CppJitModule.h

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#ifndef PROTEUS_CPPFRONTEND_H
#define PROTEUS_CPPFRONTEND_H
 
#include "proteus/CppJitCompilerBackend.h"
#include "proteus/Frontend/Dispatcher.h"
#include "proteus/JitFuncAttribute.h"
 
#include <algorithm>
#include <optional>
#include <sstream>
#include <unordered_map>
#include <vector>
 
namespace proteus {
 
struct CompiledLibrary;
class HashT;
 
class CppJitModule {
private:
  TargetModelType TargetModel;
  std::string Code;
  std::unique_ptr<HashT> ModuleHash;
  std::vector<std::string> ExtraArgs;
  CppJitCompilerBackend CompilerBackend;
 
  Dispatcher &Dispatch;
  std::unique_ptr<CompiledLibrary> Library;
  bool IsCompiled = false;
 
  struct FuncAttributeState {
    std::optional<int> MaxDynamicSharedMemorySize;
 
    void set(JitFuncAttribute Attr, int Value) {
      if (Value < 0)
        reportFatalError("Function attribute value must be non-negative");
 
      switch (Attr) {
      case JitFuncAttribute::MaxDynamicSharedMemorySize:
        MaxDynamicSharedMemorySize = Value;
        return;
      }
 
      reportFatalError("Unsupported function attribute");
    }
  };
 
  // TODO: We don't cache CodeInstances so if a user re-creates the exact same
  // instantiation it will create a new CodeInstance. This creation cost is
  // mitigated because the dispatcher caches the compiled object so we will pay
  // the overhead for building the instantiation code but not for compilation.
  // Nevertheless, we return the CodeInstance object when created, so the user
  // can avoid any re-creation overhead by using the returned object to run or
  // launch. Re-think caching and dispatchers, and on more restrictive
  // interfaces.
  struct CodeInstance {
    TargetModelType TargetModel;
    const std::string &TemplateCode;
    std::vector<std::string> ExtraArgs;
    CppJitCompilerBackend CompilerBackend;
    std::string InstanceName;
    std::unique_ptr<CppJitModule> InstanceModule;
    std::string EntryFuncName;
    void *FuncPtr = nullptr;
    FuncAttributeState FuncAttributes;
 
    CodeInstance(TargetModelType TargetModel, const std::string &TemplateCode,
                 const std::vector<std::string> &ExtraArgs,
                 CppJitCompilerBackend CompilerBackend,
                 const std::string &InstanceName,
                 FuncAttributeState FuncAttributes = {})
        : TargetModel(TargetModel), TemplateCode(TemplateCode),
          ExtraArgs(ExtraArgs), CompilerBackend(CompilerBackend),
          InstanceName(InstanceName),
          FuncAttributes(std::move(FuncAttributes)) {
      EntryFuncName = "__proteus_instance_" + this->InstanceName;
      // Replace characters '<', '>', ',' with $ to create a unique for the
      // entry function.
      std::replace_if(
          EntryFuncName.begin(), EntryFuncName.end(),
          [](char C) { return C == '<' || C == '>' || C == ','; }, '$');
    }
 
    bool useHostLaunchEntry() const {
      // Instantiated GPU kernels compile through the host+device path.
      return TargetModel == TargetModelType::CUDA ||
             TargetModel == TargetModelType::HIP;
    }
 
    TargetModelType getInstanceTargetModel() const {
      if (TargetModel == TargetModelType::CUDA) {
        return TargetModelType::HOST_CUDA;
      }
 
      if (TargetModel == TargetModelType::HIP) {
        return TargetModelType::HOST_HIP;
      }
 
      return TargetModel;
    }
 
    CppJitCompilerBackend getInstanceCompilerBackend() const {
      return CompilerBackend;
    }
 
    const char *getGPUStreamType() const {
      if (TargetModel == TargetModelType::CUDA) {
        return "cudaStream_t";
      }
 
      if (TargetModel == TargetModelType::HIP) {
        return "hipStream_t";
      }
 
      reportFatalError("Expected CUDA or HIP target model for host launcher");
    }
 
    const char *getGPUGetLastErrorName() const {
      if (TargetModel == TargetModelType::CUDA) {
        return "cudaGetLastError";
      }
 
      if (TargetModel == TargetModelType::HIP) {
        return "hipGetLastError";
      }
 
      reportFatalError("Expected CUDA or HIP target model for host launcher");
    }
 
    const char *getGPUFuncSetAttributeName() const {
      if (TargetModel == TargetModelType::CUDA) {
        return "cudaFuncSetAttribute";
      }
 
      if (TargetModel == TargetModelType::HIP) {
        return "hipFuncSetAttribute";
      }
 
      reportFatalError("Expected CUDA or HIP target model for host launcher");
    }
 
    const char *getGPUMaxDynamicSharedMemoryAttrName() const {
      if (TargetModel == TargetModelType::CUDA) {
        return "cudaFuncAttributeMaxDynamicSharedMemorySize";
      }
 
      if (TargetModel == TargetModelType::HIP) {
        return "hipFuncAttributeMaxDynamicSharedMemorySize";
      }
 
      reportFatalError("Expected CUDA or HIP target model for host launcher");
    }
 
    // Compile-time type name (no RTTI).
    template <class T> constexpr std::string_view typeName() {
      // Apparently we are more interested in clang, but leaving the others for
      // completeness.
#if defined(__clang__)
      // "std::string_view type_name() [T = int]"
      std::string_view P = __PRETTY_FUNCTION__;
      auto B = P.find("[T = ") + 5;
      auto E = P.rfind(']');
      return P.substr(B, E - B);
#elif defined(__GNUC__)
      // "... with T = int; ..."
      std::string_view P = __PRETTY_FUNCTION__;
      auto B = P.find("with T = ") + 9;
      auto E = P.find(';', B);
      return P.substr(B, E - B);
#elif defined(_MSC_VER)
      // "std::string_view __cdecl type_name<int>(void)"
      std::string_view P = __FUNCSIG__;
      auto B = P.find("type_name<") + 10;
      auto E = P.find(">(void)", B);
      return P.substr(B, B - E);
#else
      reportFatalError("Unsupported compiler");
#endif
    }
 
    template <typename RetT, typename... ArgT, std::size_t... I>
    std::string buildFunctionEntry(std::index_sequence<I...>) {
      std::stringstream OS;
 
      OS << "extern \"C\" " << typeName<RetT>() << " "
         << ((!isHostTargetModel(TargetModel)) ? "__global__ " : "")
         << EntryFuncName << "(";
      ((OS << (I ? ", " : "")
           << typeName<
                  std::decay_t<std::tuple_element_t<I, std::tuple<ArgT...>>>>()
           << " Arg" << I),
       ...);
      OS << ')';
 
      std::string ArgList;
      ((ArgList += (I == 0 ? "" : ", ") + ("Arg" + std::to_string(I))), ...);
      OS << "{ ";
      if constexpr (!std::is_void_v<RetT>) {
        OS << "return ";
      }
      OS << InstanceName << "(";
      ((OS << (I == 0 ? "" : ", ") << "Arg" << std::to_string(I)), ...);
      OS << "); }";
 
      return OS.str();
    }
 
    template <typename... ArgT, std::size_t... I>
    std::string buildGPUHostLauncher(std::index_sequence<I...>) {
      std::stringstream OS;
 
      OS << "extern \"C\" int " << EntryFuncName
         << "(unsigned GridX, unsigned GridY, unsigned GridZ, unsigned "
            "BlockX, unsigned BlockY, unsigned BlockZ, size_t ShmemSize, "
            "void *Stream";
      ((OS << ", "
           << typeName<
                  std::decay_t<std::tuple_element_t<I, std::tuple<ArgT...>>>>()
           << " Arg" << I),
       ...);
      OS << ") { ";
      if (FuncAttributes.MaxDynamicSharedMemorySize) {
        OS << "{ auto AttrErr = " << getGPUFuncSetAttributeName()
           << "((const void *)" << InstanceName << ", "
           << getGPUMaxDynamicSharedMemoryAttrName() << ", "
           << *FuncAttributes.MaxDynamicSharedMemorySize
           << "); if (AttrErr != 0) return static_cast<int>(AttrErr); } ";
      }
      // Use a typed launch so implicit C++ conversions still happen at the
      // call site.
      OS << InstanceName
         << "<<<dim3(GridX, GridY, GridZ), dim3(BlockX, BlockY, BlockZ), "
            "ShmemSize, static_cast<"
         << getGPUStreamType() << ">(Stream)>>>(";
      ((OS << (I == 0 ? "" : ", ") << "Arg" << I), ...);
      OS << "); return static_cast<int>(" << getGPUGetLastErrorName()
         << "()); }";
 
      return OS.str();
    }
 
    template <typename RetOrSig, typename... ArgT> std::string buildCode() {
      if constexpr (std::is_void_v<RetOrSig>) {
        if (useHostLaunchEntry()) {
          return TemplateCode + buildGPUHostLauncher<ArgT...>(
                                    std::index_sequence_for<ArgT...>{});
        }
      }
 
      std::string FunctionCode = buildFunctionEntry<RetOrSig, ArgT...>(
          std::index_sequence_for<ArgT...>{});
 
      auto ReplaceAll = [](std::string &S, std::string_view From,
                           std::string_view To) {
        if (From.empty())
          return;
        std::size_t Pos = 0;
        while ((Pos = S.find(From, Pos)) != std::string::npos) {
          S.replace(Pos, From.size(), To);
          // Skip over the just-inserted text.
          Pos += To.size();
        }
      };
 
      std::string InstanceCode = TemplateCode;
      // Demote kernels to device function to call the templated instance from
      // the entry function.
      ReplaceAll(InstanceCode, "__global__", "__device__");
      InstanceCode = InstanceCode + FunctionCode;
 
      return InstanceCode;
    }
 
    template <typename RetT, typename... ArgT> void compile() {
      std::string InstanceCode = buildCode<RetT, ArgT...>();
      InstanceModule = std::make_unique<CppJitModule>(
          getInstanceTargetModel(), InstanceCode, ExtraArgs,
          getInstanceCompilerBackend());
      InstanceModule->compile();
 
      FuncPtr = InstanceModule->getFunctionAddress(EntryFuncName);
    }
 
    void setFuncAttribute(JitFuncAttribute Attr, int Value) {
      FuncAttributes.set(Attr, Value);
      InstanceModule.reset();
      FuncPtr = nullptr;
    }
 
    template <typename... ArgT>
    auto launch(LaunchDims GridDim, LaunchDims BlockDim, uint64_t ShmemSize,
                void *Stream, ArgT... Args) {
      if (!InstanceModule) {
        compile<void, ArgT...>();
      }
 
      void *Ptrs[sizeof...(ArgT)] = {(void *)&Args...};
 
      if (useHostLaunchEntry()) {
        using LauncherFunc =
            int(unsigned, unsigned, unsigned, unsigned, unsigned, unsigned,
                std::size_t, void *, ArgT...);
        return DispatchResult{InstanceModule->Dispatch.run<LauncherFunc>(
            FuncPtr, GridDim.X, GridDim.Y, GridDim.Z, BlockDim.X, BlockDim.Y,
            BlockDim.Z, static_cast<std::size_t>(ShmemSize), Stream, Args...)};
      }
 
      return InstanceModule->launch(FuncPtr, GridDim, BlockDim, Ptrs, ShmemSize,
                                    Stream);
    }
 
    template <typename RetOrSig, typename... ArgT>
    RetOrSig run(ArgT &&...Args) {
      static_assert(!std::is_function_v<RetOrSig>,
                    "Function signature type is not yet supported");
 
      if (!InstanceModule) {
        compile<RetOrSig, ArgT...>();
      }
 
      if constexpr (std::is_void_v<RetOrSig>)
        InstanceModule->Dispatch.run<RetOrSig(ArgT...)>(FuncPtr, Args...);
      else
        return InstanceModule->Dispatch.run<RetOrSig(ArgT...)>(FuncPtr,
                                                               Args...);
    }
  };
 
  std::unordered_map<std::string, std::unique_ptr<CodeInstance>>
      InstantiationCache;
 
  void setFuncAttribute(void *KernelFunc, JitFuncAttribute Attr, int Value);
  void *getFunctionAddress(const std::string &Name);
  DispatchResult launch(void *KernelFunc, LaunchDims GridDim,
                        LaunchDims BlockDim, void *KernelArgs[],
                        uint64_t ShmemSize, void *Stream);
 
public:
  explicit CppJitModule(
      TargetModelType TargetModel, const std::string &Code,
      const std::vector<std::string> &ExtraArgs = {},
      CppJitCompilerBackend CompilerBackend = CppJitCompilerBackend::Clang);
  explicit CppJitModule(
      const std::string &Target, const std::string &Code,
      const std::vector<std::string> &ExtraArgs = {},
      CppJitCompilerBackend CompilerBackend = CppJitCompilerBackend::Clang);
  ~CppJitModule();
 
  void compile();
 
  CompiledLibrary &getLibrary() {
    if (!IsCompiled)
      compile();
 
    if (!Library)
      reportFatalError("Expected non-null library after compilation");
 
    return *Library;
  }
 
  template <typename... ArgT>
  auto &instantiate(const std::string &FuncName, ArgT... Args) {
    std::string InstanceName = FuncName + "<";
    bool First = true;
    ((InstanceName +=
      (First ? "" : ",") + std::string(std::forward<ArgT>(Args)),
      First = false),
     ...);
 
    InstanceName += ">";
 
    auto It = InstantiationCache.find(InstanceName);
    if (It != InstantiationCache.end()) {
      return *It->second;
    }
 
    auto [NewIt, OK] = InstantiationCache.emplace(
        InstanceName,
        std::make_unique<CodeInstance>(TargetModel, Code, ExtraArgs,
                                       CompilerBackend, InstanceName));
    return *NewIt->second;
  }
 
  template <typename Sig> struct FunctionHandle;
  template <typename RetT, typename... ArgT>
  struct FunctionHandle<RetT(ArgT...)> {
    CppJitModule &M;
    void *FuncPtr;
    explicit FunctionHandle(CppJitModule &M, void *FuncPtr)
        : M(M), FuncPtr(FuncPtr) {}
 
    RetT run(ArgT... Args) {
      if constexpr (std::is_void_v<RetT>) {
        M.Dispatch.template run<RetT(ArgT...)>(FuncPtr,
                                               std::forward<ArgT>(Args)...);
      } else {
        return M.Dispatch.template run<RetT(ArgT...)>(
            FuncPtr, std::forward<ArgT>(Args)...);
      }
    }
  };
 
  template <typename Sig> struct KernelHandle;
  template <typename RetT, typename... ArgT>
  struct KernelHandle<RetT(ArgT...)> {
    CppJitModule &M;
    void *FuncPtr = nullptr;
    explicit KernelHandle(CppJitModule &M, void *FuncPtr)
        : M(M), FuncPtr(FuncPtr) {
      static_assert(std::is_void_v<RetT>, "Kernel function must return void");
    }
 
    void setFuncAttribute(JitFuncAttribute Attr, int Value) {
      M.setFuncAttribute(FuncPtr, Attr, Value);
    }
 
    auto launch(LaunchDims GridDim, LaunchDims BlockDim, uint64_t ShmemSize,
                void *Stream, ArgT... Args) {
      void *Ptrs[sizeof...(ArgT)] = {(void *)&Args...};
 
      return M.launch(FuncPtr, GridDim, BlockDim, Ptrs, ShmemSize, Stream);
    }
  };
  template <typename Sig>
  FunctionHandle<Sig> getFunction(const std::string &Name) {
    if (!IsCompiled)
      compile();
 
    if (!isHostTargetModel(TargetModel))
      reportFatalError("Error: getFunction() applies only to host modules");
 
    void *FuncPtr = getFunctionAddress(Name);
 
    return FunctionHandle<Sig>(*this, FuncPtr);
  }
 
  template <typename Sig> KernelHandle<Sig> getKernel(const std::string &Name) {
    if (!IsCompiled)
      compile();
 
    if (TargetModel == TargetModelType::HOST)
      reportFatalError("Error: getKernel() applies only to device modules");
 
    void *FuncPtr = getFunctionAddress(Name);
 
    return KernelHandle<Sig>(*this, FuncPtr);
  }
};
 
} // namespace proteus
 
#endif