1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/js/src/jit/RegisterAllocator.cpp Wed Dec 31 06:09:35 2014 +0100
1.3 @@ -0,0 +1,513 @@
1.4 +/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
1.5 + * vim: set ts=8 sts=4 et sw=4 tw=99:
1.6 + * This Source Code Form is subject to the terms of the Mozilla Public
1.7 + * License, v. 2.0. If a copy of the MPL was not distributed with this
1.8 + * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
1.9 +
1.10 +#include "jit/RegisterAllocator.h"
1.11 +
1.12 +using namespace js;
1.13 +using namespace js::jit;
1.14 +
1.15 +bool
1.16 +AllocationIntegrityState::record()
1.17 +{
1.18 + // Ignore repeated record() calls.
1.19 + if (!instructions.empty())
1.20 + return true;
1.21 +
1.22 + if (!instructions.appendN(InstructionInfo(), graph.numInstructions()))
1.23 + return false;
1.24 +
1.25 + if (!virtualRegisters.appendN((LDefinition *)nullptr, graph.numVirtualRegisters()))
1.26 + return false;
1.27 +
1.28 + if (!blocks.reserve(graph.numBlocks()))
1.29 + return false;
1.30 + for (size_t i = 0; i < graph.numBlocks(); i++) {
1.31 + blocks.infallibleAppend(BlockInfo());
1.32 + LBlock *block = graph.getBlock(i);
1.33 + JS_ASSERT(block->mir()->id() == i);
1.34 +
1.35 + BlockInfo &blockInfo = blocks[i];
1.36 + if (!blockInfo.phis.reserve(block->numPhis()))
1.37 + return false;
1.38 +
1.39 + for (size_t j = 0; j < block->numPhis(); j++) {
1.40 + blockInfo.phis.infallibleAppend(InstructionInfo());
1.41 + InstructionInfo &info = blockInfo.phis[j];
1.42 + LPhi *phi = block->getPhi(j);
1.43 + JS_ASSERT(phi->numDefs() == 1);
1.44 + uint32_t vreg = phi->getDef(0)->virtualRegister();
1.45 + virtualRegisters[vreg] = phi->getDef(0);
1.46 + if (!info.outputs.append(*phi->getDef(0)))
1.47 + return false;
1.48 + for (size_t k = 0, kend = phi->numOperands(); k < kend; k++) {
1.49 + if (!info.inputs.append(*phi->getOperand(k)))
1.50 + return false;
1.51 + }
1.52 + }
1.53 +
1.54 + for (LInstructionIterator iter = block->begin(); iter != block->end(); iter++) {
1.55 + LInstruction *ins = *iter;
1.56 + InstructionInfo &info = instructions[ins->id()];
1.57 +
1.58 + for (size_t k = 0; k < ins->numTemps(); k++) {
1.59 + uint32_t vreg = ins->getTemp(k)->virtualRegister();
1.60 + virtualRegisters[vreg] = ins->getTemp(k);
1.61 + if (!info.temps.append(*ins->getTemp(k)))
1.62 + return false;
1.63 + }
1.64 + for (size_t k = 0; k < ins->numDefs(); k++) {
1.65 + uint32_t vreg = ins->getDef(k)->virtualRegister();
1.66 + virtualRegisters[vreg] = ins->getDef(k);
1.67 + if (!info.outputs.append(*ins->getDef(k)))
1.68 + return false;
1.69 + }
1.70 + for (LInstruction::InputIterator alloc(*ins); alloc.more(); alloc.next()) {
1.71 + if (!info.inputs.append(**alloc))
1.72 + return false;
1.73 + }
1.74 + }
1.75 + }
1.76 +
1.77 + return seen.init();
1.78 +}
1.79 +
1.80 +bool
1.81 +AllocationIntegrityState::check(bool populateSafepoints)
1.82 +{
1.83 + JS_ASSERT(!instructions.empty());
1.84 +
1.85 +#ifdef DEBUG
1.86 + if (IonSpewEnabled(IonSpew_RegAlloc))
1.87 + dump();
1.88 +
1.89 + for (size_t blockIndex = 0; blockIndex < graph.numBlocks(); blockIndex++) {
1.90 + LBlock *block = graph.getBlock(blockIndex);
1.91 +
1.92 + // Check that all instruction inputs and outputs have been assigned an allocation.
1.93 + for (LInstructionIterator iter = block->begin(); iter != block->end(); iter++) {
1.94 + LInstruction *ins = *iter;
1.95 +
1.96 + for (LInstruction::InputIterator alloc(*ins); alloc.more(); alloc.next())
1.97 + JS_ASSERT(!alloc->isUse());
1.98 +
1.99 + for (size_t i = 0; i < ins->numDefs(); i++) {
1.100 + LDefinition *def = ins->getDef(i);
1.101 + JS_ASSERT_IF(def->policy() != LDefinition::PASSTHROUGH, !def->output()->isUse());
1.102 +
1.103 + LDefinition oldDef = instructions[ins->id()].outputs[i];
1.104 + JS_ASSERT_IF(oldDef.policy() == LDefinition::MUST_REUSE_INPUT,
1.105 + *def->output() == *ins->getOperand(oldDef.getReusedInput()));
1.106 + }
1.107 +
1.108 + for (size_t i = 0; i < ins->numTemps(); i++) {
1.109 + LDefinition *temp = ins->getTemp(i);
1.110 + JS_ASSERT_IF(!temp->isBogusTemp(), temp->output()->isRegister());
1.111 +
1.112 + LDefinition oldTemp = instructions[ins->id()].temps[i];
1.113 + JS_ASSERT_IF(oldTemp.policy() == LDefinition::MUST_REUSE_INPUT,
1.114 + *temp->output() == *ins->getOperand(oldTemp.getReusedInput()));
1.115 + }
1.116 + }
1.117 + }
1.118 +#endif
1.119 +
1.120 + // Check that the register assignment and move groups preserve the original
1.121 + // semantics of the virtual registers. Each virtual register has a single
1.122 + // write (owing to the SSA representation), but the allocation may move the
1.123 + // written value around between registers and memory locations along
1.124 + // different paths through the script.
1.125 + //
1.126 + // For each use of an allocation, follow the physical value which is read
1.127 + // backward through the script, along all paths to the value's virtual
1.128 + // register's definition.
1.129 + for (size_t blockIndex = 0; blockIndex < graph.numBlocks(); blockIndex++) {
1.130 + LBlock *block = graph.getBlock(blockIndex);
1.131 + for (LInstructionIterator iter = block->begin(); iter != block->end(); iter++) {
1.132 + LInstruction *ins = *iter;
1.133 + const InstructionInfo &info = instructions[ins->id()];
1.134 +
1.135 + LSafepoint *safepoint = ins->safepoint();
1.136 + if (safepoint) {
1.137 + for (size_t i = 0; i < ins->numTemps(); i++) {
1.138 + uint32_t vreg = info.temps[i].virtualRegister();
1.139 + LAllocation *alloc = ins->getTemp(i)->output();
1.140 + if (!checkSafepointAllocation(ins, vreg, *alloc, populateSafepoints))
1.141 + return false;
1.142 + }
1.143 + JS_ASSERT_IF(ins->isCall() && !populateSafepoints,
1.144 + safepoint->liveRegs().empty(true) &&
1.145 + safepoint->liveRegs().empty(false));
1.146 + }
1.147 +
1.148 + size_t inputIndex = 0;
1.149 + for (LInstruction::InputIterator alloc(*ins); alloc.more(); alloc.next()) {
1.150 + LAllocation oldInput = info.inputs[inputIndex++];
1.151 + if (!oldInput.isUse())
1.152 + continue;
1.153 +
1.154 + uint32_t vreg = oldInput.toUse()->virtualRegister();
1.155 +
1.156 + if (safepoint && !oldInput.toUse()->usedAtStart()) {
1.157 + if (!checkSafepointAllocation(ins, vreg, **alloc, populateSafepoints))
1.158 + return false;
1.159 + }
1.160 +
1.161 + // Start checking at the previous instruction, in case this
1.162 + // instruction reuses its input register for an output.
1.163 + LInstructionReverseIterator riter = block->rbegin(ins);
1.164 + riter++;
1.165 + checkIntegrity(block, *riter, vreg, **alloc, populateSafepoints);
1.166 +
1.167 + while (!worklist.empty()) {
1.168 + IntegrityItem item = worklist.popCopy();
1.169 + checkIntegrity(item.block, *item.block->rbegin(), item.vreg, item.alloc, populateSafepoints);
1.170 + }
1.171 + }
1.172 + }
1.173 + }
1.174 +
1.175 + return true;
1.176 +}
1.177 +
1.178 +bool
1.179 +AllocationIntegrityState::checkIntegrity(LBlock *block, LInstruction *ins,
1.180 + uint32_t vreg, LAllocation alloc, bool populateSafepoints)
1.181 +{
1.182 + for (LInstructionReverseIterator iter(block->rbegin(ins)); iter != block->rend(); iter++) {
1.183 + ins = *iter;
1.184 +
1.185 + // Follow values through assignments in move groups. All assignments in
1.186 + // a move group are considered to happen simultaneously, so stop after
1.187 + // the first matching move is found.
1.188 + if (ins->isMoveGroup()) {
1.189 + LMoveGroup *group = ins->toMoveGroup();
1.190 + for (int i = group->numMoves() - 1; i >= 0; i--) {
1.191 + if (*group->getMove(i).to() == alloc) {
1.192 + alloc = *group->getMove(i).from();
1.193 + break;
1.194 + }
1.195 + }
1.196 + }
1.197 +
1.198 + const InstructionInfo &info = instructions[ins->id()];
1.199 +
1.200 + // Make sure the physical location being tracked is not clobbered by
1.201 + // another instruction, and that if the originating vreg definition is
1.202 + // found that it is writing to the tracked location.
1.203 +
1.204 + for (size_t i = 0; i < ins->numDefs(); i++) {
1.205 + LDefinition *def = ins->getDef(i);
1.206 + if (def->policy() == LDefinition::PASSTHROUGH)
1.207 + continue;
1.208 + if (info.outputs[i].virtualRegister() == vreg) {
1.209 + JS_ASSERT(*def->output() == alloc);
1.210 +
1.211 + // Found the original definition, done scanning.
1.212 + return true;
1.213 + } else {
1.214 + JS_ASSERT(*def->output() != alloc);
1.215 + }
1.216 + }
1.217 +
1.218 + for (size_t i = 0; i < ins->numTemps(); i++) {
1.219 + LDefinition *temp = ins->getTemp(i);
1.220 + if (!temp->isBogusTemp())
1.221 + JS_ASSERT(*temp->output() != alloc);
1.222 + }
1.223 +
1.224 + if (ins->safepoint()) {
1.225 + if (!checkSafepointAllocation(ins, vreg, alloc, populateSafepoints))
1.226 + return false;
1.227 + }
1.228 + }
1.229 +
1.230 + // Phis are effectless, but change the vreg we are tracking. Check if there
1.231 + // is one which produced this vreg. We need to follow back through the phi
1.232 + // inputs as it is not guaranteed the register allocator filled in physical
1.233 + // allocations for the inputs and outputs of the phis.
1.234 + for (size_t i = 0; i < block->numPhis(); i++) {
1.235 + const InstructionInfo &info = blocks[block->mir()->id()].phis[i];
1.236 + LPhi *phi = block->getPhi(i);
1.237 + if (info.outputs[0].virtualRegister() == vreg) {
1.238 + for (size_t j = 0, jend = phi->numOperands(); j < jend; j++) {
1.239 + uint32_t newvreg = info.inputs[j].toUse()->virtualRegister();
1.240 + LBlock *predecessor = graph.getBlock(block->mir()->getPredecessor(j)->id());
1.241 + if (!addPredecessor(predecessor, newvreg, alloc))
1.242 + return false;
1.243 + }
1.244 + return true;
1.245 + }
1.246 + }
1.247 +
1.248 + // No phi which defined the vreg we are tracking, follow back through all
1.249 + // predecessors with the existing vreg.
1.250 + for (size_t i = 0, iend = block->mir()->numPredecessors(); i < iend; i++) {
1.251 + LBlock *predecessor = graph.getBlock(block->mir()->getPredecessor(i)->id());
1.252 + if (!addPredecessor(predecessor, vreg, alloc))
1.253 + return false;
1.254 + }
1.255 +
1.256 + return true;
1.257 +}
1.258 +
1.259 +bool
1.260 +AllocationIntegrityState::checkSafepointAllocation(LInstruction *ins,
1.261 + uint32_t vreg, LAllocation alloc,
1.262 + bool populateSafepoints)
1.263 +{
1.264 + LSafepoint *safepoint = ins->safepoint();
1.265 + JS_ASSERT(safepoint);
1.266 +
1.267 + if (ins->isCall() && alloc.isRegister())
1.268 + return true;
1.269 +
1.270 + if (alloc.isRegister()) {
1.271 + AnyRegister reg = alloc.toRegister();
1.272 + if (populateSafepoints)
1.273 + safepoint->addLiveRegister(reg);
1.274 + JS_ASSERT(safepoint->liveRegs().has(reg));
1.275 + }
1.276 +
1.277 + LDefinition::Type type = virtualRegisters[vreg]
1.278 + ? virtualRegisters[vreg]->type()
1.279 + : LDefinition::GENERAL;
1.280 +
1.281 + switch (type) {
1.282 + case LDefinition::OBJECT:
1.283 + if (populateSafepoints) {
1.284 + IonSpew(IonSpew_RegAlloc, "Safepoint object v%u i%u %s",
1.285 + vreg, ins->id(), alloc.toString());
1.286 + if (!safepoint->addGcPointer(alloc))
1.287 + return false;
1.288 + }
1.289 + JS_ASSERT(safepoint->hasGcPointer(alloc));
1.290 + break;
1.291 + case LDefinition::SLOTS:
1.292 + if (populateSafepoints) {
1.293 + IonSpew(IonSpew_RegAlloc, "Safepoint slots v%u i%u %s",
1.294 + vreg, ins->id(), alloc.toString());
1.295 + if (!safepoint->addSlotsOrElementsPointer(alloc))
1.296 + return false;
1.297 + }
1.298 + JS_ASSERT(safepoint->hasSlotsOrElementsPointer(alloc));
1.299 + break;
1.300 +#ifdef JS_NUNBOX32
1.301 + // Do not assert that safepoint information for nunbox types is complete,
1.302 + // as if a vreg for a value's components are copied in multiple places
1.303 + // then the safepoint information may not reflect all copies. All copies
1.304 + // of payloads must be reflected, however, for generational GC.
1.305 + case LDefinition::TYPE:
1.306 + if (populateSafepoints) {
1.307 + IonSpew(IonSpew_RegAlloc, "Safepoint type v%u i%u %s",
1.308 + vreg, ins->id(), alloc.toString());
1.309 + if (!safepoint->addNunboxType(vreg, alloc))
1.310 + return false;
1.311 + }
1.312 + break;
1.313 + case LDefinition::PAYLOAD:
1.314 + if (populateSafepoints) {
1.315 + IonSpew(IonSpew_RegAlloc, "Safepoint payload v%u i%u %s",
1.316 + vreg, ins->id(), alloc.toString());
1.317 + if (!safepoint->addNunboxPayload(vreg, alloc))
1.318 + return false;
1.319 + }
1.320 + JS_ASSERT(safepoint->hasNunboxPayload(alloc));
1.321 + break;
1.322 +#else
1.323 + case LDefinition::BOX:
1.324 + if (populateSafepoints) {
1.325 + IonSpew(IonSpew_RegAlloc, "Safepoint boxed value v%u i%u %s",
1.326 + vreg, ins->id(), alloc.toString());
1.327 + if (!safepoint->addBoxedValue(alloc))
1.328 + return false;
1.329 + }
1.330 + JS_ASSERT(safepoint->hasBoxedValue(alloc));
1.331 + break;
1.332 +#endif
1.333 + default:
1.334 + break;
1.335 + }
1.336 +
1.337 + return true;
1.338 +}
1.339 +
1.340 +bool
1.341 +AllocationIntegrityState::addPredecessor(LBlock *block, uint32_t vreg, LAllocation alloc)
1.342 +{
1.343 + // There is no need to reanalyze if we have already seen this predecessor.
1.344 + // We share the seen allocations across analysis of each use, as there will
1.345 + // likely be common ground between different uses of the same vreg.
1.346 + IntegrityItem item;
1.347 + item.block = block;
1.348 + item.vreg = vreg;
1.349 + item.alloc = alloc;
1.350 + item.index = seen.count();
1.351 +
1.352 + IntegrityItemSet::AddPtr p = seen.lookupForAdd(item);
1.353 + if (p)
1.354 + return true;
1.355 + if (!seen.add(p, item))
1.356 + return false;
1.357 +
1.358 + return worklist.append(item);
1.359 +}
1.360 +
1.361 +void
1.362 +AllocationIntegrityState::dump()
1.363 +{
1.364 +#ifdef DEBUG
1.365 + fprintf(stderr, "Register Allocation:\n");
1.366 +
1.367 + for (size_t blockIndex = 0; blockIndex < graph.numBlocks(); blockIndex++) {
1.368 + LBlock *block = graph.getBlock(blockIndex);
1.369 + MBasicBlock *mir = block->mir();
1.370 +
1.371 + fprintf(stderr, "\nBlock %lu", static_cast<unsigned long>(blockIndex));
1.372 + for (size_t i = 0; i < mir->numSuccessors(); i++)
1.373 + fprintf(stderr, " [successor %u]", mir->getSuccessor(i)->id());
1.374 + fprintf(stderr, "\n");
1.375 +
1.376 + for (size_t i = 0; i < block->numPhis(); i++) {
1.377 + const InstructionInfo &info = blocks[blockIndex].phis[i];
1.378 + LPhi *phi = block->getPhi(i);
1.379 + CodePosition output(phi->id(), CodePosition::OUTPUT);
1.380 +
1.381 + // Don't print the inputOf for phi nodes, since it's never used.
1.382 + fprintf(stderr, "[,%u Phi [def v%u %s] <-",
1.383 + output.pos(),
1.384 + info.outputs[0].virtualRegister(),
1.385 + phi->getDef(0)->output()->toString());
1.386 + for (size_t j = 0; j < phi->numOperands(); j++)
1.387 + fprintf(stderr, " %s", info.inputs[j].toString());
1.388 + fprintf(stderr, "]\n");
1.389 + }
1.390 +
1.391 + for (LInstructionIterator iter = block->begin(); iter != block->end(); iter++) {
1.392 + LInstruction *ins = *iter;
1.393 + const InstructionInfo &info = instructions[ins->id()];
1.394 +
1.395 + CodePosition input(ins->id(), CodePosition::INPUT);
1.396 + CodePosition output(ins->id(), CodePosition::OUTPUT);
1.397 +
1.398 + fprintf(stderr, "[");
1.399 + if (input != CodePosition::MIN)
1.400 + fprintf(stderr, "%u,%u ", input.pos(), output.pos());
1.401 + fprintf(stderr, "%s]", ins->opName());
1.402 +
1.403 + if (ins->isMoveGroup()) {
1.404 + LMoveGroup *group = ins->toMoveGroup();
1.405 + for (int i = group->numMoves() - 1; i >= 0; i--) {
1.406 + // Use two printfs, as LAllocation::toString is not reentant.
1.407 + fprintf(stderr, " [%s", group->getMove(i).from()->toString());
1.408 + fprintf(stderr, " -> %s]", group->getMove(i).to()->toString());
1.409 + }
1.410 + fprintf(stderr, "\n");
1.411 + continue;
1.412 + }
1.413 +
1.414 + for (size_t i = 0; i < ins->numTemps(); i++) {
1.415 + LDefinition *temp = ins->getTemp(i);
1.416 + if (!temp->isBogusTemp())
1.417 + fprintf(stderr, " [temp v%u %s]", info.temps[i].virtualRegister(),
1.418 + temp->output()->toString());
1.419 + }
1.420 +
1.421 + for (size_t i = 0; i < ins->numDefs(); i++) {
1.422 + LDefinition *def = ins->getDef(i);
1.423 + fprintf(stderr, " [def v%u %s]", info.outputs[i].virtualRegister(),
1.424 + def->output()->toString());
1.425 + }
1.426 +
1.427 + size_t index = 0;
1.428 + for (LInstruction::InputIterator alloc(*ins); alloc.more(); alloc.next()) {
1.429 + fprintf(stderr, " [use %s", info.inputs[index++].toString());
1.430 + fprintf(stderr, " %s]", alloc->toString());
1.431 + }
1.432 +
1.433 + fprintf(stderr, "\n");
1.434 + }
1.435 + }
1.436 +
1.437 + fprintf(stderr, "\nIntermediate Allocations:\n\n");
1.438 +
1.439 + // Print discovered allocations at the ends of blocks, in the order they
1.440 + // were discovered.
1.441 +
1.442 + Vector<IntegrityItem, 20, SystemAllocPolicy> seenOrdered;
1.443 + seenOrdered.appendN(IntegrityItem(), seen.count());
1.444 +
1.445 + for (IntegrityItemSet::Enum iter(seen); !iter.empty(); iter.popFront()) {
1.446 + IntegrityItem item = iter.front();
1.447 + seenOrdered[item.index] = item;
1.448 + }
1.449 +
1.450 + for (size_t i = 0; i < seenOrdered.length(); i++) {
1.451 + IntegrityItem item = seenOrdered[i];
1.452 + fprintf(stderr, "block %u reg v%u alloc %s\n",
1.453 + item.block->mir()->id(), item.vreg, item.alloc.toString());
1.454 + }
1.455 +
1.456 + fprintf(stderr, "\n");
1.457 +#endif
1.458 +}
1.459 +
1.460 +const CodePosition CodePosition::MAX(UINT_MAX);
1.461 +const CodePosition CodePosition::MIN(0);
1.462 +
1.463 +bool
1.464 +RegisterAllocator::init()
1.465 +{
1.466 + if (!insData.init(mir, graph.numInstructions()))
1.467 + return false;
1.468 +
1.469 + for (size_t i = 0; i < graph.numBlocks(); i++) {
1.470 + LBlock *block = graph.getBlock(i);
1.471 + for (LInstructionIterator ins = block->begin(); ins != block->end(); ins++)
1.472 + insData[*ins].init(*ins, block);
1.473 + for (size_t j = 0; j < block->numPhis(); j++) {
1.474 + LPhi *phi = block->getPhi(j);
1.475 + insData[phi].init(phi, block);
1.476 + }
1.477 + }
1.478 +
1.479 + return true;
1.480 +}
1.481 +
1.482 +LMoveGroup *
1.483 +RegisterAllocator::getInputMoveGroup(uint32_t ins)
1.484 +{
1.485 + InstructionData *data = &insData[ins];
1.486 + JS_ASSERT(!data->ins()->isPhi());
1.487 + JS_ASSERT(!data->ins()->isLabel());
1.488 +
1.489 + if (data->inputMoves())
1.490 + return data->inputMoves();
1.491 +
1.492 + LMoveGroup *moves = LMoveGroup::New(alloc());
1.493 + data->setInputMoves(moves);
1.494 + data->block()->insertBefore(data->ins(), moves);
1.495 +
1.496 + return moves;
1.497 +}
1.498 +
1.499 +LMoveGroup *
1.500 +RegisterAllocator::getMoveGroupAfter(uint32_t ins)
1.501 +{
1.502 + InstructionData *data = &insData[ins];
1.503 + JS_ASSERT(!data->ins()->isPhi());
1.504 +
1.505 + if (data->movesAfter())
1.506 + return data->movesAfter();
1.507 +
1.508 + LMoveGroup *moves = LMoveGroup::New(alloc());
1.509 + data->setMovesAfter(moves);
1.510 +
1.511 + if (data->ins()->isLabel())
1.512 + data->block()->insertAfter(data->block()->getEntryMoveGroup(alloc()), moves);
1.513 + else
1.514 + data->block()->insertAfter(data->ins(), moves);
1.515 + return moves;
1.516 +}
