CallDAG.cpp

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Author : Olli Etuaho
Date : 2017-07-05 14:50:54
Hash : cccf2b00
Message : Reorganize AST traversal utility code Define TIntermTraverser and TIntermLValueTrackingTraverser in a separate header file. hash() function is moved out from TIntermTraverser as it is not related to the core functionality of traversing and transforming ASTs. Also reorganize some traversers to follow common conventions: - Intermediate output is now in OutputTree.h/.cpp - Max tree depth check is now in IsASTDepthBelowLimit.h/.cpp BUG=angleproject:1490 TEST=angle_unittests Change-Id: Id4968aa9d4e24d0c5bac90dc147fc9f310de0184 Reviewed-on: https://chromium-review.googlesource.com/559531 Reviewed-by: Jamie Madill <jmadill@chromium.org> Reviewed-by: Corentin Wallez <cwallez@chromium.org> Commit-Queue: Olli Etuaho <oetuaho@nvidia.com>
src/compiler/translator/CallDAG.cpp
//
// Copyright (c) 2002-2015 The ANGLE Project Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
//

// CallDAG.h: Implements a call graph DAG of functions to be re-used accross
// analyses, allows to efficiently traverse the functions in topological
// order.

#include "compiler/translator/CallDAG.h"

#include "compiler/translator/Diagnostics.h"
#include "compiler/translator/IntermTraverse.h"
#include "compiler/translator/SymbolTable.h"

namespace sh
{

// The CallDAGCreator does all the processing required to create the CallDAG
// structure so that the latter contains only the necessary variables.
class CallDAG::CallDAGCreator : public TIntermTraverser
{
  public:
    CallDAGCreator(TDiagnostics *diagnostics)
        : TIntermTraverser(true, false, true),
          mDiagnostics(diagnostics),
          mCurrentFunction(nullptr),
          mCurrentIndex(0)
    {
    }

    InitResult assignIndices()
    {
        int skipped = 0;
        for (auto &it : mFunctions)
        {
            // Skip unimplemented functions
            if (it.second.node)
            {
                InitResult result = assignIndicesInternal(&it.second);
                if (result != INITDAG_SUCCESS)
                {
                    return result;
                }
            }
            else
            {
                skipped++;
            }
        }

        ASSERT(mFunctions.size() == mCurrentIndex + skipped);
        return INITDAG_SUCCESS;
    }

    void fillDataStructures(std::vector<Record> *records, std::map<int, int> *idToIndex)
    {
        ASSERT(records->empty());
        ASSERT(idToIndex->empty());

        records->resize(mCurrentIndex);

        for (auto &it : mFunctions)
        {
            CreatorFunctionData &data = it.second;
            // Skip unimplemented functions
            if (!data.node)
            {
                continue;
            }
            ASSERT(data.index < records->size());
            Record &record = (*records)[data.index];

            record.name = data.name.data();
            record.node = data.node;

            record.callees.reserve(data.callees.size());
            for (auto &callee : data.callees)
            {
                record.callees.push_back(static_cast<int>(callee->index));
            }

            (*idToIndex)[data.node->getFunctionSymbolInfo()->getId().get()] =
                static_cast<int>(data.index);
        }
    }

  private:
    struct CreatorFunctionData
    {
        CreatorFunctionData() : node(nullptr), index(0), indexAssigned(false), visiting(false) {}

        std::set<CreatorFunctionData *> callees;
        TIntermFunctionDefinition *node;
        TString name;
        size_t index;
        bool indexAssigned;
        bool visiting;
    };

    bool visitFunctionDefinition(Visit visit, TIntermFunctionDefinition *node) override
    {
        // Create the record if need be and remember the node.
        if (visit == PreVisit)
        {
            auto it = mFunctions.find(node->getFunctionSymbolInfo()->getId().get());

            if (it == mFunctions.end())
            {
                mCurrentFunction       = &mFunctions[node->getFunctionSymbolInfo()->getId().get()];
                mCurrentFunction->name = node->getFunctionSymbolInfo()->getName();
            }
            else
            {
                mCurrentFunction = &it->second;
                ASSERT(mCurrentFunction->name == node->getFunctionSymbolInfo()->getName());
            }

            mCurrentFunction->node = node;
        }
        else if (visit == PostVisit)
        {
            mCurrentFunction = nullptr;
        }
        return true;
    }

    bool visitFunctionPrototype(Visit visit, TIntermFunctionPrototype *node) override
    {
        ASSERT(visit == PreVisit);
        if (mCurrentFunction != nullptr)
        {
            return false;
        }

        // Function declaration, create an empty record.
        auto &record = mFunctions[node->getFunctionSymbolInfo()->getId().get()];
        record.name  = node->getFunctionSymbolInfo()->getName();

        // No need to traverse the parameters.
        return false;
    }

    // Aggregates the AST node for each function as well as the name of the functions called by it
    bool visitAggregate(Visit visit, TIntermAggregate *node) override
    {
        if (visit == PreVisit && node->getOp() == EOpCallFunctionInAST)
        {
            // Function call, add the callees
            auto it = mFunctions.find(node->getFunctionSymbolInfo()->getId().get());
            ASSERT(it != mFunctions.end());

            // We might be traversing the initializer of a global variable. Even though function
            // calls in global scope are forbidden by the parser, some subsequent AST
            // transformations can add them to emulate particular features.
            if (mCurrentFunction)
            {
                mCurrentFunction->callees.insert(&it->second);
            }
        }
        return true;
    }

    // Recursively assigns indices to a sub DAG
    InitResult assignIndicesInternal(CreatorFunctionData *root)
    {
        // Iterative implementation of the index assignment algorithm. A recursive version
        // would be prettier but since the CallDAG creation runs before the limiting of the
        // call depth, we might get stack overflows (computation of the call depth uses the
        // CallDAG).

        ASSERT(root);

        if (root->indexAssigned)
        {
            return INITDAG_SUCCESS;
        }

        // If we didn't have to detect recursion, functionsToProcess could be a simple queue
        // in which we add the function being processed's callees. However in order to detect
        // recursion we need to know which functions we are currently visiting. For that reason
        // functionsToProcess will look like a concatenation of segments of the form
        // [F visiting = true, subset of F callees with visiting = false] and the following
        // segment (if any) will be start with a callee of F.
        // This way we can remember when we started visiting a function, to put visiting back
        // to false.
        TVector<CreatorFunctionData *> functionsToProcess;
        functionsToProcess.push_back(root);

        InitResult result = INITDAG_SUCCESS;

        std::stringstream errorStream;

        while (!functionsToProcess.empty())
        {
            CreatorFunctionData *function = functionsToProcess.back();

            if (function->visiting)
            {
                function->visiting      = false;
                function->index         = mCurrentIndex++;
                function->indexAssigned = true;

                functionsToProcess.pop_back();
                continue;
            }

            if (!function->node)
            {
                errorStream << "Undefined function '" << function->name
                            << ")' used in the following call chain:";
                result = INITDAG_UNDEFINED;
                break;
            }

            if (function->indexAssigned)
            {
                functionsToProcess.pop_back();
                continue;
            }

            function->visiting = true;

            for (auto callee : function->callees)
            {
                functionsToProcess.push_back(callee);

                // Check if the callee is already being visited after pushing it so that it appears
                // in the chain printed in the info log.
                if (callee->visiting)
                {
                    errorStream << "Recursive function call in the following call chain:";
                    result = INITDAG_RECURSION;
                    break;
                }
            }

            if (result != INITDAG_SUCCESS)
            {
                break;
            }
        }

        // The call chain is made of the function we were visiting when the error was detected.
        if (result != INITDAG_SUCCESS)
        {
            bool first = true;
            for (auto function : functionsToProcess)
            {
                if (function->visiting)
                {
                    if (!first)
                    {
                        errorStream << " -> ";
                    }
                    errorStream << function->name << ")";
                    first = false;
                }
            }
            if (mDiagnostics)
            {
                std::string errorStr = errorStream.str();
                mDiagnostics->globalError(errorStr.c_str());
            }
        }

        return result;
    }

    TDiagnostics *mDiagnostics;

    std::map<int, CreatorFunctionData> mFunctions;
    CreatorFunctionData *mCurrentFunction;
    size_t mCurrentIndex;
};

// CallDAG

CallDAG::CallDAG()
{
}

CallDAG::~CallDAG()
{
}

const size_t CallDAG::InvalidIndex = std::numeric_limits<size_t>::max();

size_t CallDAG::findIndex(const TFunctionSymbolInfo *functionInfo) const
{
    auto it = mFunctionIdToIndex.find(functionInfo->getId().get());

    if (it == mFunctionIdToIndex.end())
    {
        return InvalidIndex;
    }
    else
    {
        return it->second;
    }
}

const CallDAG::Record &CallDAG::getRecordFromIndex(size_t index) const
{
    ASSERT(index != InvalidIndex && index < mRecords.size());
    return mRecords[index];
}

const CallDAG::Record &CallDAG::getRecord(const TIntermAggregate *function) const
{
    size_t index = findIndex(function->getFunctionSymbolInfo());
    ASSERT(index != InvalidIndex && index < mRecords.size());
    return mRecords[index];
}

size_t CallDAG::size() const
{
    return mRecords.size();
}

void CallDAG::clear()
{
    mRecords.clear();
    mFunctionIdToIndex.clear();
}

CallDAG::InitResult CallDAG::init(TIntermNode *root, TDiagnostics *diagnostics)
{
    CallDAGCreator creator(diagnostics);

    // Creates the mapping of functions to callees
    root->traverse(&creator);

    // Does the topological sort and detects recursions
    InitResult result = creator.assignIndices();
    if (result != INITDAG_SUCCESS)
    {
        return result;
    }

    creator.fillDataStructures(&mRecords, &mFunctionIdToIndex);
    return INITDAG_SUCCESS;
}

}  // namespace sh
kc3-lang/angle/src/compiler/translator/CallDAG.cpp

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kc3-lang/angle /src/compiler/translator/CallDAG.cpp
