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Enable opportunistic coalescing

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llvm-svn: 103764
This commit is contained in:
Jakob Stoklund Olesen 2010-05-14 04:30:51 +00:00
parent 2af2c9fa14
commit 892983155c
1 changed files with 18 additions and 7 deletions
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25
lib/CodeGen/RegAllocFast.cpp
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@ -603,6 +603,7 @@ void RAFast::AllocateBasicBlock(MachineBasicBlock &MBB) {
reservePhysReg(MBB, MII, *I);
SmallVector<unsigned, 8> VirtKills, PhysKills, PhysDefs;
SmallVector<MachineInstr*, 32> Coalesced;
// Otherwise, sequentially allocate each instruction in the MBB.
while (MII != MBB.end()) {
@ -706,8 +707,7 @@ void RAFast::AllocateBasicBlock(MachineBasicBlock &MBB) {
if (!Reg || TargetRegisterInfo::isPhysicalRegister(Reg)) continue;
if (MO.isUse()) {
unsigned PhysReg = reloadVirtReg(MBB, MI, i, Reg, CopyDst);
if (CopySrc == Reg)
CopySrc = PhysReg;
CopySrc = (CopySrc == Reg || CopySrc == PhysReg) ? PhysReg : 0;
setPhysReg(MO, PhysReg);
if (MO.isKill())
VirtKills.push_back(Reg);
@ -757,11 +757,12 @@ void RAFast::AllocateBasicBlock(MachineBasicBlock &MBB) {
PhysKills.push_back(Reg);
continue;
}
if (MO.isDead())
VirtKills.push_back(Reg);
unsigned PhysReg = defineVirtReg(MBB, MI, i, Reg, CopySrc);
if (CopyDst == Reg)
CopyDst = PhysReg;
if (MO.isDead()) {
VirtKills.push_back(Reg);
CopyDst = 0; // cancel coalescing;
} else
CopyDst = (CopyDst == Reg || CopyDst == PhysReg) ? PhysReg : 0;
setPhysReg(MO, PhysReg);
}
@ -783,7 +784,12 @@ void RAFast::AllocateBasicBlock(MachineBasicBlock &MBB) {
MRI->addPhysRegsUsed(UsedInInstr);
DEBUG(dbgs() << "<< " << *MI);
if (CopyDst && CopyDst == CopySrc && CopyDstSub == CopySrcSub) {
DEBUG(dbgs() << "-- coalescing: " << *MI);
Coalesced.push_back(MI);
} else {
DEBUG(dbgs() << "<< " << *MI);
}
}
// Spill all physical registers holding virtual registers now.
@ -795,6 +801,11 @@ void RAFast::AllocateBasicBlock(MachineBasicBlock &MBB) {
spillVirtReg(MBB, MI, i, true);
LiveVirtRegs.clear();
// Erase all the coalesced copies. We are delaying it until now because
// LiveVirtsRegs might refer to the instrs.
for (unsigned i = 0, e = Coalesced.size(); i != e; ++i)
MBB.erase(Coalesced[i]);
DEBUG(MBB.dump());
}