From 2cedf089162d7ff08af2fb09e4adea44608e7233 Mon Sep 17 00:00:00 2001 From: Dimitry Andric Date: Sun, 26 Jul 2020 19:46:28 +0000 Subject: Vendor import of llvm-project branch release/11.x llvmorg-11-init-20933-g3c1fca803bc. --- llvm/lib/CodeGen/TwoAddressInstructionPass.cpp | 161 +------------------------ 1 file changed, 5 insertions(+), 156 deletions(-) (limited to 'llvm/lib/CodeGen/TwoAddressInstructionPass.cpp') diff --git a/llvm/lib/CodeGen/TwoAddressInstructionPass.cpp b/llvm/lib/CodeGen/TwoAddressInstructionPass.cpp index de336abe607a..615ff4b8789c 100644 --- a/llvm/lib/CodeGen/TwoAddressInstructionPass.cpp +++ b/llvm/lib/CodeGen/TwoAddressInstructionPass.cpp @@ -70,7 +70,6 @@ STATISTIC(NumTwoAddressInstrs, "Number of two-address instructions"); STATISTIC(NumCommuted , "Number of instructions commuted to coalesce"); STATISTIC(NumAggrCommuted , "Number of instructions aggressively commuted"); STATISTIC(NumConvertedTo3Addr, "Number of instructions promoted to 3-address"); -STATISTIC(Num3AddrSunk, "Number of 3-address instructions sunk"); STATISTIC(NumReSchedUps, "Number of instructions re-scheduled up"); STATISTIC(NumReSchedDowns, "Number of instructions re-scheduled down"); @@ -109,10 +108,6 @@ class TwoAddressInstructionPass : public MachineFunctionPass { // Set of already processed instructions in the current block. SmallPtrSet Processed; - // Set of instructions converted to three-address by target and then sunk - // down current basic block. - SmallPtrSet SunkInstrs; - // A map from virtual registers to physical registers which are likely targets // to be coalesced to due to copies from physical registers to virtual // registers. e.g. v1024 = move r0. @@ -123,9 +118,6 @@ class TwoAddressInstructionPass : public MachineFunctionPass { // registers. e.g. r1 = move v1024. DenseMap DstRegMap; - bool sink3AddrInstruction(MachineInstr *MI, unsigned Reg, - MachineBasicBlock::iterator OldPos); - bool isRevCopyChain(unsigned FromReg, unsigned ToReg, int Maxlen); bool noUseAfterLastDef(unsigned Reg, unsigned Dist, unsigned &LastDef); @@ -209,136 +201,6 @@ INITIALIZE_PASS_END(TwoAddressInstructionPass, DEBUG_TYPE, static bool isPlainlyKilled(MachineInstr *MI, unsigned Reg, LiveIntervals *LIS); -/// A two-address instruction has been converted to a three-address instruction -/// to avoid clobbering a register. Try to sink it past the instruction that -/// would kill the above mentioned register to reduce register pressure. -bool TwoAddressInstructionPass:: -sink3AddrInstruction(MachineInstr *MI, unsigned SavedReg, - MachineBasicBlock::iterator OldPos) { - // FIXME: Shouldn't we be trying to do this before we three-addressify the - // instruction? After this transformation is done, we no longer need - // the instruction to be in three-address form. - - // Check if it's safe to move this instruction. - bool SeenStore = true; // Be conservative. - if (!MI->isSafeToMove(AA, SeenStore)) - return false; - - unsigned DefReg = 0; - SmallSet UseRegs; - - for (const MachineOperand &MO : MI->operands()) { - if (!MO.isReg()) - continue; - Register MOReg = MO.getReg(); - if (!MOReg) - continue; - if (MO.isUse() && MOReg != SavedReg) - UseRegs.insert(MO.getReg()); - if (!MO.isDef()) - continue; - if (MO.isImplicit()) - // Don't try to move it if it implicitly defines a register. - return false; - if (DefReg) - // For now, don't move any instructions that define multiple registers. - return false; - DefReg = MO.getReg(); - } - - // Find the instruction that kills SavedReg. - MachineInstr *KillMI = nullptr; - if (LIS) { - LiveInterval &LI = LIS->getInterval(SavedReg); - assert(LI.end() != LI.begin() && - "Reg should not have empty live interval."); - - SlotIndex MBBEndIdx = LIS->getMBBEndIdx(MBB).getPrevSlot(); - LiveInterval::const_iterator I = LI.find(MBBEndIdx); - if (I != LI.end() && I->start < MBBEndIdx) - return false; - - --I; - KillMI = LIS->getInstructionFromIndex(I->end); - } - if (!KillMI) { - for (MachineOperand &UseMO : MRI->use_nodbg_operands(SavedReg)) { - if (!UseMO.isKill()) - continue; - KillMI = UseMO.getParent(); - break; - } - } - - // If we find the instruction that kills SavedReg, and it is in an - // appropriate location, we can try to sink the current instruction - // past it. - if (!KillMI || KillMI->getParent() != MBB || KillMI == MI || - MachineBasicBlock::iterator(KillMI) == OldPos || KillMI->isTerminator()) - return false; - - // If any of the definitions are used by another instruction between the - // position and the kill use, then it's not safe to sink it. - // - // FIXME: This can be sped up if there is an easy way to query whether an - // instruction is before or after another instruction. Then we can use - // MachineRegisterInfo def / use instead. - MachineOperand *KillMO = nullptr; - MachineBasicBlock::iterator KillPos = KillMI; - ++KillPos; - - unsigned NumVisited = 0; - for (MachineInstr &OtherMI : make_range(std::next(OldPos), KillPos)) { - // Debug instructions cannot be counted against the limit. - if (OtherMI.isDebugInstr()) - continue; - if (NumVisited > 30) // FIXME: Arbitrary limit to reduce compile time cost. - return false; - ++NumVisited; - for (unsigned i = 0, e = OtherMI.getNumOperands(); i != e; ++i) { - MachineOperand &MO = OtherMI.getOperand(i); - if (!MO.isReg()) - continue; - Register MOReg = MO.getReg(); - if (!MOReg) - continue; - if (DefReg == MOReg) - return false; - - if (MO.isKill() || (LIS && isPlainlyKilled(&OtherMI, MOReg, LIS))) { - if (&OtherMI == KillMI && MOReg == SavedReg) - // Save the operand that kills the register. We want to unset the kill - // marker if we can sink MI past it. - KillMO = &MO; - else if (UseRegs.count(MOReg)) - // One of the uses is killed before the destination. - return false; - } - } - } - assert(KillMO && "Didn't find kill"); - - if (!LIS) { - // Update kill and LV information. - KillMO->setIsKill(false); - KillMO = MI->findRegisterUseOperand(SavedReg, false, TRI); - KillMO->setIsKill(true); - - if (LV) - LV->replaceKillInstruction(SavedReg, *KillMI, *MI); - } - - // Move instruction to its destination. - MBB->remove(MI); - MBB->insert(KillPos, MI); - - if (LIS) - LIS->handleMove(*MI); - - ++Num3AddrSunk; - return true; -} - /// Return the MachineInstr* if it is the single def of the Reg in current BB. static MachineInstr *getSingleDef(unsigned Reg, MachineBasicBlock *BB, const MachineRegisterInfo *MRI) { @@ -740,26 +602,15 @@ TwoAddressInstructionPass::convertInstTo3Addr(MachineBasicBlock::iterator &mi, LLVM_DEBUG(dbgs() << "2addr: CONVERTING 2-ADDR: " << *mi); LLVM_DEBUG(dbgs() << "2addr: TO 3-ADDR: " << *NewMI); - bool Sunk = false; if (LIS) LIS->ReplaceMachineInstrInMaps(*mi, *NewMI); - if (NewMI->findRegisterUseOperand(RegB, false, TRI)) - // FIXME: Temporary workaround. If the new instruction doesn't - // uses RegB, convertToThreeAddress must have created more - // then one instruction. - Sunk = sink3AddrInstruction(NewMI, RegB, mi); - MBB->erase(mi); // Nuke the old inst. - if (!Sunk) { - DistanceMap.insert(std::make_pair(NewMI, Dist)); - mi = NewMI; - nmi = std::next(mi); - } - else - SunkInstrs.insert(NewMI); + DistanceMap.insert(std::make_pair(NewMI, Dist)); + mi = NewMI; + nmi = std::next(mi); // Update source and destination register maps. SrcRegMap.erase(RegA); @@ -1700,13 +1551,11 @@ bool TwoAddressInstructionPass::runOnMachineFunction(MachineFunction &Func) { SrcRegMap.clear(); DstRegMap.clear(); Processed.clear(); - SunkInstrs.clear(); for (MachineBasicBlock::iterator mi = MBB->begin(), me = MBB->end(); mi != me; ) { MachineBasicBlock::iterator nmi = std::next(mi); - // Don't revisit an instruction previously converted by target. It may - // contain undef register operands (%noreg), which are not handled. - if (mi->isDebugInstr() || SunkInstrs.count(&*mi)) { + // Skip debug instructions. + if (mi->isDebugInstr()) { mi = nmi; continue; } -- cgit v1.2.3