Exemplo n.º 1
0
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");
    }
}
Exemplo n.º 2
0
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;
    }
}