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[GlobalISel] Use named constant for impossible repair cost #180490

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Merged
arsenm merged 2 commits into from
Feb 9, 2026
Merged

[GlobalISel] Use named constant for impossible repair cost #180490

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[GlobalISel] Use named constant for impossible repair cost
elizhabiboullah Feb 9, 2026
58d9139
Merge branch 'main' into regbankselect-impossible-cost
elizhabiboullah Feb 9, 2026
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13 changes: 9 additions & 4 deletions llvm/lib/CodeGen/GlobalISel/RegBankSelect.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -51,6 +51,12 @@

using namespace llvm;

/// Cost value representing an impossible or invalid repairing.
/// This matches the value returned by RegisterBankInfo::copyCost() and
/// RegisterBankInfo::getBreakDownCost() when the cost cannot be computed.
static constexpr unsigned ImpossibleRepairCost =
std::numeric_limits<unsigned>::max();

static cl::opt<RegBankSelect::Mode> RegBankSelectMode(
cl::desc("Mode of the RegBankSelect pass"), cl::Hidden, cl::Optional,
cl::values(clEnumValN(RegBankSelect::Mode::Fast, "regbankselect-fast",
Expand Down Expand Up @@ -278,12 +284,11 @@ uint64_t RegBankSelect::getRepairCost(
// repairing placement.
unsigned Cost = RBI->copyCost(*DesiredRegBank, *CurRegBank,
RBI->getSizeInBits(MO.getReg(), *MRI, *TRI));
// TODO: use a dedicated constant for ImpossibleCost.
if (Cost != std::numeric_limits<unsigned>::max())
if (Cost != ImpossibleRepairCost)
return Cost;
// Return the legalization cost of that repairing.
}
return std::numeric_limits<unsigned>::max();
return ImpossibleRepairCost;
}

const RegisterBankInfo::InstructionMapping &RegBankSelect::findBestMapping(
Expand Down Expand Up @@ -535,7 +540,7 @@ RegBankSelect::MappingCost RegBankSelect::computeMapping(
uint64_t RepairCost = getRepairCost(MO, ValMapping);

// This is an impossible to repair cost.
if (RepairCost == std::numeric_limits<unsigned>::max())
if (RepairCost == ImpossibleRepairCost)
return MappingCost::ImpossibleCost();

// Bias used for splitting: 5%.
Expand Down
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