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-rw-r--r--lib/CodeGen/SimpleRegisterCoalescing.cpp148
-rw-r--r--lib/CodeGen/SimpleRegisterCoalescing.h13
2 files changed, 101 insertions, 60 deletions
diff --git a/lib/CodeGen/SimpleRegisterCoalescing.cpp b/lib/CodeGen/SimpleRegisterCoalescing.cpp
index bbb742678f..068dcda93b 100644
--- a/lib/CodeGen/SimpleRegisterCoalescing.cpp
+++ b/lib/CodeGen/SimpleRegisterCoalescing.cpp
@@ -2535,7 +2535,8 @@ void SimpleRegisterCoalescing::releaseMemory() {
ReMatDefs.clear();
}
-bool SimpleRegisterCoalescing::isZeroLengthInterval(LiveInterval *li) const {
+/// Returns true if the given live interval is zero length.
+static bool isZeroLengthInterval(LiveInterval *li, LiveIntervals *li_) {
for (LiveInterval::Ranges::const_iterator
i = li->ranges.begin(), e = li->ranges.end(); i != e; ++i)
if (li_->getPrevIndex(i->end) > i->start)
@@ -2543,6 +2544,97 @@ bool SimpleRegisterCoalescing::isZeroLengthInterval(LiveInterval *li) const {
return true;
}
+void SimpleRegisterCoalescing::CalculateSpillWeights() {
+ SmallSet<unsigned, 4> Processed;
+ for (MachineFunction::iterator mbbi = mf_->begin(), mbbe = mf_->end();
+ mbbi != mbbe; ++mbbi) {
+ MachineBasicBlock* MBB = mbbi;
+ MachineInstrIndex MBBEnd = li_->getMBBEndIdx(MBB);
+ MachineLoop* loop = loopInfo->getLoopFor(MBB);
+ unsigned loopDepth = loop ? loop->getLoopDepth() : 0;
+ bool isExit = loop ? loop->isLoopExit(MBB) : false;
+
+ for (MachineBasicBlock::iterator mii = MBB->begin(), mie = MBB->end();
+ mii != mie; ++mii) {
+ MachineInstr *MI = mii;
+
+ for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) {
+ const MachineOperand &mopi = MI->getOperand(i);
+ if (!mopi.isReg() || mopi.getReg() == 0)
+ continue;
+ unsigned Reg = mopi.getReg();
+ if (!TargetRegisterInfo::isVirtualRegister(mopi.getReg()))
+ continue;
+ // Multiple uses of reg by the same instruction. It should not
+ // contribute to spill weight again.
+ if (!Processed.insert(Reg))
+ continue;
+
+ bool HasDef = mopi.isDef();
+ bool HasUse = mopi.isUse();
+ for (unsigned j = i+1; j != e; ++j) {
+ const MachineOperand &mopj = MI->getOperand(j);
+ if (!mopj.isReg() || mopj.getReg() != Reg)
+ continue;
+ HasDef |= mopj.isDef();
+ HasUse |= mopj.isUse();
+ }
+
+ LiveInterval &RegInt = li_->getInterval(Reg);
+ float Weight = li_->getSpillWeight(HasDef, HasUse, loopDepth+1);
+ if (HasDef && isExit) {
+ // Looks like this is a loop count variable update.
+ MachineInstrIndex DefIdx =
+ li_->getDefIndex(li_->getInstructionIndex(MI));
+ const LiveRange *DLR =
+ li_->getInterval(Reg).getLiveRangeContaining(DefIdx);
+ if (DLR->end > MBBEnd)
+ Weight *= 3.0F;
+ }
+ RegInt.weight += Weight;
+ }
+ Processed.clear();
+ }
+ }
+
+ for (LiveIntervals::iterator I = li_->begin(), E = li_->end(); I != E; ++I) {
+ LiveInterval &LI = *I->second;
+ if (TargetRegisterInfo::isVirtualRegister(LI.reg)) {
+ // If the live interval length is essentially zero, i.e. in every live
+ // range the use follows def immediately, it doesn't make sense to spill
+ // it and hope it will be easier to allocate for this li.
+ if (isZeroLengthInterval(&LI, li_)) {
+ LI.weight = HUGE_VALF;
+ continue;
+ }
+
+ bool isLoad = false;
+ SmallVector<LiveInterval*, 4> SpillIs;
+ if (li_->isReMaterializable(LI, SpillIs, isLoad)) {
+ // If all of the definitions of the interval are re-materializable,
+ // it is a preferred candidate for spilling. If non of the defs are
+ // loads, then it's potentially very cheap to re-materialize.
+ // FIXME: this gets much more complicated once we support non-trivial
+ // re-materialization.
+ if (isLoad)
+ LI.weight *= 0.9F;
+ else
+ LI.weight *= 0.5F;
+ }
+
+ // Slightly prefer live interval that has been assigned a preferred reg.
+ std::pair<unsigned, unsigned> Hint = mri_->getRegAllocationHint(LI.reg);
+ if (Hint.first || Hint.second)
+ LI.weight *= 1.01F;
+
+ // Divide the weight of the interval by its size. This encourages
+ // spilling of intervals that are large and have few uses, and
+ // discourages spilling of small intervals with many uses.
+ LI.weight /= li_->getApproximateInstructionCount(LI) * InstrSlots::NUM;
+ }
+ }
+}
+
bool SimpleRegisterCoalescing::runOnMachineFunction(MachineFunction &fn) {
mf_ = &fn;
@@ -2581,8 +2673,6 @@ bool SimpleRegisterCoalescing::runOnMachineFunction(MachineFunction &fn) {
for (MachineFunction::iterator mbbi = mf_->begin(), mbbe = mf_->end();
mbbi != mbbe; ++mbbi) {
MachineBasicBlock* mbb = mbbi;
- unsigned loopDepth = loopInfo->getLoopDepth(mbb);
-
for (MachineBasicBlock::iterator mii = mbb->begin(), mie = mbb->end();
mii != mie; ) {
MachineInstr *MI = mii;
@@ -2656,62 +2746,12 @@ bool SimpleRegisterCoalescing::runOnMachineFunction(MachineFunction &fn) {
mii = mbbi->erase(mii);
++numPeep;
} else {
- SmallSet<unsigned, 4> UniqueUses;
- for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) {
- const MachineOperand &mop = MI->getOperand(i);
- if (mop.isReg() && mop.getReg() &&
- TargetRegisterInfo::isVirtualRegister(mop.getReg())) {
- unsigned reg = mop.getReg();
- // Multiple uses of reg by the same instruction. It should not
- // contribute to spill weight again.
- if (UniqueUses.count(reg) != 0)
- continue;
- LiveInterval &RegInt = li_->getInterval(reg);
- RegInt.weight +=
- li_->getSpillWeight(mop.isDef(), mop.isUse(), loopDepth);
- UniqueUses.insert(reg);
- }
- }
++mii;
}
}
}
- for (LiveIntervals::iterator I = li_->begin(), E = li_->end(); I != E; ++I) {
- LiveInterval &LI = *I->second;
- if (TargetRegisterInfo::isVirtualRegister(LI.reg)) {
- // If the live interval length is essentially zero, i.e. in every live
- // range the use follows def immediately, it doesn't make sense to spill
- // it and hope it will be easier to allocate for this li.
- if (isZeroLengthInterval(&LI))
- LI.weight = HUGE_VALF;
- else {
- bool isLoad = false;
- SmallVector<LiveInterval*, 4> SpillIs;
- if (li_->isReMaterializable(LI, SpillIs, isLoad)) {
- // If all of the definitions of the interval are re-materializable,
- // it is a preferred candidate for spilling. If non of the defs are
- // loads, then it's potentially very cheap to re-materialize.
- // FIXME: this gets much more complicated once we support non-trivial
- // re-materialization.
- if (isLoad)
- LI.weight *= 0.9F;
- else
- LI.weight *= 0.5F;
- }
- }
-
- // Slightly prefer live interval that has been assigned a preferred reg.
- std::pair<unsigned, unsigned> Hint = mri_->getRegAllocationHint(LI.reg);
- if (Hint.first || Hint.second)
- LI.weight *= 1.01F;
-
- // Divide the weight of the interval by its size. This encourages
- // spilling of intervals that are large and have few uses, and
- // discourages spilling of small intervals with many uses.
- LI.weight /= li_->getApproximateInstructionCount(LI) * InstrSlots::NUM;
- }
- }
+ CalculateSpillWeights();
DEBUG(dump());
return true;
diff --git a/lib/CodeGen/SimpleRegisterCoalescing.h b/lib/CodeGen/SimpleRegisterCoalescing.h
index 7364767ab0..20b8eb2274 100644
--- a/lib/CodeGen/SimpleRegisterCoalescing.h
+++ b/lib/CodeGen/SimpleRegisterCoalescing.h
@@ -123,7 +123,6 @@ namespace llvm {
/// classes. The registers may be either phys or virt regs.
bool differingRegisterClasses(unsigned RegA, unsigned RegB) const;
-
/// AdjustCopiesBackFrom - 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
@@ -235,13 +234,15 @@ namespace llvm {
/// lastRegisterUse - Returns the last use of the specific register between
/// cycles Start and End or NULL if there are no uses.
- MachineOperand *lastRegisterUse(MachineInstrIndex Start, MachineInstrIndex End,
- unsigned Reg, MachineInstrIndex &LastUseIdx) const;
+ MachineOperand *lastRegisterUse(MachineInstrIndex Start,
+ MachineInstrIndex End, unsigned Reg,
+ MachineInstrIndex &LastUseIdx) const;
- void printRegName(unsigned reg) const;
+ /// CalculateSpillWeights - Compute spill weights for all virtual register
+ /// live intervals.
+ void CalculateSpillWeights();
- /// Returns true if the given live interval is zero length.
- bool isZeroLengthInterval(LiveInterval *li) const;
+ void printRegName(unsigned reg) const;
};
} // End llvm namespace
generated by cgit v1.2.3-18-g5258 (git 2.32.0) at 2025-04-29 20:35:39 +0000