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JIT: fix count reconstruction problem #100385

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Merged
merged 2 commits into from
Mar 28, 2024
Merged

JIT: fix count reconstruction problem #100385

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bf5b1c0
JIT: fix count reconstruction problem
AndyAyersMS Mar 28, 2024
70d94a6
fix build
AndyAyersMS Mar 28, 2024
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11 changes: 11 additions & 0 deletions src/coreclr/jit/fgprofilesynthesis.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -1289,6 +1289,12 @@ void ProfileSynthesis::GaussSeidelSolver()
residual = change;
residualBlock = block;
}

if (newWeight >= maxCount)
{
JITDUMP("count overflow in " FMT_BB ": " FMT_WT "\n", block->bbNum, newWeight);
m_overflow = true;
}
}

// If there were no improper headers, we will have converged in one pass.
Expand All @@ -1312,6 +1318,11 @@ void ProfileSynthesis::GaussSeidelSolver()
break;
}

if (m_overflow)
{
break;
}

// If we have been iterating for a bit, estimate the dominant GS
// eigenvalue. (we might want to start with Jacobi iterations
// to get the Jacobi eigenvalue instead).
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2 changes: 2 additions & 0 deletions src/coreclr/jit/fgprofilesynthesis.h
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Expand Up @@ -51,6 +51,7 @@ class ProfileSynthesis
static constexpr weight_t ilNextLikelihood = 0.52;
static constexpr weight_t loopBackLikelihood = 0.9;
static constexpr weight_t loopExitLikelihood = 0.9;
static constexpr weight_t maxCount = 1e12;

void Run(ProfileSynthesisOption option);

Expand Down Expand Up @@ -84,6 +85,7 @@ class ProfileSynthesis
unsigned m_improperLoopHeaders = 0;
unsigned m_cappedCyclicProbabilities = 0;
bool m_approximate = false;
bool m_overflow = false;
};

#endif // !_FGPROFILESYNTHESIS_H_