From b45e4deb102d47602f5b941da7f412ecc9a867e9 Mon Sep 17 00:00:00 2001 From: Jakob Stoklund Olesen Date: Tue, 5 Feb 2013 18:21:52 +0000 Subject: [PATCH] Remove special-casing of return blocks for liveness. Now that return value registers are return instruction uses, there is no need for special treatment of return blocks. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@174416 91177308-0d34-0410-b5e6-96231b3b80d8 --- lib/CodeGen/AggressiveAntiDepBreaker.cpp | 18 +------ lib/CodeGen/CriticalAntiDepBreaker.cpp | 18 +------ lib/CodeGen/DeadMachineInstructionElim.cpp | 9 ---- lib/CodeGen/LiveVariables.cpp | 23 --------- lib/CodeGen/PostRASchedulerList.cpp | 24 ++------- lib/CodeGen/RegAllocFast.cpp | 57 ---------------------- 6 files changed, 7 insertions(+), 142 deletions(-) diff --git a/lib/CodeGen/AggressiveAntiDepBreaker.cpp b/lib/CodeGen/AggressiveAntiDepBreaker.cpp index 152d9fa3a72..c50f8b5a42a 100644 --- a/lib/CodeGen/AggressiveAntiDepBreaker.cpp +++ b/lib/CodeGen/AggressiveAntiDepBreaker.cpp @@ -151,23 +151,7 @@ void AggressiveAntiDepBreaker::StartBlock(MachineBasicBlock *BB) { std::vector &KillIndices = State->GetKillIndices(); std::vector &DefIndices = State->GetDefIndices(); - // Determine the live-out physregs for this block. - if (IsReturnBlock) { - // In a return block, examine the function live-out regs. - for (MachineRegisterInfo::liveout_iterator I = MRI.liveout_begin(), - E = MRI.liveout_end(); I != E; ++I) { - for (MCRegAliasIterator AI(*I, TRI, true); AI.isValid(); ++AI) { - unsigned Reg = *AI; - State->UnionGroups(Reg, 0); - KillIndices[Reg] = BB->size(); - DefIndices[Reg] = ~0u; - } - } - } - - // In a non-return block, examine the live-in regs of all successors. - // Note a return block can have successors if the return instruction is - // predicated. + // Examine the live-in regs of all successors. for (MachineBasicBlock::succ_iterator SI = BB->succ_begin(), SE = BB->succ_end(); SI != SE; ++SI) for (MachineBasicBlock::livein_iterator I = (*SI)->livein_begin(), diff --git a/lib/CodeGen/CriticalAntiDepBreaker.cpp b/lib/CodeGen/CriticalAntiDepBreaker.cpp index ee31dde6384..0eb74a40d58 100644 --- a/lib/CodeGen/CriticalAntiDepBreaker.cpp +++ b/lib/CodeGen/CriticalAntiDepBreaker.cpp @@ -57,23 +57,7 @@ void CriticalAntiDepBreaker::StartBlock(MachineBasicBlock *BB) { bool IsReturnBlock = (BBSize != 0 && BB->back().isReturn()); - // Determine the live-out physregs for this block. - if (IsReturnBlock) { - // In a return block, examine the function live-out regs. - for (MachineRegisterInfo::liveout_iterator I = MRI.liveout_begin(), - E = MRI.liveout_end(); I != E; ++I) { - for (MCRegAliasIterator AI(*I, TRI, true); AI.isValid(); ++AI) { - unsigned Reg = *AI; - Classes[Reg] = reinterpret_cast(-1); - KillIndices[Reg] = BBSize; - DefIndices[Reg] = ~0u; - } - } - } - - // In a non-return block, examine the live-in regs of all successors. - // Note a return block can have successors if the return instruction is - // predicated. + // Examine the live-in regs of all successors. for (MachineBasicBlock::succ_iterator SI = BB->succ_begin(), SE = BB->succ_end(); SI != SE; ++SI) for (MachineBasicBlock::livein_iterator I = (*SI)->livein_begin(), diff --git a/lib/CodeGen/DeadMachineInstructionElim.cpp b/lib/CodeGen/DeadMachineInstructionElim.cpp index a526d248883..a54217f5b2f 100644 --- a/lib/CodeGen/DeadMachineInstructionElim.cpp +++ b/lib/CodeGen/DeadMachineInstructionElim.cpp @@ -99,15 +99,6 @@ bool DeadMachineInstructionElim::runOnMachineFunction(MachineFunction &MF) { // Start out assuming that reserved registers are live out of this block. LivePhysRegs = MRI->getReservedRegs(); - // Also add any explicit live-out physregs for this block. - if (!MBB->empty() && MBB->back().isReturn()) - for (MachineRegisterInfo::liveout_iterator LOI = MRI->liveout_begin(), - LOE = MRI->liveout_end(); LOI != LOE; ++LOI) { - unsigned Reg = *LOI; - if (TargetRegisterInfo::isPhysicalRegister(Reg)) - LivePhysRegs.set(Reg); - } - // Add live-ins from sucessors to LivePhysRegs. Normally, physregs are not // live across blocks, but some targets (x86) can have flags live out of a // block. diff --git a/lib/CodeGen/LiveVariables.cpp b/lib/CodeGen/LiveVariables.cpp index f81ad1cc6b9..789eddc4277 100644 --- a/lib/CodeGen/LiveVariables.cpp +++ b/lib/CodeGen/LiveVariables.cpp @@ -619,29 +619,6 @@ bool LiveVariables::runOnMachineFunction(MachineFunction &mf) { MBB); } - // Finally, if the last instruction in the block is a return, make sure to - // mark it as using all of the live-out values in the function. - // Things marked both call and return are tail calls; do not do this for - // them. The tail callee need not take the same registers as input - // that it produces as output, and there are dependencies for its input - // registers elsewhere. - if (!MBB->empty() && MBB->back().isReturn() - && !MBB->back().isCall()) { - MachineInstr *Ret = &MBB->back(); - - for (MachineRegisterInfo::liveout_iterator - I = MF->getRegInfo().liveout_begin(), - E = MF->getRegInfo().liveout_end(); I != E; ++I) { - assert(TargetRegisterInfo::isPhysicalRegister(*I) && - "Cannot have a live-out virtual register!"); - HandlePhysRegUse(*I, Ret); - - // Add live-out registers as implicit uses. - if (!Ret->readsRegister(*I)) - Ret->addOperand(MachineOperand::CreateReg(*I, false, true)); - } - } - // MachineCSE may CSE instructions which write to non-allocatable physical // registers across MBBs. Remember if any reserved register is liveout. SmallSet LiveOuts; diff --git a/lib/CodeGen/PostRASchedulerList.cpp b/lib/CodeGen/PostRASchedulerList.cpp index 488f1d45643..53fe273a103 100644 --- a/lib/CodeGen/PostRASchedulerList.cpp +++ b/lib/CodeGen/PostRASchedulerList.cpp @@ -418,11 +418,11 @@ void SchedulePostRATDList::StartBlockForKills(MachineBasicBlock *BB) { // Start with no live registers. LiveRegs.reset(); - // Determine the live-out physregs for this block. - if (!BB->empty() && BB->back().isReturn()) { - // In a return block, examine the function live-out regs. - for (MachineRegisterInfo::liveout_iterator I = MRI.liveout_begin(), - E = MRI.liveout_end(); I != E; ++I) { + // Examine the live-in regs of all successors. + for (MachineBasicBlock::succ_iterator SI = BB->succ_begin(), + SE = BB->succ_end(); SI != SE; ++SI) { + for (MachineBasicBlock::livein_iterator I = (*SI)->livein_begin(), + E = (*SI)->livein_end(); I != E; ++I) { unsigned Reg = *I; LiveRegs.set(Reg); // Repeat, for all subregs. @@ -430,20 +430,6 @@ void SchedulePostRATDList::StartBlockForKills(MachineBasicBlock *BB) { LiveRegs.set(*SubRegs); } } - else { - // In a non-return block, examine the live-in regs of all successors. - for (MachineBasicBlock::succ_iterator SI = BB->succ_begin(), - SE = BB->succ_end(); SI != SE; ++SI) { - for (MachineBasicBlock::livein_iterator I = (*SI)->livein_begin(), - E = (*SI)->livein_end(); I != E; ++I) { - unsigned Reg = *I; - LiveRegs.set(Reg); - // Repeat, for all subregs. - for (MCSubRegIterator SubRegs(Reg, TRI); SubRegs.isValid(); ++SubRegs) - LiveRegs.set(*SubRegs); - } - } - } } bool SchedulePostRATDList::ToggleKillFlag(MachineInstr *MI, diff --git a/lib/CodeGen/RegAllocFast.cpp b/lib/CodeGen/RegAllocFast.cpp index 8d849dc55bb..840ddb123e1 100644 --- a/lib/CodeGen/RegAllocFast.cpp +++ b/lib/CodeGen/RegAllocFast.cpp @@ -177,7 +177,6 @@ namespace { unsigned VirtReg, unsigned Hint); void spillAll(MachineBasicBlock::iterator MI); bool setPhysReg(MachineInstr *MI, unsigned OpNum, unsigned PhysReg); - void addRetOperands(MachineBasicBlock *MBB); }; char RAFast::ID = 0; } @@ -774,59 +773,6 @@ void RAFast::handleThroughOperands(MachineInstr *MI, UsedInInstr.insert(PartialDefs[i]); } -/// addRetOperand - ensure that a return instruction has an operand for each -/// value live out of the function. -/// -/// Things marked both call and return are tail calls; do not do this for them. -/// The tail callee need not take the same registers as input that it produces -/// as output, and there are dependencies for its input registers elsewhere. -/// -/// FIXME: This should be done as part of instruction selection, and this helper -/// should be deleted. Until then, we use custom logic here to create the proper -/// operand under all circumstances. We can't use addRegisterKilled because that -/// doesn't make sense for undefined values. We can't simply avoid calling it -/// for undefined values, because we must ensure that the operand always exists. -void RAFast::addRetOperands(MachineBasicBlock *MBB) { - if (MBB->empty() || !MBB->back().isReturn() || MBB->back().isCall()) - return; - - MachineInstr *MI = &MBB->back(); - - for (MachineRegisterInfo::liveout_iterator - I = MBB->getParent()->getRegInfo().liveout_begin(), - E = MBB->getParent()->getRegInfo().liveout_end(); I != E; ++I) { - unsigned Reg = *I; - assert(TargetRegisterInfo::isPhysicalRegister(Reg) && - "Cannot have a live-out virtual register."); - - bool hasDef = PhysRegState[Reg] == regReserved; - - // Check if this register already has an operand. - bool Found = false; - for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) { - MachineOperand &MO = MI->getOperand(i); - if (!MO.isReg() || !MO.isUse()) - continue; - - unsigned OperReg = MO.getReg(); - if (!TargetRegisterInfo::isPhysicalRegister(OperReg)) - continue; - - if (OperReg == Reg || TRI->isSuperRegister(OperReg, Reg)) { - // If the ret already has an operand for this physreg or a superset, - // don't duplicate it. Set the kill flag if the value is defined. - if (hasDef && !MO.isKill()) - MO.setIsKill(); - Found = true; - break; - } - } - if (!Found) - MachineInstrBuilder(*MF, MI) - .addReg(Reg, llvm::RegState::Implicit | getKillRegState(hasDef)); - } -} - void RAFast::AllocateBasicBlock() { DEBUG(dbgs() << "\nAllocating " << *MBB); @@ -1109,9 +1055,6 @@ void RAFast::AllocateBasicBlock() { MBB->erase(Coalesced[i]); NumCopies += Coalesced.size(); - // addRetOperands must run after we've seen all defs in this block. - addRetOperands(MBB); - DEBUG(MBB->dump()); } -- 2.34.1