X-Git-Url: http://plrg.eecs.uci.edu/git/?a=blobdiff_plain;f=lib%2FCodeGen%2FRegisterCoalescer.cpp;h=682c26c2c833b1df724c20a6bc4dae7174afe9d6;hb=92fca73d521758012e0e425eac33bb77e888112e;hp=efe7161e16fa3bf4c2accbbcccb31a9d98f6b503;hpb=fc40386116ac01aef455fdfd56e4c1b1baff6685;p=oota-llvm.git diff --git a/lib/CodeGen/RegisterCoalescer.cpp b/lib/CodeGen/RegisterCoalescer.cpp index efe7161e16f..682c26c2c83 100644 --- a/lib/CodeGen/RegisterCoalescer.cpp +++ b/lib/CodeGen/RegisterCoalescer.cpp @@ -15,7 +15,6 @@ #define DEBUG_TYPE "regalloc" #include "RegisterCoalescer.h" -#include "llvm/ADT/OwningPtr.h" #include "llvm/ADT/STLExtras.h" #include "llvm/ADT/SmallSet.h" #include "llvm/ADT/Statistic.h" @@ -112,7 +111,7 @@ namespace { void eliminateDeadDefs(); /// LiveRangeEdit callback. - void LRE_WillEraseInstruction(MachineInstr *MI); + void LRE_WillEraseInstruction(MachineInstr *MI) override; /// coalesceLocals - coalesce the LocalWorkList. void coalesceLocals(); @@ -188,15 +187,15 @@ namespace { initializeRegisterCoalescerPass(*PassRegistry::getPassRegistry()); } - virtual void getAnalysisUsage(AnalysisUsage &AU) const; + void getAnalysisUsage(AnalysisUsage &AU) const override; - virtual void releaseMemory(); + void releaseMemory() override; /// runOnMachineFunction - pass entry point - virtual bool runOnMachineFunction(MachineFunction&); + bool runOnMachineFunction(MachineFunction&) override; /// print - Implement the dump method. - virtual void print(raw_ostream &O, const Module* = 0) const; + void print(raw_ostream &O, const Module* = 0) const override; }; } /// end anonymous namespace @@ -283,7 +282,6 @@ bool CoalescerPair::setRegisters(const MachineInstr *MI) { if (SrcSub) { Dst = TRI.getMatchingSuperReg(Dst, SrcSub, MRI.getRegClass(Src)); if (!Dst) return false; - SrcSub = 0; } else if (!MRI.getRegClass(Src)->contains(Dst)) { return false; } @@ -622,16 +620,15 @@ bool RegisterCoalescer::removeCopyByCommutingDef(const CoalescerPair &CP, // If some of the uses of IntA.reg is already coalesced away, return false. // It's not possible to determine whether it's safe to perform the coalescing. - for (MachineRegisterInfo::use_nodbg_iterator UI = - MRI->use_nodbg_begin(IntA.reg), - UE = MRI->use_nodbg_end(); UI != UE; ++UI) { - MachineInstr *UseMI = &*UI; + for (MachineOperand &MO : MRI->use_nodbg_operands(IntA.reg)) { + MachineInstr *UseMI = MO.getParent(); + unsigned OpNo = &MO - &UseMI->getOperand(0); SlotIndex UseIdx = LIS->getInstructionIndex(UseMI); LiveInterval::iterator US = IntA.FindSegmentContaining(UseIdx); if (US == IntA.end() || US->valno != AValNo) continue; // If this use is tied to a def, we can't rewrite the register. - if (UseMI->isRegTiedToDefOperand(UI.getOperandNo())) + if (UseMI->isRegTiedToDefOperand(OpNo)) return false; } @@ -669,8 +666,8 @@ bool RegisterCoalescer::removeCopyByCommutingDef(const CoalescerPair &CP, // Update uses of IntA of the specific Val# with IntB. for (MachineRegisterInfo::use_iterator UI = MRI->use_begin(IntA.reg), UE = MRI->use_end(); UI != UE;) { - MachineOperand &UseMO = UI.getOperand(); - MachineInstr *UseMI = &*UI; + MachineOperand &UseMO = *UI; + MachineInstr *UseMI = UseMO.getParent(); ++UI; if (UseMI->isDebugValue()) { // FIXME These don't have an instruction index. Not clear we have enough @@ -769,6 +766,14 @@ bool RegisterCoalescer::reMaterializeTrivialDef(CoalescerPair &CP, if (DstOperand.getSubReg() && !DstOperand.isUndef()) return false; + // If both SrcIdx and DstIdx are set, correct rematerialization would widen + // the register substantially (beyond both source and dest size). This is bad + // for performance since it can cascade through a function, introducing many + // extra spills and fills (e.g. ARM can easily end up copying QQQQPR registers + // around after a few subreg copies). + if (SrcIdx && DstIdx) + return false; + const TargetRegisterClass *DefRC = TII->getRegClass(MCID, 0, TRI, *MF); if (!DefMI->isImplicitDef()) { if (TargetRegisterInfo::isPhysicalRegister(DstReg)) { @@ -793,9 +798,9 @@ bool RegisterCoalescer::reMaterializeTrivialDef(CoalescerPair &CP, MachineBasicBlock *MBB = CopyMI->getParent(); MachineBasicBlock::iterator MII = - llvm::next(MachineBasicBlock::iterator(CopyMI)); + std::next(MachineBasicBlock::iterator(CopyMI)); TII->reMaterialize(*MBB, MII, DstReg, SrcIdx, DefMI, *TRI); - MachineInstr *NewMI = prior(MII); + MachineInstr *NewMI = std::prev(MII); LIS->ReplaceMachineInstrInMaps(CopyMI, NewMI); CopyMI->eraseFromParent(); @@ -816,30 +821,19 @@ bool RegisterCoalescer::reMaterializeTrivialDef(CoalescerPair &CP, } if (TargetRegisterInfo::isVirtualRegister(DstReg)) { - unsigned NewIdx; - const TargetRegisterClass *RCForInst; - - if (MRI->constrainRegClass(DstReg, DefRC)) { - // The materialized instruction is quite capable of setting DstReg - // directly, but it may still have a now-trivial subregister index which - // we should clear. - NewMI->getOperand(0).setSubReg(0); - } else if ((NewIdx = NewMI->getOperand(0).getSubReg()) && - (RCForInst = TRI->getMatchingSuperRegClass( - MRI->getRegClass(DstReg), DefRC, NewIdx))) { - // The subreg index on NewMI is essential; we still have to make sure - // DstReg:idx is in a class that NewMI can use. - MRI->constrainRegClass(DstReg, RCForInst); - } else { - // DstReg is actually incompatible with NewMI, we have to move to a - // super-reg's class. This could come from a sequence like: - // GR32 = MOV32r0 - // GR8 = COPY GR32:sub_8 - MRI->setRegClass(DstReg, CP.getNewRC()); - updateRegDefsUses(DstReg, DstReg, DstIdx); - NewMI->getOperand(0).setSubReg( - TRI->composeSubRegIndices(SrcIdx, DefMI->getOperand(0).getSubReg())); - } + const TargetRegisterClass *NewRC = CP.getNewRC(); + unsigned NewIdx = NewMI->getOperand(0).getSubReg(); + + if (NewIdx) + NewRC = TRI->getMatchingSuperRegClass(NewRC, DefRC, NewIdx); + else + NewRC = TRI->getCommonSubClass(NewRC, DefRC); + + assert(NewRC && "subreg chosen for remat incompatible with instruction"); + MRI->setRegClass(DstReg, NewRC); + + updateRegDefsUses(DstReg, DstReg, DstIdx); + NewMI->getOperand(0).setSubReg(NewIdx); } else if (NewMI->getOperand(0).getReg() != CopyDstReg) { // The New instruction may be defining a sub-register of what's actually // been asked for. If so it must implicitly define the whole thing. @@ -915,10 +909,7 @@ bool RegisterCoalescer::eliminateUndefCopy(MachineInstr *CopyMI, DstInt->removeValNo(DeadVNI); // Find new undef uses. - for (MachineRegisterInfo::reg_nodbg_iterator - I = MRI->reg_nodbg_begin(DstInt->reg), E = MRI->reg_nodbg_end(); - I != E; ++I) { - MachineOperand &MO = I.getOperand(); + for (MachineOperand &MO : MRI->reg_nodbg_operands(DstInt->reg)) { if (MO.isDef() || MO.isUndef()) continue; MachineInstr *MI = MO.getParent(); @@ -943,8 +934,11 @@ void RegisterCoalescer::updateRegDefsUses(unsigned SrcReg, LiveInterval *DstInt = DstIsPhys ? 0 : &LIS->getInterval(DstReg); SmallPtrSet Visited; - for (MachineRegisterInfo::reg_iterator I = MRI->reg_begin(SrcReg); - MachineInstr *UseMI = I.skipInstruction();) { + for (MachineRegisterInfo::reg_instr_iterator + I = MRI->reg_instr_begin(SrcReg), E = MRI->reg_instr_end(); + I != E; ) { + MachineInstr *UseMI = &*(I++); + // Each instruction can only be rewritten once because sub-register // composition is not always idempotent. When SrcReg != DstReg, rewriting // the UseMI operands removes them from the SrcReg use-def chain, but when @@ -955,7 +949,7 @@ void RegisterCoalescer::updateRegDefsUses(unsigned SrcReg, SmallVector Ops; bool Reads, Writes; - tie(Reads, Writes) = UseMI->readsWritesVirtualRegister(SrcReg, &Ops); + std::tie(Reads, Writes) = UseMI->readsWritesVirtualRegister(SrcReg, &Ops); // If SrcReg wasn't read, it may still be the case that DstReg is live-in // because SrcReg is a sub-register.