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[RegAllocFast] Lazily initialize InstrPosIndexes for each MBB #76275

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Merged
merged 2 commits into from
Dec 25, 2023
Merged

[RegAllocFast] Lazily initialize InstrPosIndexes for each MBB #76275

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[RegAllocFast] Lazily initialize InstrPosIndexes for each MBB
HaohaiWen Dec 23, 2023
da2c1d8
Merge remote-tracking branch 'origin/main' into fastra
HaohaiWen Dec 25, 2023
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12 changes: 11 additions & 1 deletion llvm/lib/CodeGen/RegAllocFast.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -66,6 +66,8 @@ namespace {
/// can be used to determine dominance between instructions in same MBB.
class InstrPosIndexes {
public:
void unsetInitialized() { IsInitialized = false; }

void init(const MachineBasicBlock &MBB) {
CurMBB = &MBB;
Instr2PosIndex.clear();
Expand All @@ -80,6 +82,13 @@ class InstrPosIndexes {
/// index without affecting existing instruction's index. Return true if all
/// instructions index has been reassigned.
bool getIndex(const MachineInstr &MI, uint64_t &Index) {
if (!IsInitialized) {
init(*MI.getParent());
IsInitialized = true;
Index = Instr2PosIndex.at(&MI);
return true;
}

assert(MI.getParent() == CurMBB && "MI is not in CurMBB");
auto It = Instr2PosIndex.find(&MI);
if (It != Instr2PosIndex.end()) {
Expand Down Expand Up @@ -159,6 +168,7 @@ class InstrPosIndexes {
}

private:
bool IsInitialized = false;
enum { InstrDist = 1024 };
const MachineBasicBlock *CurMBB = nullptr;
DenseMap<const MachineInstr *, uint64_t> Instr2PosIndex;
Expand Down Expand Up @@ -1665,7 +1675,7 @@ void RegAllocFast::allocateBasicBlock(MachineBasicBlock &MBB) {
this->MBB = &MBB;
LLVM_DEBUG(dbgs() << "\nAllocating " << MBB);

PosIndexes.init(MBB);
PosIndexes.unsetInitialized();
RegUnitStates.assign(TRI->getNumRegUnits(), regFree);
assert(LiveVirtRegs.empty() && "Mapping not cleared from last block?");

Expand Down