/*
 * Copyright 2010-2012, The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#include "Assert.h"
#include "Log.h"
#include "RSTransforms.h"
#include "RSUtils.h"
#include "rsDefines.h"

#include "bcc/Compiler.h"
#include "bcc/CompilerConfig.h"
#include "bcc/Config.h"
#include "bcc/Script.h"
#include "bcc/Source.h"
#include "bcinfo/MetadataExtractor.h"

#include <llvm/Analysis/Passes.h>
#include <llvm/Analysis/TargetTransformInfo.h>
#include <llvm/CodeGen/RegAllocRegistry.h>
#include <llvm/IR/LegacyPassManager.h>
#include <llvm/IR/Module.h>
#include <llvm/Support/TargetRegistry.h>
#include <llvm/Support/raw_ostream.h>
#include <llvm/IR/DataLayout.h>
#include <llvm/Target/TargetSubtargetInfo.h>
#include <llvm/Target/TargetMachine.h>
#include <llvm/Transforms/IPO.h>
#include <llvm/Transforms/IPO/PassManagerBuilder.h>
#include <llvm/Transforms/Scalar.h>
#include <llvm/Transforms/Vectorize.h>

#include <string>
#include <set>

namespace {

// Name of metadata node where list of exported types resides
// (should be synced with slang_rs_metadata.h)
static const llvm::StringRef ExportedTypeMetadataName = "#rs_export_type";

// Every exported struct type must have the same layout according to
// the Module's DataLayout that it does according to the
// TargetMachine's DataLayout -- that is, the front end (represented
// by Module) and back end (represented by TargetMachine) must agree.
bool validateLayoutOfExportedTypes(const llvm::Module &module,
                                   const llvm::DataLayout &moduleDataLayout,
                                   const llvm::DataLayout &targetDataLayout) {
  if (moduleDataLayout == targetDataLayout)
    return true;

  const llvm::NamedMDNode *const exportedTypesMD =
      module.getNamedMetadata(ExportedTypeMetadataName);
  if (!exportedTypesMD)
    return true;

  bool allOk = true;
  for (const llvm::MDNode *const exportedTypeMD : exportedTypesMD->operands()) {
    bccAssert(exportedTypeMD->getNumOperands() == 1);

    // The name of the type in LLVM is the name of the type in the
    // metadata with "struct." prepended.
    std::string exportedTypeName =
        "struct." +
        llvm::cast<llvm::MDString>(exportedTypeMD->getOperand(0))->getString().str();

    llvm::StructType *const exportedType = module.getTypeByName(exportedTypeName);

    if (!exportedType) {
      // presumably this means the type got optimized away
      continue;
    }

    const llvm::StructLayout *const moduleStructLayout = moduleDataLayout.getStructLayout(exportedType);
    const llvm::StructLayout *const targetStructLayout = targetDataLayout.getStructLayout(exportedType);

    if (moduleStructLayout->getSizeInBits() != targetStructLayout->getSizeInBits()) {
      ALOGE("%s: getSizeInBits() does not match (%u, %u)", exportedTypeName.c_str(),
            unsigned(moduleStructLayout->getSizeInBits()), unsigned(targetStructLayout->getSizeInBits()));
      allOk = false;
    }

    // We deliberately do not check alignment of the struct as a whole -- the explicit padding
    // from slang doesn't force the alignment.

    for (unsigned elementCount = exportedType->getNumElements(), elementIdx = 0;
         elementIdx < elementCount; ++elementIdx) {
      if (moduleStructLayout->getElementOffsetInBits(elementIdx) !=
          targetStructLayout->getElementOffsetInBits(elementIdx)) {
        ALOGE("%s: getElementOffsetInBits(%u) does not match (%u, %u)",
              exportedTypeName.c_str(), elementIdx,
              unsigned(moduleStructLayout->getElementOffsetInBits(elementIdx)),
              unsigned(targetStructLayout->getElementOffsetInBits(elementIdx)));
        allOk = false;
      }
    }
  }

  return allOk;
}

}  // end unnamed namespace

using namespace bcc;

const char *Compiler::GetErrorString(enum ErrorCode pErrCode) {
  switch (pErrCode) {
  case kSuccess:
    return "Successfully compiled.";
  case kInvalidConfigNoTarget:
    return "Invalid compiler config supplied (getTarget() returns nullptr.) "
           "(missing call to CompilerConfig::initialize()?)";
  case kErrCreateTargetMachine:
    return "Failed to create llvm::TargetMachine.";
  case kErrSwitchTargetMachine:
    return  "Failed to switch llvm::TargetMachine.";
  case kErrNoTargetMachine:
    return "Failed to compile the script since there's no available "
           "TargetMachine. (missing call to Compiler::config()?)";
  case kErrMaterialization:
    return "Failed to materialize the module.";
  case kErrInvalidOutputFileState:
    return "Supplied output file was invalid (in the error state.)";
  case kErrPrepareOutput:
    return "Failed to prepare file for output.";
  case kPrepareCodeGenPass:
    return "Failed to construct pass list for code-generation.";
  case kErrCustomPasses:
    return "Error occurred while adding custom passes.";
  case kErrInvalidSource:
    return "Error loading input bitcode";
  case kIllegalGlobalFunction:
    return "Use of undefined external function";
  case kErrInvalidTargetMachine:
    return "Invalid/unexpected llvm::TargetMachine.";
  case kErrInvalidLayout:
    return "Invalid layout (RenderScript ABI and native ABI are incompatible)";
  }

  // This assert should never be reached as the compiler verifies that the
  // above switch coveres all enum values.
  bccAssert(false && "Unknown error code encountered");
  return  "";
}

//===----------------------------------------------------------------------===//
// Instance Methods
//===----------------------------------------------------------------------===//
Compiler::Compiler() : mTarget(nullptr), mEnableOpt(true) {
  return;
}

Compiler::Compiler(const CompilerConfig &pConfig) : mTarget(nullptr),
                                                    mEnableOpt(true) {
  const std::string &triple = pConfig.getTriple();

  enum ErrorCode err = config(pConfig);
  if (err != kSuccess) {
    ALOGE("%s (%s, features: %s)", GetErrorString(err),
          triple.c_str(), pConfig.getFeatureString().c_str());
    return;
  }

  return;
}

enum Compiler::ErrorCode Compiler::config(const CompilerConfig &pConfig) {
  if (pConfig.getTarget() == nullptr) {
    return kInvalidConfigNoTarget;
  }

  llvm::TargetMachine *new_target =
      (pConfig.getTarget())->createTargetMachine(pConfig.getTriple(),
                                                 pConfig.getCPU(),
                                                 pConfig.getFeatureString(),
                                                 pConfig.getTargetOptions(),
                                                 pConfig.getRelocationModel(),
                                                 pConfig.getCodeModel(),
                                                 pConfig.getOptimizationLevel());

  if (new_target == nullptr) {
    return ((mTarget != nullptr) ? kErrSwitchTargetMachine :
                                   kErrCreateTargetMachine);
  }

  // Replace the old TargetMachine.
  delete mTarget;
  mTarget = new_target;

  // Adjust register allocation policy according to the optimization level.
  //  createFastRegisterAllocator: fast but bad quality
  //  createLinearScanRegisterAllocator: not so fast but good quality
  if ((pConfig.getOptimizationLevel() == llvm::CodeGenOpt::None)) {
    llvm::RegisterRegAlloc::setDefault(llvm::createFastRegisterAllocator);
  } else {
    llvm::RegisterRegAlloc::setDefault(llvm::createGreedyRegisterAllocator);
  }

  return kSuccess;
}

Compiler::~Compiler() {
  delete mTarget;
}


// This function has complete responsibility for creating and executing the
// exact list of compiler passes.
enum Compiler::ErrorCode Compiler::runPasses(Script &script,
                                             llvm::raw_pwrite_stream &pResult) {
  // Pass manager for link-time optimization
  llvm::legacy::PassManager transformPasses;

  // Empty MCContext.
  llvm::MCContext *mc_context = nullptr;

  transformPasses.add(
      createTargetTransformInfoWrapperPass(mTarget->getTargetIRAnalysis()));

  // Add some initial custom passes.
  addInvokeHelperPass(transformPasses);
  addExpandKernelPass(transformPasses);
  addDebugInfoPass(script, transformPasses);
  addInvariantPass(transformPasses);
  if (mTarget->getOptLevel() != llvm::CodeGenOpt::None) {
    if (!addInternalizeSymbolsPass(script, transformPasses))
      return kErrCustomPasses;
  }
  addGlobalInfoPass(script, transformPasses);

  if (mTarget->getOptLevel() == llvm::CodeGenOpt::None) {
    transformPasses.add(llvm::createGlobalOptimizerPass());
    transformPasses.add(llvm::createConstantMergePass());

  } else {
    // FIXME: Figure out which passes should be executed.
    llvm::PassManagerBuilder Builder;
    Builder.Inliner = llvm::createFunctionInliningPass();
    Builder.populateLTOPassManager(transformPasses);

    /* FIXME: Reenable autovectorization after rebase.
       bug 19324423
    // Add vectorization passes after LTO passes are in
    // additional flag: -unroll-runtime
    transformPasses.add(llvm::createLoopUnrollPass(-1, 16, 0, 1));
    // Need to pass appropriate flags here: -scalarize-load-store
    transformPasses.add(llvm::createScalarizerPass());
    transformPasses.add(llvm::createCFGSimplificationPass());
    transformPasses.add(llvm::createScopedNoAliasAAPass());
    transformPasses.add(llvm::createScalarEvolutionAliasAnalysisPass());
    // additional flags: -slp-vectorize-hor -slp-vectorize-hor-store (unnecessary?)
    transformPasses.add(llvm::createSLPVectorizerPass());
    transformPasses.add(llvm::createDeadCodeEliminationPass());
    transformPasses.add(llvm::createInstructionCombiningPass());
    */
  }

  // These passes have to come after LTO, since we don't want to examine
  // functions that are never actually called.
  if (llvm::Triple(getTargetMachine().getTargetTriple()).getArch() == llvm::Triple::x86_64)
    transformPasses.add(createRSX86_64CallConvPass());  // Add pass to correct calling convention for X86-64.
  transformPasses.add(createRSIsThreadablePass());      // Add pass to mark script as threadable.

  // RSEmbedInfoPass needs to come after we have scanned for non-threadable
  // functions.
  if (script.getEmbedInfo())
    transformPasses.add(createRSEmbedInfoPass());

  // Execute the passes.
  transformPasses.run(script.getSource().getModule());

  // Run backend separately to avoid interference between debug metadata
  // generation and backend initialization.
  llvm::legacy::PassManager codeGenPasses;

  // Add passes to the pass manager to emit machine code through MC layer.
  if (mTarget->addPassesToEmitMC(codeGenPasses, mc_context, pResult,
                                 /* DisableVerify */false)) {
    return kPrepareCodeGenPass;
  }

  // Execute the passes.
  codeGenPasses.run(script.getSource().getModule());

  return kSuccess;
}

enum Compiler::ErrorCode Compiler::compile(Script &script,
                                           llvm::raw_pwrite_stream &pResult,
                                           llvm::raw_ostream *IRStream) {
  llvm::Module &module = script.getSource().getModule();
  enum ErrorCode err;

  if (mTarget == nullptr) {
    return kErrNoTargetMachine;
  }

  const std::string &triple = module.getTargetTriple();
  const llvm::DataLayout dl = getTargetMachine().createDataLayout();
  unsigned int pointerSize = dl.getPointerSizeInBits();
  if (triple == "armv7-none-linux-gnueabi") {
    if (pointerSize != 32) {
      return kErrInvalidSource;
    }
  } else if (triple == "aarch64-none-linux-gnueabi") {
    if (pointerSize != 64) {
      return kErrInvalidSource;
    }
  } else {
    return kErrInvalidSource;
  }

  if (script.isStructExplicitlyPaddedBySlang()) {
    if (!validateLayoutOfExportedTypes(module, module.getDataLayout(), dl))
      return kErrInvalidLayout;
  } else {
    if (getTargetMachine().getTargetTriple().getArch() == llvm::Triple::x86) {
      // Detect and fail if TargetMachine datalayout is different than what we
      // expect.  This is to detect changes in default target layout for x86 and
      // update X86_CUSTOM_DL_STRING in include/bcc/Config/Config.h appropriately.
      if (dl.getStringRepresentation().compare(X86_DEFAULT_DL_STRING) != 0) {
        return kErrInvalidTargetMachine;
      }
    }
  }

  // Sanitize module's target information.
  module.setTargetTriple(getTargetMachine().getTargetTriple().str());
  module.setDataLayout(getTargetMachine().createDataLayout());

  // Materialize the bitcode module.
  if (module.getMaterializer() != nullptr) {
    // A module with non-null materializer means that it is a lazy-load module.
    // Materialize it now.  This function returns false when the materialization
    // is successful.
    std::error_code ec = module.materializeAll();
    if (ec) {
      ALOGE("Failed to materialize the module `%s'! (%s)",
            module.getModuleIdentifier().c_str(), ec.message().c_str());
      return kErrMaterialization;
    }
  }

  if ((err = runPasses(script, pResult)) != kSuccess) {
    return err;
  }

  if (IRStream) {
    *IRStream << module;
  }

  return kSuccess;
}

bool Compiler::addInternalizeSymbolsPass(Script &script, llvm::legacy::PassManager &pPM) {
  // Add a pass to internalize the symbols that don't need to have global
  // visibility.
  llvm::Module &module = script.getSource().getModule();
  bcinfo::MetadataExtractor me(&module);
  if (!me.extract()) {
    bccAssert(false && "Could not extract metadata for module!");
    return false;
  }

  // Set of symbols that should not be internalized.
  std::set<std::string> export_symbols;

  const char *sf[] = {
    kRoot,               // Graphics drawing function or compute kernel.
    kInit,               // Initialization routine called implicitly on startup.
    kRsDtor,             // Static global destructor for a script instance.
    kRsInfo,             // Variable containing string of RS metadata info.
    kRsGlobalEntries,    // Optional number of global variables.
    kRsGlobalNames,      // Optional global variable name info.
    kRsGlobalAddresses,  // Optional global variable address info.
    kRsGlobalSizes,      // Optional global variable size info.
    kRsGlobalProperties, // Optional global variable properties.
    nullptr              // Must be nullptr-terminated.
  };
  const char **special_functions = sf;
  // Special RS functions should always be global symbols.
  while (*special_functions != nullptr) {
    export_symbols.insert(*special_functions);
    special_functions++;
  }

  // Visibility of symbols appeared in rs_export_var and rs_export_func should
  // also be preserved.
  size_t exportVarCount = me.getExportVarCount();
  size_t exportFuncCount = me.getExportFuncCount();
  size_t exportForEachCount = me.getExportForEachSignatureCount();
  size_t exportReduceCount = me.getExportReduceCount();
  const char **exportVarNameList = me.getExportVarNameList();
  const char **exportFuncNameList = me.getExportFuncNameList();
  const char **exportForEachNameList = me.getExportForEachNameList();
  const bcinfo::MetadataExtractor::Reduce *exportReduceList = me.getExportReduceList();
  size_t i;

  for (i = 0; i < exportVarCount; ++i) {
    export_symbols.insert(exportVarNameList[i]);
  }

  for (i = 0; i < exportFuncCount; ++i) {
    export_symbols.insert(exportFuncNameList[i]);
  }

  // Expanded foreach functions should not be internalized; nor should
  // general reduction initializer, combiner, and outconverter
  // functions. keep_funcs keeps the names of these functions around
  // until createInternalizePass() is finished making its own copy of
  // the visible symbols.
  std::vector<std::string> keep_funcs;
  keep_funcs.reserve(exportForEachCount + exportReduceCount*4);

  for (i = 0; i < exportForEachCount; ++i) {
    keep_funcs.push_back(std::string(exportForEachNameList[i]) + ".expand");
  }
  auto keepFuncsPushBackIfPresent = [&keep_funcs](const char *Name) {
    if (Name) keep_funcs.push_back(Name);
  };
  for (i = 0; i < exportReduceCount; ++i) {
    keep_funcs.push_back(std::string(exportReduceList[i].mAccumulatorName) + ".expand");
    keepFuncsPushBackIfPresent(exportReduceList[i].mInitializerName);
    if (exportReduceList[i].mCombinerName != nullptr) {
      keep_funcs.push_back(exportReduceList[i].mCombinerName);
    } else {
      keep_funcs.push_back(nameReduceCombinerFromAccumulator(exportReduceList[i].mAccumulatorName));
    }
    keepFuncsPushBackIfPresent(exportReduceList[i].mOutConverterName);
  }

  for (auto &symbol_name : keep_funcs) {
    export_symbols.insert(symbol_name);
  }

  auto IsExportedSymbol = [=](const llvm::GlobalValue &GV) {
    return export_symbols.count(GV.getName()) > 0;
  };

  pPM.add(llvm::createInternalizePass(IsExportedSymbol));

  return true;
}

void Compiler::addInvokeHelperPass(llvm::legacy::PassManager &pPM) {
  llvm::Triple arch(getTargetMachine().getTargetTriple());
  if (arch.isArch64Bit()) {
    pPM.add(createRSInvokeHelperPass());
  }
}

void Compiler::addDebugInfoPass(Script &script, llvm::legacy::PassManager &pPM) {
  if (script.getSource().getDebugInfoEnabled())
    pPM.add(createRSAddDebugInfoPass());
}

void Compiler::addExpandKernelPass(llvm::legacy::PassManager &pPM) {
  // Expand ForEach and reduce on CPU path to reduce launch overhead.
  bool pEnableStepOpt = true;
  pPM.add(createRSKernelExpandPass(pEnableStepOpt));
}

void Compiler::addGlobalInfoPass(Script &script, llvm::legacy::PassManager &pPM) {
  // Add additional information about RS global variables inside the Module.
  if (script.getEmbedGlobalInfo()) {
    pPM.add(createRSGlobalInfoPass(script.getEmbedGlobalInfoSkipConstant()));
  }
}

void Compiler::addInvariantPass(llvm::legacy::PassManager &pPM) {
  // Mark Loads from RsExpandKernelDriverInfo as "load.invariant".
  // Should run after ExpandForEach and before inlining.
  pPM.add(createRSInvariantPass());
}

enum Compiler::ErrorCode Compiler::screenGlobalFunctions(Script &script) {
  llvm::Module &module = script.getSource().getModule();

  // Materialize the bitcode module in case this is a lazy-load module.  Do not
  // clear the materializer by calling materializeAllPermanently since the
  // runtime library has not been merged into the module yet.
  if (module.getMaterializer() != nullptr) {
    std::error_code ec = module.materializeAll();
    if (ec) {
      ALOGE("Failed to materialize module `%s' when screening globals! (%s)",
            module.getModuleIdentifier().c_str(), ec.message().c_str());
      return kErrMaterialization;
    }
  }

  // Add pass to check for illegal function calls.
  llvm::legacy::PassManager pPM;
  pPM.add(createRSScreenFunctionsPass());
  pPM.run(module);

  return kSuccess;

}

void Compiler::translateGEPs(Script &script) {
  llvm::legacy::PassManager pPM;
  pPM.add(createRSX86TranslateGEPPass());

  // Materialization done in screenGlobalFunctions above.
  pPM.run(script.getSource().getModule());
}