index 682c26c2c833b1df724c20a6bc4dae7174afe9d6..0596b60a19aef916ee8a1c523c24dd8085dcda0b 100644 (file)
//
//===----------------------------------------------------------------------===//
-#define DEBUG_TYPE "regalloc"
#include "RegisterCoalescer.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/ADT/SmallSet.h"
#include <cmath>
using namespace llvm;
+#define DEBUG_TYPE "regalloc"
+
STATISTIC(numJoins , "Number of interval joins performed");
STATISTIC(numCrossRCs , "Number of cross class joins performed");
STATISTIC(numCommutes , "Number of instruction commuting performed");
/// blocks exclusively containing copies.
bool JoinSplitEdges;
- /// WorkList - Copy instructions yet to be coalesced.
+ /// Copy instructions yet to be coalesced.
SmallVector<MachineInstr*, 8> WorkList;
SmallVector<MachineInstr*, 8> LocalWorkList;
- /// ErasedInstrs - Set of instruction pointers that have been erased, and
+ /// Set of instruction pointers that have been erased, and
/// that may be present in WorkList.
SmallPtrSet<MachineInstr*, 8> ErasedInstrs;
/// LiveRangeEdit callback.
void LRE_WillEraseInstruction(MachineInstr *MI) override;
- /// coalesceLocals - coalesce the LocalWorkList.
+ /// Coalesce the LocalWorkList.
void coalesceLocals();
- /// joinAllIntervals - join compatible live intervals
+ /// Join compatible live intervals
void joinAllIntervals();
- /// copyCoalesceInMBB - Coalesce copies in the specified MBB, putting
+ /// Coalesce copies in the specified MBB, putting
/// copies that cannot yet be coalesced into WorkList.
void copyCoalesceInMBB(MachineBasicBlock *MBB);
- /// copyCoalesceWorkList - Try to coalesce all copies in CurrList. Return
+ /// Try to coalesce all copies in CurrList. Return
/// true if any progress was made.
bool copyCoalesceWorkList(MutableArrayRef<MachineInstr*> CurrList);
- /// joinCopy - Attempt to join intervals corresponding to SrcReg/DstReg,
+ /// Attempt to join intervals corresponding to SrcReg/DstReg,
/// which are the src/dst of the copy instruction CopyMI. This returns
/// true if the copy was successfully coalesced away. If it is not
/// currently possible to coalesce this interval, but it may be possible if
/// 'Again'.
bool joinCopy(MachineInstr *TheCopy, bool &Again);
- /// joinIntervals - Attempt to join these two intervals. On failure, this
+ /// Attempt to join these two intervals. On failure, this
/// returns false. The output "SrcInt" will not have been modified, so we
/// can use this information below to update aliases.
bool joinIntervals(CoalescerPair &CP);
/// Attempt joining with a reserved physreg.
bool joinReservedPhysReg(CoalescerPair &CP);
- /// adjustCopiesBackFrom - We found a non-trivially-coalescable copy. If
+ /// We found a non-trivially-coalescable copy. If
/// the source value number is defined by a copy from the destination reg
/// see if we can merge these two destination reg valno# into a single
/// value number, eliminating a copy.
bool adjustCopiesBackFrom(const CoalescerPair &CP, MachineInstr *CopyMI);
- /// hasOtherReachingDefs - Return true if there are definitions of IntB
+ /// Return true if there are definitions of IntB
/// other than BValNo val# that can reach uses of AValno val# of IntA.
bool hasOtherReachingDefs(LiveInterval &IntA, LiveInterval &IntB,
VNInfo *AValNo, VNInfo *BValNo);
- /// removeCopyByCommutingDef - We found a non-trivially-coalescable copy.
+ /// We found a non-trivially-coalescable copy.
/// If the source value number is defined by a commutable instruction and
/// its other operand is coalesced to the copy dest register, see if we
/// can transform the copy into a noop by commuting the definition.
bool removeCopyByCommutingDef(const CoalescerPair &CP,MachineInstr *CopyMI);
- /// reMaterializeTrivialDef - If the source of a copy is defined by a
+ /// If the source of a copy is defined by a
/// trivial computation, replace the copy by rematerialize the definition.
bool reMaterializeTrivialDef(CoalescerPair &CP, MachineInstr *CopyMI,
bool &IsDefCopy);
- /// canJoinPhys - Return true if a physreg copy should be joined.
+ /// Return true if a physreg copy should be joined.
bool canJoinPhys(const CoalescerPair &CP);
- /// updateRegDefsUses - Replace all defs and uses of SrcReg to DstReg and
+ /// Replace all defs and uses of SrcReg to DstReg and
/// update the subregister number if it is not zero. If DstReg is a
/// physical register and the existing subregister number of the def / use
/// being updated is not zero, make sure to set it to the correct physical
/// subregister.
void updateRegDefsUses(unsigned SrcReg, unsigned DstReg, unsigned SubIdx);
- /// eliminateUndefCopy - Handle copies of undef values.
+ /// Handle copies of undef values.
bool eliminateUndefCopy(MachineInstr *CopyMI, const CoalescerPair &CP);
public:
void releaseMemory() override;
- /// runOnMachineFunction - pass entry point
+ /// This is the pass entry point.
bool runOnMachineFunction(MachineFunction&) override;
- /// print - Implement the dump method.
- void print(raw_ostream &O, const Module* = 0) const override;
+ /// Implement the dump method.
+ void print(raw_ostream &O, const Module* = nullptr) const override;
};
} /// end anonymous namespace
if (MBB->pred_size() != 1 || MBB->succ_size() != 1)
return false;
- for (MachineBasicBlock::const_iterator MII = MBB->begin(), E = MBB->end();
- MII != E; ++MII) {
- if (!MII->isCopyLike() && !MII->isUnconditionalBranch())
+ for (const auto &MI : *MBB) {
+ if (!MI.isCopyLike() && !MI.isUnconditionalBranch())
return false;
}
return true;
bool CoalescerPair::setRegisters(const MachineInstr *MI) {
SrcReg = DstReg = 0;
SrcIdx = DstIdx = 0;
- NewRC = 0;
+ NewRC = nullptr;
Flipped = CrossClass = false;
unsigned Src, Dst, SrcSub, DstSub;
void RegisterCoalescer::eliminateDeadDefs() {
SmallVector<unsigned, 8> NewRegs;
- LiveRangeEdit(0, NewRegs, *MF, *LIS, 0, this).eliminateDeadDefs(DeadDefs);
+ LiveRangeEdit(nullptr, NewRegs, *MF, *LIS,
+ nullptr, this).eliminateDeadDefs(DeadDefs);
}
// Callback from eliminateDeadDefs().
ErasedInstrs.insert(MI);
}
-/// adjustCopiesBackFrom - We found a non-trivially-coalescable copy with IntA
+/// We found a non-trivially-coalescable copy with IntA
/// being the source and IntB being the dest, thus this defines a value number
/// in IntB. If the source value number (in IntA) is defined by a copy from B,
/// see if we can merge these two pieces of B into a single value number,
return true;
}
-/// hasOtherReachingDefs - Return true if there are definitions of IntB
+/// Return true if there are definitions of IntB
/// other than BValNo val# that can reach uses of AValno val# of IntA.
bool RegisterCoalescer::hasOtherReachingDefs(LiveInterval &IntA,
LiveInterval &IntB,
return false;
}
-/// removeCopyByCommutingDef - We found a non-trivially-coalescable copy with
+/// We found a non-trivially-coalescable copy with
/// IntA being the source and IntB being the dest, thus this defines a value
/// number in IntB. If the source value number (in IntA) is defined by a
/// commutable instruction and its other operand is coalesced to the copy dest
return true;
}
-/// reMaterializeTrivialDef - If the source of a copy is defined by a trivial
+/// If the source of a copy is defined by a trivial
/// computation, replace the copy by rematerialize the definition.
bool RegisterCoalescer::reMaterializeTrivialDef(CoalescerPair &CP,
MachineInstr *CopyMI,
IsDefCopy = true;
return false;
}
- if (!DefMI->isAsCheapAsAMove())
+ if (!TII->isAsCheapAsAMove(DefMI))
return false;
if (!TII->isTriviallyReMaterializable(DefMI, AA))
return false;
true /*IsDef*/,
true /*IsImp*/,
false /*IsKill*/));
+ // Record small dead def live-ranges for all the subregisters
+ // of the destination register.
+ // Otherwise, variables that live through may miss some
+ // interferences, thus creating invalid allocation.
+ // E.g., i386 code:
+ // vreg1 = somedef ; vreg1 GR8
+ // vreg2 = remat ; vreg2 GR32
+ // CL = COPY vreg2.sub_8bit
+ // = somedef vreg1 ; vreg1 GR8
+ // =>
+ // vreg1 = somedef ; vreg1 GR8
+ // ECX<def, dead> = remat ; CL<imp-def>
+ // = somedef vreg1 ; vreg1 GR8
+ // vreg1 will see the inteferences with CL but not with CH since
+ // no live-ranges would have been created for ECX.
+ // Fix that!
+ SlotIndex NewMIIdx = LIS->getInstructionIndex(NewMI);
+ for (MCRegUnitIterator Units(NewMI->getOperand(0).getReg(), TRI);
+ Units.isValid(); ++Units)
+ if (LiveRange *LR = LIS->getCachedRegUnit(*Units))
+ LR->createDeadDef(NewMIIdx.getRegSlot(), LIS->getVNInfoAllocator());
}
if (NewMI->getOperand(0).getSubReg())
// The source interval can become smaller because we removed a use.
LIS->shrinkToUses(&SrcInt, &DeadDefs);
- if (!DeadDefs.empty())
+ if (!DeadDefs.empty()) {
+ // If the virtual SrcReg is completely eliminated, update all DBG_VALUEs
+ // to describe DstReg instead.
+ for (MachineRegisterInfo::use_iterator UI = MRI->use_begin(SrcReg),
+ UE = MRI->use_end(); UI != UE; ++UI) {
+ MachineOperand &UseMO = *UI;
+ MachineInstr *UseMI = UseMO.getParent();
+ if (UseMI->isDebugValue()) {
+ UseMO.setReg(DstReg);
+ DEBUG({dbgs() << "\t\tupdated: " << *UseMI;});
+ }
+ }
eliminateDeadDefs();
+ }
return true;
}
-/// eliminateUndefCopy - ProcessImpicitDefs may leave some copies of <undef>
+/// ProcessImpicitDefs may leave some copies of <undef>
/// values, it only removes local variables. When we have a copy like:
///
/// %vreg1 = COPY %vreg2<undef>
// No intervals are live-in to CopyMI - it is undef.
if (CP.isFlipped())
DstInt = SrcInt;
- SrcInt = 0;
+ SrcInt = nullptr;
VNInfo *DeadVNI = DstInt->getVNInfoAt(Idx.getRegSlot());
assert(DeadVNI && "No value defined in DstInt");
return true;
}
-/// updateRegDefsUses - Replace all defs and uses of SrcReg to DstReg and
-/// update the subregister number if it is not zero. If DstReg is a
-/// physical register and the existing subregister number of the def / use
-/// being updated is not zero, make sure to set it to the correct physical
-/// subregister.
+/// Replace all defs and uses of SrcReg to DstReg and update the subregister
+/// number if it is not zero. If DstReg is a physical register and the existing
+/// subregister number of the def / use being updated is not zero, make sure to
+/// set it to the correct physical subregister.
void RegisterCoalescer::updateRegDefsUses(unsigned SrcReg,
unsigned DstReg,
unsigned SubIdx) {
bool DstIsPhys = TargetRegisterInfo::isPhysicalRegister(DstReg);
- LiveInterval *DstInt = DstIsPhys ? 0 : &LIS->getInterval(DstReg);
+ LiveInterval *DstInt = DstIsPhys ? nullptr : &LIS->getInterval(DstReg);
SmallPtrSet<MachineInstr*, 8> Visited;
for (MachineRegisterInfo::reg_instr_iterator
// the UseMI operands removes them from the SrcReg use-def chain, but when
// SrcReg is DstReg we could encounter UseMI twice if it has multiple
// operands mentioning the virtual register.
- if (SrcReg == DstReg && !Visited.insert(UseMI))
+ if (SrcReg == DstReg && !Visited.insert(UseMI).second)
continue;
SmallVector<unsigned,8> Ops;
}
}
-/// canJoinPhys - Return true if a copy involving a physreg should be joined.
+/// Return true if a copy involving a physreg should be joined.
bool RegisterCoalescer::canJoinPhys(const CoalescerPair &CP) {
/// Always join simple intervals that are defined by a single copy from a
/// reserved register. This doesn't increase register pressure, so it is
return false;
}
-/// joinCopy - Attempt to join intervals corresponding to SrcReg/DstReg,
+/// Attempt to join intervals corresponding to SrcReg/DstReg,
/// which are the src/dst of the copy instruction CopyMI. This returns true
/// if the copy was successfully coalesced away. If it is not currently
/// possible to coalesce this interval, but it may be possible if other
return false;
}
+ if (CP.getNewRC()) {
+ auto SrcRC = MRI->getRegClass(CP.getSrcReg());
+ auto DstRC = MRI->getRegClass(CP.getDstReg());
+ unsigned SrcIdx = CP.getSrcIdx();
+ unsigned DstIdx = CP.getDstIdx();
+ if (CP.isFlipped()) {
+ std::swap(SrcIdx, DstIdx);
+ std::swap(SrcRC, DstRC);
+ }
+ if (!TRI->shouldCoalesce(CopyMI, SrcRC, SrcIdx, DstRC, DstIdx,
+ CP.getNewRC())) {
+ DEBUG(dbgs() << "\tSubtarget bailed on coalescing.\n");
+ return false;
+ }
+ }
+
// Dead code elimination. This really should be handled by MachineDCE, but
// sometimes dead copies slip through, and we can't generate invalid live
// ranges.
return false;
}
} else {
+ // When possible, let DstReg be the larger interval.
+ if (!CP.isPartial() && LIS->getInterval(CP.getSrcReg()).size() >
+ LIS->getInterval(CP.getDstReg()).size())
+ CP.flip();
+
DEBUG({
- dbgs() << "\tConsidering merging to " << CP.getNewRC()->getName()
- << " with ";
+ dbgs() << "\tConsidering merging to "
+ << TRI->getRegClassName(CP.getNewRC()) << " with ";
if (CP.getDstIdx() && CP.getSrcIdx())
dbgs() << PrintReg(CP.getDstReg()) << " in "
<< TRI->getSubRegIndexName(CP.getDstIdx()) << " and "
dbgs() << PrintReg(CP.getSrcReg(), TRI) << " in "
<< PrintReg(CP.getDstReg(), TRI, CP.getSrcIdx()) << '\n';
});
-
- // When possible, let DstReg be the larger interval.
- if (!CP.isPartial() && LIS->getInterval(CP.getSrcReg()).size() >
- LIS->getInterval(CP.getDstReg()).size())
- CP.flip();
}
// Okay, attempt to join these two intervals. On failure, this returns false.
TRI->UpdateRegAllocHint(CP.getSrcReg(), CP.getDstReg(), *MF);
DEBUG({
- dbgs() << "\tJoined. Result = ";
+ dbgs() << "\tSuccess: " << PrintReg(CP.getSrcReg(), TRI, CP.getSrcIdx())
+ << " -> " << PrintReg(CP.getDstReg(), TRI, CP.getDstIdx()) << '\n';
+ dbgs() << "\tResult = ";
if (CP.isPhys())
dbgs() << PrintReg(CP.getDstReg(), TRI);
else
bool PrunedComputed;
Val() : Resolution(CR_Keep), WriteLanes(0), ValidLanes(0),
- RedefVNI(0), OtherVNI(0), ErasableImplicitDef(false),
+ RedefVNI(nullptr), OtherVNI(nullptr), ErasableImplicitDef(false),
Pruned(false), PrunedComputed(false) {}
bool isAnalyzed() const { return WriteLanes != 0; }
/// Add erased instructions to ErasedInstrs.
/// Add foreign virtual registers to ShrinkRegs if their live range ended at
/// the erased instrs.
- void eraseInstrs(SmallPtrSet<MachineInstr*, 8> &ErasedInstrs,
+ void eraseInstrs(SmallPtrSetImpl<MachineInstr*> &ErasedInstrs,
SmallVectorImpl<unsigned> &ShrinkRegs);
/// Get the value assignments suitable for passing to LiveInterval::join.
}
// Get the instruction defining this value, compute the lanes written.
- const MachineInstr *DefMI = 0;
+ const MachineInstr *DefMI = nullptr;
if (VNI->isPHIDef()) {
// Conservatively assume that all lanes in a PHI are valid.
V.ValidLanes = V.WriteLanes = TRI->getSubRegIndexLaneMask(SubIdx);
}
}
-void JoinVals::eraseInstrs(SmallPtrSet<MachineInstr*, 8> &ErasedInstrs,
+void JoinVals::eraseInstrs(SmallPtrSetImpl<MachineInstr*> &ErasedInstrs,
SmallVectorImpl<unsigned> &ShrinkRegs) {
for (unsigned i = 0, e = LI.getNumValNums(); i != e; ++i) {
// Get the def location before markUnused() below invalidates it.
return true;
}
-/// joinIntervals - Attempt to join these two intervals. On failure, this
-/// returns false.
+/// Attempt to join these two intervals. On failure, this returns false.
bool RegisterCoalescer::joinIntervals(CoalescerPair &CP) {
return CP.isPhys() ? joinReservedPhysReg(CP) : joinVirtRegs(CP);
}
// Skip instruction pointers that have already been erased, for example by
// dead code elimination.
if (ErasedInstrs.erase(CurrList[i])) {
- CurrList[i] = 0;
+ CurrList[i] = nullptr;
continue;
}
bool Again = false;
bool Success = joinCopy(CurrList[i], Again);
Progress |= Success;
if (Success || !Again)
- CurrList[i] = 0;
+ CurrList[i] = nullptr;
}
return Progress;
}
CurrList(WorkList.begin() + PrevSize, WorkList.end());
if (copyCoalesceWorkList(CurrList))
WorkList.erase(std::remove(WorkList.begin() + PrevSize, WorkList.end(),
- (MachineInstr*)0), WorkList.end());
+ (MachineInstr*)nullptr), WorkList.end());
}
void RegisterCoalescer::coalesceLocals() {
MF = &fn;
MRI = &fn.getRegInfo();
TM = &fn.getTarget();
- TRI = TM->getRegisterInfo();
- TII = TM->getInstrInfo();
+ TRI = TM->getSubtargetImpl()->getRegisterInfo();
+ TII = TM->getSubtargetImpl()->getInstrInfo();
LIS = &getAnalysis<LiveIntervals>();
AA = &getAnalysis<AliasAnalysis>();
Loops = &getAnalysis<MachineLoopInfo>();
continue;
if (MRI->recomputeRegClass(Reg, *TM)) {
DEBUG(dbgs() << PrintReg(Reg) << " inflated to "
- << MRI->getRegClass(Reg)->getName() << '\n');
+ << TRI->getRegClassName(MRI->getRegClass(Reg)) << '\n');
++NumInflated;
}
}
return true;
}
-/// print - Implement the dump method.
+/// Implement the dump method.
void RegisterCoalescer::print(raw_ostream &O, const Module* m) const {
LIS->print(O, m);
}