[llvm-commits] CVS: llvm/lib/CodeGen/LiveIntervals.cpp
Alkis Evlogimenos
alkis at cs.uiuc.edu
Fri Jan 30 22:57:07 PST 2004
Changes in directory llvm/lib/CodeGen:
LiveIntervals.cpp updated: 1.32 -> 1.33
---
Log message:
Several performance enhancements and cleanups from Chris.
Simplification of LiveIntervals::Interval::overlaps() and addition of
examples to overlaps() and liveAt() to make them clearer.
---
Diffs of the changes: (+108 -108)
Index: llvm/lib/CodeGen/LiveIntervals.cpp
diff -u llvm/lib/CodeGen/LiveIntervals.cpp:1.32 llvm/lib/CodeGen/LiveIntervals.cpp:1.33
--- llvm/lib/CodeGen/LiveIntervals.cpp:1.32 Fri Jan 23 07:37:51 2004
+++ llvm/lib/CodeGen/LiveIntervals.cpp Fri Jan 30 22:56:07 2004
@@ -17,24 +17,19 @@
#define DEBUG_TYPE "liveintervals"
#include "llvm/CodeGen/LiveIntervals.h"
-#include "llvm/Function.h"
#include "llvm/Analysis/LoopInfo.h"
#include "llvm/CodeGen/LiveVariables.h"
#include "llvm/CodeGen/MachineFrameInfo.h"
-#include "llvm/CodeGen/MachineFunctionPass.h"
#include "llvm/CodeGen/MachineInstr.h"
#include "llvm/CodeGen/Passes.h"
#include "llvm/CodeGen/SSARegMap.h"
#include "llvm/Target/MRegisterInfo.h"
#include "llvm/Target/TargetInstrInfo.h"
#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"
-#include <cmath>
#include <iostream>
#include <limits>
@@ -45,6 +40,7 @@
"Live Interval Analysis");
Statistic<> numIntervals("liveintervals", "Number of intervals");
+ Statistic<> numJoined ("liveintervals", "Number of intervals joined");
cl::opt<bool>
join("join-liveintervals",
@@ -63,6 +59,16 @@
MachineFunctionPass::getAnalysisUsage(AU);
}
+void LiveIntervals::releaseMemory()
+{
+ mbbi2mbbMap_.clear();
+ mi2iMap_.clear();
+ r2iMap_.clear();
+ r2iMap_.clear();
+ r2rMap_.clear();
+ intervals_.clear();
+}
+
/// runOnMachineFunction - Register allocate the whole function
///
bool LiveIntervals::runOnMachineFunction(MachineFunction &fn) {
@@ -71,19 +77,13 @@
tm_ = &fn.getTarget();
mri_ = tm_->getRegisterInfo();
lv_ = &getAnalysis<LiveVariables>();
- mbbi2mbbMap_.clear();
- mi2iMap_.clear();
- r2iMap_.clear();
- r2iMap_.clear();
- r2rMap_.clear();
- intervals_.clear();
// number MachineInstrs
unsigned miIndex = 0;
for (MachineFunction::iterator mbb = mf_->begin(), mbbEnd = mf_->end();
mbb != mbbEnd; ++mbb) {
const std::pair<MachineBasicBlock*, unsigned>& entry =
- lv_->getMachineBasicBlockInfo(&*mbb);
+ lv_->getMachineBasicBlockInfo(mbb);
bool inserted = mbbi2mbbMap_.insert(std::make_pair(entry.second,
entry.first)).second;
assert(inserted && "multiple index -> MachineBasicBlock");
@@ -107,20 +107,22 @@
const MachineBasicBlock* mbb = mbbi;
unsigned loopDepth = loopInfo.getLoopDepth(mbb->getBasicBlock());
- 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;
-
- unsigned reg = mop.getAllocatedRegNum();
- Reg2IntervalMap::iterator r2iit = r2iMap_.find(reg);
- assert(r2iit != r2iMap_.end());
- r2iit->second->weight += pow(10.0F, loopDepth);
+ if (loopDepth) {
+ 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;
+
+ unsigned reg = mop.getAllocatedRegNum();
+ Reg2IntervalMap::iterator r2iit = r2iMap_.find(reg);
+ assert(r2iit != r2iMap_.end());
+ r2iit->second->weight += pow(10.0F, loopDepth);
+ }
}
}
}
@@ -152,31 +154,27 @@
LiveVariables::VarInfo& vi = lv_->getVarInfo(reg);
Interval* interval = 0;
- Reg2IntervalMap::iterator r2iit = r2iMap_.find(reg);
- if (r2iit == r2iMap_.end()) {
+ Reg2IntervalMap::iterator r2iit = r2iMap_.lower_bound(reg);
+ if (r2iit == r2iMap_.end() || r2iit->first != reg) {
// add new interval
intervals_.push_back(Interval(reg));
// update interval index for this register
- bool inserted =
- r2iMap_.insert(std::make_pair(reg, --intervals_.end())).second;
- assert(inserted);
+ r2iMap_.insert(r2iit, std::make_pair(reg, --intervals_.end()));
interval = &intervals_.back();
}
else {
interval = &*r2iit->second;
}
- for (MbbIndex2MbbMap::iterator
- it = mbbi2mbbMap_.begin(), itEnd = mbbi2mbbMap_.end();
- it != itEnd; ++it) {
- unsigned liveBlockIndex = it->first;
- MachineBasicBlock* liveBlock = it->second;
- if (liveBlockIndex < vi.AliveBlocks.size() &&
- vi.AliveBlocks[liveBlockIndex] &&
- !liveBlock->empty()) {
- unsigned start = getInstructionIndex(liveBlock->front());
- unsigned end = getInstructionIndex(liveBlock->back()) + 1;
- interval->addRange(start, end);
+ // iterate over all of the blocks that the variable is completely
+ // live in, adding them to the live interval
+ for (unsigned i = 0, e = vi.AliveBlocks.size(); i != e; ++i) {
+ if (vi.AliveBlocks[i]) {
+ MachineBasicBlock* mbb = lv_->getIndexMachineBasicBlock(i);
+ if (!mbb->empty()) {
+ interval->addRange(getInstructionIndex(mbb->front()),
+ getInstructionIndex(mbb->back()));
+ }
}
}
@@ -207,62 +205,49 @@
DEBUG(std::cerr << "\t\tregister: "; printRegName(reg));
unsigned start = getInstructionIndex(*mi);
- unsigned end = start;
+ unsigned end = start + 1;
// register can be dead by the instruction defining it but it can
// only be killed by subsequent instructions
-
for (LiveVariables::killed_iterator
ki = lv_->dead_begin(*mi),
ke = lv_->dead_end(*mi);
ki != ke; ++ki) {
if (reg == ki->second) {
- end = getInstructionIndex(ki->first) + 1;
DEBUG(std::cerr << " dead\n");
goto exit;
}
}
- ++mi;
-
- for (MachineBasicBlock::iterator e = mbb->end(); mi != e; ++mi) {
- for (LiveVariables::killed_iterator
- ki = lv_->dead_begin(*mi),
- ke = lv_->dead_end(*mi);
- ki != ke; ++ki) {
- if (reg == ki->second) {
- end = getInstructionIndex(ki->first) + 1;
- DEBUG(std::cerr << " dead\n");
- goto exit;
- }
- }
- for (LiveVariables::killed_iterator
- ki = lv_->killed_begin(*mi),
- ke = lv_->killed_end(*mi);
- ki != ke; ++ki) {
- if (reg == ki->second) {
- end = getInstructionIndex(ki->first) + 1;
- DEBUG(std::cerr << " killed\n");
- goto exit;
+ {
+ MachineBasicBlock::iterator e = mbb->end();
+ do {
+ ++mi;
+ for (LiveVariables::killed_iterator
+ ki = lv_->killed_begin(*mi),
+ ke = lv_->killed_end(*mi);
+ ki != ke; ++ki) {
+ if (reg == ki->second) {
+ DEBUG(std::cerr << " killed\n");
+ goto exit;
+ }
}
- }
+ ++end;
+ } while (mi != e);
}
+
exit:
assert(start < end && "did not find end of interval?");
- Reg2IntervalMap::iterator r2iit = r2iMap_.find(reg);
- if (r2iit != r2iMap_.end()) {
- Interval& interval = *r2iit->second;
- interval.addRange(start, end);
+ Reg2IntervalMap::iterator r2iit = r2iMap_.lower_bound(reg);
+ if (r2iit != r2iMap_.end() && r2iit->first == reg) {
+ r2iit->second->addRange(start, end);
}
else {
intervals_.push_back(Interval(reg));
- Interval& interval = intervals_.back();
// update interval index for this register
- bool inserted =
- r2iMap_.insert(std::make_pair(reg, --intervals_.end())).second;
- assert(inserted);
- interval.addRange(start, end);
+ r2iMap_.insert(r2iit, std::make_pair(reg, --intervals_.end()));
+ intervals_.back().addRange(start, end);
}
}
@@ -282,16 +267,9 @@
}
}
-unsigned LiveIntervals::getInstructionIndex(MachineInstr* instr) const
-{
- assert(mi2iMap_.find(instr) != mi2iMap_.end() &&
- "instruction not assigned a number");
- return mi2iMap_.find(instr)->second;
-}
-
/// computeIntervals - computes the live intervals for virtual
-/// registers. for some ordering of the machine instructions [1,N] a
-/// live interval is an interval [i, j] where 1 <= i <= j <= N for
+/// registers. for some ordering of the machine instructions [1,N) a
+/// live interval is an interval [i, j) where 1 <= i <= j < N for
/// which a variable is live
void LiveIntervals::computeIntervals()
{
@@ -318,13 +296,9 @@
// handle explicit defs
for (int i = instr->getNumOperands() - 1; i >= 0; --i) {
+ // handle register defs - build intervals
MachineOperand& mop = instr->getOperand(i);
-
- if (!mop.isRegister())
- continue;
-
- // handle defs - build intervals
- if (mop.isDef())
+ if (mop.isRegister() && mop.isDef())
handleRegisterDef(mbb, mi, mop.getAllocatedRegNum());
}
}
@@ -424,6 +398,7 @@
intervals_.erase(dstInt);
}
}
+ ++numJoined;
}
}
}
@@ -434,7 +409,7 @@
DEBUG(for (Reg2RegMap::const_iterator i = r2rMap_.begin(),
e = r2rMap_.end(); i != e; ++i)
std::cerr << i->first << " -> " << i->second << '\n';);
-
+
}
bool LiveIntervals::overlapsAliases(const Interval& lhs,
@@ -461,6 +436,15 @@
}
+// This example is provided becaues liveAt() is non-obvious:
+//
+// this = [1,2), liveAt(1) will return false. The idea is that the
+// variable is defined in 1 and not live after definition. So it was
+// dead to begin with (defined but never used).
+//
+// this = [1,3), liveAt(2) will return false. The variable is used at
+// 2 but 2 is the last use so the variable's allocated register is
+// available for reuse.
bool LiveIntervals::Interval::liveAt(unsigned index) const
{
Ranges::const_iterator r = ranges.begin();
@@ -472,13 +456,38 @@
return false;
}
+// This example is provided because overlaps() is non-obvious:
+//
+// 0: A = ...
+// 1: B = ...
+// 2: C = A + B ;; last use of A
+//
+// The live intervals should look like:
+//
+// A = [0, 3)
+// B = [1, x)
+// C = [2, y)
+//
+// A->overlaps(C) should return false since we want to be able to join
+// A and C.
bool LiveIntervals::Interval::overlaps(const Interval& other) const
{
Ranges::const_iterator i = ranges.begin();
+ Ranges::const_iterator ie = ranges.end();
Ranges::const_iterator j = other.ranges.begin();
+ Ranges::const_iterator je = other.ranges.end();
+
+ while (i != ie && j != je) {
+ if (i->first == j->first) {
+ return true;
+ }
+ else {
+ if (i->first > j->first) {
+ swap(i, j);
+ swap(ie, je);
+ }
+ assert(i->first < j->first);
- while (i != ranges.end() && j != other.ranges.end()) {
- if (i->first < j->first) {
if ((i->second - 1) > j->first) {
return true;
}
@@ -486,17 +495,6 @@
++i;
}
}
- else if (j->first < i->first) {
- if ((j->second - 1) > i->first) {
- return true;
- }
- else {
- ++j;
- }
- }
- else {
- return true;
- }
}
return false;
@@ -504,6 +502,7 @@
void LiveIntervals::Interval::addRange(unsigned start, unsigned end)
{
+ assert(start < end && "Invalid range to add!");
DEBUG(std::cerr << "\t\t\tadding range: [" << start <<','<< end << ") -> ");
//assert(start < end && "invalid range?");
Range range = std::make_pair(start, end);
@@ -548,12 +547,13 @@
LiveIntervals::Interval::Ranges::iterator
LiveIntervals::Interval::mergeRangesBackward(Ranges::iterator it)
{
- for (Ranges::iterator prev = it - 1;
- it != ranges.begin() && it->first <= prev->second; ) {
+ while (it != ranges.begin()) {
+ Ranges::iterator prev = it - 1;
+ if (it->first > prev->second) break;
+
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;
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