/// LHS expression extractor.
/// @param e expression
/// @param pos position of operator term to be extracted from
static Expr
ExtractLHS(Expr& e, int pos)
{
Expr retval;
ExprTerms& terms = e.getTerms();
if (terms.empty())
return retval;
if (pos < 0)
pos += terms.size();
assert(pos >= 0 && pos < static_cast<int>(terms.size()));
if (pos == 0)
return retval;
ExprTerms& rvterms = retval.getTerms();
// Delete the operator
int parent_depth = terms[pos].m_depth;
terms[pos].Clear();
// Bring up the RHS terms
int n = --pos;
for (; n >= 0; --n)
{
ExprTerm& child = terms[n];
if (child.isEmpty())
continue;
if (child.m_depth <= parent_depth)
break;
if (n != pos && child.m_depth == parent_depth+1)
break; // stop when we've reached the second (LHS) child
child.m_depth--;
}
// Extract the LHS terms.
for (; n >= 0; --n)
{
ExprTerm& child = terms[n];
if (child.isEmpty())
continue;
if (child.m_depth <= parent_depth)
break;
// Fix up depth for new expression.
child.m_depth -= parent_depth+1;
// Add a NONE term to retval, then swap it with the child.
rvterms.push_back(ExprTerm());
std::swap(rvterms.back(), child);
}
// We added in reverse order, so fix up.
std::reverse(rvterms.begin(), rvterms.end());
// Clean up NONE terms.
e.Cleanup();
return retval;
}
bool
yasm::isNeg1Sym(Expr& e,
/*@out@*/ int* sym,
/*@out@*/ int* neg1,
int* pos,
bool loc_ok)
{
ExprTerms& terms = e.getTerms();
if (terms.empty())
return false;
if (*pos < 0)
*pos += terms.size();
assert(*pos >= 0 && *pos < static_cast<int>(terms.size()));
ExprTerm& root = terms[*pos];
if (!root.isOp(Op::MUL) || root.getNumChild() != 2)
return false;
bool have_neg1 = false, have_sym = false;
int n;
for (n = *pos-1; n >= 0; --n)
{
ExprTerm& child = terms[n];
if (child.isEmpty())
continue;
if (child.m_depth <= root.m_depth)
break;
if (child.m_depth != root.m_depth+1)
return false; // more than one level
if (IntNum* intn = child.getIntNum())
{
if (!intn->isNeg1())
return false;
*neg1 = n;
have_neg1 = true;
}
else if (child.isType(ExprTerm::SYM) ||
(loc_ok && child.isType(ExprTerm::LOC)))
{
*sym = n;
have_sym = true;
}
else
return false; // something else
}
if (have_neg1 && have_sym)
{
*pos = n;
return true;
}
return false;
}
bool
yasm::getChildren(Expr& e, /*@out@*/ int* lhs, /*@out@*/ int* rhs, int* pos)
{
ExprTerms& terms = e.getTerms();
if (*pos < 0)
*pos += terms.size();
ExprTerm& root = terms[*pos];
if (!root.isOp())
return false;
*rhs = -1;
if (lhs)
{
if (root.getNumChild() != 2)
return false;
*lhs = -1;
}
else if (root.getNumChild() != 1)
return false;
int n;
for (n = *pos-1; n >= 0; --n)
{
ExprTerm& child = terms[n];
if (child.isEmpty())
continue;
if (child.m_depth <= root.m_depth)
break;
if (child.m_depth != root.m_depth+1)
continue; // not an immediate child
if (*rhs < 0)
*rhs = n;
else if (lhs && *lhs < 0)
*lhs = n;
else
return false; // too many children
}
*pos = n;
if (*rhs >= 0 && (!lhs || *lhs >= 0))
return true;
return false; // too few children
}
static int
TransformNegImpl(Expr& e,
int pos,
int stop_depth,
int depth_delta,
bool negating)
{
ExprTerms& terms = e.getTerms();
int n = pos;
for (; n >= 0; --n)
{
ExprTerm* child = &terms[n];
if (child->isEmpty())
continue;
// Update depth as required
child->m_depth += depth_delta;
int child_depth = child->m_depth;
switch (child->getOp())
{
case Op::NEG:
{
int new_depth = child->m_depth;
child->Clear();
// Invert current negation state and bring up children
n = TransformNegImpl(e, n-1, new_depth, depth_delta - 1,
!negating);
break;
}
case Op::SUB:
{
child->setOp(Op::ADD);
int new_depth = child->m_depth+1;
if (negating)
{
// -(a-b) ==> -a+b, so don't negate right side,
// but do negate left side.
n = TransformNegImpl(e, n-1, new_depth, depth_delta, false);
n = TransformNegImpl(e, n-1, new_depth, depth_delta, true);
}
else
{
// a-b ==> a+(-1*b), so negate right side only.
n = TransformNegImpl(e, n-1, new_depth, depth_delta, true);
n = TransformNegImpl(e, n-1, new_depth, depth_delta, false);
}
break;
}
case Op::ADD:
{
if (!negating)
break;
// Negate all children
int new_depth = child->m_depth+1;
for (int x = 0, nchild = child->getNumChild(); x < nchild; ++x)
n = TransformNegImpl(e, n-1, new_depth, depth_delta, true);
break;
}
case Op::MUL:
{
if (!negating)
break;
// Insert -1 term. Do this by inserting a new MUL op
// and changing this term to -1, to avoid having to
// deal with updating n.
terms.insert(terms.begin()+n+1,
ExprTerm(child->getOp(),
child->getNumChild()+1,
child->getSource(),
child->m_depth));
child = &terms[n]; // need to re-get as terms may move
*child = ExprTerm(-1, child->getSource(), child->m_depth+1);
break;
}
default:
{
if (!negating)
break;
// Directly negate if possible (integers or floats)
if (IntNum* intn = child->getIntNum())
{
intn->CalcAssert(Op::NEG);
break;
}
if (APFloat* fltn = child->getFloat())
{
fltn->changeSign();
break;
}
// Couldn't replace directly; instead replace with -1*e
// Insert -1 one level down, add operator at this level,
// and move all subterms one level down.
terms.insert(terms.begin()+n+1, 2,
ExprTerm(Op::MUL, 2, child->getSource(),
child->m_depth));
child = &terms[n]; // need to re-get as terms may move
terms[n+1] = ExprTerm(-1, child->getSource(), child->m_depth+1);
child->m_depth++;
int new_depth = child->m_depth+1;
for (int x = 0, nchild = child->getNumChild(); x < nchild; ++x)
n = TransformNegImpl(e, n-1, new_depth, depth_delta+1,
false);
}
}
if (child_depth <= stop_depth)
break;
}
return n;
}
static void
Infix(raw_ostream& os, const Expr& e, int base, int pos=-1)
{
const char* opstr = "";
const ExprTerms& terms = e.getTerms();
if (terms.empty())
return;
if (pos < 0)
pos += terms.size();
assert(pos >= 0 && pos < static_cast<int>(terms.size()));
while (pos >= 0 && terms[pos].isEmpty())
--pos;
if (pos == -1)
return;
if (!terms[pos].isOp())
{
terms[pos].Print(os, base);
return;
}
Op::Op op = terms[pos].getOp();
switch (op)
{
case Op::ADD: opstr = "+"; break;
case Op::SUB: opstr = "-"; break;
case Op::MUL: opstr = "*"; break;
case Op::DIV: opstr = "/"; break;
case Op::SIGNDIV: opstr = "//"; break;
case Op::MOD: opstr = "%"; break;
case Op::SIGNMOD: opstr = "%%"; break;
case Op::NEG: os << "-"; break;
case Op::NOT: os << "~"; break;
case Op::OR: opstr = "|"; break;
case Op::AND: opstr = "&"; break;
case Op::XOR: opstr = "^"; break;
case Op::XNOR: opstr = "XNOR"; break;
case Op::NOR: opstr = "NOR"; break;
case Op::SHL: opstr = "<<"; break;
case Op::SHR: opstr = ">>"; break;
case Op::LOR: opstr = "||"; break;
case Op::LAND: opstr = "&&"; break;
case Op::LNOT: opstr = "!"; break;
case Op::LXOR: opstr = "^^"; break;
case Op::LXNOR: opstr = "LXNOR"; break;
case Op::LNOR: opstr = "LNOR"; break;
case Op::LT: opstr = "<"; break;
case Op::GT: opstr = ">"; break;
case Op::LE: opstr = "<="; break;
case Op::GE: opstr = ">="; break;
case Op::NE: opstr = "!="; break;
case Op::EQ: opstr = "=="; break;
case Op::SEG: os << "SEG "; break;
case Op::WRT: opstr = " WRT "; break;
case Op::SEGOFF: opstr = ":"; break;
case Op::IDENT: break;
case Op::NONNUM: return;
default: opstr = " !UNK! "; break;
}
typedef SmallVector<int, 32> CVector;
CVector children;
const ExprTerm& root = terms[pos];
--pos;
for (; pos >= 0; --pos)
{
const ExprTerm& child = terms[pos];
if (child.isEmpty())
continue;
if (child.m_depth <= root.m_depth)
break;
if (child.m_depth != root.m_depth+1)
continue;
children.push_back(pos);
}
for (CVector::const_reverse_iterator i=children.rbegin(),
end=children.rend(); i != end; ++i)
{
if (i != CVector::const_reverse_iterator(children.rbegin()))
{
os << opstr;
// Force RHS of shift operations to decimal
if (op == Op::SHL || op == Op::SHR)
base = 10;
}
if (terms[*i].isOp())
{
os << '(';
Infix(os, e, base, *i);
os << ')';
}
else
terms[*i].Print(os, base);
}
}
// Transforms instances of Symbol-Symbol [Symbol+(-1*Symbol)] into single
// ExprTerms if possible. Uses a simple n^2 algorithm because n is usually
// quite small. Also works for loc-loc (or Symbol-loc, loc-Symbol).
static void
TransformDistBase(Expr& e, int pos,
const TR1::function<bool (ExprTerm& term,
Location loc1,
Location loc2)> func)
{
ExprTerms& terms = e.getTerms();
if (pos < 0)
pos += static_cast<int>(terms.size());
ExprTerm& root = terms[pos];
if (!root.isOp(Op::ADD))
return;
// Handle symrec-symrec by checking for (-1*symrec)
// and symrec term pairs (where both symrecs are in the same
// segment).
llvm::SmallVector<int, 3> relpos, subpos, subneg1, subroot;
// Scan for symrec and (-1*symrec) terms (or location equivalents)
int n = pos-1;
while (n >= 0)
{
ExprTerm& child = terms[n];
if (child.isEmpty())
{
--n;
continue;
}
if (child.m_depth <= root.m_depth)
break;
if (child.m_depth != root.m_depth+1)
{
--n;
continue;
}
// Remember symrec terms
if (child.isType(ExprTerm::SYM | ExprTerm::LOC))
{
relpos.push_back(pos-n);
--n;
continue;
}
int curpos = n;
int sym, neg1;
// Remember (-1*symrec) terms
if (isNeg1Sym(e, &sym, &neg1, &n, true))
{
subpos.push_back(pos-sym);
subneg1.push_back(pos-neg1);
subroot.push_back(pos-curpos);
continue;
}
--n;
}
// Match additive and subtractive symbols.
for (size_t i=0; i<relpos.size(); ++i)
{
ExprTerm& relterm = terms[pos-relpos[i]];
SymbolRef rel = relterm.getSymbol();
for (size_t j=0; j<subpos.size(); ++j)
{
if (subpos[j] == 0xff)
continue; // previously matched
ExprTerm& subterm = terms[pos-subpos[j]];
SymbolRef sub = subterm.getSymbol();
// If it's the same symbol, even if it's external,
// they should cancel out.
if (rel && rel == sub)
{
relterm.Zero();
terms[pos-subpos[j]].Clear();
terms[pos-subneg1[j]].Clear();
terms[pos-subroot[j]].Zero();
subpos[j] = 0xff; // mark as matched
break;
}
Location rel_loc;
if (rel)
{
if (!rel->getLabel(&rel_loc))
continue; // external
}
else if (const Location* loc = relterm.getLocation())
rel_loc = *loc;
else
assert(false);
Location sub_loc;
if (sub)
{
if (!sub->getLabel(&sub_loc))
continue; // external
}
else if (const Location* loc = subterm.getLocation())
sub_loc = *loc;
else
assert(false);
// If both are in the same segment, we leave them in the
// expression but consider them to "match".
if (rel_loc.bc->getContainer() !=
sub_loc.bc->getContainer())
continue;
if (func(relterm, sub_loc, rel_loc))
{
// Set the matching (-1*Symbol) term to 0
// (will remove from expression during simplify)
terms[pos-subpos[j]].Clear();
terms[pos-subneg1[j]].Clear();
terms[pos-subroot[j]].Zero();
subpos[j] = 0xff; // mark as matched
break; // stop looking
}
}
}
}
bool
yasm::Evaluate(const Expr& e,
Diagnostic& diags,
ExprTerm* result,
const ExprTerm* subst,
unsigned int nsubst,
bool valueloc,
bool zeroreg)
{
if (e.isEmpty())
return false;
const ExprTerms& terms = e.getTerms();
// Shortcut the most common case: a single integer or float
if (terms.size() == 1
&& terms.front().isType(ExprTerm::INT|ExprTerm::FLOAT))
{
*result = terms.front();
return true;
}
llvm::SmallVector<ExprTerm, 8> stack;
for (ExprTerms::const_iterator i=terms.begin(), end=terms.end();
i != end; ++i)
{
const ExprTerm& term = *i;
if (term.isOp())
{
size_t nchild = term.getNumChild();
assert(stack.size() >= nchild && "not enough terms to evaluate op");
Op::Op op = term.getOp();
SourceLocation op_source = term.getSource();
// Get first child (will be used as result)
size_t resultindex = stack.size()-nchild;
ExprTerm& result = stack[resultindex];
// For SEG:OFF, throw away the SEG and keep the OFF.
if (op == Op::SEGOFF)
{
assert(nchild == 2 && "SEGOFF without 2 terms");
stack[resultindex].swap(stack[resultindex+1]);
stack.pop_back();
continue;
}
// Don't allow any other non-numeric operators (e.g. WRT).
if (op >= Op::NONNUM)
return false;
// Calculate through other children
for (size_t j = resultindex+1; j<stack.size(); ++j)
{
ExprTerm& child = stack[j];
// Promote to float as needed
if (result.isType(ExprTerm::FLOAT))
child.PromoteToFloat(result.getFloat()->getSemantics());
else if (child.isType(ExprTerm::FLOAT))
result.PromoteToFloat(child.getFloat()->getSemantics());
// Perform calculation
if (result.isType(ExprTerm::INT))
result.getIntNum()->Calc(op, *child.getIntNum(), op_source,
diags);
else if (op < Op::NEG)
CalcFloat(result.getFloat(), op, *child.getFloat(),
op_source, diags);
else
return false;
}
// Handle unary op
if (nchild == 1)
{
assert(isUnary(op) && "single-term subexpression is non-unary");
if (result.isType(ExprTerm::INT))
result.getIntNum()->Calc(op, op_source, diags);
else if (op == Op::NEG)
result.getFloat()->changeSign();
else
return false;
}
// Pop other children off stack, leaving first child as result
result.m_depth = term.m_depth;
stack.erase(stack.begin()+resultindex+1, stack.end());
}
else if (!term.isEmpty())
{
// Convert term to int or float before pushing onto stack.
// If cannot convert, return false.
switch (term.getType())
{
case ExprTerm::REG:
if (!zeroreg)
return false;
stack.push_back(ExprTerm(0, term.getSource(),
term.m_depth));
break;
case ExprTerm::SUBST:
{
unsigned int substindex = *term.getSubst();
if (!subst || substindex >= nsubst)
return false;
assert((subst[substindex].getType() == ExprTerm::INT ||
subst[substindex].getType() == ExprTerm::FLOAT) &&
"substitution must be integer or float");
stack.push_back(subst[substindex]);
break;
}
case ExprTerm::INT:
case ExprTerm::FLOAT:
stack.push_back(term);
break;
case ExprTerm::SYM:
{
Location loc;
if (!valueloc || !term.getSymbol()->getLabel(&loc) ||
!loc.bc)
return false;
stack.push_back(ExprTerm(loc.getOffset(), term.getSource(),
term.m_depth));
break;
}
case ExprTerm::LOC:
{
Location loc = *term.getLocation();
if (!valueloc || !loc.bc)
return false;
stack.push_back(ExprTerm(loc.getOffset(), term.getSource(),
term.m_depth));
break;
}
default:
return false;
}
}
}
assert(stack.size() == 1 && "did not fully evaluate expression");
result->swap(stack.back());
return true;
}