IGC/DebugInfo/VISADebugEmitter.cpp

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

Copyright (C) 2017-2021 Intel Corporation

SPDX-License-Identifier: MIT

============================= end_copyright_notice ===========================*/

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

This file is distributed under the University of Illinois Open Source License.
See LICENSE.TXT for details.

============================= end_copyright_notice ===========================*/

#include "llvm/Config/llvm-config.h"
#include "common/LLVMWarningsPush.hpp"
#include "llvm/IR/Module.h"
#include "llvm/IR/DIBuilder.h"
#include "llvm/IR/Verifier.h"
#include "llvm/MC/MCDwarf.h"
#include "llvm/MC/MCSymbol.h"
#include "llvm/BinaryFormat/ELF.h"
#include "common/LLVMWarningsPop.hpp"

#include "VISADebugEmitter.hpp"
#include "DwarfDebug.hpp"
#include "StreamEmitter.hpp"
#include "VISAModule.hpp"

#include "Probe/Assertion.h"
#include "secure_mem.h"

#include "CLElfLib/CLElfTypes.h"

#define DEBUG_TYPE "dwarfdebug"

using namespace llvm;
using namespace IGC;
using namespace CLElfLib;   // ElfReader related typedefs

IDebugEmitter* IDebugEmitter::Create()
{
    return new DebugEmitter();
}

void IDebugEmitter::Release(IDebugEmitter* pDebugEmitter)
{
    delete pDebugEmitter;
}

DebugEmitter::DebugEmitter() : IDebugEmitter(), m_outStream(m_str)
{
}
DebugEmitter::~DebugEmitter()
{
    Reset();
}

void DebugEmitter::Reset()
{
    m_str.clear();
    m_pVISAModule = nullptr;

    m_pStreamEmitter.reset();
    m_pDwarfDebug.reset();

    m_initialized = false;
}


void DebugEmitter::Initialize(std::unique_ptr<VISAModule> VM,
                              const DebugEmitterOpts& Opts)
{
    IGC_ASSERT_MESSAGE(false == m_initialized, "DebugEmitter is already initialized!");
    // IGC_ASSERT(!doneOnce);
    m_initialized = true;

    m_pVISAModule = VM.get();
    m_debugEnabled = Opts.DebugEnabled;
    // VISA module will be initialized even when debugger is disabled.
    // Its overhead is minimum and it will be used in debug mode to
    // assertion test on calling DebugEmitter in the right order.
    toFree.push_back(std::move(VM));

    if (!m_debugEnabled)
    {
        return;
    }

    const auto &dataLayout = m_pVISAModule->GetDataLayout();
    m_pStreamEmitter = std::make_unique<StreamEmitter>(
                        m_outStream, dataLayout, m_pVISAModule->GetTargetTriple(), Opts);
    m_pDwarfDebug = std::make_unique<DwarfDebug>(m_pStreamEmitter.get(), m_pVISAModule);

    registerVISA(m_pVISAModule);
}

void DebugEmitter::processCurrentFunction(bool finalize, const DbgDecoder* decodedDbg) {

    auto EmitIpLabel = [&](unsigned int ip)
    {
        // Emit label before %ip
        if (m_pStreamEmitter->GetEmitterSettings().EnableRelocation)
        {
            auto instLabel = m_pDwarfDebug->GetLabelBeforeIp(ip);
            m_pStreamEmitter->EmitLabel(instLabel);
        }
    };

    m_pVISAModule->buildDirectElfMaps(*decodedDbg);
    auto co = m_pVISAModule->getCompileUnit(*decodedDbg);

    // Emit src line mapping directly instead of
    // relying on dbgmerge. elf generated will have
    // text section and debug_line sections populated.
    const auto& VISAIndexToInst = m_pVISAModule->VISAIndexToInst;
    const auto& VISAIndexToSize = m_pVISAModule->VISAIndexToSize;
    decltype(m_pVISAModule->GenISAToVISAIndex) GenISAToVISAIndex;
    unsigned int subEnd = m_pVISAModule->GetCurrentVISAId();
    unsigned int prevLastGenOff = lastGenOff;
    m_pDwarfDebug->lowPc = lastGenOff;

    // SIMD width
    m_pDwarfDebug->simdWidth = m_pVISAModule->GetSIMDSize();

    if (co->subs.size() == 0)
    {
        GenISAToVISAIndex = m_pVISAModule->GenISAToVISAIndex;
        if (GenISAToVISAIndex.size() > 0)
            lastGenOff = GenISAToVISAIndex.back().GenOffset;
        m_pDwarfDebug->lowPc = co->relocOffset;
    }
    else
    {
        for (auto item : m_pVISAModule->GenISAToVISAIndex)
        {
            if ((item.GenOffset >= lastGenOff) || ((item.GenOffset | lastGenOff) == 0))
            {
                if (item.VisaOffset <= subEnd || item.VisaOffset == 0xffffffff)
                {
                    GenISAToVISAIndex.push_back(item);
                    auto size = m_pVISAModule->GenISAInstSizeBytes[item.GenOffset];
                    lastGenOff = item.GenOffset + size;
                    continue;
                }

                if (item.VisaOffset > subEnd)
                    break;
            }
        }
    }

    auto genxISA = m_pVISAModule->getGenBinary();
    DebugLoc prevSrcLoc = DebugLoc();
    unsigned int pc = prevLastGenOff;

    if (!GenISAToVISAIndex.empty()) {
        IGC_ASSERT(GenISAToVISAIndex.rbegin()->GenOffset <= genxISA.size());
        IGC_ASSERT(pc < genxISA.size());
        IGC_ASSERT(GenISAToVISAIndex.begin()->GenOffset >= pc);
    }
    for (auto item : GenISAToVISAIndex)
    {
        for (unsigned int i = pc; i != item.GenOffset; i++)
        {
            EmitIpLabel(i);
            m_pStreamEmitter->EmitInt8(genxISA[i]);
        }

        pc = item.GenOffset;

        auto instIt = VISAIndexToInst.end();
        auto sizeIt = VISAIndexToSize.find(item.VisaOffset);
        if (sizeIt != VISAIndexToSize.end())
        {
            // Lookup all VISA instructions that may
            // map to an llvm::Instruction. This is useful
            // when an llvm::Instruction leads to multiple
            // VISA instructions, and VISA optimizer
            // optimizes some of those away. Src line
            // mapping for all VISA instructions is the
            // same. So lookup any one that still exists.
            auto startIdx = sizeIt->second.VisaOffset;
            auto numVISAInsts = sizeIt->second.VisaInstrNum;
            // Loop till at least one VISA instruction
            // is found.
            for (unsigned int visaId = startIdx;
                visaId != (startIdx + numVISAInsts); visaId++)
            {
                instIt = VISAIndexToInst.find(visaId);
                if (instIt != VISAIndexToInst.end())
                    break;
            }
        }

        if (instIt == VISAIndexToInst.end())
            continue;
        if (!m_pVISAModule->IsExecutableInst(*instIt->second))
            continue;

        const auto& loc = instIt->second->getDebugLoc();
        if (!loc || loc == prevSrcLoc)
            continue;

        const auto* scope = loc->getScope();
        auto src = m_pDwarfDebug->getOrCreateSourceID(scope->getFilename(), scope->getDirectory(), m_pStreamEmitter->GetDwarfCompileUnitID());

        unsigned int Flags = 0;
        if (!m_pDwarfDebug->isStmtExists(loc.getLine(), loc.getInlinedAt(), true))
        {
            Flags |= DWARF2_FLAG_IS_STMT;
        }

        if (!m_pDwarfDebug->prologueEndExists(loc.get()->getScope()->getSubprogram(),
                                              loc.getInlinedAt(), true))
        {
            Flags |= DWARF2_FLAG_PROLOGUE_END;
        }
        m_pStreamEmitter->EmitDwarfLocDirective(src, loc.getLine(), loc.getCol(), Flags, 0, 0, scope->getFilename());

        prevSrcLoc = loc;
    }

    if (finalize)
    {
        size_t unpaddedSize = m_pVISAModule->getUnpaddedProgramSize();

        IGC_ASSERT(unpaddedSize <= genxISA.size());
        IGC_ASSERT((pc < genxISA.size() && pc < unpaddedSize) || pc == unpaddedSize);

        for (unsigned int i = pc; i != unpaddedSize; i++)
        {
            m_pStreamEmitter->EmitInt8(genxISA[i]);
            lastGenOff++;
        }
    }
    else if (pc != lastGenOff)
    {
        IGC_ASSERT(lastGenOff <= genxISA.size());
        IGC_ASSERT((pc < genxISA.size() && pc < lastGenOff) || pc == lastGenOff);
        // for subroutines
        for (unsigned int i = pc; i != lastGenOff; i++)
        {
            EmitIpLabel(i);
            m_pStreamEmitter->EmitInt8(genxISA[i]);
        }
    }

    m_pDwarfDebug->highPc = lastGenOff;
}

void DebugEmitter::SetDISPCache(DwarfDISubprogramCache *DISPCache) {
    IGC_ASSERT(m_pDwarfDebug);
    m_pDwarfDebug->setDISPCache(DISPCache);
}

std::vector<char> DebugEmitter::Finalize(bool finalize,
                                         const DbgDecoder* decodedDbg)
{
    if (!m_debugEnabled)
    {
        return {};
    }

    IGC_ASSERT_MESSAGE(m_pVISAModule, "active visa object must be selected before finalization");
    IGC_ASSERT(m_pDwarfDebug);
    m_pDwarfDebug->setDecodedDbg(decodedDbg);

    if (!doneOnce)
    {
        m_pDwarfDebug->beginModule();
        doneOnce = true;
    }

    const Function* pFunc = m_pVISAModule->GetEntryFunction();
    // Collect debug information for given function.
    m_pStreamEmitter->SwitchSection(m_pStreamEmitter->GetTextSection());

    LLVM_DEBUG(dbgs() << "[DwarfDebug] beginFunction called for <" <<
               pFunc->getName() << "> ---\n");
    m_pDwarfDebug->beginFunction(pFunc, m_pVISAModule);
    LLVM_DEBUG(dbgs() << "[DwarfDebug] beginFunction end ***\n");

    processCurrentFunction(finalize, decodedDbg);

    // Emit post-function debug information
    LLVM_DEBUG(dbgs() << "[DwarfDebug] endFunction start ---\n");
    m_pDwarfDebug->endFunction(pFunc);
    LLVM_DEBUG(dbgs() << "[DwarfDebug] endFunction done ***\n");

    if (!finalize)
    {
        LLVM_DEBUG(dbgs() << "[DwarfDebug] non-finalized exit ***\n");
        return {};
    }
    LLVM_DEBUG(dbgs() << "[DwarfDebug] starting finalization ---\n");

    IGC_ASSERT(doneOnce);

    // Finalize debug information.
    m_pDwarfDebug->endModule();

    m_pStreamEmitter->Finalize();
    LLVM_DEBUG(dbgs() << "[DwarfDebug] finalized***\n");

    LLVM_DEBUG(dbgs() << "Finalized Visa Module:\n");
    LLVM_DEBUG(m_pVISAModule->dump());

    // Add program header table to satisfy latest gdb
    bool is64Bit = m_pVISAModule->getPointerSize() == 8;
    unsigned int phtSize = sizeof(llvm::ELF::Elf32_Phdr);
    if (is64Bit)
        phtSize = sizeof(llvm::ELF::Elf64_Phdr);

    const Function* PrimaryEntry = m_pDwarfDebug->GetPrimaryEntry();
    std::string EntryNameWithDot = ("." + PrimaryEntry->getName()).str();
    size_t ContentSize = m_str.size();
    if (m_pStreamEmitter->GetEmitterSettings().ZeBinCompatible)
        ContentSize += EntryNameWithDot.size();

    size_t elfWithProgramHeaderSize = phtSize + ContentSize;
    std::vector<char> Result(elfWithProgramHeaderSize);

    if (!m_pStreamEmitter->GetEmitterSettings().ZeBinCompatible)
    {
        // Text section remains with its standard name .text
        std::copy(m_str.begin(), m_str.end(), Result.begin());
    }
    else
    {
        // Text section's name to be extended by a kernel name.
        size_t endOfDotTextNameOffset = 0;
        prepareElfForZeBinary(is64Bit, m_str.begin(), m_str.size(),
                              EntryNameWithDot.size(), &endOfDotTextNameOffset);

        // First copy ELF binary from the beginning to the .text name (included) located in the .str.tab
        std::copy(m_str.begin(), m_str.begin() + endOfDotTextNameOffset, Result.begin());
        // Next concatenate .text with a kernel name (a dot joining both names also added).
        std::copy(EntryNameWithDot.begin(), EntryNameWithDot.end(),
                  Result.begin() + endOfDotTextNameOffset);
        // Finally copy remaining part of ELF binary.
        std::copy(m_str.begin() + endOfDotTextNameOffset + 1, m_str.end(),
                  Result.begin() + endOfDotTextNameOffset + 1 + EntryNameWithDot.size());
    }

    writeProgramHeaderTable(is64Bit, Result.data(), ContentSize);
    setElfType(is64Bit, Result.data());

    m_errs = m_pStreamEmitter->getErrors();
    Reset();

    return std::move(Result);
}

void DebugEmitter::prepareElfForZeBinary(bool is64Bit, char* pElfBuffer, size_t elfBufferSize, size_t kernelNameWithDotSize,
    size_t* pEndOfDotTextNameInStrtab)
{
    // ELF binary header contains 'SectionHeadersOffset' (e_shoff in ELF spec.), which is an offset
    // to section headers placed one by one. A location (index) of the header with names (including section name)
    // is stored in the ELF binary header at 'SectionNameTableIndex' (e_shstrndx). A section header under this index
    // contains an offset to location of the String Table data, which may look as showed in the line below:
    //  .debug_abbrev .text.stackcall .debug_ranges .debug_str .debug_info
    // ^NULL         ^NULL           ^NULL         ^NULL      ^NULL       ^NULL
    //
    // Each section header contain 'Name' (sh_name) fields which is a byte offset to this data showed above.
    // The String Table is a simple chunk of memory, where the names are placed one by one and separated by NULL (\0).
    // String Table contains NULL (\0) also at the beginning (i.e. 'Name' equal 0 means no name).

    if (is64Bit)
    {
        SElf64Header* pElf64Header = (SElf64Header*)pElfBuffer;

        // First simply validate ELF binary
        IGC_ASSERT_MESSAGE(pElf64Header &&
            (pElf64Header->Identity[ID_IDX_MAGIC0] == ELF_MAG0) &&
            (pElf64Header->Identity[ID_IDX_MAGIC1] == ELF_MAG1) &&
            (pElf64Header->Identity[ID_IDX_MAGIC2] == ELF_MAG2) &&
            (pElf64Header->Identity[ID_IDX_MAGIC3] == ELF_MAG3) &&
            (pElf64Header->Identity[ID_IDX_CLASS] == EH_CLASS_64), "ELF file header incorrect");

        // Using the Section Name Table Index, calculate the offset to the String Table (.strtab) header.
        size_t entrySize = pElf64Header->SectionHeaderEntrySize;
        size_t nameSectionHeaderOffset = (size_t)pElf64Header->SectionHeadersOffset + (pElf64Header->SectionNameTableIndex * entrySize);
        IGC_ASSERT_MESSAGE(pElf64Header->SectionNameTableIndex < pElf64Header->NumSectionHeaderEntries, "ELF header incorrect");
        IGC_ASSERT_MESSAGE(nameSectionHeaderOffset < elfBufferSize, "ELF header incorrect");

        // Using the offset found above get a header of the String Table section
        SElf64SectionHeader* pNamesSectionHeader = (SElf64SectionHeader*)((char*)pElf64Header + nameSectionHeaderOffset);
        SElf64SectionHeader* pSectionHeader = NULL;
        size_t indexedSectionHeaderOffset = 0;
        Elf64_Word textSectionHeaderName = 0;
        char* pSectionName = NULL;
        size_t sectionNameOffset = 0;
        size_t textSectionNameOffset = 0;

        // Scan section headers to find the Text section using simple section name comparison.
        for (unsigned int elfSectionIdx = 1; elfSectionIdx < pElf64Header->NumSectionHeaderEntries; elfSectionIdx++)
        {
            // Calculate a byte offset to the current section's header
            indexedSectionHeaderOffset = (size_t)pElf64Header->SectionHeadersOffset + (elfSectionIdx * entrySize);

            // Get a header of the current section
            pSectionHeader = (SElf64SectionHeader*)((char*)pElf64Header + indexedSectionHeaderOffset);

            // Using the byte offset from the current section's header, find the current section's name
            // in the String Table.
            sectionNameOffset = (size_t)pNamesSectionHeader->DataOffset + pSectionHeader->Name;
            pSectionName = (char*)pElf64Header + sectionNameOffset;

            // Check if the Text section is found.
            if (pSectionName && (strcmp(pSectionName, ".text") == 0))
            {
                textSectionHeaderName = pSectionHeader->Name;   // Remember for the next loop over sections.
                textSectionNameOffset = sectionNameOffset;      // Remember for the next loop over sections.
                pNamesSectionHeader->DataSize += kernelNameWithDotSize; //.strtab size increases not .text section

                // Return an offset (from the beginning of ELF binary) to the first character after '.text'
                *pEndOfDotTextNameInStrtab = sectionNameOffset + sizeof(".text") - 1;
                break; // Text section found, its location saved.
            }
        }

        // Update headers of ELF sections due to a longer Text section name
        // (i.e. in strtab .text will be replaced with .text.kernelName).
        // - change location of each section name located after the Text section name in .strtab
        // - change data offset of each section located after the .strtab section
        for (unsigned int elfSectionIdx = 1; elfSectionIdx < pElf64Header->NumSectionHeaderEntries; elfSectionIdx++)
        {
            indexedSectionHeaderOffset = (size_t)pElf64Header->SectionHeadersOffset + (elfSectionIdx * entrySize);

            pSectionHeader = (SElf64SectionHeader*)((char*)pElf64Header + indexedSectionHeaderOffset);
            if (pSectionHeader->Name > textSectionHeaderName)
            {
                pSectionHeader->Name += kernelNameWithDotSize;
            }
            if (pSectionHeader->DataOffset > textSectionNameOffset)
            {
                pSectionHeader->DataOffset += kernelNameWithDotSize;
                // This data offset update may be not enough if such a section contains elf global offsets
                // (i.e. relative to the beginning of the elf binary).
                // However, as long as .strtab is the last section in our ELF binary then there is no side-effects.
                // If location of this section changes in the future, then a copy (or move) of this section content
                // will be required. This future need must be verified if the assertion below hits (then
                // assertion below must be changed based on results of such verification).
                IGC_ASSERT(0);
            }
        }

        if (pSectionHeader)
        {
            // ELF binary header also must be updated to reflect offsets changes.
            if (pElf64Header->SectionHeadersOffset > pSectionHeader->DataOffset)
            {
                pElf64Header->SectionHeadersOffset += kernelNameWithDotSize;
            }
            if (pElf64Header->ProgramHeadersOffset > pSectionHeader->DataOffset)
            {
                pElf64Header->ProgramHeadersOffset += kernelNameWithDotSize;
            }
        }
    }
    else
    {
        IGC_ASSERT_MESSAGE(is64Bit, "64-bit ELF file only supported");
    }
}

void DebugEmitter::setElfType(bool is64Bit, void* pBuffer)
{
    // Set 1-step elf's e_type to ET_EXEC
    if (!pBuffer)
        return;

    if (is64Bit)
    {
        void* etypeOff = ((char*)pBuffer) + (offsetof(llvm::ELF::Elf64_Ehdr, e_type));
        if (m_pStreamEmitter->GetEmitterSettings().EnableRelocation)
        {
            *((llvm::ELF::Elf64_Half*)etypeOff) = llvm::ELF::ET_REL;
        }
        else
        {
            *((llvm::ELF::Elf64_Half*)etypeOff) = llvm::ELF::ET_EXEC;
        }
    }
    else
    {
        void* etypeOff = ((char*)pBuffer) + (offsetof(llvm::ELF::Elf32_Ehdr, e_type));
        if (m_pStreamEmitter->GetEmitterSettings().EnableRelocation)
        {
            *((llvm::ELF::Elf32_Half*)etypeOff) = llvm::ELF::ET_REL;
        }
        else
        {
            *((llvm::ELF::Elf32_Half*)etypeOff) = llvm::ELF::ET_EXEC;
        }
    }
}

void DebugEmitter::writeProgramHeaderTable(bool is64Bit, void* pBuffer, unsigned int size)
{
    // Write program header table at end of elf
    if (is64Bit)
    {
        llvm::ELF::Elf64_Phdr hdr;
        hdr.p_type = llvm::ELF::PT_LOAD;
        hdr.p_flags = 0;
        hdr.p_offset = 0;
        hdr.p_vaddr = 0;
        hdr.p_paddr = 0;
        hdr.p_filesz = size;
        hdr.p_memsz = size;
        hdr.p_align = 4;
        void* phOffAddr = ((char*)pBuffer) + (offsetof(llvm::ELF::Elf64_Ehdr, e_phoff));
        *(llvm::ELF::Elf64_Off*)(phOffAddr) = size;
        ((char*)pBuffer)[offsetof(llvm::ELF::Elf64_Ehdr, e_phentsize)] = sizeof(llvm::ELF::Elf64_Phdr);
        ((char*)pBuffer)[offsetof(llvm::ELF::Elf64_Ehdr, e_phnum)] = 1;
        memcpy_s((char*)pBuffer + size, sizeof(llvm::ELF::Elf64_Phdr), &hdr, sizeof(hdr));
    }
    else
    {
        llvm::ELF::Elf32_Phdr hdr;
        hdr.p_type = llvm::ELF::PT_LOAD;
        hdr.p_offset = 0;
        hdr.p_vaddr = 0;
        hdr.p_paddr = 0;
        hdr.p_filesz = size;
        hdr.p_memsz = size;
        hdr.p_flags = 0;
        hdr.p_align = 4;
        void* phOffAddr = ((char*)pBuffer) + (offsetof(llvm::ELF::Elf32_Ehdr, e_phoff));
        *(llvm::ELF::Elf32_Off*)(phOffAddr) = size;
        ((char*)pBuffer)[offsetof(llvm::ELF::Elf32_Ehdr, e_phentsize)] = sizeof(llvm::ELF::Elf32_Phdr);
        ((char*)pBuffer)[offsetof(llvm::ELF::Elf32_Ehdr, e_phnum)] = 1;
        memcpy_s((char*)pBuffer + size, sizeof(llvm::ELF::Elf32_Phdr), &hdr, sizeof(hdr));
    }
}

void DebugEmitter::BeginInstruction(Instruction* pInst)
{
    BeginEncodingMark();
    if (!m_debugEnabled)
    {
        return;
    }
    m_pVISAModule->BeginInstruction(pInst);
}

void DebugEmitter::EndInstruction(Instruction* pInst)
{
    EndEncodingMark();
    if (!m_debugEnabled)
    {
        return;
    }
    m_pVISAModule->EndInstruction(pInst);
}

void DebugEmitter::BeginEncodingMark()
{
    m_pVISAModule->BeginEncodingMark();
}

void DebugEmitter::EndEncodingMark()
{
    m_pVISAModule->EndEncodingMark();
}
// TODO: do we really need it?
void DebugEmitter::registerVISA(IGC::VISAModule* VM)
{
    m_pDwarfDebug->registerVISA(VM);
}
void DebugEmitter::setCurrentVISA(IGC::VISAModule* VM) {
    // TODO: add assertion statement to check that this module is registered/owned
    m_pVISAModule = VM;
}
void DebugEmitter::resetModule(std::unique_ptr<IGC::VISAModule> VM) {
    m_pVISAModule = VM.get();
    toFree.push_back(std::move(VM));
}

const std::string& DebugEmitter::getErrors() const {
    return m_errs;
}