/** Read memory.
*
* If multi-path is enabled, then return a new memory expression that describes the process of reading a value from the
* specified address; otherwise, actually read the value and return it. In any case, record some information about the
* address that's being read if we've never seen it before. */
BaseSemantics::SValuePtr
RiscOperators::readMemory(RegisterDescriptor segreg, const BaseSemantics::SValuePtr &addr,
const BaseSemantics::SValuePtr &dflt_, const BaseSemantics::SValuePtr &cond) {
BaseSemantics::SValuePtr dflt = dflt_;
const size_t nBytes = dflt->get_width() / 8;
if (cond->is_number() && !cond->get_number())
return dflt_;
// If we know the address and that memory exists, then read the memory to obtain the default value.
uint8_t buf[8];
if (addr->is_number() && nBytes < sizeof(buf) &&
nBytes == partitioner_->memoryMap()->at(addr->get_number()).limit(nBytes).read(buf).size()) {
// FIXME[Robb P. Matzke 2015-05-25]: assuming little endian
uint64_t value = 0;
for (size_t i=0; i<nBytes; ++i)
value |= (uint64_t)buf[i] << (8*i);
dflt = number_(dflt->get_width(), value);
}
// Read from the symbolic state, and update the state with the default from real memory if known.
BaseSemantics::SValuePtr retval = Super::readMemory(segreg, addr, dflt, cond);
if (!currentInstruction())
return retval; // not called from dispatcher on behalf of an instruction
// Save a description of the variable
SymbolicExpr::Ptr valExpr = SValue::promote(retval)->get_expression();
if (valExpr->isLeafNode() && valExpr->isLeafNode()->isVariable()) {
std::string comment = commentForVariable(addr, "read");
State::promote(currentState())->varComment(valExpr->isLeafNode()->toString(), comment);
}
// Save a description for its addresses
for (size_t i=0; i<nBytes; ++i) {
SValuePtr va = SValue::promote(add(addr, number_(addr->get_width(), i)));
if (va->get_expression()->isLeafNode()) {
std::string comment = commentForVariable(addr, "read", i, nBytes);
State::promote(currentState())->varComment(va->get_expression()->isLeafNode()->toString(), comment);
}
}
return retval;
}
BaseSemantics::SValuePtr
RiscOperators::readRegister(RegisterDescriptor reg, const BaseSemantics::SValuePtr &dflt) {
SValuePtr retval = SValue::promote(Super::readRegister(reg, dflt));
SymbolicExpr::Ptr expr = retval->get_expression();
if (expr->isLeafNode()) {
std::string comment = commentForVariable(reg, "read");
State::promote(currentState())->varComment(expr->isLeafNode()->toString(), comment);
}
return retval;
}
/** Write value to memory.
*
* If multi-path is enabled, then return a new memory expression that updates memory with a new address/value pair;
* otherwise update the memory directly. In any case, record some information about the address that was written if we've
* never seen it before. */
void
RiscOperators::writeMemory(RegisterDescriptor segreg, const BaseSemantics::SValuePtr &addr,
const BaseSemantics::SValuePtr &value, const BaseSemantics::SValuePtr &cond) {
if (cond->is_number() && !cond->get_number())
return;
Super::writeMemory(segreg, addr, value, cond);
// Save a description of the variable
SymbolicExpr::Ptr valExpr = SValue::promote(value)->get_expression();
if (valExpr->isLeafNode() && valExpr->isLeafNode()->isVariable()) {
std::string comment = commentForVariable(addr, "write");
State::promote(currentState())->varComment(valExpr->isLeafNode()->toString(), comment);
}
// Save a description for its addresses
size_t nBytes = value->get_width() / 8;
for (size_t i=0; i<nBytes; ++i) {
SValuePtr va = SValue::promote(add(addr, number_(addr->get_width(), i)));
if (va->get_expression()->isLeafNode()) {
std::string comment = commentForVariable(addr, "read", i, nBytes);
State::promote(currentState())->varComment(va->get_expression()->isLeafNode()->toString(), comment);
}
}
}