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LiveRangeEdit: Simplify code; NFC 

Simplify the code slightly: Instead of creating empty subranges in one
case and immediately removing them, do not create them in the first
place.

llvm-svn: 322226
This commit is contained in:
Matthias Braun 2018-01-10 21:41:02 +00:00
parent 90e29b81d6
commit 63449f93a0
2 changed files with 18 additions and 16 deletions
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8
llvm/include/llvm/CodeGen/LiveRangeEdit.h
View File

@ -121,6 +121,9 @@ private:
/// main live range of \p LI or in one of the matching subregister ranges.
bool useIsKill(const LiveInterval &LI, const MachineOperand &MO) const;
/// Create a new empty interval based on OldReg.
LiveInterval &createEmptyIntervalFrom(unsigned OldReg, bool createSubRanges);
public:
/// Create a LiveRangeEdit for breaking down parent into smaller pieces.
/// @param parent The register being spilled or split.
@ -174,16 +177,13 @@ public:
return makeArrayRef(NewRegs).slice(FirstNew);
}
/// createEmptyIntervalFrom - Create a new empty interval based on OldReg.
LiveInterval &createEmptyIntervalFrom(unsigned OldReg);
/// createFrom - Create a new virtual register based on OldReg.
unsigned createFrom(unsigned OldReg);
/// create - Create a new register with the same class and original slot as
/// parent.
LiveInterval &createEmptyInterval() {
return createEmptyIntervalFrom(getReg());
return createEmptyIntervalFrom(getReg(), true);
}
unsigned create() { return createFrom(getReg()); }

26
llvm/lib/CodeGen/LiveRangeEdit.cpp
View File

@ -31,21 +31,24 @@ STATISTIC(NumFracRanges, "Number of live ranges fractured by DCE");
void LiveRangeEdit::Delegate::anchor() { }
LiveInterval &LiveRangeEdit::createEmptyIntervalFrom(unsigned OldReg) {
LiveInterval &LiveRangeEdit::createEmptyIntervalFrom(unsigned OldReg,
bool createSubRanges) {
unsigned VReg = MRI.createVirtualRegister(MRI.getRegClass(OldReg));
if (VRM) {
if (VRM)
VRM->setIsSplitFromReg(VReg, VRM->getOriginal(OldReg));
}
LiveInterval &LI = LIS.createEmptyInterval(VReg);
if (Parent && !Parent->isSpillable())
LI.markNotSpillable();
// Create empty subranges if the OldReg's interval has them. Do not create
// the main range here---it will be constructed later after the subranges
// have been finalized.
LiveInterval &OldLI = LIS.getInterval(OldReg);
VNInfo::Allocator &Alloc = LIS.getVNInfoAllocator();
for (LiveInterval::SubRange &S : OldLI.subranges())
LI.createSubRange(Alloc, S.LaneMask);
if (createSubRanges) {
// Create empty subranges if the OldReg's interval has them. Do not create
// the main range here---it will be constructed later after the subranges
// have been finalized.
LiveInterval &OldLI = LIS.getInterval(OldReg);
VNInfo::Allocator &Alloc = LIS.getVNInfoAllocator();
for (LiveInterval::SubRange &S : OldLI.subranges())
LI.createSubRange(Alloc, S.LaneMask);
}
return LI;
}
@ -357,8 +360,7 @@ void LiveRangeEdit::eliminateDeadDef(MachineInstr *MI, ToShrinkSet &ToShrink,
// LiveRangeEdit::DeadRemats and will be deleted after all the
// allocations of the func are done.
if (isOrigDef && DeadRemats && TII.isTriviallyReMaterializable(*MI, AA)) {
LiveInterval &NewLI = createEmptyIntervalFrom(Dest);
NewLI.removeEmptySubRanges();
LiveInterval &NewLI = createEmptyIntervalFrom(Dest, false);
VNInfo *VNI = NewLI.getNextValue(Idx, LIS.getVNInfoAllocator());
NewLI.addSegment(LiveInterval::Segment(Idx, Idx.getDeadSlot(), VNI));
pop_back();