/*===================== begin_copyright_notice ==================================

Copyright (c) 2017 Intel Corporation

Permission is hereby granted, free of charge, to any person obtaining a
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"Software"), to deal in the Software without restriction, including
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permit persons to whom the Software is furnished to do so, subject to
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The above copyright notice and this permission notice shall be included
in all copies or substantial portions of the Software.

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OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
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IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
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======================= end_copyright_notice ==================================*/

#include "Compiler/Optimizer/OpenCLPasses/UndefinedReferences/UndefinedReferencesPass.hpp"
#include "Compiler/IGCPassSupport.h"
#include "Compiler/CodeGenPublic.h"

#include "common/LLVMWarningsPush.hpp"
#include <llvm/IR/Module.h>
#include <llvm/IR/Function.h>
#include "common/LLVMWarningsPop.hpp"
#include "GenISAIntrinsics/GenIntrinsics.h"

using namespace llvm;
using namespace IGC;

// Register pass to igc-opt
#define PASS_FLAG "undefined-references"
#define PASS_DESCRIPTION "Emit linker warnings to user"
#define PASS_CFG_ONLY false
#define PASS_ANALYSIS true
IGC_INITIALIZE_PASS_BEGIN(UndefinedReferencesPass, PASS_FLAG, PASS_DESCRIPTION, PASS_CFG_ONLY, PASS_ANALYSIS)
IGC_INITIALIZE_PASS_END(UndefinedReferencesPass, PASS_FLAG, PASS_DESCRIPTION, PASS_CFG_ONLY, PASS_ANALYSIS)

char UndefinedReferencesPass::ID = 0;

UndefinedReferencesPass::UndefinedReferencesPass() : ModulePass(ID)
{
    initializeUndefinedReferencesPassPass(*PassRegistry::getPassRegistry());
}

///////////////////////////////////////////////////////////////////////////////
//
// ExistUndefinedReferencesInModule()
//
// LLVM's linker only does the job of tying together references across modules;
// for LLVM since a declaration in LLVM IR is perfectly valid, it does not make
// sense to check for any remaining undefined references.  Call this function
// after linking to determine this.  A true return value indicates there are
// undefined references and errorMessage will be appended with the appropriate
// information.
//
static bool ExistUndefinedReferencesInModule(Module &module, std::string &errorMessage)
{
    raw_string_ostream strStream(errorMessage);
    bool foundUndef = false;

    std::string msg = "undefined reference to `";

    Module::global_iterator GVarIter = module.global_begin();
    for (; GVarIter != module.global_end();)
    {
        GlobalVariable *pGVar = &(*GVarIter);
        if (pGVar->isDeclaration() && pGVar->hasNUsesOrMore(1))
        {
            strStream << msg << GVarIter->getName().str() << "'\n";
            foundUndef = true;
        }

        // Increment the iterator before attempting to remove a global variable
        GVarIter++;

        if (!pGVar->isDeclaration() && pGVar->use_empty())
        {
            // Remove the declaration
            pGVar->eraseFromParent();
        }
    }

    for (auto &F : module)
    {
        if (F.isDeclaration() && !F.isIntrinsic() && !GenISAIntrinsic::isIntrinsic(&F) && F.hasNUsesOrMore(1))
        {
            StringRef funcName = F.getName();
            if (!funcName.startswith("__builtin_IB") && funcName != "printf" &&
                !funcName.startswith("__igcbuiltin_") &&
                !funcName.startswith("__translate_sampler_initializer"))
            {
                strStream << msg << funcName << "()'\n";
                foundUndef = true;
            }
        }
    }

    strStream.flush();

    return foundUndef;
}

bool UndefinedReferencesPass::runOnModule(Module &M)
{
    // At this point all references should have been linked to definitions, any
    // undefined references should generate errors.
    std::string errorMessage;
    if (ExistUndefinedReferencesInModule(M, errorMessage))
    {
        if (!errorMessage.empty())
        {
            getAnalysis<CodeGenContextWrapper>().getCodeGenContext()->EmitError(errorMessage.c_str());
        }
    }

    return false;
}