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RegAllocFast: Factor spill/reload creation into their own functions; NFC

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This is in preparation of https://reviews.llvm.org/D52010.

llvm-svn: 346289
This commit is contained in:
Matthias Braun 2018-11-07 02:04:12 +00:00
parent 54fad8e39d
commit b375e31b89
1 changed files with 49 additions and 31 deletions
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80
lib/CodeGen/RegAllocFast.cpp
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@ -181,7 +181,6 @@ namespace {
void allocateBasicBlock(MachineBasicBlock &MBB);
void handleThroughOperands(MachineInstr &MI,
SmallVectorImpl<unsigned> &VirtDead);
int getStackSpaceFor(unsigned VirtReg);
bool isLastUseOfLocalReg(const MachineOperand &MO) const;
void addKillFlag(const LiveReg &LRI);
@ -214,6 +213,12 @@ namespace {
void spillAll(MachineBasicBlock::iterator MI);
bool setPhysReg(MachineInstr &MI, unsigned OpNum, MCPhysReg PhysReg);
int getStackSpaceFor(unsigned VirtReg);
void spill(MachineBasicBlock::iterator Before, unsigned VirtReg,
MCPhysReg AssignedReg, bool Kill);
void reload(MachineBasicBlock::iterator Before, unsigned VirtReg,
MCPhysReg PhysReg);
void dumpState();
};
@ -244,6 +249,46 @@ int RegAllocFast::getStackSpaceFor(unsigned VirtReg) {
return FrameIdx;
}
/// Insert spill instruction for \p AssignedReg before \p Before. Update
/// DBG_VALUEs with \p VirtReg operands with the stack slot.
void RegAllocFast::spill(MachineBasicBlock::iterator Before, unsigned VirtReg,
MCPhysReg AssignedReg, bool Kill) {
LLVM_DEBUG(dbgs() << "Spilling " << printReg(VirtReg, TRI)
<< " in " << printReg(AssignedReg, TRI));
int FI = getStackSpaceFor(VirtReg);
LLVM_DEBUG(dbgs() << " to stack slot #" << FI << "\n");
const TargetRegisterClass &RC = *MRI->getRegClass(VirtReg);
TII->storeRegToStackSlot(*MBB, Before, AssignedReg, Kill, FI, &RC, TRI);
++NumStores;
// If this register is used by DBG_VALUE then insert new DBG_VALUE to
// identify spilled location as the place to find corresponding variable's
// value.
SmallVectorImpl<MachineInstr *> &LRIDbgValues = LiveDbgValueMap[VirtReg];
for (MachineInstr *DBG : LRIDbgValues) {
MachineInstr *NewDV = buildDbgValueForSpill(*MBB, Before, *DBG, FI);
assert(NewDV->getParent() == MBB && "dangling parent pointer");
(void)NewDV;
LLVM_DEBUG(dbgs() << "Inserting debug info due to spill:\n" << *NewDV);
}
// Now this register is spilled there is should not be any DBG_VALUE
// pointing to this register because they are all pointing to spilled value
// now.
LRIDbgValues.clear();
}
/// Insert reload instruction for \p PhysReg before \p Before.
void RegAllocFast::reload(MachineBasicBlock::iterator Before, unsigned VirtReg,
MCPhysReg PhysReg) {
LLVM_DEBUG(dbgs() << "Reloading " << printReg(VirtReg, TRI) << " into "
<< printReg(PhysReg, TRI) << "\n");
int FI = getStackSpaceFor(VirtReg);
const TargetRegisterClass &RC = *MRI->getRegClass(VirtReg);
TII->loadRegFromStackSlot(*MBB, Before, PhysReg, FI, &RC, TRI);
++NumLoads;
}
/// Return true if MO is the only remaining reference to its virtual register,
/// and it is guaranteed to be a block-local register.
bool RegAllocFast::isLastUseOfLocalReg(const MachineOperand &MO) const {
@ -320,31 +365,9 @@ void RegAllocFast::spillVirtReg(MachineBasicBlock::iterator MI,
// instruction, not on the spill.
bool SpillKill = MachineBasicBlock::iterator(LR.LastUse) != MI;
LR.Dirty = false;
LLVM_DEBUG(dbgs() << "Spilling " << printReg(LRI->VirtReg, TRI) << " in "
<< printReg(LR.PhysReg, TRI));
const TargetRegisterClass &RC = *MRI->getRegClass(LRI->VirtReg);
int FI = getStackSpaceFor(LRI->VirtReg);
LLVM_DEBUG(dbgs() << " to stack slot #" << FI << "\n");
TII->storeRegToStackSlot(*MBB, MI, LR.PhysReg, SpillKill, FI, &RC, TRI);
++NumStores; // Update statistics
// If this register is used by DBG_VALUE then insert new DBG_VALUE to
// identify spilled location as the place to find corresponding variable's
// value.
SmallVectorImpl<MachineInstr *> &LRIDbgValues =
LiveDbgValueMap[LRI->VirtReg];
for (MachineInstr *DBG : LRIDbgValues) {
MachineInstr *NewDV = buildDbgValueForSpill(*MBB, MI, *DBG, FI);
assert(NewDV->getParent() == MBB && "dangling parent pointer");
(void)NewDV;
LLVM_DEBUG(dbgs() << "Inserting debug info due to spill:"
<< "\n"
<< *NewDV);
}
// Now this register is spilled there is should not be any DBG_VALUE
// pointing to this register because they are all pointing to spilled value
// now.
LRIDbgValues.clear();
spill(MI, LRI->VirtReg, LR.PhysReg, SpillKill);
if (SpillKill)
LR.LastUse = nullptr; // Don't kill register again
}
@ -653,12 +676,7 @@ RegAllocFast::LiveRegMap::iterator RegAllocFast::reloadVirtReg(MachineInstr &MI,
MachineOperand &MO = MI.getOperand(OpNum);
if (New) {
LRI = allocVirtReg(MI, LRI, Hint);
const TargetRegisterClass &RC = *MRI->getRegClass(VirtReg);
int FrameIndex = getStackSpaceFor(VirtReg);
LLVM_DEBUG(dbgs() << "Reloading " << printReg(VirtReg, TRI) << " into "
<< printReg(LRI->PhysReg, TRI) << "\n");
TII->loadRegFromStackSlot(*MBB, MI, LRI->PhysReg, FrameIndex, &RC, TRI);
++NumLoads;
reload(MI, VirtReg, LRI->PhysReg);
} else if (LRI->Dirty) {
if (isLastUseOfLocalReg(MO)) {
LLVM_DEBUG(dbgs() << "Killing last use: " << MO << "\n");