CodeBlock::optimizeAfterLongWarmUp):
(JSC::CodeBlock::optimizeSoon):
(JSC::CodeBlock::adjustedExitCountThreshold):
(JSC::CodeBlock::exitCountThresholdForReoptimization):
(JSC::CodeBlock::exitCountThresholdForReoptimizationFromLoop):
(JSC::CodeBlock::shouldReoptimizeNow):
(JSC::CodeBlock::shouldReoptimizeFromLoopNow):

• bytecode/CodeBlock.h:
• bytecode/ExecutionCounter.cpp:

(JSC::ExecutionCounter::hasCrossedThreshold):

• bytecode/ReduceWhitespace.cpp: Added.

(JSC::reduceWhitespace):

• bytecode/ReduceWhitespace.h: Added.
• dfg/DFGCapabilities.cpp:

(JSC::DFG::mightCompileEval):
(JSC::DFG::mightCompileProgram):
(JSC::DFG::mightCompileFunctionForCall):
(JSC::DFG::mightCompileFunctionForConstruct):
(JSC::DFG::mightInlineFunctionForCall):
(JSC::DFG::mightInlineFunctionForConstruct):

• dfg/DFGCapabilities.h:
• dfg/DFGDisassembler.cpp:

(JSC::DFG::Disassembler::dumpHeader):

• dfg/DFGOSREntry.cpp:

(JSC::DFG::prepareOSREntry):

• jit/JITDisassembler.cpp:

(JSC::JITDisassembler::dumpHeader):

• jit/JITStubs.cpp:

(JSC::DEFINE_STUB_FUNCTION):

• llint/LLIntSlowPaths.cpp:

(JSC::LLInt::entryOSR):
(JSC::LLInt::LLINT_SLOW_PATH_DECL):

• profiler/ProfilerDatabase.cpp:

(JSC::Profiler::Database::ensureBytecodesFor):

• runtime/Options.h:

File:

• trunk/Source/JavaScriptCore/bytecode/ExecutionCounter.cpp (modified) (1 diff)

trunk/Source/JavaScriptCore/bytecode/ExecutionCounter.cpp

@@ -114 +114 @@
     
     return static_cast<double>(m_totalCount) + m_counter >=
-         modifiedThreshold - static_cast<double>(m_activeThreshold) / 2;
+        modifiedThreshold - static_cast<double>(
+            std::min(m_activeThreshold, Options::maximumExecutionCountsBetweenCheckpoints())) / 2;
 }