OffsetSet instrSuccOffsets(PC opc, const Unit* unit) {
OffsetSet succBcOffs;
auto const bcStart = unit->entry();
auto const op = peek_op(opc);
if (!instrIsControlFlow(op)) {
Offset succOff = opc + instrLen(opc) - bcStart;
succBcOffs.insert(succOff);
return succBcOffs;
}
if (instrAllowsFallThru(op)) {
Offset succOff = opc + instrLen(opc) - bcStart;
succBcOffs.insert(succOff);
}
if (isSwitch(op)) {
foreachSwitchTarget(opc, [&](Offset offset) {
succBcOffs.insert(offset + opc - bcStart);
});
} else {
Offset target = instrJumpTarget(bcStart, opc - bcStart);
if (target != InvalidAbsoluteOffset) {
succBcOffs.insert(target);
}
}
return succBcOffs;
}
OffsetSet instrSuccOffsets(Op* opc, const Unit* unit) {
OffsetSet succBcOffs;
Op* bcStart = (Op*)(unit->entry());
if (!instrIsControlFlow(*opc)) {
Offset succOff = opc + instrLen(opc) - bcStart;
succBcOffs.insert(succOff);
return succBcOffs;
}
if (instrAllowsFallThru(*opc)) {
Offset succOff = opc + instrLen(opc) - bcStart;
succBcOffs.insert(succOff);
}
if (isSwitch(*opc)) {
foreachSwitchTarget(opc, [&](Offset& offset) {
succBcOffs.insert(offset + opc - bcStart);
});
} else {
Offset target = instrJumpTarget(bcStart, opc - bcStart);
if (target != InvalidAbsoluteOffset) {
succBcOffs.insert(target);
}
}
return succBcOffs;
}
/**
* Create blocks for each entry point as well as ordinary control
* flow boundaries. Calls are not treated as basic-block ends.
*/
void GraphBuilder::createBlocks() {
PC bc = m_unit->entry();
m_graph->param_count = m_func->params().size();
m_graph->first_linear = createBlock(m_func->base());
// DV entry points
m_graph->entries = new (m_arena) Block*[m_graph->param_count + 1];
int dv_index = 0;
for (Range<Func::ParamInfoVec> p(m_func->params()); !p.empty(); ) {
const Func::ParamInfo& param = p.popFront();
m_graph->entries[dv_index++] = !param.hasDefaultValue() ? 0 :
createBlock(param.funcletOff());
}
// main entry point
assert(dv_index == m_graph->param_count);
m_graph->entries[dv_index] = createBlock(m_func->base());
// ordinary basic block boundaries
for (InstrRange i = funcInstrs(m_func); !i.empty(); ) {
PC pc = i.popFront();
if (isCF(pc) && !i.empty()) createBlock(i.front());
if (isSwitch(*reinterpret_cast<const Op*>(pc))) {
foreachSwitchTarget(reinterpret_cast<const Op*>(pc), [&](Offset& o) {
createBlock(pc + o);
});
} else {
Offset target = instrJumpTarget((Op*)bc, pc - bc);
if (target != InvalidAbsoluteOffset) createBlock(target);
}
}
}
/**
* Create blocks for each entry point as well as ordinary control
* flow boundaries. Calls are not treated as basic-block ends.
*/
void GraphBuilder::createBlocks() {
PC bc = m_unit->entry();
m_graph->param_count = m_func->params().size();
m_graph->first_linear = createBlock(m_func->base());
// DV entry points
m_graph->entries = new (m_arena) Block*[m_graph->param_count + 1];
int dv_index = 0;
for (auto& param : m_func->params()) {
m_graph->entries[dv_index++] = !param.hasDefaultValue() ? 0 :
createBlock(param.funcletOff);
}
// main entry point
assert(dv_index == m_graph->param_count);
m_graph->entries[dv_index] = createBlock(m_func->base());
// ordinary basic block boundaries
for (InstrRange i = funcInstrs(m_func); !i.empty(); ) {
PC pc = i.popFront();
if ((isCF(pc) || isTF(pc)) && !i.empty()) createBlock(i.front());
if (isSwitch(peek_op(pc))) {
foreachSwitchTarget(pc, [&](Offset o) { createBlock(pc + o); });
} else {
Offset target = instrJumpTarget(bc, pc - bc);
if (target != InvalidAbsoluteOffset) createBlock(target);
}
}
}
// Place internal breakpoints to get out of the current function. This may place
// multiple internal breakpoints, and it may place them more than one frame up.
// Some instructions can cause PHP to be invoked without an explicit call. A set
// which causes a destructor to run, a iteration init which causes an object's
// next() method to run, a RetC which causes destructors to run, etc. This
// recgonizes such cases and ensures we have internal breakpoints to cover the
// destination(s) of such instructions.
void CmdFlowControl::setupStepOuts() {
// Existing step outs should be cleaned up before making new ones.
assert(!hasStepOuts());
auto fp = g_context->getFP();
if (!fp) return; // No place to step out to!
Offset returnOffset;
bool fromVMEntry;
while (!hasStepOuts()) {
fp = g_context->getPrevVMState(fp, &returnOffset, nullptr, &fromVMEntry);
// If we've run off the top of the stack, just return having setup no
// step outs. This will cause cmds like Next and Out to just let the program
// run, which is appropriate.
if (!fp) break;
Unit* returnUnit = fp->m_func->unit();
PC returnPC = returnUnit->at(returnOffset);
TRACE(2, "CmdFlowControl::setupStepOuts: at '%s' offset %d opcode %s\n",
fp->m_func->fullName()->data(), returnOffset,
opcodeToName(*reinterpret_cast<const Op*>(returnPC)));
// Don't step out to generated functions, keep looking.
if (fp->m_func->line1() == 0) continue;
if (fromVMEntry) {
TRACE(2, "CmdFlowControl::setupStepOuts: VM entry\n");
// We only execute this for opcodes which invoke more PHP, and that does
// not include switches. Thus, we'll have at most two destinations.
assert(!isSwitch(*reinterpret_cast<const Op*>(returnPC)) &&
(numSuccs(reinterpret_cast<const Op*>(returnPC)) <= 2));
// Set an internal breakpoint after the instruction if it can fall thru.
if (instrAllowsFallThru(*reinterpret_cast<const Op*>(returnPC))) {
Offset nextOffset = returnOffset + instrLen((Op*)returnPC);
TRACE(2, "CmdFlowControl: step out to '%s' offset %d (fall-thru)\n",
fp->m_func->fullName()->data(), nextOffset);
m_stepOut1 = StepDestination(returnUnit, nextOffset);
}
// Set an internal breakpoint at the target of a control flow instruction.
// A good example of a control flow op that invokes PHP is IterNext.
if (instrIsControlFlow(*reinterpret_cast<const Op*>(returnPC))) {
Offset target =
instrJumpTarget(reinterpret_cast<const Op*>(returnPC), 0);
if (target != InvalidAbsoluteOffset) {
Offset targetOffset = returnOffset + target;
TRACE(2, "CmdFlowControl: step out to '%s' offset %d (jump target)\n",
fp->m_func->fullName()->data(), targetOffset);
m_stepOut2 = StepDestination(returnUnit, targetOffset);
}
}
// If we have no place to step out to, then unwind another frame and try
// again. The most common case that leads here is Ret*, which does not
// fall-thru and has no encoded target.
} else {
TRACE(2, "CmdFlowControl: step out to '%s' offset %d\n",
fp->m_func->fullName()->data(), returnOffset);
m_stepOut1 = StepDestination(returnUnit, returnOffset);
}
}
}
/**
* Link ordinary blocks with ordinary edges and set their last instruction
* and end offsets
*/
void GraphBuilder::linkBlocks() {
PC bc = m_unit->entry();
Block* block = m_graph->first_linear;
block->id = m_graph->block_count++;
for (InstrRange i = funcInstrs(m_func); !i.empty(); ) {
PC pc = i.popFront();
block->last = pc;
if (isCF(pc)) {
if (isSwitch(*reinterpret_cast<const Op*>(pc))) {
int i = 0;
foreachSwitchTarget((Op*)pc, [&](Offset& o) {
succs(block)[i++] = at(pc + o);
});
} else {
Offset target = instrJumpTarget((Op*)bc, pc - bc);
if (target != InvalidAbsoluteOffset) {
assert(numSuccBlocks(block) > 0);
succs(block)[numSuccBlocks(block) - 1] = at(target);
}
}
}
PC next_pc = !i.empty() ? i.front() : m_unit->at(m_func->past());
Block* next = at(next_pc);
if (next) {
block->next_linear = next;
block->end = next_pc;
if (!isTF(pc)) {
assert(numSuccBlocks(block) > 0);
succs(block)[0] = next;
}
block = next;
block->id = m_graph->block_count++;
}
}
block->end = m_unit->at(m_func->past());
}
FuncInfo find_func_info(const Func* func) {
auto finfo = FuncInfo(func->unit(), func);
auto label_num = uint32_t{0};
auto gen_label = [&] (const char* kind) {
return folly::format("{}{}", kind, label_num++).str();
};
auto add_target = [&] (const char* kind, Offset off) -> std::string {
auto it = finfo.labels.find(off);
if (it != end(finfo.labels)) return it->second;
auto const label = gen_label(kind);
finfo.labels[off] = label;
return label;
};
auto find_jump_targets = [&] {
auto it = func->unit()->at(func->base());
auto const stop = func->unit()->at(func->past());
auto const bcBase = reinterpret_cast<const Op*>(func->unit()->at(0));
for (; it != stop; it += instrLen(reinterpret_cast<const Op*>(it))) {
auto const pop = reinterpret_cast<const Op*>(it);
auto const off = func->unit()->offsetOf(pop);
if (isSwitch(*pop)) {
foreachSwitchTarget(pop, [&] (Offset off) {
add_target("L", pop - bcBase + off);
});
continue;
}
auto const target = instrJumpTarget(bcBase, off);
if (target != InvalidAbsoluteOffset) {
add_target("L", target);
continue;
}
}
};
auto find_eh_entries = [&] {
for (auto& eh : func->ehtab()) {
finfo.ehInfo[&eh] = [&]() -> EHInfo {
switch (eh.m_type) {
case EHEnt::Type::Catch:
{
auto catches = EHCatch {};
for (auto& kv : eh.m_catches) {
auto const clsName = func->unit()->lookupLitstrId(kv.first);
catches.blocks[clsName->data()] = add_target("C", kv.second);
}
return catches;
}
case EHEnt::Type::Fault:
return EHFault { add_target("F", eh.m_fault) };
}
not_reached();
}();
finfo.ehStarts.emplace_back(eh.m_base, &eh);
}
};
auto find_dv_entries = [&] {
for (auto i = uint32_t{0}; i < func->numParams(); ++i) {
auto& param = func->params()[i];
if (param.hasDefaultValue()) {
add_target("DV", func->params()[i].funcletOff());
}
}
};
find_jump_targets();
find_eh_entries();
find_dv_entries();
return finfo;
}
