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ReMaterializeTrivialDef need to trim the live interval to the last kill if the copy kills the source register. This fixes uint64tof64.ll after ARM::MOVi is marked as isAsCheapAsAMove.

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llvm-svn: 63853
This commit is contained in:
Evan Cheng 2009-02-05 08:45:04 +00:00
parent 87def37f67
commit 7ed9ce65f7
2 changed files with 108 additions and 79 deletions
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178
lib/CodeGen/SimpleRegisterCoalescing.cpp
View File

@ -450,6 +450,97 @@ bool SimpleRegisterCoalescing::RemoveCopyByCommutingDef(LiveInterval &IntA,
return true;
}
/// isSameOrFallThroughBB - Return true if MBB == SuccMBB or MBB simply
/// fallthoughs to SuccMBB.
static bool isSameOrFallThroughBB(MachineBasicBlock *MBB,
MachineBasicBlock *SuccMBB,
const TargetInstrInfo *tii_) {
if (MBB == SuccMBB)
return true;
MachineBasicBlock *TBB = 0, *FBB = 0;
SmallVector<MachineOperand, 4> Cond;
return !tii_->AnalyzeBranch(*MBB, TBB, FBB, Cond) && !TBB && !FBB &&
MBB->isSuccessor(SuccMBB);
}
/// removeRange - Wrapper for LiveInterval::removeRange. This removes a range
/// from a physical register live interval as well as from the live intervals
/// of its sub-registers.
static void removeRange(LiveInterval &li, unsigned Start, unsigned End,
LiveIntervals *li_, const TargetRegisterInfo *tri_) {
li.removeRange(Start, End, true);
if (TargetRegisterInfo::isPhysicalRegister(li.reg)) {
for (const unsigned* SR = tri_->getSubRegisters(li.reg); *SR; ++SR) {
if (!li_->hasInterval(*SR))
continue;
LiveInterval &sli = li_->getInterval(*SR);
unsigned RemoveEnd = Start;
while (RemoveEnd != End) {
LiveInterval::iterator LR = sli.FindLiveRangeContaining(Start);
if (LR == sli.end())
break;
RemoveEnd = (LR->end < End) ? LR->end : End;
sli.removeRange(Start, RemoveEnd, true);
Start = RemoveEnd;
}
}
}
}
/// TrimLiveIntervalToLastUse - If there is a last use in the same basic block
/// as the copy instruction, trim the ive interval to the last use and return
/// true.
bool
SimpleRegisterCoalescing::TrimLiveIntervalToLastUse(unsigned CopyIdx,
MachineBasicBlock *CopyMBB,
LiveInterval &li,
const LiveRange *LR) {
unsigned MBBStart = li_->getMBBStartIdx(CopyMBB);
unsigned LastUseIdx;
MachineOperand *LastUse = lastRegisterUse(LR->start, CopyIdx-1, li.reg,
LastUseIdx);
if (LastUse) {
MachineInstr *LastUseMI = LastUse->getParent();
if (!isSameOrFallThroughBB(LastUseMI->getParent(), CopyMBB, tii_)) {
// r1024 = op
// ...
// BB1:
// = r1024
//
// BB2:
// r1025<dead> = r1024<kill>
if (MBBStart < LR->end)
removeRange(li, MBBStart, LR->end, li_, tri_);
return true;
}
// There are uses before the copy, just shorten the live range to the end
// of last use.
LastUse->setIsKill();
removeRange(li, li_->getDefIndex(LastUseIdx), LR->end, li_, tri_);
unsigned SrcReg, DstReg, SrcSubIdx, DstSubIdx;
if (tii_->isMoveInstr(*LastUseMI, SrcReg, DstReg, SrcSubIdx, DstSubIdx) &&
DstReg == li.reg) {
// Last use is itself an identity code.
int DeadIdx = LastUseMI->findRegisterDefOperandIdx(li.reg, false, tri_);
LastUseMI->getOperand(DeadIdx).setIsDead();
}
return true;
}
// Is it livein?
if (LR->start <= MBBStart && LR->end > MBBStart) {
if (LR->start == 0) {
assert(TargetRegisterInfo::isPhysicalRegister(li.reg));
// Live-in to the function but dead. Remove it from entry live-in set.
mf_->begin()->removeLiveIn(li.reg);
}
// FIXME: Shorten intervals in BBs that reaches this BB.
}
return false;
}
/// ReMaterializeTrivialDef - If the source of a copy is defined by a trivial
/// computation, replace the copy by rematerialize the definition.
bool SimpleRegisterCoalescing::ReMaterializeTrivialDef(LiveInterval &SrcInt,
@ -485,7 +576,12 @@ bool SimpleRegisterCoalescing::ReMaterializeTrivialDef(LiveInterval &SrcInt,
}
}
// If copy kills the source register, find the last use and propagate
// kill.
MachineBasicBlock *MBB = CopyMI->getParent();
if (CopyMI->killsRegister(SrcInt.reg))
TrimLiveIntervalToLastUse(CopyIdx, MBB, SrcInt, SrcLR);
MachineBasicBlock::iterator MII = next(MachineBasicBlock::iterator(CopyMI));
CopyMI->removeFromParent();
tii_->reMaterialize(*MBB, MII, DstReg, DefMI);
@ -660,30 +756,6 @@ void SimpleRegisterCoalescing::RemoveUnnecessaryKills(unsigned Reg,
}
}
/// removeRange - Wrapper for LiveInterval::removeRange. This removes a range
/// from a physical register live interval as well as from the live intervals
/// of its sub-registers.
static void removeRange(LiveInterval &li, unsigned Start, unsigned End,
LiveIntervals *li_, const TargetRegisterInfo *tri_) {
li.removeRange(Start, End, true);
if (TargetRegisterInfo::isPhysicalRegister(li.reg)) {
for (const unsigned* SR = tri_->getSubRegisters(li.reg); *SR; ++SR) {
if (!li_->hasInterval(*SR))
continue;
LiveInterval &sli = li_->getInterval(*SR);
unsigned RemoveEnd = Start;
while (RemoveEnd != End) {
LiveInterval::iterator LR = sli.FindLiveRangeContaining(Start);
if (LR == sli.end())
break;
RemoveEnd = (LR->end < End) ? LR->end : End;
sli.removeRange(Start, RemoveEnd, true);
Start = RemoveEnd;
}
}
}
}
/// removeIntervalIfEmpty - Check if the live interval of a physical register
/// is empty, if so remove it and also remove the empty intervals of its
/// sub-registers. Return true if live interval is removed.
@ -752,19 +824,6 @@ static void PropagateDeadness(LiveInterval &li, MachineInstr *CopyMI,
}
}
/// isSameOrFallThroughBB - Return true if MBB == SuccMBB or MBB simply
/// fallthoughs to SuccMBB.
static bool isSameOrFallThroughBB(MachineBasicBlock *MBB,
MachineBasicBlock *SuccMBB,
const TargetInstrInfo *tii_) {
if (MBB == SuccMBB)
return true;
MachineBasicBlock *TBB = 0, *FBB = 0;
SmallVector<MachineOperand, 4> Cond;
return !tii_->AnalyzeBranch(*MBB, TBB, FBB, Cond) && !TBB && !FBB &&
MBB->isSuccessor(SuccMBB);
}
/// ShortenDeadCopySrcLiveRange - Shorten a live range as it's artificially
/// extended by a dead copy. Mark the last use (if any) of the val# as kill as
/// ends the live range there. If there isn't another use, then this live range
@ -796,49 +855,10 @@ SimpleRegisterCoalescing::ShortenDeadCopySrcLiveRange(LiveInterval &li,
// More uses past this copy? Nothing to do.
return false;
MachineBasicBlock *CopyMBB = CopyMI->getParent();
unsigned MBBStart = li_->getMBBStartIdx(CopyMBB);
unsigned LastUseIdx;
MachineOperand *LastUse = lastRegisterUse(LR->start, CopyIdx-1, li.reg,
LastUseIdx);
if (LastUse) {
MachineInstr *LastUseMI = LastUse->getParent();
if (!isSameOrFallThroughBB(LastUseMI->getParent(), CopyMBB, tii_)) {
// r1024 = op
// ...
// BB1:
// = r1024
//
// BB2:
// r1025<dead> = r1024<kill>
if (MBBStart < LR->end)
removeRange(li, MBBStart, LR->end, li_, tri_);
return false;
}
// There are uses before the copy, just shorten the live range to the end
// of last use.
LastUse->setIsKill();
removeRange(li, li_->getDefIndex(LastUseIdx), LR->end, li_, tri_);
unsigned SrcReg, DstReg, SrcSubIdx, DstSubIdx;
if (tii_->isMoveInstr(*LastUseMI, SrcReg, DstReg, SrcSubIdx, DstSubIdx) &&
DstReg == li.reg) {
// Last use is itself an identity code.
int DeadIdx = LastUseMI->findRegisterDefOperandIdx(li.reg, false, tri_);
LastUseMI->getOperand(DeadIdx).setIsDead();
}
// If there is a last use in the same bb, we can't remove the live range.
// Shorten the live interval and return.
if (TrimLiveIntervalToLastUse(CopyIdx, CopyMI->getParent(), li, LR))
return false;
}
// Is it livein?
if (LR->start <= MBBStart && LR->end > MBBStart) {
if (LR->start == 0) {
assert(TargetRegisterInfo::isPhysicalRegister(li.reg));
// Live-in to the function but dead. Remove it from entry live-in set.
mf_->begin()->removeLiveIn(li.reg);
}
// FIXME: Shorten intervals in BBs that reaches this BB.
}
if (LR->valno->def == RemoveStart)
// If the def MI defines the val#, propagate the dead marker.

9
lib/CodeGen/SimpleRegisterCoalescing.h
View File

@ -196,6 +196,15 @@ namespace llvm {
bool RemoveCopyByCommutingDef(LiveInterval &IntA, LiveInterval &IntB,
MachineInstr *CopyMI);
/// TrimLiveIntervalToLastUse - If there is a last use in the same basic
/// block as the copy instruction, trim the ive interval to the last use
/// and return true.
bool TrimLiveIntervalToLastUse(unsigned CopyIdx,
MachineBasicBlock *CopyMBB,
LiveInterval &li, const LiveRange *LR);
/// ReMaterializeTrivialDef - If the source of a copy is defined by a trivial
/// computation, replace the copy by rematerialize the definition.
bool ReMaterializeTrivialDef(LiveInterval &SrcInt, unsigned DstReg,
MachineInstr *CopyMI);