static void PrintDefinition(char* buf, size_t size, const LDefinition& def) { char* cursor = buf; char* end = buf + size; cursor += JS_snprintf(cursor, end - cursor, "v%u", def.virtualRegister()); cursor += JS_snprintf(cursor, end - cursor, "<%s>", TypeChars[def.type()]); if (def.policy() == LDefinition::FIXED) cursor += JS_snprintf(cursor, end - cursor, ":%s", def.output()->toString()); else if (def.policy() == LDefinition::MUST_REUSE_INPUT) cursor += JS_snprintf(cursor, end - cursor, ":tied(%u)", def.getReusedInput()); }
static void PrintDefinition(FILE *fp, const LDefinition &def) { fprintf(fp, "[%s", TypeChars[def.type()]); if (def.virtualRegister()) fprintf(fp, ":%d", def.virtualRegister()); if (def.policy() == LDefinition::PRESET) { fprintf(fp, " (%s)", def.output()->toString()); } else if (def.policy() == LDefinition::MUST_REUSE_INPUT) { fprintf(fp, " (!)"); } else if (def.policy() == LDefinition::PASSTHROUGH) { fprintf(fp, " (-)"); } fprintf(fp, "]"); }
bool GreedyAllocator::allocateInstruction(LBlock *block, LInstruction *ins) { if (!gen->ensureBallast()) return false; // Reset internal state used for evicting. reset(); assertValidRegisterState(); // Step 1. Around a call, save all registers used downstream. if (ins->isCall() && !spillForCall(ins)) return false; // Step 2. Find all fixed writable registers, adding them to the // disallow set. if (!prescanDefinitions(ins)) return false; // Step 3. For each use, add fixed policies to the disallow set and // already allocated registers to the discouraged set. if (!prescanUses(ins)) return false; // Step 4. Allocate registers for each definition. if (!allocateDefinitions(ins)) return false; // Step 5. Allocate temporaries before inputs, since temporaries // require a register and may have a MUST_REUSE_INPUT policy. if (!allocateTemporaries(ins)) return false; // Step 6. Allocate inputs. if (!allocateInputs(ins)) return false; // Step 7. Assign fields of a snapshot. if (ins->snapshot()) informSnapshot(ins); // Step 8. Free any allocated stack slots. for (size_t i = 0; i < ins->numDefs(); i++) { LDefinition *def = ins->getDef(i); if (def->policy() == LDefinition::PASSTHROUGH) continue; killStack(getVirtualRegister(def)); } // Step 9. If this instruction has a safepoint, fill it with any stack // slots and registers that are live. if (ins->safepoint()) { if (!informSafepoint(ins->safepoint())) return false; } return true; }
bool LiveRangeAllocator<VREG>::init() { if (!RegisterAllocator::init()) return false; liveIn = lir->mir()->allocate<BitSet*>(graph.numBlockIds()); if (!liveIn) return false; // Initialize fixed intervals. for (size_t i = 0; i < AnyRegister::Total; i++) { AnyRegister reg = AnyRegister::FromCode(i); LiveInterval *interval = new LiveInterval(0); interval->setAllocation(LAllocation(reg)); fixedIntervals[i] = interval; } fixedIntervalsUnion = new LiveInterval(0); if (!vregs.init(lir->mir(), graph.numVirtualRegisters())) return false; // Build virtual register objects for (size_t i = 0; i < graph.numBlocks(); i++) { if (mir->shouldCancel("LSRA create data structures (main loop)")) return false; LBlock *block = graph.getBlock(i); for (LInstructionIterator ins = block->begin(); ins != block->end(); ins++) { for (size_t j = 0; j < ins->numDefs(); j++) { LDefinition *def = ins->getDef(j); if (def->policy() != LDefinition::PASSTHROUGH) { uint32_t reg = def->virtualRegister(); if (!vregs[reg].init(reg, block, *ins, def, /* isTemp */ false)) return false; } } for (size_t j = 0; j < ins->numTemps(); j++) { LDefinition *def = ins->getTemp(j); if (def->isBogusTemp()) continue; if (!vregs[def].init(def->virtualRegister(), block, *ins, def, /* isTemp */ true)) return false; } } for (size_t j = 0; j < block->numPhis(); j++) { LPhi *phi = block->getPhi(j); LDefinition *def = phi->getDef(0); if (!vregs[def].init(phi->id(), block, phi, def, /* isTemp */ false)) return false; } } return true; }
LAllocation * StupidAllocator::stackLocation(uint32_t vreg) { LDefinition *def = virtualRegisters[vreg]; if (def->policy() == LDefinition::PRESET && def->output()->isArgument()) return def->output(); return new LStackSlot(DefaultStackSlot(vreg), def->type() == LDefinition::DOUBLE); }
LAllocation * StupidAllocator::stackLocation(uint32_t vreg) { LDefinition *def = virtualRegisters[vreg]; if (def->policy() == LDefinition::FIXED && def->output()->isArgument()) return def->output(); return new(alloc()) LStackSlot(DefaultStackSlot(vreg)); }
void GreedyAllocator::findDefinitionsInLIR(LInstruction *ins) { for (size_t i = 0; i < ins->numDefs(); i++) { LDefinition *def = ins->getDef(i); JS_ASSERT(def->virtualRegister() < graph.numVirtualRegisters()); if (def->policy() == LDefinition::PASSTHROUGH) continue; vars[def->virtualRegister()].define(def, ins); } for (size_t i = 0; i < ins->numTemps(); i++) { LDefinition *temp = ins->getTemp(i); JS_ASSERT(temp->virtualRegister() < graph.numVirtualRegisters()); JS_ASSERT(temp->policy() != LDefinition::PASSTHROUGH); vars[temp->virtualRegister()].define(temp, ins); } }
bool StupidAllocator::init() { if (!RegisterAllocator::init()) return false; if (!virtualRegisters.reserve(graph.numVirtualRegisters())) return false; for (size_t i = 0; i < graph.numVirtualRegisters(); i++) virtualRegisters.infallibleAppend(NULL); for (size_t i = 0; i < graph.numBlocks(); i++) { LBlock *block = graph.getBlock(i); for (LInstructionIterator ins = block->begin(); ins != block->end(); ins++) { for (size_t j = 0; j < ins->numDefs(); j++) { LDefinition *def = ins->getDef(j); if (def->policy() != LDefinition::PASSTHROUGH) virtualRegisters[def->virtualRegister()] = def; } for (size_t j = 0; j < ins->numTemps(); j++) { LDefinition *def = ins->getTemp(j); if (def->isBogusTemp()) continue; virtualRegisters[def->virtualRegister()] = def; } } for (size_t j = 0; j < block->numPhis(); j++) { LPhi *phi = block->getPhi(j); LDefinition *def = phi->getDef(0); uint32 vreg = def->virtualRegister(); virtualRegisters[vreg] = def; } } // Assign physical registers to the tracked allocation. { registerCount = 0; RegisterSet remainingRegisters(allRegisters_); while (!remainingRegisters.empty(/* float = */ false)) registers[registerCount++].reg = AnyRegister(remainingRegisters.takeGeneral()); while (!remainingRegisters.empty(/* float = */ true)) registers[registerCount++].reg = AnyRegister(remainingRegisters.takeFloat()); JS_ASSERT(registerCount <= MAX_REGISTERS); } return true; }
bool AllocationIntegrityState::check(bool populateSafepoints) { MOZ_ASSERT(!instructions.empty()); #ifdef DEBUG if (JitSpewEnabled(JitSpew_RegAlloc)) dump(); for (size_t blockIndex = 0; blockIndex < graph.numBlocks(); blockIndex++) { LBlock* block = graph.getBlock(blockIndex); // Check that all instruction inputs and outputs have been assigned an allocation. for (LInstructionIterator iter = block->begin(); iter != block->end(); iter++) { LInstruction* ins = *iter; for (LInstruction::InputIterator alloc(*ins); alloc.more(); alloc.next()) MOZ_ASSERT(!alloc->isUse()); for (size_t i = 0; i < ins->numDefs(); i++) { LDefinition* def = ins->getDef(i); MOZ_ASSERT(!def->output()->isUse()); LDefinition oldDef = instructions[ins->id()].outputs[i]; MOZ_ASSERT_IF(oldDef.policy() == LDefinition::MUST_REUSE_INPUT, *def->output() == *ins->getOperand(oldDef.getReusedInput())); } for (size_t i = 0; i < ins->numTemps(); i++) { LDefinition* temp = ins->getTemp(i); MOZ_ASSERT_IF(!temp->isBogusTemp(), temp->output()->isRegister()); LDefinition oldTemp = instructions[ins->id()].temps[i]; MOZ_ASSERT_IF(oldTemp.policy() == LDefinition::MUST_REUSE_INPUT, *temp->output() == *ins->getOperand(oldTemp.getReusedInput())); } } } #endif // Check that the register assignment and move groups preserve the original // semantics of the virtual registers. Each virtual register has a single // write (owing to the SSA representation), but the allocation may move the // written value around between registers and memory locations along // different paths through the script. // // For each use of an allocation, follow the physical value which is read // backward through the script, along all paths to the value's virtual // register's definition. for (size_t blockIndex = 0; blockIndex < graph.numBlocks(); blockIndex++) { LBlock* block = graph.getBlock(blockIndex); for (LInstructionIterator iter = block->begin(); iter != block->end(); iter++) { LInstruction* ins = *iter; const InstructionInfo& info = instructions[ins->id()]; LSafepoint* safepoint = ins->safepoint(); if (safepoint) { for (size_t i = 0; i < ins->numTemps(); i++) { if (ins->getTemp(i)->isBogusTemp()) continue; uint32_t vreg = info.temps[i].virtualRegister(); LAllocation* alloc = ins->getTemp(i)->output(); if (!checkSafepointAllocation(ins, vreg, *alloc, populateSafepoints)) return false; } MOZ_ASSERT_IF(ins->isCall() && !populateSafepoints, safepoint->liveRegs().emptyFloat() && safepoint->liveRegs().emptyGeneral()); } size_t inputIndex = 0; for (LInstruction::InputIterator alloc(*ins); alloc.more(); alloc.next()) { LAllocation oldInput = info.inputs[inputIndex++]; if (!oldInput.isUse()) continue; uint32_t vreg = oldInput.toUse()->virtualRegister(); if (safepoint && !oldInput.toUse()->usedAtStart()) { if (!checkSafepointAllocation(ins, vreg, **alloc, populateSafepoints)) return false; } // Start checking at the previous instruction, in case this // instruction reuses its input register for an output. LInstructionReverseIterator riter = block->rbegin(ins); riter++; checkIntegrity(block, *riter, vreg, **alloc, populateSafepoints); while (!worklist.empty()) { IntegrityItem item = worklist.popCopy(); checkIntegrity(item.block, *item.block->rbegin(), item.vreg, item.alloc, populateSafepoints); } } } } return true; }
bool LiveRangeAllocator<VREG>::buildLivenessInfo() { if (!init()) return false; Vector<MBasicBlock *, 1, SystemAllocPolicy> loopWorkList; BitSet *loopDone = BitSet::New(alloc(), graph.numBlockIds()); if (!loopDone) return false; for (size_t i = graph.numBlocks(); i > 0; i--) { if (mir->shouldCancel("Build Liveness Info (main loop)")) return false; LBlock *block = graph.getBlock(i - 1); MBasicBlock *mblock = block->mir(); BitSet *live = BitSet::New(alloc(), graph.numVirtualRegisters()); if (!live) return false; liveIn[mblock->id()] = live; // Propagate liveIn from our successors to us for (size_t i = 0; i < mblock->lastIns()->numSuccessors(); i++) { MBasicBlock *successor = mblock->lastIns()->getSuccessor(i); // Skip backedges, as we fix them up at the loop header. if (mblock->id() < successor->id()) live->insertAll(liveIn[successor->id()]); } // Add successor phis if (mblock->successorWithPhis()) { LBlock *phiSuccessor = mblock->successorWithPhis()->lir(); for (unsigned int j = 0; j < phiSuccessor->numPhis(); j++) { LPhi *phi = phiSuccessor->getPhi(j); LAllocation *use = phi->getOperand(mblock->positionInPhiSuccessor()); uint32_t reg = use->toUse()->virtualRegister(); live->insert(reg); } } // Variables are assumed alive for the entire block, a define shortens // the interval to the point of definition. for (BitSet::Iterator liveRegId(*live); liveRegId; liveRegId++) { if (!vregs[*liveRegId].getInterval(0)->addRangeAtHead(inputOf(block->firstId()), outputOf(block->lastId()).next())) { return false; } } // Shorten the front end of live intervals for live variables to their // point of definition, if found. for (LInstructionReverseIterator ins = block->rbegin(); ins != block->rend(); ins++) { // Calls may clobber registers, so force a spill and reload around the callsite. if (ins->isCall()) { for (AnyRegisterIterator iter(allRegisters_); iter.more(); iter++) { if (forLSRA) { if (!addFixedRangeAtHead(*iter, inputOf(*ins), outputOf(*ins))) return false; } else { bool found = false; for (size_t i = 0; i < ins->numDefs(); i++) { if (ins->getDef(i)->isPreset() && *ins->getDef(i)->output() == LAllocation(*iter)) { found = true; break; } } if (!found && !addFixedRangeAtHead(*iter, outputOf(*ins), outputOf(*ins).next())) return false; } } } for (size_t i = 0; i < ins->numDefs(); i++) { if (ins->getDef(i)->policy() != LDefinition::PASSTHROUGH) { LDefinition *def = ins->getDef(i); CodePosition from; if (def->policy() == LDefinition::PRESET && def->output()->isRegister() && forLSRA) { // The fixed range covers the current instruction so the // interval for the virtual register starts at the next // instruction. If the next instruction has a fixed use, // this can lead to unnecessary register moves. To avoid // special handling for this, assert the next instruction // has no fixed uses. defineFixed guarantees this by inserting // an LNop. JS_ASSERT(!NextInstructionHasFixedUses(block, *ins)); AnyRegister reg = def->output()->toRegister(); if (!addFixedRangeAtHead(reg, inputOf(*ins), outputOf(*ins).next())) return false; from = outputOf(*ins).next(); } else { from = forLSRA ? inputOf(*ins) : outputOf(*ins); } if (def->policy() == LDefinition::MUST_REUSE_INPUT) { // MUST_REUSE_INPUT is implemented by allocating an output // register and moving the input to it. Register hints are // used to avoid unnecessary moves. We give the input an // LUse::ANY policy to avoid allocating a register for the // input. LUse *inputUse = ins->getOperand(def->getReusedInput())->toUse(); JS_ASSERT(inputUse->policy() == LUse::REGISTER); JS_ASSERT(inputUse->usedAtStart()); *inputUse = LUse(inputUse->virtualRegister(), LUse::ANY, /* usedAtStart = */ true); } LiveInterval *interval = vregs[def].getInterval(0); interval->setFrom(from); // Ensure that if there aren't any uses, there's at least // some interval for the output to go into. if (interval->numRanges() == 0) { if (!interval->addRangeAtHead(from, from.next())) return false; } live->remove(def->virtualRegister()); } } for (size_t i = 0; i < ins->numTemps(); i++) { LDefinition *temp = ins->getTemp(i); if (temp->isBogusTemp()) continue; if (forLSRA) { if (temp->policy() == LDefinition::PRESET) { if (ins->isCall()) continue; AnyRegister reg = temp->output()->toRegister(); if (!addFixedRangeAtHead(reg, inputOf(*ins), outputOf(*ins))) return false; // Fixed intervals are not added to safepoints, so do it // here. if (LSafepoint *safepoint = ins->safepoint()) AddRegisterToSafepoint(safepoint, reg, *temp); } else { JS_ASSERT(!ins->isCall()); if (!vregs[temp].getInterval(0)->addRangeAtHead(inputOf(*ins), outputOf(*ins))) return false; } } else { // Normally temps are considered to cover both the input // and output of the associated instruction. In some cases // though we want to use a fixed register as both an input // and clobbered register in the instruction, so watch for // this and shorten the temp to cover only the output. CodePosition from = inputOf(*ins); if (temp->policy() == LDefinition::PRESET) { AnyRegister reg = temp->output()->toRegister(); for (LInstruction::InputIterator alloc(**ins); alloc.more(); alloc.next()) { if (alloc->isUse()) { LUse *use = alloc->toUse(); if (use->isFixedRegister()) { if (GetFixedRegister(vregs[use].def(), use) == reg) from = outputOf(*ins); } } } } CodePosition to = ins->isCall() ? outputOf(*ins) : outputOf(*ins).next(); if (!vregs[temp].getInterval(0)->addRangeAtHead(from, to)) return false; } } DebugOnly<bool> hasUseRegister = false; DebugOnly<bool> hasUseRegisterAtStart = false; for (LInstruction::InputIterator inputAlloc(**ins); inputAlloc.more(); inputAlloc.next()) { if (inputAlloc->isUse()) { LUse *use = inputAlloc->toUse(); // The first instruction, LLabel, has no uses. JS_ASSERT(inputOf(*ins) > outputOf(block->firstId())); // Call uses should always be at-start or fixed, since the fixed intervals // use all registers. JS_ASSERT_IF(ins->isCall() && !inputAlloc.isSnapshotInput(), use->isFixedRegister() || use->usedAtStart()); #ifdef DEBUG // Don't allow at-start call uses if there are temps of the same kind, // so that we don't assign the same register. if (ins->isCall() && use->usedAtStart()) { for (size_t i = 0; i < ins->numTemps(); i++) JS_ASSERT(vregs[ins->getTemp(i)].isDouble() != vregs[use].isDouble()); } // If there are both useRegisterAtStart(x) and useRegister(y) // uses, we may assign the same register to both operands due to // interval splitting (bug 772830). Don't allow this for now. if (use->policy() == LUse::REGISTER) { if (use->usedAtStart()) { if (!IsInputReused(*ins, use)) hasUseRegisterAtStart = true; } else { hasUseRegister = true; } } JS_ASSERT(!(hasUseRegister && hasUseRegisterAtStart)); #endif // Don't treat RECOVERED_INPUT uses as keeping the vreg alive. if (use->policy() == LUse::RECOVERED_INPUT) continue; CodePosition to; if (forLSRA) { if (use->isFixedRegister()) { AnyRegister reg = GetFixedRegister(vregs[use].def(), use); if (!addFixedRangeAtHead(reg, inputOf(*ins), outputOf(*ins))) return false; to = inputOf(*ins); // Fixed intervals are not added to safepoints, so do it // here. LSafepoint *safepoint = ins->safepoint(); if (!ins->isCall() && safepoint) AddRegisterToSafepoint(safepoint, reg, *vregs[use].def()); } else { to = use->usedAtStart() ? inputOf(*ins) : outputOf(*ins); } } else { to = (use->usedAtStart() || ins->isCall()) ? inputOf(*ins) : outputOf(*ins); if (use->isFixedRegister()) { LAllocation reg(AnyRegister::FromCode(use->registerCode())); for (size_t i = 0; i < ins->numDefs(); i++) { LDefinition *def = ins->getDef(i); if (def->policy() == LDefinition::PRESET && *def->output() == reg) to = inputOf(*ins); } } } LiveInterval *interval = vregs[use].getInterval(0); if (!interval->addRangeAtHead(inputOf(block->firstId()), forLSRA ? to : to.next())) return false; interval->addUse(new(alloc()) UsePosition(use, to)); live->insert(use->virtualRegister()); } } } // Phis have simultaneous assignment semantics at block begin, so at // the beginning of the block we can be sure that liveIn does not // contain any phi outputs. for (unsigned int i = 0; i < block->numPhis(); i++) { LDefinition *def = block->getPhi(i)->getDef(0); if (live->contains(def->virtualRegister())) { live->remove(def->virtualRegister()); } else { // This is a dead phi, so add a dummy range over all phis. This // can go away if we have an earlier dead code elimination pass. if (!vregs[def].getInterval(0)->addRangeAtHead(inputOf(block->firstId()), outputOf(block->firstId()))) { return false; } } } if (mblock->isLoopHeader()) { // A divergence from the published algorithm is required here, as // our block order does not guarantee that blocks of a loop are // contiguous. As a result, a single live interval spanning the // loop is not possible. Additionally, we require liveIn in a later // pass for resolution, so that must also be fixed up here. MBasicBlock *loopBlock = mblock->backedge(); while (true) { // Blocks must already have been visited to have a liveIn set. JS_ASSERT(loopBlock->id() >= mblock->id()); // Add an interval for this entire loop block CodePosition from = inputOf(loopBlock->lir()->firstId()); CodePosition to = outputOf(loopBlock->lir()->lastId()).next(); for (BitSet::Iterator liveRegId(*live); liveRegId; liveRegId++) { if (!vregs[*liveRegId].getInterval(0)->addRange(from, to)) return false; } // Fix up the liveIn set to account for the new interval liveIn[loopBlock->id()]->insertAll(live); // Make sure we don't visit this node again loopDone->insert(loopBlock->id()); // If this is the loop header, any predecessors are either the // backedge or out of the loop, so skip any predecessors of // this block if (loopBlock != mblock) { for (size_t i = 0; i < loopBlock->numPredecessors(); i++) { MBasicBlock *pred = loopBlock->getPredecessor(i); if (loopDone->contains(pred->id())) continue; if (!loopWorkList.append(pred)) return false; } } // Terminate loop if out of work. if (loopWorkList.empty()) break; // Grab the next block off the work list, skipping any OSR block. while (!loopWorkList.empty()) { loopBlock = loopWorkList.popCopy(); if (loopBlock->lir() != graph.osrBlock()) break; } // If end is reached without finding a non-OSR block, then no more work items were found. if (loopBlock->lir() == graph.osrBlock()) { JS_ASSERT(loopWorkList.empty()); break; } } // Clear the done set for other loops loopDone->clear(); } JS_ASSERT_IF(!mblock->numPredecessors(), live->empty()); } validateVirtualRegisters(); // If the script has an infinite loop, there may be no MReturn and therefore // no fixed intervals. Add a small range to fixedIntervalsUnion so that the // rest of the allocator can assume it has at least one range. if (fixedIntervalsUnion->numRanges() == 0) { if (!fixedIntervalsUnion->addRangeAtHead(CodePosition(0, CodePosition::INPUT), CodePosition(0, CodePosition::OUTPUT))) { return false; } } return true; }
void StupidAllocator::allocateForInstruction(LInstruction *ins) { // Sync all registers before making a call. if (ins->isCall()) { for (size_t i = 0; i < registerCount; i++) syncRegister(ins, i); } // Allocate for inputs which are required to be in registers. for (LInstruction::InputIterator alloc(*ins); alloc.more(); alloc.next()) { if (!alloc->isUse()) continue; LUse *use = alloc->toUse(); uint32_t vreg = use->virtualRegister(); if (use->policy() == LUse::REGISTER) { AnyRegister reg = ensureHasRegister(ins, vreg); alloc.replace(LAllocation(reg)); } else if (use->policy() == LUse::FIXED) { AnyRegister reg = GetFixedRegister(virtualRegisters[use->virtualRegister()], use); RegisterIndex index = registerIndex(reg); if (registers[index].vreg != vreg) { evictRegister(ins, index); RegisterIndex existing = findExistingRegister(vreg); if (existing != UINT32_MAX) evictRegister(ins, existing); loadRegister(ins, vreg, index); } alloc.replace(LAllocation(reg)); } else { // Inputs which are not required to be in a register are not // allocated until after temps/definitions, as the latter may need // to evict registers which hold these inputs. } } // Find registers to hold all temporaries and outputs of the instruction. for (size_t i = 0; i < ins->numTemps(); i++) { LDefinition *def = ins->getTemp(i); if (!def->isBogusTemp()) allocateForDefinition(ins, def); } for (size_t i = 0; i < ins->numDefs(); i++) { LDefinition *def = ins->getDef(i); if (def->policy() != LDefinition::PASSTHROUGH) allocateForDefinition(ins, def); } // Allocate for remaining inputs which do not need to be in registers. for (LInstruction::InputIterator alloc(*ins); alloc.more(); alloc.next()) { if (!alloc->isUse()) continue; LUse *use = alloc->toUse(); uint32_t vreg = use->virtualRegister(); JS_ASSERT(use->policy() != LUse::REGISTER && use->policy() != LUse::FIXED); RegisterIndex index = findExistingRegister(vreg); if (index == UINT32_MAX) { LAllocation *stack = stackLocation(use->virtualRegister()); alloc.replace(*stack); } else { registers[index].age = ins->id(); alloc.replace(LAllocation(registers[index].reg)); } } // If this is a call, evict all registers except for those holding outputs. if (ins->isCall()) { for (size_t i = 0; i < registerCount; i++) { if (!registers[i].dirty) registers[i].set(MISSING_ALLOCATION); } } }
bool AllocationIntegrityState::checkIntegrity(LBlock *block, LInstruction *ins, uint32_t vreg, LAllocation alloc, bool populateSafepoints) { for (LInstructionReverseIterator iter(block->rbegin(ins)); iter != block->rend(); iter++) { ins = *iter; // Follow values through assignments in move groups. All assignments in // a move group are considered to happen simultaneously, so stop after // the first matching move is found. if (ins->isMoveGroup()) { LMoveGroup *group = ins->toMoveGroup(); for (int i = group->numMoves() - 1; i >= 0; i--) { if (*group->getMove(i).to() == alloc) { alloc = *group->getMove(i).from(); break; } } } const InstructionInfo &info = instructions[ins->id()]; // Make sure the physical location being tracked is not clobbered by // another instruction, and that if the originating vreg definition is // found that it is writing to the tracked location. for (size_t i = 0; i < ins->numDefs(); i++) { LDefinition *def = ins->getDef(i); if (def->policy() == LDefinition::PASSTHROUGH) continue; if (info.outputs[i].virtualRegister() == vreg) { JS_ASSERT(*def->output() == alloc); // Found the original definition, done scanning. return true; } else { JS_ASSERT(*def->output() != alloc); } } for (size_t i = 0; i < ins->numTemps(); i++) { LDefinition *temp = ins->getTemp(i); if (!temp->isBogusTemp()) JS_ASSERT(*temp->output() != alloc); } if (ins->safepoint()) { if (!checkSafepointAllocation(ins, vreg, alloc, populateSafepoints)) return false; } } // Phis are effectless, but change the vreg we are tracking. Check if there // is one which produced this vreg. We need to follow back through the phi // inputs as it is not guaranteed the register allocator filled in physical // allocations for the inputs and outputs of the phis. for (size_t i = 0; i < block->numPhis(); i++) { InstructionInfo &info = blocks[block->mir()->id()].phis[i]; LPhi *phi = block->getPhi(i); if (info.outputs[0].virtualRegister() == vreg) { for (size_t j = 0; j < phi->numOperands(); j++) { uint32_t newvreg = info.inputs[j].toUse()->virtualRegister(); LBlock *predecessor = graph.getBlock(block->mir()->getPredecessor(j)->id()); if (!addPredecessor(predecessor, newvreg, alloc)) return false; } return true; } } // No phi which defined the vreg we are tracking, follow back through all // predecessors with the existing vreg. for (size_t i = 0; i < block->mir()->numPredecessors(); i++) { LBlock *predecessor = graph.getBlock(block->mir()->getPredecessor(i)->id()); if (!addPredecessor(predecessor, vreg, alloc)) return false; } return true; }