Add option to join live intervals. Two intervals are joined if there
is a move between two registers, at least one of the registers is
virtual and the two live intervals do not overlap.
This results in about 40% reduction in intervals, 30% decrease in the
register allocators running time and a 20% increase in peephole
optimizations (mainly move eliminations).
The option can be enabled by passing -join-liveintervals where
appropriate.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@10965 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/LiveIntervalAnalysis.cpp b/lib/CodeGen/LiveIntervalAnalysis.cpp
index eb9cf38..fb11ff0 100644
--- a/lib/CodeGen/LiveIntervalAnalysis.cpp
+++ b/lib/CodeGen/LiveIntervalAnalysis.cpp
@@ -30,6 +30,7 @@
#include "llvm/Target/TargetMachine.h"
#include "llvm/Target/TargetRegInfo.h"
#include "llvm/Support/CFG.h"
+#include "Support/CommandLine.h"
#include "Support/Debug.h"
#include "Support/DepthFirstIterator.h"
#include "Support/Statistic.h"
@@ -44,6 +45,11 @@
"Live Interval Analysis");
Statistic<> numIntervals("liveintervals", "Number of intervals");
+
+ cl::opt<bool>
+ join("join-liveintervals",
+ cl::desc("Join compatible live intervals"),
+ cl::init(false));
};
void LiveIntervals::getAnalysisUsage(AnalysisUsage &AU) const
@@ -69,6 +75,7 @@
mi2iMap_.clear();
r2iMap_.clear();
r2iMap_.clear();
+ r2rMap_.clear();
intervals_.clear();
// number MachineInstrs
@@ -95,18 +102,17 @@
const LoopInfo& loopInfo = getAnalysis<LoopInfo>();
const TargetInstrInfo& tii = tm_->getInstrInfo();
- for (MbbIndex2MbbMap::iterator
- it = mbbi2mbbMap_.begin(), itEnd = mbbi2mbbMap_.end();
- it != itEnd; ++it) {
- MachineBasicBlock* mbb = it->second;
-
+ for (MachineFunction::const_iterator mbbi = mf_->begin(),
+ mbbe = mf_->end(); mbbi != mbbe; ++mbbi) {
+ const MachineBasicBlock* mbb = mbbi;
unsigned loopDepth = loopInfo.getLoopDepth(mbb->getBasicBlock());
- for (MachineBasicBlock::iterator mi = mbb->begin(), miEnd = mbb->end();
- mi != miEnd; ++mi) {
- MachineInstr* instr = *mi;
- for (int i = instr->getNumOperands() - 1; i >= 0; --i) {
- MachineOperand& mop = instr->getOperand(i);
+ for (MachineBasicBlock::const_iterator mii = mbb->begin(),
+ mie = mbb->end(); mii != mie; ++mii) {
+ MachineInstr* mi = *mii;
+
+ for (int i = mi->getNumOperands() - 1; i >= 0; --i) {
+ MachineOperand& mop = mi->getOperand(i);
if (!mop.isVirtualRegister())
continue;
@@ -119,6 +125,9 @@
}
}
+ // join intervals if requested
+ if (join) joinIntervals();
+
numIntervals += intervals_.size();
return true;
@@ -326,48 +335,111 @@
std::ostream_iterator<Interval>(std::cerr, "\n")));
}
+unsigned LiveIntervals::rep(unsigned reg)
+{
+ Reg2RegMap::iterator it = r2rMap_.find(reg);
+ if (it != r2rMap_.end())
+ return it->second = rep(it->second);
+ return reg;
+}
+
+void LiveIntervals::joinIntervals()
+{
+ DEBUG(std::cerr << "joining compatible intervals:\n");
+
+ const TargetInstrInfo& tii = tm_->getInstrInfo();
+
+ for (MachineFunction::const_iterator mbbi = mf_->begin(),
+ mbbe = mf_->end(); mbbi != mbbe; ++mbbi) {
+ const MachineBasicBlock* mbb = mbbi;
+ DEBUG(std::cerr << "machine basic block: "
+ << mbb->getBasicBlock()->getName() << "\n");
+
+ for (MachineBasicBlock::const_iterator mii = mbb->begin(),
+ mie = mbb->end(); mii != mie; ++mii) {
+ MachineInstr* mi = *mii;
+ const TargetInstrDescriptor& tid =
+ tm_->getInstrInfo().get(mi->getOpcode());
+ DEBUG(std::cerr << "\t\tinstruction["
+ << getInstructionIndex(mi) << "]: ";
+ mi->print(std::cerr, *tm_););
+
+ unsigned srcReg, dstReg;
+ if (tii.isMoveInstr(*mi, srcReg, dstReg) &&
+ (srcReg >= MRegisterInfo::FirstVirtualRegister ||
+ lv_->getAllocatablePhysicalRegisters()[srcReg]) &&
+ (dstReg >= MRegisterInfo::FirstVirtualRegister ||
+ lv_->getAllocatablePhysicalRegisters()[dstReg])) {
+
+ // get representative registers
+ srcReg = rep(srcReg);
+ dstReg = rep(dstReg);
+
+ // if they are already joined we continue
+ if (srcReg == dstReg)
+ continue;
+
+ Reg2IntervalMap::iterator r2iSrc = r2iMap_.find(srcReg);
+ assert(r2iSrc != r2iMap_.end());
+ Reg2IntervalMap::iterator r2iDst = r2iMap_.find(dstReg);
+ assert(r2iDst != r2iMap_.end());
+
+ Intervals::iterator srcInt = r2iSrc->second;
+ Intervals::iterator dstInt = r2iDst->second;
+
+ if (srcInt->reg < MRegisterInfo::FirstVirtualRegister) {
+ if (dstInt->reg == srcInt->reg ||
+ (dstInt->reg >= MRegisterInfo::FirstVirtualRegister &&
+ !dstInt->overlaps(*srcInt))) {
+ srcInt->join(*dstInt);
+ r2iDst->second = r2iSrc->second;
+ r2rMap_.insert(std::make_pair(dstInt->reg, srcInt->reg));
+ intervals_.erase(dstInt);
+ }
+ }
+ else if (dstInt->reg < MRegisterInfo::FirstVirtualRegister) {
+ if (srcInt->reg == dstInt->reg ||
+ (srcInt->reg >= MRegisterInfo::FirstVirtualRegister &&
+ !srcInt->overlaps(*dstInt))) {
+ dstInt->join(*srcInt);
+ r2iSrc->second = r2iDst->second;
+ r2rMap_.insert(std::make_pair(srcInt->reg, dstInt->reg));
+ intervals_.erase(srcInt);
+ }
+ }
+ else {
+ const TargetRegisterClass *srcRc, *dstRc;
+ srcRc = mf_->getSSARegMap()->getRegClass(srcInt->reg);
+ dstRc = mf_->getSSARegMap()->getRegClass(dstInt->reg);
+
+ if (srcRc == dstRc && !dstInt->overlaps(*srcInt)) {
+ srcInt->join(*dstInt);
+ r2iDst->second = r2iSrc->second;
+ r2rMap_.insert(std::make_pair(dstInt->reg, srcInt->reg));
+ intervals_.erase(dstInt);
+ }
+ }
+ }
+ }
+ }
+
+ intervals_.sort(StartPointComp());
+ DEBUG(std::copy(intervals_.begin(), intervals_.end(),
+ std::ostream_iterator<Interval>(std::cerr, "\n")));
+ DEBUG(for (Reg2RegMap::const_iterator i = r2rMap_.begin(),
+ e = r2rMap_.end(); i != e; ++i)
+ std::cerr << i->first << " -> " << i->second << '\n';);
+
+}
+
LiveIntervals::Interval::Interval(unsigned r)
- : reg(r), hint(0),
+ : reg(r),
weight((r < MRegisterInfo::FirstVirtualRegister ?
std::numeric_limits<float>::max() : 0.0F))
{
}
-void LiveIntervals::Interval::addRange(unsigned start, unsigned end)
-{
- DEBUG(std::cerr << "\t\t\tadding range: [" << start <<','<< end << ") -> ");
- //assert(start < end && "invalid range?");
- Range range = std::make_pair(start, end);
- Ranges::iterator it =
- ranges.insert(std::upper_bound(ranges.begin(), ranges.end(), range),
- range);
-
- mergeRangesForward(it);
- mergeRangesBackward(it);
- DEBUG(std::cerr << *this << '\n');
-}
-
-void LiveIntervals::Interval::mergeRangesForward(Ranges::iterator it)
-{
- for (Ranges::iterator next = it + 1;
- next != ranges.end() && it->second >= next->first; ) {
- it->second = std::max(it->second, next->second);
- next = ranges.erase(next);
- }
-}
-
-void LiveIntervals::Interval::mergeRangesBackward(Ranges::iterator it)
-{
- for (Ranges::iterator prev = it - 1;
- it != ranges.begin() && it->first <= prev->second; ) {
- it->first = std::min(it->first, prev->first);
- it->second = std::max(it->second, prev->second);
- it = ranges.erase(prev);
- prev = it - 1;
- }
-}
-
bool LiveIntervals::Interval::liveAt(unsigned index) const
{
Ranges::const_iterator r = ranges.begin();
@@ -409,6 +481,63 @@
return false;
}
+void LiveIntervals::Interval::addRange(unsigned start, unsigned end)
+{
+ DEBUG(std::cerr << "\t\t\tadding range: [" << start <<','<< end << ") -> ");
+ //assert(start < end && "invalid range?");
+ Range range = std::make_pair(start, end);
+ Ranges::iterator it =
+ ranges.insert(std::upper_bound(ranges.begin(), ranges.end(), range),
+ range);
+
+ it = mergeRangesForward(it);
+ it = mergeRangesBackward(it);
+ DEBUG(std::cerr << "\t\t\t\tafter merging: " << *this << '\n');
+}
+
+void LiveIntervals::Interval::join(const LiveIntervals::Interval& other)
+{
+ DEBUG(std::cerr << "\t\t\t\tjoining intervals: "
+ << other << " and " << *this << '\n');
+ Ranges::iterator cur = ranges.begin();
+
+ for (Ranges::const_iterator i = other.ranges.begin(),
+ e = other.ranges.end(); i != e; ++i) {
+ cur = ranges.insert(std::upper_bound(cur, ranges.end(), *i), *i);
+ cur = mergeRangesForward(cur);
+ cur = mergeRangesBackward(cur);
+ }
+ if (reg >= MRegisterInfo::FirstVirtualRegister)
+ weight += other.weight;
+
+ DEBUG(std::cerr << "\t\t\t\tafter merging: " << *this << '\n');
+}
+
+LiveIntervals::Interval::Ranges::iterator
+LiveIntervals::Interval::mergeRangesForward(Ranges::iterator it)
+{
+ for (Ranges::iterator next = it + 1;
+ next != ranges.end() && it->second >= next->first; ) {
+ it->second = std::max(it->second, next->second);
+ next = ranges.erase(next);
+ }
+ return it;
+}
+
+LiveIntervals::Interval::Ranges::iterator
+LiveIntervals::Interval::mergeRangesBackward(Ranges::iterator it)
+{
+ for (Ranges::iterator prev = it - 1;
+ it != ranges.begin() && it->first <= prev->second; ) {
+ it->first = std::min(it->first, prev->first);
+ it->second = std::max(it->second, prev->second);
+ it = ranges.erase(prev);
+ prev = it - 1;
+ }
+
+ return it;
+}
+
std::ostream& llvm::operator<<(std::ostream& os,
const LiveIntervals::Interval& li)
{