diff options
| -rw-r--r-- | include/llvm/CodeGen/GlobalISel/RegBankSelect.h | 7 | ||||
| -rw-r--r-- | lib/CodeGen/GlobalISel/RegBankSelect.cpp | 21 |
2 files changed, 24 insertions, 4 deletions
diff --git a/include/llvm/CodeGen/GlobalISel/RegBankSelect.h b/include/llvm/CodeGen/GlobalISel/RegBankSelect.h index 5d300198e15..b210a8e9f6e 100644 --- a/include/llvm/CodeGen/GlobalISel/RegBankSelect.h +++ b/include/llvm/CodeGen/GlobalISel/RegBankSelect.h @@ -533,10 +533,15 @@ private: /// Compute the cost of mapping \p MI with \p InstrMapping and /// compute the repairing placement for such mapping in \p /// RepairPts. + /// \p BestCost is used to specify when the cost becomes too high + /// and thus it is not worth computing the RepairPts. Moreover if + /// \p BestCost == nullptr, the mapping cost is actually not + /// computed. MappingCost computeMapping(MachineInstr &MI, const RegisterBankInfo::InstructionMapping &InstrMapping, - SmallVectorImpl<RepairingPlacement> &RepairPts); + SmallVectorImpl<RepairingPlacement> &RepairPts, + const MappingCost *BestCost = nullptr); /// When \p RepairPt involves splitting to repair \p MO for the /// given \p ValMapping, try to change the way we repair such that diff --git a/lib/CodeGen/GlobalISel/RegBankSelect.cpp b/lib/CodeGen/GlobalISel/RegBankSelect.cpp index b244137f1ac..d8bc7b43c81 100644 --- a/lib/CodeGen/GlobalISel/RegBankSelect.cpp +++ b/lib/CodeGen/GlobalISel/RegBankSelect.cpp @@ -291,7 +291,9 @@ void RegBankSelect::tryAvoidingSplit( RegBankSelect::MappingCost RegBankSelect::computeMapping( MachineInstr &MI, const RegisterBankInfo::InstructionMapping &InstrMapping, - SmallVectorImpl<RepairingPlacement> &RepairPts) { + SmallVectorImpl<RepairingPlacement> &RepairPts, + const RegBankSelect::MappingCost *BestCost) { + assert((MBFI || !BestCost) && "Costs comparison require MBFI"); // If mapped with InstrMapping, MI will have the recorded cost. MappingCost Cost(MBFI ? MBFI->getBlockFreq(MI.getParent()) : 1); @@ -300,6 +302,9 @@ RegBankSelect::MappingCost RegBankSelect::computeMapping( DEBUG(dbgs() << "Evaluating mapping cost for: " << MI); DEBUG(dbgs() << "With: " << InstrMapping << '\n'); RepairPts.clear(); + if (BestCost && Cost > *BestCost) + return Cost; + // Moreover, to realize this mapping, the register bank of each operand must // match this mapping. In other words, we may need to locally reassign the // register banks. Account for that repairing cost as well. @@ -356,10 +361,14 @@ RegBankSelect::MappingCost RegBankSelect::computeMapping( return MappingCost::ImpossibleCost(); // Account for the split cost and repair cost. - // Unless the cost is already saturated. - if (Saturated) + // Unless the cost is already saturated or we do not care about the cost. + if (!BestCost || Saturated) continue; + // To get accurate information we need MBFI and MBPI. + // Thus, if we end up here this information should be here. + assert(MBFI && MBPI && "Cost computation requires MBFI and MBPI"); + // Sums up the repairing cost of at each insertion point. // TODO: Get the actual repairing cost. uint64_t RepairCost = 1; @@ -393,6 +402,12 @@ RegBankSelect::MappingCost RegBankSelect::computeMapping( else Saturated = Cost.addNonLocalCost(PtCost); } + + // Stop looking into what it takes to repair, this is already + // too expensive. + if (BestCost && Cost > *BestCost) + return Cost; + // No need to accumulate more cost information. // We need to still gather the repairing information though. if (Saturated) |