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//===-- LiveRegMatrix.cpp - Track register interference -------------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file defines the LiveRegMatrix analysis pass.
//
//===----------------------------------------------------------------------===//
#include "llvm/CodeGen/LiveRegMatrix.h"
#include "RegisterCoalescer.h"
#include "llvm/ADT/Statistic.h"
#include "llvm/CodeGen/LiveIntervalAnalysis.h"
#include "llvm/CodeGen/VirtRegMap.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/raw_ostream.h"
#include "llvm/Target/TargetRegisterInfo.h"
#include "llvm/Target/TargetSubtargetInfo.h"
using namespace llvm;
#define DEBUG_TYPE "regalloc"
STATISTIC(NumAssigned , "Number of registers assigned");
STATISTIC(NumUnassigned , "Number of registers unassigned");
char LiveRegMatrix::ID = 0;
INITIALIZE_PASS_BEGIN(LiveRegMatrix, "liveregmatrix",
"Live Register Matrix", false, false)
INITIALIZE_PASS_DEPENDENCY(LiveIntervals)
INITIALIZE_PASS_DEPENDENCY(VirtRegMap)
INITIALIZE_PASS_END(LiveRegMatrix, "liveregmatrix",
"Live Register Matrix", false, false)
LiveRegMatrix::LiveRegMatrix() : MachineFunctionPass(ID),
UserTag(0), RegMaskTag(0), RegMaskVirtReg(0) {}
void LiveRegMatrix::getAnalysisUsage(AnalysisUsage &AU) const {
AU.setPreservesAll();
AU.addRequiredTransitive<LiveIntervals>();
AU.addRequiredTransitive<VirtRegMap>();
MachineFunctionPass::getAnalysisUsage(AU);
}
bool LiveRegMatrix::runOnMachineFunction(MachineFunction &MF) {
TRI = MF.getSubtarget().getRegisterInfo();
LIS = &getAnalysis<LiveIntervals>();
VRM = &getAnalysis<VirtRegMap>();
unsigned NumRegUnits = TRI->getNumRegUnits();
if (NumRegUnits != Matrix.size())
Queries.reset(new LiveIntervalUnion::Query[NumRegUnits]);
Matrix.init(LIUAlloc, NumRegUnits);
// Make sure no stale queries get reused.
invalidateVirtRegs();
return false;
}
void LiveRegMatrix::releaseMemory() {
for (unsigned i = 0, e = Matrix.size(); i != e; ++i) {
Matrix[i].clear();
// No need to clear Queries here, since LiveIntervalUnion::Query doesn't
// have anything important to clear and LiveRegMatrix's runOnFunction()
// does a std::unique_ptr::reset anyways.
}
}
template<typename Callable>
bool foreachUnit(const TargetRegisterInfo *TRI, LiveInterval &VRegInterval,
unsigned PhysReg, Callable Func) {
if (VRegInterval.hasSubRanges()) {
for (MCRegUnitMaskIterator Units(PhysReg, TRI); Units.isValid(); ++Units) {
unsigned Unit = (*Units).first;
LaneBitmask Mask = (*Units).second;
for (LiveInterval::SubRange &S : VRegInterval.subranges()) {
if (S.LaneMask & Mask) {
if (Func(Unit, S))
return true;
break;
}
}
}
} else {
for (MCRegUnitIterator Units(PhysReg, TRI); Units.isValid(); ++Units) {
if (Func(*Units, VRegInterval))
return true;
}
}
return false;
}
void LiveRegMatrix::assign(LiveInterval &VirtReg, unsigned PhysReg) {
DEBUG(dbgs() << "assigning " << PrintReg(VirtReg.reg, TRI)
<< " to " << PrintReg(PhysReg, TRI) << ':');
assert(!VRM->hasPhys(VirtReg.reg) && "Duplicate VirtReg assignment");
VRM->assignVirt2Phys(VirtReg.reg, PhysReg);
foreachUnit(TRI, VirtReg, PhysReg, [&](unsigned Unit,
const LiveRange &Range) {
DEBUG(dbgs() << ' ' << PrintRegUnit(Unit, TRI) << ' ' << Range);
Matrix[Unit].unify(VirtReg, Range);
return false;
});
++NumAssigned;
DEBUG(dbgs() << '\n');
}
void LiveRegMatrix::unassign(LiveInterval &VirtReg) {
unsigned PhysReg = VRM->getPhys(VirtReg.reg);
DEBUG(dbgs() << "unassigning " << PrintReg(VirtReg.reg, TRI)
<< " from " << PrintReg(PhysReg, TRI) << ':');
VRM->clearVirt(VirtReg.reg);
foreachUnit(TRI, VirtReg, PhysReg, [&](unsigned Unit,
const LiveRange &Range) {
DEBUG(dbgs() << ' ' << PrintRegUnit(Unit, TRI));
Matrix[Unit].extract(VirtReg, Range);
return false;
});
++NumUnassigned;
DEBUG(dbgs() << '\n');
}
bool LiveRegMatrix::isPhysRegUsed(unsigned PhysReg) const {
for (MCRegUnitIterator Unit(PhysReg, TRI); Unit.isValid(); ++Unit) {
if (!Matrix[*Unit].empty())
return true;
}
return false;
}
bool LiveRegMatrix::checkRegMaskInterference(LiveInterval &VirtReg,
unsigned PhysReg) {
// Check if the cached information is valid.
// The same BitVector can be reused for all PhysRegs.
// We could cache multiple VirtRegs if it becomes necessary.
if (RegMaskVirtReg != VirtReg.reg || RegMaskTag != UserTag) {
RegMaskVirtReg = VirtReg.reg;
RegMaskTag = UserTag;
RegMaskUsable.clear();
LIS->checkRegMaskInterference(VirtReg, RegMaskUsable);
}
// The BitVector is indexed by PhysReg, not register unit.
// Regmask interference is more fine grained than regunits.
// For example, a Win64 call can clobber %ymm8 yet preserve %xmm8.
return !RegMaskUsable.empty() && (!PhysReg || !RegMaskUsable.test(PhysReg));
}
bool LiveRegMatrix::checkRegUnitInterference(LiveInterval &VirtReg,
unsigned PhysReg) {
if (VirtReg.empty())
return false;
CoalescerPair CP(VirtReg.reg, PhysReg, *TRI);
bool Result = foreachUnit(TRI, VirtReg, PhysReg, [&](unsigned Unit,
const LiveRange &Range) {
const LiveRange &UnitRange = LIS->getRegUnit(Unit);
return Range.overlaps(UnitRange, CP, *LIS->getSlotIndexes());
});
return Result;
}
LiveIntervalUnion::Query &LiveRegMatrix::query(LiveInterval &VirtReg,
unsigned RegUnit) {
LiveIntervalUnion::Query &Q = Queries[RegUnit];
Q.init(UserTag, &VirtReg, &Matrix[RegUnit]);
return Q;
}
LiveRegMatrix::InterferenceKind
LiveRegMatrix::checkInterference(LiveInterval &VirtReg, unsigned PhysReg) {
if (VirtReg.empty())
return IK_Free;
// Regmask interference is the fastest check.
if (checkRegMaskInterference(VirtReg, PhysReg))
return IK_RegMask;
// Check for fixed interference.
if (checkRegUnitInterference(VirtReg, PhysReg))
return IK_RegUnit;
// Check the matrix for virtual register interference.
for (MCRegUnitIterator Units(PhysReg, TRI); Units.isValid(); ++Units)
if (query(VirtReg, *Units).checkInterference())
return IK_VirtReg;
return IK_Free;
}
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