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;
}
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;
}
void endRegion(IRGS& env) {
auto const curSk = curSrcKey(env);
if (!instrAllowsFallThru(curSk.op())) return; // nothing to do here
auto const nextSk = curSk.advanced(curUnit(env));
endRegion(env, nextSk);
}
// 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);
}
}
}
