//
//===----------------------------------------------------------------------===//
-#define DEBUG_TYPE "twoaddrinstr"
#include "llvm/CodeGen/Passes.h"
#include "llvm/ADT/BitVector.h"
#include "llvm/ADT/DenseMap.h"
#include "llvm/CodeGen/MachineRegisterInfo.h"
#include "llvm/IR/Function.h"
#include "llvm/MC/MCInstrItineraries.h"
+#include "llvm/Support/CommandLine.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/ErrorHandling.h"
+#include "llvm/Support/raw_ostream.h"
#include "llvm/Target/TargetInstrInfo.h"
#include "llvm/Target/TargetMachine.h"
-#include "llvm/Target/TargetOptions.h"
#include "llvm/Target/TargetRegisterInfo.h"
+#include "llvm/Target/TargetSubtargetInfo.h"
using namespace llvm;
+#define DEBUG_TYPE "twoaddrinstr"
+
STATISTIC(NumTwoAddressInstrs, "Number of two-address instructions");
STATISTIC(NumCommuted , "Number of instructions commuted to coalesce");
STATISTIC(NumAggrCommuted , "Number of instructions aggressively commuted");
STATISTIC(NumReSchedUps, "Number of instructions re-scheduled up");
STATISTIC(NumReSchedDowns, "Number of instructions re-scheduled down");
+// Temporary flag to disable rescheduling.
+static cl::opt<bool>
+EnableRescheduling("twoaddr-reschedule",
+ cl::desc("Coalesce copies by rescheduling (default=true)"),
+ cl::init(true), cl::Hidden);
+
namespace {
class TwoAddressInstructionPass : public MachineFunctionPass {
MachineFunction *MF;
// The current basic block being processed.
MachineBasicBlock *MBB;
- // DistanceMap - Keep track the distance of a MI from the start of the
- // current basic block.
+ // Keep track the distance of a MI from the start of the current basic block.
DenseMap<MachineInstr*, unsigned> DistanceMap;
// Set of already processed instructions in the current block.
SmallPtrSet<MachineInstr*, 8> Processed;
- // SrcRegMap - 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.
+ // 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.
DenseMap<unsigned, unsigned> SrcRegMap;
- // DstRegMap - A map from virtual registers to physical registers which are
- // likely targets to be coalesced to due to copies to physical registers from
- // virtual registers. e.g. r1 = move v1024.
+ // A map from virtual registers to physical registers which are likely targets
+ // to be coalesced to due to copies to physical registers from virtual
+ // registers. e.g. r1 = move v1024.
DenseMap<unsigned, unsigned> 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);
bool isProfitableToCommute(unsigned regA, unsigned regB, unsigned regC,
MachineInstr *MI, unsigned Dist);
- bool commuteInstruction(MachineBasicBlock::iterator &mi,
- unsigned RegB, unsigned RegC, unsigned Dist);
+ bool commuteInstruction(MachineInstr *MI,
+ unsigned RegBIdx, unsigned RegCIdx, unsigned Dist);
bool isProfitableToConv3Addr(unsigned RegA, unsigned RegB);
bool tryInstructionTransform(MachineBasicBlock::iterator &mi,
MachineBasicBlock::iterator &nmi,
unsigned SrcIdx, unsigned DstIdx,
- unsigned Dist);
+ unsigned Dist, bool shouldOnlyCommute);
+ bool tryInstructionCommute(MachineInstr *MI,
+ unsigned DstOpIdx,
+ unsigned BaseOpIdx,
+ bool BaseOpKilled,
+ unsigned Dist);
void scanUses(unsigned DstReg);
void processCopy(MachineInstr *MI);
initializeTwoAddressInstructionPassPass(*PassRegistry::getPassRegistry());
}
- virtual void getAnalysisUsage(AnalysisUsage &AU) const {
+ void getAnalysisUsage(AnalysisUsage &AU) const override {
AU.setPreservesCFG();
- AU.addRequired<AliasAnalysis>();
+ AU.addRequired<AAResultsWrapperPass>();
AU.addPreserved<LiveVariables>();
AU.addPreserved<SlotIndexes>();
AU.addPreserved<LiveIntervals>();
MachineFunctionPass::getAnalysisUsage(AU);
}
- /// runOnMachineFunction - Pass entry point.
- bool runOnMachineFunction(MachineFunction&);
+ /// Pass entry point.
+ bool runOnMachineFunction(MachineFunction&) override;
};
} // end anonymous namespace
char TwoAddressInstructionPass::ID = 0;
INITIALIZE_PASS_BEGIN(TwoAddressInstructionPass, "twoaddressinstruction",
"Two-Address instruction pass", false, false)
-INITIALIZE_AG_DEPENDENCY(AliasAnalysis)
+INITIALIZE_PASS_DEPENDENCY(AAResultsWrapperPass)
INITIALIZE_PASS_END(TwoAddressInstructionPass, "twoaddressinstruction",
"Two-Address instruction pass", false, false)
char &llvm::TwoAddressInstructionPassID = TwoAddressInstructionPass::ID;
-/// sink3AddrInstruction - 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.
+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) {
// Check if it's safe to move this instruction.
bool SeenStore = true; // Be conservative.
- if (!MI->isSafeToMove(TII, AA, SeenStore))
+ if (!MI->isSafeToMove(AA, SeenStore))
return false;
unsigned DefReg = 0;
SmallSet<unsigned, 4> UseRegs;
- for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) {
- const MachineOperand &MO = MI->getOperand(i);
+ for (const MachineOperand &MO : MI->operands()) {
if (!MO.isReg())
continue;
unsigned MOReg = MO.getReg();
}
// Find the instruction that kills SavedReg.
- MachineInstr *KillMI = NULL;
- for (MachineRegisterInfo::use_nodbg_iterator
- UI = MRI->use_nodbg_begin(SavedReg),
- UE = MRI->use_nodbg_end(); UI != UE; ++UI) {
- MachineOperand &UseMO = UI.getOperand();
- if (!UseMO.isKill())
- continue;
- KillMI = UseMO.getParent();
- break;
+ 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
// 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 = NULL;
+ MachineOperand *KillMO = nullptr;
MachineBasicBlock::iterator KillPos = KillMI;
++KillPos;
unsigned NumVisited = 0;
- for (MachineBasicBlock::iterator I = llvm::next(OldPos); I != KillPos; ++I) {
+ for (MachineBasicBlock::iterator I = std::next(OldPos); I != KillPos; ++I) {
MachineInstr *OtherMI = I;
// DBG_VALUE cannot be counted against the limit.
if (OtherMI->isDebugValue())
if (DefReg == MOReg)
return false;
- if (MO.isKill()) {
+ 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.
}
assert(KillMO && "Didn't find kill");
- // Update kill and LV information.
- KillMO->setIsKill(false);
- KillMO = MI->findRegisterUseOperand(SavedReg, false, TRI);
- KillMO->setIsKill(true);
+ 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);
+ if (LV)
+ LV->replaceKillInstruction(SavedReg, KillMI, MI);
+ }
// Move instruction to its destination.
MBB->remove(MI);
return true;
}
-/// noUseAfterLastDef - Return true if there are no intervening uses between the
-/// last instruction in the MBB that defines the specified register and the
-/// two-address instruction which is being processed. It also returns the last
-/// def location by reference
+/// 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) {
+ MachineInstr *Ret = nullptr;
+ for (MachineInstr &DefMI : MRI->def_instructions(Reg)) {
+ if (DefMI.getParent() != BB || DefMI.isDebugValue())
+ continue;
+ if (!Ret)
+ Ret = &DefMI;
+ else if (Ret != &DefMI)
+ return nullptr;
+ }
+ return Ret;
+}
+
+/// Check if there is a reversed copy chain from FromReg to ToReg:
+/// %Tmp1 = copy %Tmp2;
+/// %FromReg = copy %Tmp1;
+/// %ToReg = add %FromReg ...
+/// %Tmp2 = copy %ToReg;
+/// MaxLen specifies the maximum length of the copy chain the func
+/// can walk through.
+bool TwoAddressInstructionPass::isRevCopyChain(unsigned FromReg, unsigned ToReg,
+ int Maxlen) {
+ unsigned TmpReg = FromReg;
+ for (int i = 0; i < Maxlen; i++) {
+ MachineInstr *Def = getSingleDef(TmpReg, MBB, MRI);
+ if (!Def || !Def->isCopy())
+ return false;
+
+ TmpReg = Def->getOperand(1).getReg();
+
+ if (TmpReg == ToReg)
+ return true;
+ }
+ return false;
+}
+
+/// Return true if there are no intervening uses between the last instruction
+/// in the MBB that defines the specified register and the two-address
+/// instruction which is being processed. It also returns the last def location
+/// by reference.
bool TwoAddressInstructionPass::noUseAfterLastDef(unsigned Reg, unsigned Dist,
unsigned &LastDef) {
LastDef = 0;
unsigned LastUse = Dist;
- for (MachineRegisterInfo::reg_iterator I = MRI->reg_begin(Reg),
- E = MRI->reg_end(); I != E; ++I) {
- MachineOperand &MO = I.getOperand();
+ for (MachineOperand &MO : MRI->reg_operands(Reg)) {
MachineInstr *MI = MO.getParent();
if (MI->getParent() != MBB || MI->isDebugValue())
continue;
return !(LastUse > LastDef && LastUse < Dist);
}
-/// isCopyToReg - Return true if the specified MI is a copy instruction or
-/// a extract_subreg instruction. It also returns the source and destination
-/// registers and whether they are physical registers by reference.
+/// Return true if the specified MI is a copy instruction or an extract_subreg
+/// instruction. It also returns the source and destination registers and
+/// whether they are physical registers by reference.
static bool isCopyToReg(MachineInstr &MI, const TargetInstrInfo *TII,
unsigned &SrcReg, unsigned &DstReg,
bool &IsSrcPhys, bool &IsDstPhys) {
return true;
}
-/// isPLainlyKilled - Test if the given register value, which is used by the
-// given instruction, is killed by the given instruction.
+/// Test if the given register value, which is used by the
+/// given instruction, is killed by the given instruction.
static bool isPlainlyKilled(MachineInstr *MI, unsigned Reg,
LiveIntervals *LIS) {
if (LIS && TargetRegisterInfo::isVirtualRegister(Reg) &&
SlotIndex useIdx = LIS->getInstructionIndex(MI);
LiveInterval::const_iterator I = LI.find(useIdx);
assert(I != LI.end() && "Reg must be live-in to use.");
- return SlotIndex::isSameInstr(I->end, useIdx);
+ return !I->end.isBlock() && SlotIndex::isSameInstr(I->end, useIdx);
}
return MI->killsRegister(Reg);
}
-/// isKilled - Test if the given register value, which is used by the given
+/// Test if the given register value, which is used by the given
/// instruction, is killed by the given instruction. This looks through
/// coalescable copies to see if the original value is potentially not killed.
///
MachineRegisterInfo::def_iterator Begin = MRI->def_begin(Reg);
// If there are multiple defs, we can't do a simple analysis, so just
// go with what the kill flag says.
- if (llvm::next(Begin) != MRI->def_end())
+ if (std::next(Begin) != MRI->def_end())
return true;
- DefMI = &*Begin;
+ DefMI = Begin->getParent();
bool IsSrcPhys, IsDstPhys;
unsigned SrcReg, DstReg;
// If the def is something other than a copy, then it isn't going to
}
}
-/// isTwoAddrUse - Return true if the specified MI uses the specified register
-/// as a two-address use. If so, return the destination register by reference.
+/// Return true if the specified MI uses the specified register as a two-address
+/// use. If so, return the destination register by reference.
static bool isTwoAddrUse(MachineInstr &MI, unsigned Reg, unsigned &DstReg) {
- const MCInstrDesc &MCID = MI.getDesc();
- unsigned NumOps = MI.isInlineAsm()
- ? MI.getNumOperands() : MCID.getNumOperands();
- for (unsigned i = 0; i != NumOps; ++i) {
+ for (unsigned i = 0, NumOps = MI.getNumOperands(); i != NumOps; ++i) {
const MachineOperand &MO = MI.getOperand(i);
if (!MO.isReg() || !MO.isUse() || MO.getReg() != Reg)
continue;
return false;
}
-/// findOnlyInterestingUse - Given a register, if has a single in-basic block
-/// use, return the use instruction if it's a copy or a two-address use.
+/// Given a register, if has a single in-basic block use, return the use
+/// instruction if it's a copy or a two-address use.
static
MachineInstr *findOnlyInterestingUse(unsigned Reg, MachineBasicBlock *MBB,
MachineRegisterInfo *MRI,
unsigned &DstReg, bool &IsDstPhys) {
if (!MRI->hasOneNonDBGUse(Reg))
// None or more than one use.
- return 0;
- MachineInstr &UseMI = *MRI->use_nodbg_begin(Reg);
+ return nullptr;
+ MachineInstr &UseMI = *MRI->use_instr_nodbg_begin(Reg);
if (UseMI.getParent() != MBB)
- return 0;
+ return nullptr;
unsigned SrcReg;
bool IsSrcPhys;
if (isCopyToReg(UseMI, TII, SrcReg, DstReg, IsSrcPhys, IsDstPhys)) {
IsDstPhys = TargetRegisterInfo::isPhysicalRegister(DstReg);
return &UseMI;
}
- return 0;
+ return nullptr;
}
-/// getMappedReg - Return the physical register the specified virtual register
-/// might be mapped to.
+/// Return the physical register the specified virtual register might be mapped
+/// to.
static unsigned
getMappedReg(unsigned Reg, DenseMap<unsigned, unsigned> &RegMap) {
while (TargetRegisterInfo::isVirtualRegister(Reg)) {
return 0;
}
-/// regsAreCompatible - Return true if the two registers are equal or aliased.
-///
+/// Return true if the two registers are equal or aliased.
static bool
regsAreCompatible(unsigned RegA, unsigned RegB, const TargetRegisterInfo *TRI) {
if (RegA == RegB)
}
-/// isProfitableToCommute - Return true if it's potentially profitable to commute
-/// the two-address instruction that's being processed.
+/// Return true if it's potentially profitable to commute the two-address
+/// instruction that's being processed.
bool
TwoAddressInstructionPass::
isProfitableToCommute(unsigned regA, unsigned regB, unsigned regC,
if (ToRegA) {
unsigned FromRegB = getMappedReg(regB, SrcRegMap);
unsigned FromRegC = getMappedReg(regC, SrcRegMap);
- bool BComp = !FromRegB || regsAreCompatible(FromRegB, ToRegA, TRI);
- bool CComp = !FromRegC || regsAreCompatible(FromRegC, ToRegA, TRI);
- if (BComp != CComp)
- return !BComp && CComp;
+ bool CompB = FromRegB && regsAreCompatible(FromRegB, ToRegA, TRI);
+ bool CompC = FromRegC && regsAreCompatible(FromRegC, ToRegA, TRI);
+
+ // Compute if any of the following are true:
+ // -RegB is not tied to a register and RegC is compatible with RegA.
+ // -RegB is tied to the wrong physical register, but RegC is.
+ // -RegB is tied to the wrong physical register, and RegC isn't tied.
+ if ((!FromRegB && CompC) || (FromRegB && !CompB && (!FromRegC || CompC)))
+ return true;
+ // Don't compute if any of the following are true:
+ // -RegC is not tied to a register and RegB is compatible with RegA.
+ // -RegC is tied to the wrong physical register, but RegB is.
+ // -RegC is tied to the wrong physical register, and RegB isn't tied.
+ if ((!FromRegC && CompB) || (FromRegC && !CompC && (!FromRegB || CompB)))
+ return false;
}
// If there is a use of regC between its last def (could be livein) and this
if (!noUseAfterLastDef(regB, Dist, LastDefB))
return true;
+ // Look for situation like this:
+ // %reg101 = MOV %reg100
+ // %reg102 = ...
+ // %reg103 = ADD %reg102, %reg101
+ // ... = %reg103 ...
+ // %reg100 = MOV %reg103
+ // If there is a reversed copy chain from reg101 to reg103, commute the ADD
+ // to eliminate an otherwise unavoidable copy.
+ // FIXME:
+ // We can extend the logic further: If an pair of operands in an insn has
+ // been merged, the insn could be regarded as a virtual copy, and the virtual
+ // copy could also be used to construct a copy chain.
+ // To more generally minimize register copies, ideally the logic of two addr
+ // instruction pass should be integrated with register allocation pass where
+ // interference graph is available.
+ if (isRevCopyChain(regC, regA, 3))
+ return true;
+
+ if (isRevCopyChain(regB, regA, 3))
+ return false;
+
// Since there are no intervening uses for both registers, then commute
// if the def of regC is closer. Its live interval is shorter.
return LastDefB && LastDefC && LastDefC > LastDefB;
}
-/// commuteInstruction - Commute a two-address instruction and update the basic
-/// block, distance map, and live variables if needed. Return true if it is
-/// successful.
-bool TwoAddressInstructionPass::
-commuteInstruction(MachineBasicBlock::iterator &mi,
- unsigned RegB, unsigned RegC, unsigned Dist) {
- MachineInstr *MI = mi;
+/// Commute a two-address instruction and update the basic block, distance map,
+/// and live variables if needed. Return true if it is successful.
+bool TwoAddressInstructionPass::commuteInstruction(MachineInstr *MI,
+ unsigned RegBIdx,
+ unsigned RegCIdx,
+ unsigned Dist) {
+ unsigned RegC = MI->getOperand(RegCIdx).getReg();
DEBUG(dbgs() << "2addr: COMMUTING : " << *MI);
- MachineInstr *NewMI = TII->commuteInstruction(MI);
+ MachineInstr *NewMI = TII->commuteInstruction(MI, false, RegBIdx, RegCIdx);
- if (NewMI == 0) {
+ if (NewMI == nullptr) {
DEBUG(dbgs() << "2addr: COMMUTING FAILED!\n");
return false;
}
DEBUG(dbgs() << "2addr: COMMUTED TO: " << *NewMI);
- // If the instruction changed to commute it, update livevar.
- if (NewMI != MI) {
- if (LV)
- // Update live variables
- LV->replaceKillInstruction(RegC, MI, NewMI);
- if (LIS)
- LIS->ReplaceMachineInstrInMaps(MI, NewMI);
-
- MBB->insert(mi, NewMI); // Insert the new inst
- MBB->erase(mi); // Nuke the old inst.
- mi = NewMI;
- DistanceMap.insert(std::make_pair(NewMI, Dist));
- }
+ assert(NewMI == MI &&
+ "TargetInstrInfo::commuteInstruction() should not return a new "
+ "instruction unless it was requested.");
// Update source register map.
unsigned FromRegC = getMappedReg(RegC, SrcRegMap);
return true;
}
-/// isProfitableToConv3Addr - Return true if it is profitable to convert the
-/// given 2-address instruction to a 3-address one.
+/// Return true if it is profitable to convert the given 2-address instruction
+/// to a 3-address one.
bool
TwoAddressInstructionPass::isProfitableToConv3Addr(unsigned RegA,unsigned RegB){
// Look for situations like this:
return (ToRegA && !regsAreCompatible(FromRegB, ToRegA, TRI));
}
-/// convertInstTo3Addr - Convert the specified two-address instruction into a
-/// three address one. Return true if this transformation was successful.
+/// Convert the specified two-address instruction into a three address one.
+/// Return true if this transformation was successful.
bool
TwoAddressInstructionPass::convertInstTo3Addr(MachineBasicBlock::iterator &mi,
MachineBasicBlock::iterator &nmi,
unsigned RegA, unsigned RegB,
unsigned Dist) {
// FIXME: Why does convertToThreeAddress() need an iterator reference?
- MachineFunction::iterator MFI = MBB;
+ MachineFunction::iterator MFI = MBB->getIterator();
MachineInstr *NewMI = TII->convertToThreeAddress(MFI, mi, LV);
- assert(MBB == MFI && "convertToThreeAddress changed iterator reference");
+ assert(MBB->getIterator() == MFI &&
+ "convertToThreeAddress changed iterator reference");
if (!NewMI)
return false;
if (!Sunk) {
DistanceMap.insert(std::make_pair(NewMI, Dist));
mi = NewMI;
- nmi = llvm::next(mi);
+ nmi = std::next(mi);
}
// Update source and destination register maps.
return true;
}
-/// scanUses - Scan forward recursively for only uses, update maps if the use
-/// is a copy or a two-address instruction.
+/// Scan forward recursively for only uses, update maps if the use is a copy or
+/// a two-address instruction.
void
TwoAddressInstructionPass::scanUses(unsigned DstReg) {
SmallVector<unsigned, 4> VirtRegPairs;
unsigned Reg = DstReg;
while (MachineInstr *UseMI = findOnlyInterestingUse(Reg, MBB, MRI, TII,IsCopy,
NewReg, IsDstPhys)) {
- if (IsCopy && !Processed.insert(UseMI))
+ if (IsCopy && !Processed.insert(UseMI).second)
break;
DenseMap<MachineInstr*, unsigned>::iterator DI = DistanceMap.find(UseMI);
}
}
-/// processCopy - If the specified instruction is not yet processed, process it
-/// if it's a copy. For a copy instruction, we find the physical registers the
+/// If the specified instruction is not yet processed, process it if it's a
+/// copy. For a copy instruction, we find the physical registers the
/// source and destination registers might be mapped to. These are kept in
/// point-to maps used to determine future optimizations. e.g.
/// v1024 = mov r0
return;
}
-/// rescheduleMIBelowKill - If there is one more local instruction that reads
-/// 'Reg' and it kills 'Reg, consider moving the instruction below the kill
-/// instruction in order to eliminate the need for the copy.
+/// If there is one more local instruction that reads 'Reg' and it kills 'Reg,
+/// consider moving the instruction below the kill instruction in order to
+/// eliminate the need for the copy.
bool TwoAddressInstructionPass::
rescheduleMIBelowKill(MachineBasicBlock::iterator &mi,
MachineBasicBlock::iterator &nmi,
// Must be created from unfolded load. Don't waste time trying this.
return false;
- MachineInstr *KillMI = 0;
+ MachineInstr *KillMI = nullptr;
if (LIS) {
LiveInterval &LI = LIS->getInterval(Reg);
assert(LI.end() != LI.begin() &&
return false;
bool SeenStore = true;
- if (!MI->isSafeToMove(TII, AA, SeenStore))
+ if (!MI->isSafeToMove(AA, SeenStore))
return false;
if (TII->getInstrLatency(InstrItins, MI) > 1)
// Move the copies connected to MI down as well.
MachineBasicBlock::iterator Begin = MI;
- MachineBasicBlock::iterator AfterMI = llvm::next(Begin);
+ MachineBasicBlock::iterator AfterMI = std::next(Begin);
MachineBasicBlock::iterator End = AfterMI;
while (End->isCopy() && Defs.count(End->getOperand(1).getReg())) {
}
// Move debug info as well.
- while (Begin != MBB->begin() && llvm::prior(Begin)->isDebugValue())
+ while (Begin != MBB->begin() && std::prev(Begin)->isDebugValue())
--Begin;
nmi = End;
LIS->handleMove(CopyMI);
InsertPos = CopyMI;
}
- End = llvm::next(MachineBasicBlock::iterator(MI));
+ End = std::next(MachineBasicBlock::iterator(MI));
}
// Copies following MI may have been moved as well.
return true;
}
-/// isDefTooClose - Return true if the re-scheduling will put the given
-/// instruction too close to the defs of its register dependencies.
+/// Return true if the re-scheduling will put the given instruction too close
+/// to the defs of its register dependencies.
bool TwoAddressInstructionPass::isDefTooClose(unsigned Reg, unsigned Dist,
MachineInstr *MI) {
- for (MachineRegisterInfo::def_iterator DI = MRI->def_begin(Reg),
- DE = MRI->def_end(); DI != DE; ++DI) {
- MachineInstr *DefMI = &*DI;
- if (DefMI->getParent() != MBB || DefMI->isCopy() || DefMI->isCopyLike())
+ for (MachineInstr &DefMI : MRI->def_instructions(Reg)) {
+ if (DefMI.getParent() != MBB || DefMI.isCopy() || DefMI.isCopyLike())
continue;
- if (DefMI == MI)
+ if (&DefMI == MI)
return true; // MI is defining something KillMI uses
- DenseMap<MachineInstr*, unsigned>::iterator DDI = DistanceMap.find(DefMI);
+ DenseMap<MachineInstr*, unsigned>::iterator DDI = DistanceMap.find(&DefMI);
if (DDI == DistanceMap.end())
return true; // Below MI
unsigned DefDist = DDI->second;
assert(Dist > DefDist && "Visited def already?");
- if (TII->getInstrLatency(InstrItins, DefMI) > (Dist - DefDist))
+ if (TII->getInstrLatency(InstrItins, &DefMI) > (Dist - DefDist))
return true;
}
return false;
}
-/// rescheduleKillAboveMI - If there is one more local instruction that reads
-/// 'Reg' and it kills 'Reg, consider moving the kill instruction above the
-/// current two-address instruction in order to eliminate the need for the
-/// copy.
+/// If there is one more local instruction that reads 'Reg' and it kills 'Reg,
+/// consider moving the kill instruction above the current two-address
+/// instruction in order to eliminate the need for the copy.
bool TwoAddressInstructionPass::
rescheduleKillAboveMI(MachineBasicBlock::iterator &mi,
MachineBasicBlock::iterator &nmi,
// Must be created from unfolded load. Don't waste time trying this.
return false;
- MachineInstr *KillMI = 0;
+ MachineInstr *KillMI = nullptr;
if (LIS) {
LiveInterval &LI = LIS->getInterval(Reg);
assert(LI.end() != LI.begin() &&
return false;
bool SeenStore = true;
- if (!KillMI->isSafeToMove(TII, AA, SeenStore))
+ if (!KillMI->isSafeToMove(AA, SeenStore))
return false;
SmallSet<unsigned, 2> Uses;
// Move the old kill above MI, don't forget to move debug info as well.
MachineBasicBlock::iterator InsertPos = mi;
- while (InsertPos != MBB->begin() && llvm::prior(InsertPos)->isDebugValue())
+ while (InsertPos != MBB->begin() && std::prev(InsertPos)->isDebugValue())
--InsertPos;
MachineBasicBlock::iterator From = KillMI;
- MachineBasicBlock::iterator To = llvm::next(From);
- while (llvm::prior(From)->isDebugValue())
+ MachineBasicBlock::iterator To = std::next(From);
+ while (std::prev(From)->isDebugValue())
--From;
MBB->splice(InsertPos, MBB, From, To);
- nmi = llvm::prior(InsertPos); // Backtrack so we process the moved instr.
+ nmi = std::prev(InsertPos); // Backtrack so we process the moved instr.
DistanceMap.erase(DI);
// Update live variables
return true;
}
-/// tryInstructionTransform - For the case where an instruction has a single
-/// pair of tied register operands, attempt some transformations that may
-/// either eliminate the tied operands or improve the opportunities for
-/// coalescing away the register copy. Returns true if no copy needs to be
-/// inserted to untie mi's operands (either because they were untied, or
-/// because mi was rescheduled, and will be visited again later).
+/// Tries to commute the operand 'BaseOpIdx' and some other operand in the
+/// given machine instruction to improve opportunities for coalescing and
+/// elimination of a register to register copy.
+///
+/// 'DstOpIdx' specifies the index of MI def operand.
+/// 'BaseOpKilled' specifies if the register associated with 'BaseOpIdx'
+/// operand is killed by the given instruction.
+/// The 'Dist' arguments provides the distance of MI from the start of the
+/// current basic block and it is used to determine if it is profitable
+/// to commute operands in the instruction.
+///
+/// Returns true if the transformation happened. Otherwise, returns false.
+bool TwoAddressInstructionPass::tryInstructionCommute(MachineInstr *MI,
+ unsigned DstOpIdx,
+ unsigned BaseOpIdx,
+ bool BaseOpKilled,
+ unsigned Dist) {
+ unsigned DstOpReg = MI->getOperand(DstOpIdx).getReg();
+ unsigned BaseOpReg = MI->getOperand(BaseOpIdx).getReg();
+ unsigned OpsNum = MI->getDesc().getNumOperands();
+ unsigned OtherOpIdx = MI->getDesc().getNumDefs();
+ for (; OtherOpIdx < OpsNum; OtherOpIdx++) {
+ // The call of findCommutedOpIndices below only checks if BaseOpIdx
+ // and OtherOpIdx are commutable, it does not really search for
+ // other commutable operands and does not change the values of passed
+ // variables.
+ if (OtherOpIdx == BaseOpIdx ||
+ !TII->findCommutedOpIndices(MI, BaseOpIdx, OtherOpIdx))
+ continue;
+
+ unsigned OtherOpReg = MI->getOperand(OtherOpIdx).getReg();
+ bool AggressiveCommute = false;
+
+ // If OtherOp dies but BaseOp does not, swap the OtherOp and BaseOp
+ // operands. This makes the live ranges of DstOp and OtherOp joinable.
+ bool DoCommute =
+ !BaseOpKilled && isKilled(*MI, OtherOpReg, MRI, TII, LIS, false);
+
+ if (!DoCommute &&
+ isProfitableToCommute(DstOpReg, BaseOpReg, OtherOpReg, MI, Dist)) {
+ DoCommute = true;
+ AggressiveCommute = true;
+ }
+
+ // If it's profitable to commute, try to do so.
+ if (DoCommute && commuteInstruction(MI, BaseOpIdx, OtherOpIdx, Dist)) {
+ ++NumCommuted;
+ if (AggressiveCommute)
+ ++NumAggrCommuted;
+ return true;
+ }
+ }
+ return false;
+}
+
+/// For the case where an instruction has a single pair of tied register
+/// operands, attempt some transformations that may either eliminate the tied
+/// operands or improve the opportunities for coalescing away the register copy.
+/// Returns true if no copy needs to be inserted to untie mi's operands
+/// (either because they were untied, or because mi was rescheduled, and will
+/// be visited again later). If the shouldOnlyCommute flag is true, only
+/// instruction commutation is attempted.
bool TwoAddressInstructionPass::
tryInstructionTransform(MachineBasicBlock::iterator &mi,
MachineBasicBlock::iterator &nmi,
- unsigned SrcIdx, unsigned DstIdx, unsigned Dist) {
+ unsigned SrcIdx, unsigned DstIdx,
+ unsigned Dist, bool shouldOnlyCommute) {
if (OptLevel == CodeGenOpt::None)
return false;
if (TargetRegisterInfo::isVirtualRegister(regA))
scanUses(regA);
- // Check if it is profitable to commute the operands.
- unsigned SrcOp1, SrcOp2;
- unsigned regC = 0;
- unsigned regCIdx = ~0U;
- bool TryCommute = false;
- bool AggressiveCommute = false;
- if (MI.isCommutable() && MI.getNumOperands() >= 3 &&
- TII->findCommutedOpIndices(&MI, SrcOp1, SrcOp2)) {
- if (SrcIdx == SrcOp1)
- regCIdx = SrcOp2;
- else if (SrcIdx == SrcOp2)
- regCIdx = SrcOp1;
-
- if (regCIdx != ~0U) {
- regC = MI.getOperand(regCIdx).getReg();
- if (!regBKilled && isKilled(MI, regC, MRI, TII, LIS, false))
- // If C dies but B does not, swap the B and C operands.
- // This makes the live ranges of A and C joinable.
- TryCommute = true;
- else if (isProfitableToCommute(regA, regB, regC, &MI, Dist)) {
- TryCommute = true;
- AggressiveCommute = true;
- }
- }
- }
+ bool Commuted = tryInstructionCommute(&MI, DstIdx, SrcIdx, regBKilled, Dist);
+
+ // If the instruction is convertible to 3 Addr, instead
+ // of returning try 3 Addr transformation aggresively and
+ // use this variable to check later. Because it might be better.
+ // For example, we can just use `leal (%rsi,%rdi), %eax` and `ret`
+ // instead of the following code.
+ // addl %esi, %edi
+ // movl %edi, %eax
+ // ret
+ if (Commuted && !MI.isConvertibleTo3Addr())
+ return false;
- // If it's profitable to commute, try to do so.
- if (TryCommute && commuteInstruction(mi, regB, regC, Dist)) {
- ++NumCommuted;
- if (AggressiveCommute)
- ++NumAggrCommuted;
+ if (shouldOnlyCommute)
return false;
- }
// If there is one more use of regB later in the same MBB, consider
// re-schedule this MI below it.
- if (rescheduleMIBelowKill(mi, nmi, regB)) {
+ if (!Commuted && EnableRescheduling && rescheduleMIBelowKill(mi, nmi, regB)) {
++NumReSchedDowns;
return true;
}
+ // If we commuted, regB may have changed so we should re-sample it to avoid
+ // confusing the three address conversion below.
+ if (Commuted) {
+ regB = MI.getOperand(SrcIdx).getReg();
+ regBKilled = isKilled(MI, regB, MRI, TII, LIS, true);
+ }
+
if (MI.isConvertibleTo3Addr()) {
// This instruction is potentially convertible to a true
// three-address instruction. Check if it is profitable.
}
}
+ // Return if it is commuted but 3 addr conversion is failed.
+ if (Commuted)
+ return false;
+
// If there is one more use of regB later in the same MBB, consider
// re-schedule it before this MI if it's legal.
- if (rescheduleKillAboveMI(mi, nmi, regB)) {
+ if (EnableRescheduling && rescheduleKillAboveMI(mi, nmi, regB)) {
++NumReSchedUps;
return true;
}
unsigned NewDstIdx = NewMIs[1]->findRegisterDefOperandIdx(regA);
unsigned NewSrcIdx = NewMIs[1]->findRegisterUseOperandIdx(regB);
MachineBasicBlock::iterator NewMI = NewMIs[1];
- bool TransformSuccess =
- tryInstructionTransform(NewMI, mi, NewSrcIdx, NewDstIdx, Dist);
- if (TransformSuccess ||
- NewMIs[1]->getOperand(NewSrcIdx).isKill()) {
+ bool TransformResult =
+ tryInstructionTransform(NewMI, mi, NewSrcIdx, NewDstIdx, Dist, true);
+ (void)TransformResult;
+ assert(!TransformResult &&
+ "tryInstructionTransform() should return false.");
+ if (NewMIs[1]->getOperand(NewSrcIdx).isKill()) {
// Success, or at least we made an improvement. Keep the unfolded
// instructions and discard the original.
if (LV) {
SmallVector<unsigned, 4> OrigRegs;
if (LIS) {
- for (MachineInstr::const_mop_iterator MOI = MI.operands_begin(),
- MOE = MI.operands_end(); MOI != MOE; ++MOI) {
- if (MOI->isReg())
- OrigRegs.push_back(MOI->getReg());
+ for (const MachineOperand &MO : MI.operands()) {
+ if (MO.isReg())
+ OrigRegs.push_back(MO.getReg());
}
}
}
mi = NewMIs[1];
- if (TransformSuccess)
- return true;
} else {
// Transforming didn't eliminate the tie and didn't lead to an
// improvement. Clean up the unfolded instructions and keep the
assert(SrcReg && SrcMO.isUse() && "two address instruction invalid");
// Deal with <undef> uses immediately - simply rewrite the src operand.
- if (SrcMO.isUndef()) {
+ if (SrcMO.isUndef() && !DstMO.getSubReg()) {
// Constrain the DstReg register class if required.
if (TargetRegisterInfo::isVirtualRegister(DstReg))
if (const TargetRegisterClass *RC = TII->getRegClass(MCID, SrcIdx,
TRI, *MF))
MRI->constrainRegClass(DstReg, RC);
SrcMO.setReg(DstReg);
+ SrcMO.setSubReg(0);
DEBUG(dbgs() << "\t\trewrite undef:\t" << *MI);
continue;
}
unsigned LastCopiedReg = 0;
SlotIndex LastCopyIdx;
unsigned RegB = 0;
+ unsigned SubRegB = 0;
for (unsigned tpi = 0, tpe = TiedPairs.size(); tpi != tpe; ++tpi) {
unsigned SrcIdx = TiedPairs[tpi].first;
unsigned DstIdx = TiedPairs[tpi].second;
// Grab RegB from the instruction because it may have changed if the
// instruction was commuted.
RegB = MI->getOperand(SrcIdx).getReg();
+ SubRegB = MI->getOperand(SrcIdx).getSubReg();
if (RegA == RegB) {
// The register is tied to multiple destinations (or else we would
#endif
// Emit a copy.
- BuildMI(*MI->getParent(), MI, MI->getDebugLoc(),
- TII->get(TargetOpcode::COPY), RegA).addReg(RegB);
+ MachineInstrBuilder MIB = BuildMI(*MI->getParent(), MI, MI->getDebugLoc(),
+ TII->get(TargetOpcode::COPY), RegA);
+ // If this operand is folding a truncation, the truncation now moves to the
+ // copy so that the register classes remain valid for the operands.
+ MIB.addReg(RegB, 0, SubRegB);
+ const TargetRegisterClass *RC = MRI->getRegClass(RegB);
+ if (SubRegB) {
+ if (TargetRegisterInfo::isVirtualRegister(RegA)) {
+ assert(TRI->getMatchingSuperRegClass(RC, MRI->getRegClass(RegA),
+ SubRegB) &&
+ "tied subregister must be a truncation");
+ // The superreg class will not be used to constrain the subreg class.
+ RC = nullptr;
+ }
+ else {
+ assert(TRI->getMatchingSuperReg(RegA, SubRegB, MRI->getRegClass(RegB))
+ && "tied subregister must be a truncation");
+ }
+ }
// Update DistanceMap.
MachineBasicBlock::iterator PrevMI = MI;
VNInfo *VNI = LI.getNextValue(LastCopyIdx, LIS->getVNInfoAllocator());
SlotIndex endIdx =
LIS->getInstructionIndex(MI).getRegSlot(IsEarlyClobber);
- LI.addRange(LiveRange(LastCopyIdx, endIdx, VNI));
+ LI.addSegment(LiveInterval::Segment(LastCopyIdx, endIdx, VNI));
}
}
- DEBUG(dbgs() << "\t\tprepend:\t" << *PrevMI);
+ DEBUG(dbgs() << "\t\tprepend:\t" << *MIB);
MachineOperand &MO = MI->getOperand(SrcIdx);
assert(MO.isReg() && MO.getReg() == RegB && MO.isUse() &&
// Make sure regA is a legal regclass for the SrcIdx operand.
if (TargetRegisterInfo::isVirtualRegister(RegA) &&
TargetRegisterInfo::isVirtualRegister(RegB))
- MRI->constrainRegClass(RegA, MRI->getRegClass(RegB));
-
+ MRI->constrainRegClass(RegA, RC);
MO.setReg(RegA);
+ // The getMatchingSuper asserts guarantee that the register class projected
+ // by SubRegB is compatible with RegA with no subregister. So regardless of
+ // whether the dest oper writes a subreg, the source oper should not.
+ MO.setSubReg(0);
// Propagate SrcRegMap.
SrcRegMap[RegA] = RegB;
}
-
if (AllUsesCopied) {
if (!IsEarlyClobber) {
// Replace other (un-tied) uses of regB with LastCopiedReg.
for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) {
MachineOperand &MO = MI->getOperand(i);
- if (MO.isReg() && MO.getReg() == RegB && MO.isUse()) {
+ if (MO.isReg() && MO.getReg() == RegB && MO.getSubReg() == SubRegB &&
+ MO.isUse()) {
if (MO.isKill()) {
MO.setIsKill(false);
RemovedKillFlag = true;
}
MO.setReg(LastCopiedReg);
+ MO.setSubReg(0);
}
}
}
SlotIndex UseIdx = MIIdx.getRegSlot(IsEarlyClobber);
if (I->end == UseIdx)
- LI.removeRange(LastCopyIdx, UseIdx);
+ LI.removeSegment(LastCopyIdx, UseIdx);
}
} else if (RemovedKillFlag) {
}
}
-/// runOnMachineFunction - Reduce two-address instructions to two operands.
-///
+/// Reduce two-address instructions to two operands.
bool TwoAddressInstructionPass::runOnMachineFunction(MachineFunction &Func) {
MF = &Func;
const TargetMachine &TM = MF->getTarget();
MRI = &MF->getRegInfo();
- TII = TM.getInstrInfo();
- TRI = TM.getRegisterInfo();
- InstrItins = TM.getInstrItineraryData();
+ TII = MF->getSubtarget().getInstrInfo();
+ TRI = MF->getSubtarget().getRegisterInfo();
+ InstrItins = MF->getSubtarget().getInstrItineraryData();
LV = getAnalysisIfAvailable<LiveVariables>();
LIS = getAnalysisIfAvailable<LiveIntervals>();
- AA = &getAnalysis<AliasAnalysis>();
+ AA = &getAnalysis<AAResultsWrapperPass>().getAAResults();
OptLevel = TM.getOptLevel();
bool MadeChange = false;
TiedOperandMap TiedOperands;
for (MachineFunction::iterator MBBI = MF->begin(), MBBE = MF->end();
MBBI != MBBE; ++MBBI) {
- MBB = MBBI;
+ MBB = &*MBBI;
unsigned Dist = 0;
DistanceMap.clear();
SrcRegMap.clear();
Processed.clear();
for (MachineBasicBlock::iterator mi = MBB->begin(), me = MBB->end();
mi != me; ) {
- MachineBasicBlock::iterator nmi = llvm::next(mi);
+ MachineBasicBlock::iterator nmi = std::next(mi);
if (mi->isDebugValue()) {
mi = nmi;
continue;
// transformations that may either eliminate the tied operands or
// improve the opportunities for coalescing away the register copy.
if (TiedOperands.size() == 1) {
- SmallVector<std::pair<unsigned, unsigned>, 4> &TiedPairs
+ SmallVectorImpl<std::pair<unsigned, unsigned> > &TiedPairs
= TiedOperands.begin()->second;
if (TiedPairs.size() == 1) {
unsigned SrcIdx = TiedPairs[0].first;
unsigned SrcReg = mi->getOperand(SrcIdx).getReg();
unsigned DstReg = mi->getOperand(DstIdx).getReg();
if (SrcReg != DstReg &&
- tryInstructionTransform(mi, nmi, SrcIdx, DstIdx, Dist)) {
- // The tied operands have been eliminated or shifted further down the
- // block to ease elimination. Continue processing with 'nmi'.
+ tryInstructionTransform(mi, nmi, SrcIdx, DstIdx, Dist, false)) {
+ // The tied operands have been eliminated or shifted further down
+ // the block to ease elimination. Continue processing with 'nmi'.
TiedOperands.clear();
mi = nmi;
continue;
}
// Now iterate over the information collected above.
- for (TiedOperandMap::iterator OI = TiedOperands.begin(),
- OE = TiedOperands.end(); OI != OE; ++OI) {
- processTiedPairs(mi, OI->second, Dist);
+ for (auto &TO : TiedOperands) {
+ processTiedPairs(mi, TO.second, Dist);
DEBUG(dbgs() << "\t\trewrite to:\t" << *mi);
}
TargetRegisterInfo::isPhysicalRegister(DstReg) ||
!(MI->getNumOperands() & 1)) {
DEBUG(dbgs() << "Illegal REG_SEQUENCE instruction:" << *MI);
- llvm_unreachable(0);
+ llvm_unreachable(nullptr);
}
SmallVector<unsigned, 4> OrigRegs;
}
MachineBasicBlock::iterator EndMBBI =
- llvm::next(MachineBasicBlock::iterator(MI));
+ std::next(MachineBasicBlock::iterator(MI));
if (!DefEmitted) {
DEBUG(dbgs() << "Turned: " << *MI << " into an IMPLICIT_DEF");
projects / oota-llvm.git / blobdiff