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lib/typecheck/CheckCall.cpp

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//===-- typecheck/CheckCall.cpp ------------------------------- -*- C++ -*-===//
//
// This file is distributed under the MIT license. See LICENSE.txt for details.
//
// Copyright (C) 2009, Stephen Wilson
//
//===----------------------------------------------------------------------===//

//===----------------------------------------------------------------------===//
//===----------------------------------------------------------------------===//

#include "TypeCheck.h"
#include "comma/ast/AggExpr.h"
#include "comma/ast/KeywordSelector.h"
#include "comma/ast/DiagPrint.h"
#include "comma/ast/Stmt.h"

using namespace comma;
using llvm::dyn_cast;
using llvm::cast;
using llvm::isa;

namespace {

bool routineAcceptsKeywords(SubroutineDecl *decl,
                            unsigned numPositional,
                            llvm::SmallVectorImpl<KeywordSelector*> &keys)
{
    for (unsigned j = 0; j < keys.size(); ++j) {
        KeywordSelector *selector = keys[j];
        IdentifierInfo *key = selector->getKeyword();
        int keyIndex = decl->getKeywordIndex(key);

        if (keyIndex < 0 || unsigned(keyIndex) < numPositional)
            return false;
    }
    return true;
}

SubroutineCall *
makeSubroutineCall(SubroutineRef *ref,
                   Expr **positionalArgs, unsigned numPositional,
                   KeywordSelector **keyedArgs, unsigned numKeys)
{
    assert(!ref->empty() && "Empty subroutine reference!");

    if (ref->referencesFunctions())
        return new FunctionCallExpr(ref, positionalArgs, numPositional,
                                    keyedArgs, numKeys);
    else
        return new ProcedureCallStmt(ref, positionalArgs, numPositional,
                                     keyedArgs, numKeys);
}

void
convertSubroutineArguments(SubroutineDecl *decl,
                           llvm::SmallVectorImpl<Expr*> &posArgs,
                           llvm::SmallVectorImpl<KeywordSelector*> &keyArgs)
{
    typedef llvm::SmallVectorImpl<Expr*>::iterator pos_iterator;
    pos_iterator PI = posArgs.begin();
    for (unsigned i = 0; PI != posArgs.end(); ++PI, ++i) {
        Expr *arg = *PI;
        Type *targetType = decl->getParamType(i);
        *PI = TypeCheck::convertIfNeeded(arg, targetType);
    }

    typedef llvm::SmallVectorImpl<KeywordSelector*>::iterator key_iterator;
    key_iterator KI = keyArgs.begin();
    for ( ; KI != keyArgs.end(); ++KI) {
        KeywordSelector *selector = *KI;
        Expr *arg = selector->getExpression();
        unsigned index = unsigned(decl->getKeywordIndex(selector));
        Type *targetType = decl->getParamType(index);
        selector->setRHS(TypeCheck::convertIfNeeded(arg, targetType));
    }
}

void convertSubroutineCallArguments(SubroutineCall *call)
{
    assert(call->isUnambiguous() && "Expected resolved call!");

    typedef SubroutineCall::arg_iterator iterator;
    iterator I = call->begin_arguments();
    iterator E = call->end_arguments();
    SubroutineDecl *decl = call->getConnective();
    for (unsigned i = 0; I != E; ++I, ++i) {
        Expr *arg = *I;
        Type *targetType = decl->getParamType(i);
        call->setArgument(I, TypeCheck::convertIfNeeded(arg, targetType));
    }
}

} // End anonymous namespace.

bool TypeCheck::checkApplicableArgument(Expr *arg, Type *targetType)
{
    // If the argument as a fully resolved type, all we currently do is test for
    // type equality.
    if (arg->hasResolvedType())
        return covers(arg->getType(), targetType);

    // We have an unresolved argument expression.  If the expression is an
    // integer literal it is compatible if the target is an integer type.
    if (isa<IntegerLiteral>(arg))
        return targetType->isIntegerType();

    // Similarly for null expressions, but in this case the target must be an
    // access type.
    if (isa<NullExpr>(arg))
        return targetType->isAccessType();

    // If the expression is an unresolved aggregate or string literal it is
    // compatible if the target is an aggregate type.
    //
    // FIXME: In the case of a string literal we should explicitly check for an
    // array of character enumeration type.
    if (isa<AggregateExpr>(arg) || isa<StringLiteral>(arg))
        return targetType->isCompositeType();

    // The expression must be an ambiguous function call.  Check that at least
    // one interpretation of the call satisfies the target type.
    typedef FunctionCallExpr::fun_iterator iterator;
    FunctionCallExpr *call = cast<FunctionCallExpr>(arg);

    iterator I = call->begin_functions();
    iterator E = call->end_functions();
    for ( ; I != E; ++I) {
        FunctionDecl *connective = *I;
        Type *returnType = connective->getReturnType();
        if (covers(returnType, targetType))
            return true;
    }
    return false;
}

bool TypeCheck::routineAcceptsArgs(SubroutineDecl *decl,
                                   SVImpl<Expr*>::Type &args)
{
    unsigned numArgs = args.size();
    for (unsigned i = 0; i < numArgs; ++i) {
        Expr *arg = args[i];
        Type *targetType = decl->getParamType(i);
        if (!checkApplicableArgument(arg, targetType))
            return false;
    }
    return true;
}

bool
TypeCheck::routineAcceptsArgs(SubroutineDecl *decl,
                              SVImpl<KeywordSelector*>::Type &args)
{
    unsigned numKeys = args.size();
    for (unsigned i = 0; i < numKeys; ++i) {
        KeywordSelector *selector = args[i];
        Expr *arg = selector->getExpression();
        IdentifierInfo *key = selector->getKeyword();
        unsigned targetIndex = decl->getKeywordIndex(key);
        Type *targetType = decl->getParamType(targetIndex);

        if (!checkApplicableArgument(arg, targetType))
            return false;
    }
    return true;
}

Ast* TypeCheck::acceptSubroutineCall(SubroutineRef *ref,
                                     SVImpl<Expr*>::Type &positionalArgs,
                                     SVImpl<KeywordSelector*>::Type &keyedArgs)
{
    Location loc = ref->getLocation();
    unsigned numPositional = positionalArgs.size();
    unsigned numKeys = keyedArgs.size();

    // If there is only one interpretation as a call check it immediately and
    // return a resolved call node if successful.
    if (ref->isResolved()) {
        SubroutineCall *call;
        call = checkSubroutineCall(ref, positionalArgs, keyedArgs);
        return call ? call->asAst() : 0;
    }

    // Reduce the subroutine reference to include only those which can accept
    // the keyword selectors provided.
    SubroutineRef::iterator I = ref->begin();
    while (I != ref->end()) {
        SubroutineDecl *decl = *I;
        if (routineAcceptsKeywords(decl, numPositional, keyedArgs))
            ++I;
        else
            I = ref->erase(I);
    }

    // If none of the declarations support the keywords given, just report the
    // call as ambiguous.
    if (ref->empty()) {
        report(loc, diag::AMBIGUOUS_EXPRESSION);
        return 0;
    }

    // Reduce the set of declarations with respect to the types of the
    // arguments.
    for (I = ref->begin(); I != ref->end();) {
        SubroutineDecl *decl = *I;

        // First process the positional parameters.  Move on to the next
        // declaration if is cannot accept the given arguments.
        if (!routineAcceptsArgs(decl, positionalArgs)) {
            I = ref->erase(I);
            continue;
        }

        // Check the keyed arguments for compatibility.
        if (!routineAcceptsArgs(decl, keyedArgs)) {
            I = ref->erase(I);
            continue;
        }

        // We have a compatible declaration.
        ++I;
    }

    // If all of the declarations have been filtered out, it is due to ambiguous
    // arguments.
    if (ref->empty()) {
        report(loc, diag::AMBIGUOUS_EXPRESSION);
        return 0;
    }

    // If we have a unique declaration, check the matching call.
    if (ref->isResolved()) {
        SubroutineCall *call;
        call = checkSubroutineCall(ref, positionalArgs, keyedArgs);
        return call ? call->asAst() : 0;
    }

    // If we are dealing with procedures the call is ambiguous since we cannot
    // use a return type to resolve any further.
    if (ref->referencesProcedures()) {
        report(loc, diag::AMBIGUOUS_EXPRESSION);
        for (SubroutineRef::iterator I = ref->begin(); I != ref->end(); ++I)
            report(loc, diag::CANDIDATE_NOTE) << diag::PrintDecl(*I);
        return 0;
    }

    SubroutineCall *call =
        makeSubroutineCall(ref,
                           positionalArgs.data(), numPositional,
                           keyedArgs.data(), numKeys);
    return call->asAst();
}

FunctionDecl *TypeCheck::resolvePreferredConnective(FunctionCallExpr *call,
                                                    Type *targetType)
{
    typedef FunctionCallExpr::fun_iterator iterator;

    // Build a vector of candidate declarations which are covered by the target
    // type.
    llvm::SmallVector<FunctionDecl *, 8> candidates;
    iterator I = call->begin_functions();
    iterator E = call->end_functions();
    for ( ; I != E; ++I) {
        FunctionDecl *candidate = *I;
        Type *returnType = candidate->getReturnType();
        if (covers(returnType, targetType))
            candidates.push_back(candidate);
    }

    // If there are no candidate declarations we cannot resolve this call.  If
    // there is one candidate, the call is resolved.  If there is more than one
    // candidate, attempt to refine even further by showing preference to the
    // primitive operators.
    FunctionDecl *preference;
    if (candidates.empty())
        preference = 0;
    else if (candidates.size() == 1)
        preference = candidates.front();
    else
        preference = resolvePreferredOperator(candidates);
    return preference;
}

FunctionDecl *
TypeCheck::resolvePreferredOperator(SVImpl<FunctionDecl*>::Type &decls)
{
    // Walk the set of connectives and check that each possible interpretation
    // denotes a primitive operator, and find one of the operators provided by
    // root_integer.
    IntegerDecl *theRootInteger = resource.getTheRootIntegerDecl();
    FunctionDecl *preference = 0;

    typedef SVImpl<FunctionDecl*>::Type::iterator iterator;
    iterator I = decls.begin();
    iterator E = decls.end();
    for ( ; I != E; ++I) {
        FunctionDecl *candidate = *I;
        if (candidate->isPrimitive()) {
            if (candidate->isDeclaredIn(theRootInteger)) {
                // We have a prefered function.  We should never get more than
                // one match.
                assert(preference == 0 && "More than one prefered decl!");
                preference = candidate;
            }
        }
        else {
            // There are non-primitive operations. We cannot prefer a primitive
            // operator in this case.
            return 0;
        }
    }
    return preference;
}

SubroutineCall *
TypeCheck::checkSubroutineCall(SubroutineRef *ref,
                               SVImpl<Expr*>::Type &posArgs,
                               SVImpl<KeywordSelector*>::Type &keyArgs)
{
    assert(ref->isResolved() && "Cannot check call for unresolved reference!");

    Location loc = ref->getLocation();
    SubroutineDecl *decl = ref->getDeclaration();
    unsigned numArgs = posArgs.size() + keyArgs.size();

    if (decl->getArity() != numArgs) {
        report(loc, diag::WRONG_NUM_ARGS_FOR_SUBROUTINE) << decl->getIdInfo();
        return 0;
    }

    if (!checkSubroutineArguments(decl, posArgs, keyArgs))
        return 0;

    convertSubroutineArguments(decl, posArgs, keyArgs);
    return makeSubroutineCall(ref, posArgs.data(), posArgs.size(),
                              keyArgs.data(), keyArgs.size());
}

Expr *TypeCheck::checkSubroutineArgument(Expr *arg, Type *targetType,
                                         PM::ParameterMode targetMode)
{
    // If the target mode is either "out" or "in out", ensure that the
    // argument provided is compatible.
    if (targetMode == PM::MODE_OUT || targetMode == PM::MODE_IN_OUT) {
        Expr *immutable;
        if (!arg->isMutable(immutable)) {
            Location loc = immutable->getLocation();

            // Diagnose common mistakes.
            if (DeclRefExpr *ref = dyn_cast<DeclRefExpr>(immutable)) {
                if (isa<LoopDecl>(ref->getDeclaration())) {
                    report(loc, diag::LOOP_PARAM_NOT_VARIABLE);
                    return 0;
                }
            }

            // Generic diagnostic.
            report(loc, diag::EXPRESSION_NOT_MODE_COMPATIBLE) << targetMode;
            return 0;
        }
    }
    return checkExprInContext(arg, targetType);
}

bool
TypeCheck::checkSubroutineArguments(SubroutineDecl *decl,
                                    SVImpl<Expr*>::Type &posArgs,
                                    SVImpl<KeywordSelector*>::Type &keyArgs)
{
    // Check each positional argument.
    typedef SVImpl<Expr*>::Type::iterator pos_iterator;
    pos_iterator PI = posArgs.begin();
    for (unsigned i = 0; PI != posArgs.end(); ++PI, ++i) {
        Expr *arg = *PI;
        Type *targetType = decl->getParamType(i);
        PM::ParameterMode targetMode = decl->getParamMode(i);

        if (!(arg = checkSubroutineArgument(arg, targetType, targetMode)))
            return false;
        else
            *PI = arg;
    }

    // Check each keyed argument.
    typedef SVImpl<KeywordSelector*>::Type::iterator key_iterator;
    key_iterator KI = keyArgs.begin();
    for ( ; KI != keyArgs.end(); ++KI) {
        KeywordSelector *selector = *KI;
        IdentifierInfo *key = selector->getKeyword();
        Location keyLoc = selector->getLocation();
        Expr *arg = selector->getExpression();
        int keyIndex = decl->getKeywordIndex(key);

        // Ensure the given keyword exists.
        if (keyIndex < 0) {
            report(keyLoc, diag::SUBROUTINE_HAS_NO_SUCH_KEYWORD)
                << key << decl->getIdInfo();
            return false;
        }
        unsigned argIndex = unsigned(keyIndex);

        // The corresponding index of the keyword must be greater than the
        // number of supplied positional parameters (otherwise it would
        // `overlap' a positional parameter).
        if (argIndex < posArgs.size()) {
                report(keyLoc, diag::PARAM_PROVIDED_POSITIONALLY) << key;
                return false;
        }

        // Ensure that this keyword is not a duplicate of any preceding
        // keyword.
        for (key_iterator I = keyArgs.begin(); I != KI; ++I) {
            KeywordSelector *prevSelector = *I;
            if (prevSelector->getKeyword() == key) {
                report(keyLoc, diag::DUPLICATE_KEYWORD) << key;
                return false;
            }
        }

        // Ensure the type of the selected expression is compatible.
        Type *targetType = decl->getParamType(argIndex);
        PM::ParameterMode targetMode = decl->getParamMode(argIndex);
        if (!(arg = checkSubroutineArgument(arg, targetType, targetMode)))
            return false;
        else
            selector->setRHS(arg);
    }
    return true;
}

bool TypeCheck::checkSubroutineCallArguments(SubroutineCall *call)
{
    assert(call->isUnambiguous() && "Expected unambiguous call!");

    typedef SubroutineCall::arg_iterator iterator;
    iterator I = call->begin_arguments();
    iterator E = call->end_arguments();
    bool status = true;
    SubroutineDecl *decl = call->getConnective();

    for (unsigned i = 0; I != E; ++I, ++i) {
        PM::ParameterMode targetMode = decl->getParamMode(i);
        Type *targetType = decl->getParamType(i);
        Expr *arg = *I;
        if (!(arg = checkSubroutineArgument(*I, targetType, targetMode)))
            status = false;
        else
            call->setArgument(I, arg);
    }
    return status;
}

Expr *TypeCheck::resolveFunctionCall(FunctionCallExpr *call, Type *targetType)
{
    if (!call->isAmbiguous())
        return checkExprAndDereferenceInContext(call, targetType);

    FunctionDecl *preference = resolvePreferredConnective(call, targetType);

    if (!preference)  {
        Location loc = call->getLocation();
        report(loc, diag::AMBIGUOUS_EXPRESSION);
        for (SubroutineCall::connective_iterator I = call->begin_connectives();
             I != call->end_connectives(); ++I) {
            report(loc, diag::CANDIDATE_NOTE) << diag::PrintDecl(*I);
        }
        return 0;
    }

    // Resolve the call and check its final interpretation.  Inject any implicit
    // conversions or dereferences needed by the arguments and on the return value.
    call->resolveConnective(preference);
    if (!checkSubroutineCallArguments(call))
        return 0;
    convertSubroutineCallArguments(call);
    return convertIfNeeded(call, targetType);
}

bool TypeCheck::resolveFunctionCall(FunctionCallExpr *call,
                                    Type::Classification ID)
{
    typedef FunctionCallExpr::fun_iterator iterator;

    if (!call->isAmbiguous()) {
        // The function call is not ambiguous.  Ensure that the return type of
        // the call is a member of the target classification.
        if (call->getType()->memberOf(ID))
            return true;

        // FIXME: Need a better diagnostic here.
        report(call->getLocation(), diag::INCOMPATIBLE_TYPES);
        return false;
    }

    llvm::SmallVector<FunctionDecl*, 8> candidates;
    iterator I = call->begin_functions();
    iterator E = call->end_functions();
    for ( ; I != E; ++I) {
        FunctionDecl *candidate  = *I;
        Type *returnType = candidate->getReturnType();
        if (returnType->memberOf(ID))
            candidates.push_back(candidate);
    }

    // If there are no candidate declarations we cannot resolve this call.  If
    // there is one candidate the call is resolved.  If there is more than one
    // candidate, attempt to refine even further by showing preference to the
    // primitive operators.
    FunctionDecl *preference = 0;
    if (candidates.empty())
        preference = 0;
    else if (candidates.size() == 1)
        preference = candidates.front();
    else
        preference = resolvePreferredOperator(candidates);

    if (!preference) {
        report(call->getLocation(), diag::AMBIGUOUS_EXPRESSION);

        for (unsigned i = 0; i < candidates.size(); ++i) {
            Type *type = candidates[i]->getType();
            report(0, diag::CANDIDATE_NOTE) << diag::PrintType(type);
        }
        return false;
    }

    // Resolve the call and check its final interpretation.  Inject any implicit
    // conversions needed by the arguments.
    call->resolveConnective(preference);
    if (!checkSubroutineCallArguments(call))
        return false;
    convertSubroutineCallArguments(call);
    return true;
}


Expr *TypeCheck::resolveFunctionCall(FunctionCallExpr *call,
                                     IdentifierInfo *selector,
                                     Type *targetType)
{
    assert(call->isAmbiguous());

    // Collect the set of connectives which return record types which admit a
    // component with the given name and type.
    typedef llvm::SmallVector<FunctionDecl*, 8> CandidateVec;
    typedef FunctionCallExpr::fun_iterator iterator;
    CandidateVec candidates;
    iterator I = call->begin_functions();
    iterator E = call->end_functions();
    for ( ; I != E; ++I) {
        FunctionDecl *candidate = *I;
        Type *returnType = resolveType(candidate->getReturnType());
        if (RecordType *recType = dyn_cast<RecordType>(returnType)) {
            RecordDecl *decl = recType->getDefiningDecl();
            ComponentDecl *component = decl->getComponent(selector);
            if (component) {
                Type *componentType = component->getType();
                if (covers(componentType, targetType))
                    candidates.push_back(candidate);
            }
        }
    }

    // We must have a unique match.  We cannot apply the reference for root
    // integer since there are no primitive operations returing a record type.
    if (candidates.size() != 1) {
        Location loc = call->getLocation();
        report(loc, diag::AMBIGUOUS_EXPRESSION);
        for (CandidateVec::iterator I = candidates.begin();
             I != candidates.end(); ++I) {
            report(loc, diag::CANDIDATE_NOTE) << diag::PrintDecl(*I);
        }
        return 0;
    }

    FunctionDecl *connective = candidates.front();
    call->resolveConnective(connective);
    if (!checkSubroutineCallArguments(call))
        return 0;
    convertSubroutineCallArguments(call);

    // Do not apply any conversions to this function call since the target type
    // is with respect to a selected component, not to the returned record.
    return call;
}

---