src/OpenGL/compiler/AnalyzeCallDepth.cpp

//
// Copyright (c) 2002-2013 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.
//

#include "AnalyzeCallDepth.h"

AnalyzeCallDepth::FunctionNode::FunctionNode(TIntermAggregate *node) : node(node)
{
	visit = PreVisit;
	callDepth = 0;
}

const TString &AnalyzeCallDepth::FunctionNode::getName() const
{
	return node->getName();
}

void AnalyzeCallDepth::FunctionNode::addCallee(AnalyzeCallDepth::FunctionNode *callee)
{
    for(size_t i = 0; i < callees.size(); i++)
	{
        if(callees[i] == callee)
		{
            return;
		}
    }

    callees.push_back(callee);
}

unsigned int AnalyzeCallDepth::FunctionNode::analyzeCallDepth(AnalyzeCallDepth *analyzeCallDepth)
{
    ASSERT(visit == PreVisit);
    ASSERT(analyzeCallDepth);

    callDepth = 0;
    visit = InVisit;

    for(size_t i = 0; i < callees.size(); i++)
	{
		unsigned int calleeDepth = 0;
        switch(callees[i]->visit)
		{
        case InVisit:
            // Cycle detected (recursion)
            return UINT_MAX;
        case PostVisit:
			calleeDepth = callees[i]->getLastDepth();
            break;
        case PreVisit:
			calleeDepth = callees[i]->analyzeCallDepth(analyzeCallDepth);
			break;
        default:
            UNREACHABLE(callees[i]->visit);
            break;
        }
		if(calleeDepth != UINT_MAX) ++calleeDepth;
		callDepth = std::max(callDepth, calleeDepth);
    }

    visit = PostVisit;
    return callDepth;
}

unsigned int AnalyzeCallDepth::FunctionNode::getLastDepth() const
{
	return callDepth;
}

void AnalyzeCallDepth::FunctionNode::removeIfUnreachable()
{
	if(visit == PreVisit)
	{
		node->setOp(EOpPrototype);
		node->getSequence().resize(1);   // Remove function body
	}
}

AnalyzeCallDepth::AnalyzeCallDepth(TIntermNode *root)
    : TIntermTraverser(true, false, true, false),
      currentFunction(0)
{
	root->traverse(this);
}

AnalyzeCallDepth::~AnalyzeCallDepth()
{
    for(size_t i = 0; i < functions.size(); i++)
	{
        delete functions[i];
	}
}

bool AnalyzeCallDepth::visitAggregate(Visit visit, TIntermAggregate *node)
{
    switch(node->getOp())
    {
    case EOpFunction:   // Function definition
		{
			if(visit == PreVisit)
			{
				currentFunction = findFunctionByName(node->getName());

				if(!currentFunction)
				{
					currentFunction = new FunctionNode(node);
					functions.push_back(currentFunction);
				}
			}
			else if(visit == PostVisit)
			{
				currentFunction = 0;
			}
		}
        break;
    case EOpFunctionCall:
		{
			if(!node->isUserDefined())
			{
				return true;   // Check the arguments for function calls
			}

			if(visit == PreVisit)
			{
				FunctionNode *function = findFunctionByName(node->getName());

				if(!function)
				{
					function = new FunctionNode(node);
					functions.push_back(function);
				}
				
				if(currentFunction)
				{
					currentFunction->addCallee(function);
				}
				else
				{
					globalFunctionCalls.insert(function);
				}
			}
		}
        break;
    default:
        break;
    }

    return true;
}

unsigned int AnalyzeCallDepth::analyzeCallDepth()
{
    FunctionNode *main = findFunctionByName("main(");
    
	if(!main)
	{
		return 0;
	}

    unsigned int depth = main->analyzeCallDepth(this);
	if(depth != UINT_MAX) ++depth;

	for(FunctionSet::iterator globalCall = globalFunctionCalls.begin(); globalCall != globalFunctionCalls.end(); globalCall++)
	{
		unsigned int globalDepth = (*globalCall)->analyzeCallDepth(this);
		if(globalDepth != UINT_MAX) ++globalDepth;

		if(globalDepth > depth)
		{
			depth = globalDepth;
		}
	}

	for(size_t i = 0; i < functions.size(); i++)
	{
		functions[i]->removeIfUnreachable();
    }

    return depth;
}

AnalyzeCallDepth::FunctionNode *AnalyzeCallDepth::findFunctionByName(const TString &name)
{
    for(size_t i = 0; i < functions.size(); i++)
	{
        if(functions[i]->getName() == name)
		{
            return functions[i];
		}
    }

    return 0;
}