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JIT: Skip cost improvement check in 3-opt for exceptionally costly layouts #110069

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Merged
amanasifkhalid merged 3 commits into from
Nov 22, 2024
Merged

JIT: Skip cost improvement check in 3-opt for exceptionally costly layouts #110069

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3c6d407
Detect imprecision in layout cost computation
amanasifkhalid Nov 21, 2024
11ba6bd
Revert "Detect imprecision in layout cost computation"
amanasifkhalid Nov 22, 2024
04d8e07
Skip assert if layout cost is large
amanasifkhalid Nov 22, 2024
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13 changes: 10 additions & 3 deletions src/coreclr/jit/fgopt.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -5059,9 +5059,16 @@ bool Compiler::ThreeOptLayout::TrySwappingPartitions(
std::swap(blockOrder, tempOrder);

#ifdef DEBUG
// Ensure the swap improved the overall layout. Tolerate some imprecision.
const weight_t newLayoutCost = GetLayoutCost(s1Start, s4End);
assert((newLayoutCost < currLayoutCost) || Compiler::fgProfileWeightsEqual(newLayoutCost, currLayoutCost, 0.001));
// Don't bother checking if the cost improved for exceptionally costly layouts.
// Imprecision from summing large floating-point values can falsely trigger the below assert.
constexpr weight_t maxLayoutCostToCheck = (weight_t)UINT32_MAX;
if (currLayoutCost < maxLayoutCostToCheck)
{
// Ensure the swap improved the overall layout. Tolerate some imprecision.
const weight_t newLayoutCost = GetLayoutCost(s1Start, s4End);
assert((newLayoutCost < currLayoutCost) ||
Compiler::fgProfileWeightsEqual(newLayoutCost, currLayoutCost, 0.001));
}
#endif // DEBUG

return true;
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