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[RegAlloc] Keep a copy of live interval for the spilled vregs in Hois…
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…tSpillHelper.

This is to fix PR34502. After rL311401, the live range of spilled vreg will be
cleared. HoistSpill need to use the live range of the original vreg before splitting
to know the moving range of the spills. The patch saves a copy of live interval for
the spilled vreg inside of HoistSpillHelper.

Differential Revision: https://reviews.llvm.org/D37578


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@313197 91177308-0d34-0410-b5e6-96231b3b80d8
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@wmi-11
wmi-11 committed Sep 13, 2017
1 parent 307e53c commit 57d83cb
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Showing 2 changed files with 553 additions and 24 deletions.
53 changes: 29 additions & 24 deletions lib/CodeGen/InlineSpiller.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -93,8 +93,11 @@ class HoistSpillHelper : private LiveRangeEdit::Delegate {

InsertPointAnalysis IPA;

// Map from StackSlot to its original register.
DenseMap<int, unsigned> StackSlotToReg;
// Map from StackSlot to the LiveInterval of the original register.
// Note the LiveInterval of the original register may have been deleted
// after it is spilled. We keep a copy here to track the range where
// spills can be moved.
DenseMap<int, std::unique_ptr<LiveInterval>> StackSlotToOrigLI;

// Map from pair of (StackSlot and Original VNI) to a set of spills which
// have the same stackslot and have equal values defined by Original VNI.
Expand All @@ -108,8 +111,8 @@ class HoistSpillHelper : private LiveRangeEdit::Delegate {
/// sibling there and use it as the source of the new spill.
DenseMap<unsigned, SmallSetVector<unsigned, 16>> Virt2SiblingsMap;

bool isSpillCandBB(unsigned OrigReg, VNInfo &OrigVNI, MachineBasicBlock &BB,
unsigned &LiveReg);
bool isSpillCandBB(LiveInterval &OrigLI, VNInfo &OrigVNI,
MachineBasicBlock &BB, unsigned &LiveReg);

void rmRedundantSpills(
SmallPtrSet<MachineInstr *, 16> &Spills,
Expand All @@ -123,7 +126,7 @@ class HoistSpillHelper : private LiveRangeEdit::Delegate {
DenseMap<MachineDomTreeNode *, unsigned> &SpillsToKeep,
DenseMap<MachineDomTreeNode *, MachineInstr *> &SpillBBToSpill);

void runHoistSpills(unsigned OrigReg, VNInfo &OrigVNI,
void runHoistSpills(LiveInterval &OrigLI, VNInfo &OrigVNI,
SmallPtrSet<MachineInstr *, 16> &Spills,
SmallVectorImpl<MachineInstr *> &SpillsToRm,
DenseMap<MachineBasicBlock *, unsigned> &SpillsToIns);
Expand Down Expand Up @@ -1095,9 +1098,17 @@ void InlineSpiller::postOptimization() { HSpiller.hoistAllSpills(); }
/// When a spill is inserted, add the spill to MergeableSpills map.
void HoistSpillHelper::addToMergeableSpills(MachineInstr &Spill, int StackSlot,
unsigned Original) {
StackSlotToReg[StackSlot] = Original;
BumpPtrAllocator &Allocator = LIS.getVNInfoAllocator();
LiveInterval &OrigLI = LIS.getInterval(Original);
// save a copy of LiveInterval in StackSlotToOrigLI because the original
// LiveInterval may be cleared after all its references are spilled.
if (StackSlotToOrigLI.find(StackSlot) == StackSlotToOrigLI.end()) {
auto LI = llvm::make_unique<LiveInterval>(OrigLI.reg, OrigLI.weight);
LI->assign(OrigLI, Allocator);
StackSlotToOrigLI[StackSlot] = std::move(LI);
}
SlotIndex Idx = LIS.getInstructionIndex(Spill);
VNInfo *OrigVNI = LIS.getInterval(Original).getVNInfoAt(Idx.getRegSlot());
VNInfo *OrigVNI = StackSlotToOrigLI[StackSlot]->getVNInfoAt(Idx.getRegSlot());
std::pair<int, VNInfo *> MIdx = std::make_pair(StackSlot, OrigVNI);
MergeableSpills[MIdx].insert(&Spill);
}
Expand All @@ -1106,29 +1117,28 @@ void HoistSpillHelper::addToMergeableSpills(MachineInstr &Spill, int StackSlot,
/// Return true if the spill is removed successfully.
bool HoistSpillHelper::rmFromMergeableSpills(MachineInstr &Spill,
int StackSlot) {
int Original = StackSlotToReg[StackSlot];
if (!Original)
auto It = StackSlotToOrigLI.find(StackSlot);
if (It == StackSlotToOrigLI.end())
return false;
SlotIndex Idx = LIS.getInstructionIndex(Spill);
VNInfo *OrigVNI = LIS.getInterval(Original).getVNInfoAt(Idx.getRegSlot());
VNInfo *OrigVNI = It->second->getVNInfoAt(Idx.getRegSlot());
std::pair<int, VNInfo *> MIdx = std::make_pair(StackSlot, OrigVNI);
return MergeableSpills[MIdx].erase(&Spill);
}

/// Check BB to see if it is a possible target BB to place a hoisted spill,
/// i.e., there should be a living sibling of OrigReg at the insert point.
bool HoistSpillHelper::isSpillCandBB(unsigned OrigReg, VNInfo &OrigVNI,
bool HoistSpillHelper::isSpillCandBB(LiveInterval &OrigLI, VNInfo &OrigVNI,
MachineBasicBlock &BB, unsigned &LiveReg) {
SlotIndex Idx;
LiveInterval &OrigLI = LIS.getInterval(OrigReg);
unsigned OrigReg = OrigLI.reg;
MachineBasicBlock::iterator MI = IPA.getLastInsertPointIter(OrigLI, BB);
if (MI != BB.end())
Idx = LIS.getInstructionIndex(*MI);
else
Idx = LIS.getMBBEndIdx(&BB).getPrevSlot();
SmallSetVector<unsigned, 16> &Siblings = Virt2SiblingsMap[OrigReg];
assert((LIS.getInterval(OrigReg)).getVNInfoAt(Idx) == &OrigVNI &&
"Unexpected VNI");
assert(OrigLI.getVNInfoAt(Idx) == &OrigVNI && "Unexpected VNI");

for (auto const SibReg : Siblings) {
LiveInterval &LI = LIS.getInterval(SibReg);
Expand Down Expand Up @@ -1263,7 +1273,8 @@ void HoistSpillHelper::getVisitOrders(
/// be saved in \p SpillsToRm. The spills to be inserted will be saved in
/// \p SpillsToIns.
void HoistSpillHelper::runHoistSpills(
unsigned OrigReg, VNInfo &OrigVNI, SmallPtrSet<MachineInstr *, 16> &Spills,
LiveInterval &OrigLI, VNInfo &OrigVNI,
SmallPtrSet<MachineInstr *, 16> &Spills,
SmallVectorImpl<MachineInstr *> &SpillsToRm,
DenseMap<MachineBasicBlock *, unsigned> &SpillsToIns) {
// Visit order of dominator tree nodes.
Expand Down Expand Up @@ -1339,7 +1350,7 @@ void HoistSpillHelper::runHoistSpills(

// Check whether Block is a possible candidate to insert spill.
unsigned LiveReg = 0;
if (!isSpillCandBB(OrigReg, OrigVNI, *Block, LiveReg))
if (!isSpillCandBB(OrigLI, OrigVNI, *Block, LiveReg))
continue;

// If there are multiple spills that could be merged, bias a little
Expand Down Expand Up @@ -1403,13 +1414,8 @@ void HoistSpillHelper::hoistAllSpills() {
SmallVector<unsigned, 4> NewVRegs;
LiveRangeEdit Edit(nullptr, NewVRegs, MF, LIS, &VRM, this);

// Save the mapping between stackslot and its original reg.
DenseMap<int, unsigned> SlotToOrigReg;
for (unsigned i = 0, e = MRI.getNumVirtRegs(); i != e; ++i) {
unsigned Reg = TargetRegisterInfo::index2VirtReg(i);
int Slot = VRM.getStackSlot(Reg);
if (Slot != VirtRegMap::NO_STACK_SLOT)
SlotToOrigReg[Slot] = VRM.getOriginal(Reg);
unsigned Original = VRM.getPreSplitReg(Reg);
if (!MRI.def_empty(Reg))
Virt2SiblingsMap[Original].insert(Reg);
Expand All @@ -1418,8 +1424,7 @@ void HoistSpillHelper::hoistAllSpills() {
// Each entry in MergeableSpills contains a spill set with equal values.
for (auto &Ent : MergeableSpills) {
int Slot = Ent.first.first;
unsigned OrigReg = SlotToOrigReg[Slot];
LiveInterval &OrigLI = LIS.getInterval(OrigReg);
LiveInterval &OrigLI = *StackSlotToOrigLI[Slot];
VNInfo *OrigVNI = Ent.first.second;
SmallPtrSet<MachineInstr *, 16> &EqValSpills = Ent.second;
if (Ent.second.empty())
Expand All @@ -1438,7 +1443,7 @@ void HoistSpillHelper::hoistAllSpills() {
// SpillsToIns is the spill set to be newly inserted after hoisting.
DenseMap<MachineBasicBlock *, unsigned> SpillsToIns;

runHoistSpills(OrigReg, *OrigVNI, EqValSpills, SpillsToRm, SpillsToIns);
runHoistSpills(OrigLI, *OrigVNI, EqValSpills, SpillsToRm, SpillsToIns);

DEBUG({
dbgs() << "Finally inserted spills in BB: ";
Expand Down
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