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Retry failed profiled very-hot compilations at hot instead of warm #21053

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Feb 3, 2025
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Retry failed profiled very-hot compilations at hot instead of warm #21053

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38 changes: 31 additions & 7 deletions runtime/compiler/control/CompilationThread.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -2347,24 +2347,29 @@ bool TR::CompilationInfo::shouldRetryCompilation(J9VMThread *vmThread, TR_Method
bodyInfo = 0;
if (comp->allowRecompilation() && entry->_optimizationPlan && entry->_optimizationPlan->getOptLevel() > minHotness)
{
// Compile only if the method is interpreted or if it's compiled with
// profiling information.
// Compile if the method is interpreted.
if (entry->_oldStartPC == 0) // interpreter method
{
tryCompilingAgain = true;
}
else // Does the existing body contain profiling info?
else
{
// Try again if existing body is compiled with profiling information
// because we don't want to be stuck in profiling mode forever.
bodyInfo = TR::Recompilation::getJittedBodyInfoFromPC(entry->_oldStartPC);
if (bodyInfo->getIsProfilingBody())
tryCompilingAgain = true;
// if existing body is invalidated, retry the compilation
// If existing body is invalidated, retry the compilation.
else if (bodyInfo->getIsInvalidated())
tryCompilingAgain = true;
// if the existing body uses pre-existence, retry the compilation
// otherwise we will revert to interpreted when failing this compilation
// If the existing body uses pre-existence, retry the compilation,
// otherwise we will revert to interpreted when failing this compilation.
else if (bodyInfo->getUsesPreexistence())
tryCompilingAgain = true;
// If the compilation that failed is at a higher opt level than hot
// but the existing compiled body is lower than hot, try to recompile at hot.
else if (comp->getOptLevel() > hot && bodyInfo->getHotness() <= warm)
tryCompilingAgain = true;
}
}

Expand All @@ -2373,11 +2378,30 @@ bool TR::CompilationInfo::shouldRetryCompilation(J9VMThread *vmThread, TR_Method
TR_Hotness hotness = entry->_optimizationPlan->getOptLevel();
TR_Hotness newHotness;
if (hotness == veryHot)
newHotness = warm; // skip over hot and go down two levels
{
if (comp->isProfilingCompilation())
{
// A hot compilation might succeed where a
// profiled very-hot compilation might fail.
newHotness = hot;
// Prevent internal switching to profiling.
entry->_optimizationPlan->setDoNotSwitchToProfiling(true);
}
else
{
// Very-hot without profiling is as expensive as hot,
// so we should not retry at hot because it may fail again.
newHotness = warm;
}
}
else if (hotness <= scorching)
{
newHotness = (TR_Hotness)(hotness - 1);
}
else // Why would we use hotness greater than scorching
{
newHotness = noOpt;
}
entry->_optimizationPlan->setOptLevel(newHotness);
entry->_optimizationPlan->setInsertInstrumentation(false); // prevent profiling
entry->_optimizationPlan->setUseSampling(false); // disable recompilation of this method
Expand Down