CallDAG.cpp

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Author : Stuart Morgan
Date : 2019-08-14 12:25:12
Hash : 9d737966
Message : Standardize copyright notices to project style For all "ANGLE Project" copyrights, standardize to the format specified by the style guide. Changes: - "Copyright (c)" and "Copyright(c)" changed to just "Copyright". - Removed the second half of date ranges ("Y1Y1-Y2Y2"->"Y1Y1"). - Fixed a small number of files that had no copyright date using the initial commit year from the version control history. - Fixed one instance of copyright being "The ANGLE Project" rather than "The ANGLE Project Authors" These changes are applied both to the copyright of source file, and where applicable to copyright statements that are generated by templates. BUG=angleproject:3811 Change-Id: I973dd65e4ef9deeba232d5be74c768256a0eb2e5 Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/1754397 Commit-Queue: Jamie Madill <jmadill@chromium.org> Reviewed-by: Jamie Madill <jmadill@chromium.org>

src/compiler/translator/CallDAG.cpp

//
// Copyright 2002 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/SymbolTable.h"
#include "compiler/translator/tree_util/IntermTraverse.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, false),
          mDiagnostics(diagnostics),
          mCurrentFunction(nullptr),
          mCurrentIndex(0)
    {}

    InitResult assignIndices()
    {
        int skipped = 0;
        for (auto &it : mFunctions)
        {
            // Skip unimplemented functions
            if (it.second.definitionNode)
            {
                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.definitionNode)
            {
                continue;
            }
            ASSERT(data.index < records->size());
            Record &record = (*records)[data.index];

            record.node = data.definitionNode;

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

            (*idToIndex)[it.first] = static_cast<int>(data.index);
        }
    }

  private:
    struct CreatorFunctionData
    {
        CreatorFunctionData()
            : definitionNode(nullptr), name(""), index(0), indexAssigned(false), visiting(false)
        {}

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

    bool visitFunctionDefinition(Visit visit, TIntermFunctionDefinition *node) override
    {
        // Create the record if need be and remember the definition node.
        mCurrentFunction = &mFunctions[node->getFunction()->uniqueId().get()];
        // Name will be overwritten here. If we've already traversed the prototype of this function,
        // it should have had the same name.
        ASSERT(mCurrentFunction->name == "" ||
               mCurrentFunction->name == node->getFunction()->name());
        mCurrentFunction->name           = node->getFunction()->name();
        mCurrentFunction->definitionNode = node;

        node->getBody()->traverse(this);
        mCurrentFunction = nullptr;
        return false;
    }

    void visitFunctionPrototype(TIntermFunctionPrototype *node) override
    {
        ASSERT(mCurrentFunction == nullptr);

        // Function declaration, create an empty record.
        auto &record = mFunctions[node->getFunction()->uniqueId().get()];
        record.name  = node->getFunction()->name();
    }

    // Track functions called from another function.
    bool visitAggregate(Visit visit, TIntermAggregate *node) override
    {
        if (node->getOp() == EOpCallFunctionInAST)
        {
            // Function call, add the callees
            auto it = mFunctions.find(node->getFunction()->uniqueId().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 = sh::InitializeStream<std::stringstream>();

        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->definitionNode)
            {
                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 TSymbolUniqueId &id) const
{
    auto it = mFunctionIdToIndex.find(id.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];
}

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