RegionDescPtr selectRegion(const RegionContext& context,
TransKind kind) {
auto const mode = regionMode();
FTRACE(1,
"Select region: mode={} context:\n{}",
static_cast<int>(mode), show(context)
);
auto region = [&]{
try {
switch (mode) {
case RegionMode::None:
return RegionDescPtr{nullptr};
case RegionMode::Method:
return selectMethod(context);
case RegionMode::Tracelet:
return selectTracelet(context, kind == TransKind::Profile);
}
not_reached();
} catch (const std::exception& e) {
FTRACE(1, "region selector threw: {}\n", e.what());
return RegionDescPtr{nullptr};
}
}();
if (region) {
FTRACE(3, "{}", show(*region));
always_assert(region->instrSize() <= RuntimeOption::EvalJitMaxRegionInstrs);
} else {
FTRACE(1, "no region selectable; using tracelet compiler\n");
}
return region;
}
void visit(TransID tid) {
auto tidRegion = m_profData->transRegion(tid);
auto tidInstrs = tidRegion->instrSize();
if (m_numBCInstrs + tidInstrs > RuntimeOption::EvalJitMaxRegionInstrs) {
return;
}
if (m_visited.count(tid)) return;
m_visited.insert(tid);
m_visiting.insert(tid);
if (!breaksRegion(*(m_profData->transLastInstr(tid)))) {
auto srcBlockId = tidRegion->blocks().back().get()->id();
for (auto const arc : m_cfg.outArcs(tid)) {
auto dst = arc->dst();
// If dst is in the visiting set then this arc forms a cycle. Don't
// include it unless we've asked for loops.
if (!RuntimeOption::EvalJitLoops && m_visiting.count(dst)) continue;
// Skip dst if we already generated a region starting at that SrcKey.
auto dstSK = m_profData->transSrcKey(dst);
if (m_profData->optimized(dstSK)) continue;
auto dstBlockId = m_profData->transRegion(dst)->entry()->id();
m_arcs.push_back({srcBlockId, dstBlockId});
visit(dst);
}
}
// Now insert the region for tid in the front of m_region. We do
// this last so that the region ends up in (quasi-)topological order
// (it'll be in topological order for acyclic regions).
m_region->prepend(*tidRegion);
m_selectedSet.insert(tid);
if (m_selectedVec) m_selectedVec->push_back(tid);
m_numBCInstrs += tidRegion->instrSize();
always_assert(m_numBCInstrs <= RuntimeOption::EvalJitMaxRegionInstrs);
m_visiting.erase(tid);
}
RegionDescPtr selectHotTrace(HotTransContext& ctx,
TransIDSet& selectedSet,
TransIDVec* selectedVec /* = nullptr */) {
auto region = std::make_shared<RegionDesc>();
TransID tid = ctx.tid;
TransID prevId = kInvalidTransID;
selectedSet.clear();
if (selectedVec) selectedVec->clear();
TypedLocations accumPostConds;
// Maps from BlockIds to accumulated post conditions for that block.
// Used to determine if we can add branch-over edges by checking the
// pre-conditions of the successor block.
hphp_hash_map<RegionDesc::BlockId, TypedLocations> blockPostConds;
auto numBCInstrs = ctx.maxBCInstrs;
FTRACE(1, "selectHotTrace: starting with maxBCInstrs = {}\n", numBCInstrs);
while (!selectedSet.count(tid)) {
auto rec = ctx.profData->transRec(tid);
auto blockRegion = rec->region();
if (blockRegion == nullptr) break;
// Break if region would be larger than the specified limit.
if (blockRegion->instrSize() > numBCInstrs) {
FTRACE(2, "selectHotTrace: breaking region at Translation {} because "
"size would exceed of maximum translation limit\n", tid);
break;
}
// If the debugger is attached, only allow single-block regions.
if (prevId != kInvalidTransID && isDebuggerAttachedProcess()) {
FTRACE(2, "selectHotTrace: breaking region at Translation {} "
"because of debugger is attached\n", tid);
break;
}
// Break if block is not the first and it corresponds to the main
// function body entry. This is to prevent creating multiple
// large regions containing the function body (starting at various
// DV funclets).
if (prevId != kInvalidTransID) {
auto const func = rec->func();
auto const bcOffset = rec->startBcOff();
if (func->base() == bcOffset) {
FTRACE(2, "selectHotTrace: breaking region because reached the main "
"function body entry at Translation {} (BC offset {})\n",
tid, bcOffset);
break;
}
}
if (prevId != kInvalidTransID) {
auto sk = rec->srcKey();
if (ctx.profData->optimized(sk)) {
FTRACE(2, "selectHotTrace: breaking region because next sk already "
"optimized, for Translation {}\n", tid);
break;
}
}
bool hasPredBlock = !region->empty();
RegionDesc::BlockId predBlockId = (hasPredBlock ?
region->blocks().back().get()->id() : 0);
auto const& newFirstBlock = blockRegion->entry();
auto newFirstBlockId = newFirstBlock->id();
// Add blockRegion's blocks and arcs to region.
region->append(*blockRegion);
numBCInstrs -= blockRegion->instrSize();
assertx(numBCInstrs >= 0);
if (hasPredBlock) {
region->addArc(predBlockId, newFirstBlockId);
}
selectedSet.insert(tid);
if (selectedVec) selectedVec->push_back(tid);
const auto lastSk = rec->lastSrcKey();
if (breaksRegion(lastSk)) {
FTRACE(2, "selectHotTrace: breaking region because of last instruction "
"in Translation {}: {}\n", tid, opcodeToName(lastSk.op()));
break;
}
auto outArcs = ctx.cfg->outArcs(tid);
if (outArcs.size() == 0) {
FTRACE(2, "selectHotTrace: breaking region because there's no successor "
"for Translation {}\n", tid);
break;
}
auto newLastBlock = blockRegion->blocks().back();
discardPoppedTypes(accumPostConds,
blockRegion->entry()->initialSpOffset());
mergePostConds(accumPostConds, newLastBlock->postConds());
blockPostConds[newLastBlock->id()] = accumPostConds;
TransCFG::ArcPtrVec possibleOutArcs;
for (auto arc : outArcs) {
auto dstRec = ctx.profData->transRec(arc->dst());
auto possibleNext = dstRec->region()->entry();
if (preCondsAreSatisfied(possibleNext, accumPostConds)) {
possibleOutArcs.emplace_back(arc);
}
}
if (possibleOutArcs.size() == 0) {
FTRACE(2, "selectHotTrace: breaking region because postcondition check "
"pruned all successors of Translation {}\n", tid);
break;
}
auto maxWeight = std::numeric_limits<int64_t>::min();
TransCFG::Arc* maxArc = nullptr;
for (auto arc : possibleOutArcs) {
if (arc->weight() >= maxWeight) {
maxWeight = arc->weight();
maxArc = arc;
}
}
assertx(maxArc != nullptr);
prevId = tid;
tid = maxArc->dst();
}
FTRACE(3, "selectHotTrace: before chainRetransBlocks:\n{}\n", show(*region));
region->chainRetransBlocks();
FTRACE(3, "selectHotTrace: after chainRetransBlocks:\n{}\n", show(*region));
return region;
}
bool RegionFormer::tryInline(uint32_t& instrSize) {
assertx(m_inst.source == m_sk);
assertx(m_inst.func() == curFunc());
assertx(m_sk.resumed() == resumed());
instrSize = 0;
if (!m_inl.canInlineAt(m_inst.source, m_inst.funcd, *m_region)) {
return false;
}
auto refuse = [this](const std::string& str) {
FTRACE(2, "selectTracelet not inlining {}: {}\n",
m_inst.toString(), str);
return false;
};
auto callee = m_inst.funcd;
// Make sure the FPushOp wasn't interpreted.
if (m_irgs.fpiStack.empty()) {
return refuse("fpistack empty; fpush was in a different region");
}
auto spillFrame = m_irgs.fpiStack.top().spillFrame;
if (!spillFrame) {
return refuse("couldn't find SpillFrame for FPushOp");
}
auto numArgs = m_inst.imm[0].u_IVA;
auto numParams = callee->numParams();
// Set up the region context, mapping stack slots in the caller to locals in
// the callee.
RegionContext ctx;
ctx.func = callee;
ctx.bcOffset = callee->getEntryForNumArgs(numArgs);
ctx.spOffset = FPInvOffset{safe_cast<int32_t>(callee->numSlotsInFrame())};
ctx.resumed = false;
for (int i = 0; i < numArgs; ++i) {
auto type = irgen::publicTopType(m_irgs, BCSPOffset{i});
uint32_t paramIdx = numArgs - 1 - i;
ctx.liveTypes.push_back({RegionDesc::Location::Local{paramIdx}, type});
}
for (unsigned i = numArgs; i < numParams; ++i) {
// These locals will be populated by DV init funclets but they'll start
// out as Uninit.
ctx.liveTypes.push_back({RegionDesc::Location::Local{i}, TUninit});
}
FTRACE(1, "selectTracelet analyzing callee {} with context:\n{}",
callee->fullName()->data(), show(ctx));
auto region = selectTracelet(ctx, m_profiling, false /* noinline */);
if (!region) {
return refuse("failed to select region in callee");
}
instrSize = region->instrSize();
auto newInstrSize = instrSize + m_numBCInstrs + m_pendingInlinedInstrs;
if (newInstrSize > RuntimeOption::EvalJitMaxRegionInstrs) {
return refuse("new region would be too large");
}
if (!m_inl.shouldInline(callee, *region)) {
return refuse("shouldIRInline failed");
}
return true;
}
