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[RISCV] Change heuristic used for load clustering #75341

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Merged
merged 2 commits into from
Jan 2, 2024
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[RISCV] Change heuristic used for load clustering #75341

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5785636
[RISCV] Change heuristic used for load clustering
asb Dec 13, 2023
96e8828
Tweak heuristic to limit the maximum cluster size
asb Dec 13, 2023
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11 changes: 8 additions & 3 deletions llvm/lib/Target/RISCV/RISCVInstrInfo.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -2282,9 +2282,14 @@ bool RISCVInstrInfo::shouldClusterMemOps(
return false;
}

// TODO: Use a more carefully chosen heuristic, e.g. only cluster if offsets
// indicate they likely share a cache line.
return ClusterSize <= 4;
unsigned CacheLineSize =
BaseOps1.front()->getParent()->getMF()->getSubtarget().getCacheLineSize();
// Assume a cache line size of 64 bytes if no size is set in RISCVSubtarget.
CacheLineSize = CacheLineSize ? CacheLineSize : 64;
// Cluster if the memory operations are on the same or a neighbouring cache
// line, but limit the maximum ClusterSize to avoid creating too much
// additional register pressure.
return ClusterSize <= 4 && std::abs(Offset1 - Offset2) < CacheLineSize;
}

// Set BaseReg (the base register operand), Offset (the byte offset being
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