void CFGGenerator::addStatement(CFG& cfg, std::unique_ptr<Statement>* s) {
switch ((*s)->fKind) {
case Statement::kBlock_Kind:
for (auto& child : ((Block&) **s).fStatements) {
addStatement(cfg, &child);
}
break;
case Statement::kIf_Kind: {
IfStatement& ifs = (IfStatement&) **s;
this->addExpression(cfg, &ifs.fTest, true);
cfg.fBlocks[cfg.fCurrent].fNodes.push_back({ BasicBlock::Node::kStatement_Kind, false,
nullptr, s });
BlockId start = cfg.fCurrent;
cfg.newBlock();
this->addStatement(cfg, &ifs.fIfTrue);
BlockId next = cfg.newBlock();
if (ifs.fIfFalse) {
cfg.fCurrent = start;
cfg.newBlock();
this->addStatement(cfg, &ifs.fIfFalse);
cfg.addExit(cfg.fCurrent, next);
cfg.fCurrent = next;
} else {
cfg.addExit(start, next);
}
break;
}
case Statement::kExpression_Kind: {
this->addExpression(cfg, &((ExpressionStatement&) **s).fExpression, true);
cfg.fBlocks[cfg.fCurrent].fNodes.push_back({ BasicBlock::Node::kStatement_Kind, false,
nullptr, s });
break;
}
case Statement::kVarDeclarations_Kind: {
VarDeclarationsStatement& decls = ((VarDeclarationsStatement&) **s);
for (auto& stmt : decls.fDeclaration->fVars) {
if (stmt->fKind == Statement::kNop_Kind) {
continue;
}
VarDeclaration& vd = (VarDeclaration&) *stmt;
if (vd.fValue) {
this->addExpression(cfg, &vd.fValue, true);
}
cfg.fBlocks[cfg.fCurrent].fNodes.push_back({ BasicBlock::Node::kStatement_Kind,
false, nullptr, &stmt });
}
cfg.fBlocks[cfg.fCurrent].fNodes.push_back({ BasicBlock::Node::kStatement_Kind, false,
nullptr, s });
break;
}
case Statement::kDiscard_Kind:
cfg.fBlocks[cfg.fCurrent].fNodes.push_back({ BasicBlock::Node::kStatement_Kind, false,
nullptr, s });
cfg.fCurrent = cfg.newIsolatedBlock();
break;
case Statement::kReturn_Kind: {
ReturnStatement& r = ((ReturnStatement&) **s);
if (r.fExpression) {
this->addExpression(cfg, &r.fExpression, true);
}
cfg.fBlocks[cfg.fCurrent].fNodes.push_back({ BasicBlock::Node::kStatement_Kind, false,
nullptr, s });
cfg.fCurrent = cfg.newIsolatedBlock();
break;
}
case Statement::kBreak_Kind:
cfg.fBlocks[cfg.fCurrent].fNodes.push_back({ BasicBlock::Node::kStatement_Kind, false,
nullptr, s });
cfg.addExit(cfg.fCurrent, fLoopExits.top());
cfg.fCurrent = cfg.newIsolatedBlock();
break;
case Statement::kContinue_Kind:
cfg.fBlocks[cfg.fCurrent].fNodes.push_back({ BasicBlock::Node::kStatement_Kind, false,
nullptr, s });
cfg.addExit(cfg.fCurrent, fLoopContinues.top());
cfg.fCurrent = cfg.newIsolatedBlock();
break;
case Statement::kWhile_Kind: {
WhileStatement& w = (WhileStatement&) **s;
BlockId loopStart = cfg.newBlock();
fLoopContinues.push(loopStart);
BlockId loopExit = cfg.newIsolatedBlock();
fLoopExits.push(loopExit);
this->addExpression(cfg, &w.fTest, true);
BlockId test = cfg.fCurrent;
cfg.addExit(test, loopExit);
cfg.newBlock();
this->addStatement(cfg, &w.fStatement);
cfg.addExit(cfg.fCurrent, loopStart);
fLoopContinues.pop();
fLoopExits.pop();
cfg.fCurrent = loopExit;
break;
}
case Statement::kDo_Kind: {
DoStatement& d = (DoStatement&) **s;
BlockId loopStart = cfg.newBlock();
fLoopContinues.push(loopStart);
BlockId loopExit = cfg.newIsolatedBlock();
fLoopExits.push(loopExit);
this->addStatement(cfg, &d.fStatement);
this->addExpression(cfg, &d.fTest, true);
cfg.addExit(cfg.fCurrent, loopExit);
cfg.addExit(cfg.fCurrent, loopStart);
fLoopContinues.pop();
fLoopExits.pop();
cfg.fCurrent = loopExit;
break;
}
case Statement::kFor_Kind: {
ForStatement& f = (ForStatement&) **s;
if (f.fInitializer) {
this->addStatement(cfg, &f.fInitializer);
}
BlockId loopStart = cfg.newBlock();
BlockId next = cfg.newIsolatedBlock();
fLoopContinues.push(next);
BlockId loopExit = cfg.newIsolatedBlock();
fLoopExits.push(loopExit);
if (f.fTest) {
this->addExpression(cfg, &f.fTest, true);
// this isn't quite right; we should have an exit from here to the loop exit, and
// remove the exit from the loop body to the loop exit. Structuring it like this
// forces the optimizer to believe that the loop body is always executed at least
// once. While not strictly correct, this avoids incorrect "variable not assigned"
// errors on variables which are assigned within the loop. The correct solution to
// this is to analyze the loop to see whether or not at least one iteration is
// guaranteed to happen, but for the time being we take the easy way out.
}
cfg.newBlock();
this->addStatement(cfg, &f.fStatement);
cfg.addExit(cfg.fCurrent, next);
cfg.fCurrent = next;
if (f.fNext) {
this->addExpression(cfg, &f.fNext, true);
}
cfg.addExit(cfg.fCurrent, loopStart);
cfg.addExit(cfg.fCurrent, loopExit);
fLoopContinues.pop();
fLoopExits.pop();
cfg.fCurrent = loopExit;
break;
}
case Statement::kSwitch_Kind: {
SwitchStatement& ss = (SwitchStatement&) **s;
this->addExpression(cfg, &ss.fValue, true);
cfg.fBlocks[cfg.fCurrent].fNodes.push_back({ BasicBlock::Node::kStatement_Kind, false,
nullptr, s });
BlockId start = cfg.fCurrent;
BlockId switchExit = cfg.newIsolatedBlock();
fLoopExits.push(switchExit);
for (const auto& c : ss.fCases) {
cfg.newBlock();
cfg.addExit(start, cfg.fCurrent);
if (c->fValue) {
// technically this should go in the start block, but it doesn't actually matter
// because it must be constant. Not worth running two loops for.
this->addExpression(cfg, &c->fValue, true);
}
for (auto& caseStatement : c->fStatements) {
this->addStatement(cfg, &caseStatement);
}
}
cfg.addExit(cfg.fCurrent, switchExit);
// note that unlike GLSL, our grammar requires the default case to be last
if (0 == ss.fCases.size() || ss.fCases[ss.fCases.size() - 1]->fValue) {
// switch does not have a default clause, mark that it can skip straight to the end
cfg.addExit(start, switchExit);
}
fLoopExits.pop();
cfg.fCurrent = switchExit;
break;
}
case Statement::kNop_Kind:
break;
default:
printf("statement: %s\n", (*s)->description().c_str());
ABORT("unsupported statement kind");
}
}
void CFGGenerator::addExpression(CFG& cfg, std::unique_ptr<Expression>* e, bool constantPropagate) {
ASSERT(e);
switch ((*e)->fKind) {
case Expression::kBinary_Kind: {
BinaryExpression* b = (BinaryExpression*) e->get();
switch (b->fOperator) {
case Token::LOGICALAND: // fall through
case Token::LOGICALOR: {
// this isn't as precise as it could be -- we don't bother to track that if we
// early exit from a logical and/or, we know which branch of an 'if' we're going
// to hit -- but it won't make much difference in practice.
this->addExpression(cfg, &b->fLeft, constantPropagate);
BlockId start = cfg.fCurrent;
cfg.newBlock();
this->addExpression(cfg, &b->fRight, constantPropagate);
cfg.newBlock();
cfg.addExit(start, cfg.fCurrent);
cfg.fBlocks[cfg.fCurrent].fNodes.push_back({
BasicBlock::Node::kExpression_Kind,
constantPropagate,
e,
nullptr
});
break;
}
case Token::EQ: {
this->addExpression(cfg, &b->fRight, constantPropagate);
this->addLValue(cfg, &b->fLeft);
cfg.fBlocks[cfg.fCurrent].fNodes.push_back({
BasicBlock::Node::kExpression_Kind,
constantPropagate,
e,
nullptr
});
break;
}
default:
this->addExpression(cfg, &b->fLeft, !Token::IsAssignment(b->fOperator));
this->addExpression(cfg, &b->fRight, constantPropagate);
cfg.fBlocks[cfg.fCurrent].fNodes.push_back({
BasicBlock::Node::kExpression_Kind,
constantPropagate,
e,
nullptr
});
}
break;
}
case Expression::kConstructor_Kind: {
Constructor* c = (Constructor*) e->get();
for (auto& arg : c->fArguments) {
this->addExpression(cfg, &arg, constantPropagate);
}
cfg.fBlocks[cfg.fCurrent].fNodes.push_back({ BasicBlock::Node::kExpression_Kind,
constantPropagate, e, nullptr });
break;
}
case Expression::kFunctionCall_Kind: {
FunctionCall* c = (FunctionCall*) e->get();
for (auto& arg : c->fArguments) {
this->addExpression(cfg, &arg, constantPropagate);
}
cfg.fBlocks[cfg.fCurrent].fNodes.push_back({ BasicBlock::Node::kExpression_Kind,
constantPropagate, e, nullptr });
break;
}
case Expression::kFieldAccess_Kind:
this->addExpression(cfg, &((FieldAccess*) e->get())->fBase, constantPropagate);
cfg.fBlocks[cfg.fCurrent].fNodes.push_back({ BasicBlock::Node::kExpression_Kind,
constantPropagate, e, nullptr });
break;
case Expression::kIndex_Kind:
this->addExpression(cfg, &((IndexExpression*) e->get())->fBase, constantPropagate);
this->addExpression(cfg, &((IndexExpression*) e->get())->fIndex, constantPropagate);
cfg.fBlocks[cfg.fCurrent].fNodes.push_back({ BasicBlock::Node::kExpression_Kind,
constantPropagate, e, nullptr });
break;
case Expression::kPrefix_Kind: {
PrefixExpression* p = (PrefixExpression*) e->get();
this->addExpression(cfg, &p->fOperand, constantPropagate &&
p->fOperator != Token::PLUSPLUS &&
p->fOperator != Token::MINUSMINUS);
cfg.fBlocks[cfg.fCurrent].fNodes.push_back({ BasicBlock::Node::kExpression_Kind,
constantPropagate, e, nullptr });
break;
}
case Expression::kPostfix_Kind:
this->addExpression(cfg, &((PostfixExpression*) e->get())->fOperand, false);
cfg.fBlocks[cfg.fCurrent].fNodes.push_back({ BasicBlock::Node::kExpression_Kind,
constantPropagate, e, nullptr });
break;
case Expression::kSwizzle_Kind:
this->addExpression(cfg, &((Swizzle*) e->get())->fBase, constantPropagate);
cfg.fBlocks[cfg.fCurrent].fNodes.push_back({ BasicBlock::Node::kExpression_Kind,
constantPropagate, e, nullptr });
break;
case Expression::kBoolLiteral_Kind: // fall through
case Expression::kFloatLiteral_Kind: // fall through
case Expression::kIntLiteral_Kind: // fall through
case Expression::kSetting_Kind: // fall through
case Expression::kVariableReference_Kind:
cfg.fBlocks[cfg.fCurrent].fNodes.push_back({ BasicBlock::Node::kExpression_Kind,
constantPropagate, e, nullptr });
break;
case Expression::kTernary_Kind: {
TernaryExpression* t = (TernaryExpression*) e->get();
this->addExpression(cfg, &t->fTest, constantPropagate);
cfg.fBlocks[cfg.fCurrent].fNodes.push_back({ BasicBlock::Node::kExpression_Kind,
constantPropagate, e, nullptr });
BlockId start = cfg.fCurrent;
cfg.newBlock();
this->addExpression(cfg, &t->fIfTrue, constantPropagate);
BlockId next = cfg.newBlock();
cfg.fCurrent = start;
cfg.newBlock();
this->addExpression(cfg, &t->fIfFalse, constantPropagate);
cfg.addExit(cfg.fCurrent, next);
cfg.fCurrent = next;
break;
}
case Expression::kFunctionReference_Kind: // fall through
case Expression::kTypeReference_Kind: // fall through
case Expression::kDefined_Kind:
ASSERT(false);
break;
}
}