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[SOL] Fine tune memcmp threshold #160

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Jul 1, 2025
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[SOL] Fine tune memcmp threshold #160

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7 changes: 5 additions & 2 deletions llvm/lib/Target/SBF/SBFISelLowering.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -160,8 +160,11 @@ SBFTargetLowering::SBFTargetLowering(const TargetMachine &TM,
// Memcmp expands to three instructions for each load:
// 1. One load for each pointer being compared.
// 2. One jne for each load.
// The limit here should be three, since 3*3 = 9;
MaxLoadsPerMemcmp = MaxLoadsPerMemcmpOptSize = 3;
// There is also a 3 CUs overhead for adjusting the arguments to memcmp.
// We need at least three mov64 to set them.
// A syscall takes at least 10 + 3 CUs.
// The limit here should be four, since 3*4 = 12;
MaxLoadsPerMemcmp = MaxLoadsPerMemcmpOptSize = 4;

// CPU/Feature control
HasAlu32 = STI.getHasAlu32();
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