[HIPSPV][2/4] Add HIPSPV tool chain

[linjamaki]

Summary

This patch adds a new tool chain, HIPSPVToolChain, for emitting HIP
device code as SPIR-V binary. The SPIR-V binary is emitted by using an
external tool, SPIRV-LLVM-Translator, temporarily. We intend to switch
the translator to the llc tool when the SPIR-V backend lands on LLVM
and proves to work well on HIP implementations which consume SPIR-V.

Before the SPIR-V emission the tool chain loads an optional external
pass plugin, either automatically from a HIP installation or from a
path pointed by --hipspv-pass-plugin, and runs passes that are meant
to expand/lower HIP features that do not have direct counterpart in
SPIR-V (e.g. dynamic shared memory).

Code emission for SPIR-V will be enabled and HIPSPVToolChain tests
will be added in the follow up patch part 3.

Other changes: New option ‘-nohipwrapperinc’ is added to exclude HIP
include wrappers. The reason for the addition is that they cause
compile errors when compiling HIP sources for the host side for HIPCL
and HIPLZ implementations. New option is added to avoid this issue.

[linjamaki]

Style fixes.

[tra]

clang/include/clang/Driver/Options.td

3769

Is the idea to still add relevant include paths to the wrappers and SDK headers, but not -include the wrapper?

If that's the case, it should probably be generalized into -nogpuwrapperinc and apply to both CUDA and HIP.

[Anastasia]

Considering that SPIR-V translation step is also required for other languages would it make sense to add llvm-spirv as a common tool like for example C/C++ linkers and create a bit of common infrastructure? It might be something we can do as a separate step too but it would be good to make sure nothing prevents us from doing this in the future... We should probably also think about the command line interface unification as it probably doesn't make sense for every language to add their own flags for locating SPIR-V translator.

Another question I have is whether --hipspv-pass-plugin would be needed when we switch to SPIR-V backend or is this something that would be integrated fully upstream eventually. Then we might need to think more of the suitable transition path.

[linjamaki]

In D110618#3032899, @Anastasia wrote:

Considering that SPIR-V translation step is also required for other languages would it make sense to add llvm-spirv as a common tool like for example C/C++ linkers and create a bit of common infrastructure? It might be something we can do as a separate step too but it would be good to make sure nothing prevents us from doing this in the future... We should probably also think about the command line interface unification as it probably doesn't make sense for every language to add their own flags for locating SPIR-V translator.

I don’t think it would work out well. llvm-spirv (or other tool relying on LLVM bitcode input) and LLVM may have version differences that cause obscure error cases - like newer LLVM producing bitcode with new features the tools are not expecting and ready for them. The usage of llvm-spirv tool in the HIPSPV tool chain is not intended to be a longer term solution due to this shortcoming.

Another question I have is whether --hipspv-pass-plugin would be needed when we switch to SPIR-V backend or is this something that would be integrated fully upstream eventually. Then we might need to think more of the suitable transition path.

It’s too early to say if we can integrate --hipspv-pass-plugin fully in the future. It would be the preferred outcome. We are not finished with the HIP expanders we need for supporting various HIP features so we don’t know for certain what will be the outcome for the integration. It’s possible that some of the solutions are going to be tightly coupled with runtimes (HIPLZ, HIPCL) and others that may not generalize for different SPIR-V execution environments.

clang/include/clang/Driver/Options.td

3769

Is the idea to still add relevant include paths to the wrappers and SDK headers, but not -include the wrapper?

Include paths are meant to be excluded too. I’ll fix the option description.

If that's the case, it should probably be generalized into -nogpuwrapperinc and apply to both CUDA and HIP.

I don’t see an immediate need to generalize the option as I don’t think there will be a need for it in the CUDA path. The option could be generalized later if the need comes (add generalized option, set -nohipwrapperinc to be alias to it).

[linjamaki]

Update option description.

[Anastasia]

In D110618#3039275, @linjamaki wrote:

In D110618#3032899, @Anastasia wrote:

Considering that SPIR-V translation step is also required for other languages would it make sense to add llvm-spirv as a common tool like for example C/C++ linkers and create a bit of common infrastructure? It might be something we can do as a separate step too but it would be good to make sure nothing prevents us from doing this in the future... We should probably also think about the command line interface unification as it probably doesn't make sense for every language to add their own flags for locating SPIR-V translator.

I don’t think it would work out well. llvm-spirv (or other tool relying on LLVM bitcode input) and LLVM may have version differences that cause obscure error cases - like newer LLVM producing bitcode with new features the tools are not expecting and ready for them. The usage of llvm-spirv tool in the HIPSPV tool chain is not intended to be a longer term solution due to this shortcoming.

I don't feel it is different for OpenCL though... I am not in favour of repeating the same functionality for every language since the requirement will be likely identical. There is no timeline for when this functionality will be dropped so we have to assume that even though temporary it might be a solution for long enough.

[pekka.jaaskelainen]

I don't feel it is different for OpenCL though... I am not in favour of repeating the same functionality for every language since the requirement will be likely identical. There is no timeline for when this functionality will be dropped so we have to assume that even though temporary it might be a solution for long enough.

If it is likely the SPIR-V backend won’t land soon and it is expected that also other languages might benefit from the calls to the llvm-spirv tool, the functionality to do so would be better placed in a more generally useful place. Do you have suggestions where this functionality could be moved?

I believe it concerns mostly the call to the llvm-spriv (this is sought in PATH, not given via a command line parameter) inside constructEmitSpirvCommand(). This could be extracted to another function in a utility library so it could be accessed by other languages/tools in the future. Does it sound OK?

[Anastasia]

In D110618#3054257, @pekka.jaaskelainen wrote:

I don't feel it is different for OpenCL though... I am not in favour of repeating the same functionality for every language since the requirement will be likely identical. There is no timeline for when this functionality will be dropped so we have to assume that even though temporary it might be a solution for long enough.

If it is likely the SPIR-V backend won’t land soon and it is expected that also other languages might benefit from the calls to the llvm-spirv tool, the functionality to do so would be better placed in a more generally useful place. Do you have suggestions where this functionality could be moved?

I believe it concerns mostly the call to the llvm-spriv (this is sought in PATH, not given via a command line parameter) inside constructEmitSpirvCommand(). This could be extracted to another function in a utility library so it could be accessed by other languages/tools in the future. Does it sound OK?

I believe this is indeed the most common functionality at this point, so if we could factor it out already now it would make sense. However, towards the common tooling we would probably need to create a special Tool/ToolChain for SPIR-V which could be derived from or used for the languages/toochains that target SPIR-V generation.

[linjamaki]

Rebase and use SPIRV::constructTranslateCommand() to contruct
the LLVM-SPIR-V translation command.

[linjamaki]

Gentle ping. Is anything needed to be addressed to get this patch accepted?

[linjamaki]

Update for changes in D112404.

[linjamaki]

Rebase.

[linjamaki]

Gentle ping.

[yaxunl]

LGTM. I will leave to @tra about -nohipwrapperinc

[tra]

LGTM in general, modulo push_back/append nits.

clang/include/clang/Driver/Options.td

3769

Fair enough. Indeed, without the wrappers, we will not be able to parse CUDA SDK headers.

clang/lib/Driver/ToolChains/HIPSPV.cpp

146

Nit: combine with -fcuda-is-device into append({})

152–153

Nit: Combine all unconditional push_back() calls into append();

165–166

Nit: combine into single append.

210–211

-> append({}).

[linjamaki]

Combine options with append().

[linjamaki]

Retry push changes.

[linjamaki]

Thanks for the review.

[Anastasia]

Could you please clarify the interface to SPIRV-LLVM-Translator tool, specifically:

• Does clang lookup the path to the translator or assume any default path?
• Is there any diagnostic provided if the translator not installed/found?
• How does clang synchronize with the translator versions i.e. some LLVM IR might not be ingested by certain version of the translator. Would this results in the translator ICE or error in the translator, or is it something that can be diagnosed early by clang or during clang build/installation?

[linjamaki]

In D110618#3148501, @Anastasia wrote:

Could you please clarify the interface to SPIRV-LLVM-Translator tool, specifically:

• Does clang lookup the path to the translator or assume any default path?

HIPSPV primarily relies on the system’s PATH for locating the translator.

Additionally, the translator is sought in the same directory where the Clang driver is installed in. This is rather a side-effect than a feature. The directory is added to Clang’s internal search paths for looking up the clang-offload-bundler tool required by the HIPSPV tool chain.

• Is there any diagnostic provided if the translator not installed/found?

Clang displays the following standard error if the translator is not found:

error: unable to execute command: Executable "llvm-spirv" doesn't exist!

• How does clang synchronize with the translator versions i.e. some LLVM IR might not be ingested by certain version of the translator. Would this results in the translator ICE or error in the translator, or is it something that can be diagnosed early by clang or during clang build/installation?

A version mismatch may result in an error in the translator. This is a known issue and a reason we want to switch to the SPIR-V backend when it lands on the LLVM - the translator is meant to be used temporarily by the HIPSPV. The synchronization could be improved by having the Clang to seek a SPIR-V Translator binary that is named with the LLVM version it has been built against - e.g. “llvm-spirv-14” for the next LLVM release.

AFAIK, Clang’s infrastructure does not support early diagnosis on external tools. The diagnosis during Clang’s build and installation probably won’t matter much if the Clang is distributed as binary to other systems - the destination system might not have the required translator version.

[linjamaki]

Disable debug info generation for device code.

[Anastasia]

In D110618#3152939, @linjamaki wrote:

In D110618#3148501, @Anastasia wrote:

Could you please clarify the interface to SPIRV-LLVM-Translator tool, specifically:

• Does clang lookup the path to the translator or assume any default path?

HIPSPV primarily relies on the system’s PATH for locating the translator.

Additionally, the translator is sought in the same directory where the Clang driver is installed in. This is rather a side-effect than a feature. The directory is added to Clang’s internal search paths for looking up the clang-offload-bundler tool required by the HIPSPV tool chain.

• Is there any diagnostic provided if the translator not installed/found?

Clang displays the following standard error if the translator is not found:

error: unable to execute command: Executable "llvm-spirv" doesn't exist!

• How does clang synchronize with the translator versions i.e. some LLVM IR might not be ingested by certain version of the translator. Would this results in the translator ICE or error in the translator, or is it something that can be diagnosed early by clang or during clang build/installation?

A version mismatch may result in an error in the translator. This is a known issue and a reason we want to switch to the SPIR-V backend when it lands on the LLVM - the translator is meant to be used temporarily by the HIPSPV. The synchronization could be improved by having the Clang to seek a SPIR-V Translator binary that is named with the LLVM version it has been built against - e.g. “llvm-spirv-14” for the next LLVM release.

AFAIK, Clang’s infrastructure does not support early diagnosis on external tools. The diagnosis during Clang’s build and installation probably won’t matter much if the Clang is distributed as binary to other systems - the destination system might not have the required translator version.

Alternatively, we could see if translator could emit a diagnostic by looking at the clang version emitted in metadata... I presume this might not be too hard to implement...

[linjamaki]

Rebase.

[linjamaki]

Rebase.

[linjamaki]

This patch should be ready to land. @tra, could you please commit this to the LLVM for us. Thanks.

[linjamaki]

Thanks, @tra.

clang/include/clang/Basic/DiagnosticDriverKinds.td

 def err_drv_no_rocm_device_lib : Error<
   "cannot find ROCm device library%select{| for %1}0; provide its path via "
   "'--rocm-path' or '--rocm-device-lib-path', or pass '-nogpulib' to build "
   "without ROCm device library">;
 def err_drv_no_hip_runtime : Error<
   "cannot find HIP runtime; provide its path via '--rocm-path', or pass "
   "'-nogpuinc' to build without HIP runtime">;
 
+def err_drv_no_hipspv_device_lib : Error<
+  "cannot find HIP device library%select{| for %1}0; provide its path via "
+  "'--hip-path' or '--hip-device-lib-path', or pass '-nogpulib' to build "
+  "without HIP device library">;
+def err_drv_hipspv_no_hip_path : Error<
+  "'--hip-path' must be specified when offloading to "
+  "SPIR-V%select{| unless %1 is given}0.">;
+
 def err_drv_undetermined_amdgpu_arch : Error<
   "cannot determine AMDGPU architecture: %0; consider passing it via "
   "'--march'">;
 def err_drv_cuda_version_unsupported : Error<
   "GPU arch %0 is supported by CUDA versions between %1 and %2 (inclusive), "
   "but installation at %3 is %4; use '--cuda-path' to specify a different CUDA "
   "install, pass a different GPU arch with '--cuda-gpu-arch', or pass "
   "'--no-cuda-version-check'">;

clang/include/clang/Driver/Options.td

defm hip_new_launch_api : BoolFOption<"hip-new-launch-api",
   BothFlags<[], " new kernel launching API for HIP">>;
 defm hip_fp32_correctly_rounded_divide_sqrt : BoolFOption<"hip-fp32-correctly-rounded-divide-sqrt",
   CodeGenOpts<"HIPCorrectlyRoundedDivSqrt">, DefaultTrue,
   PosFlag<SetTrue, [], "Specify">,
   NegFlag<SetFalse, [CC1Option], "Don't specify">,
   BothFlags<[], " that single precision floating-point divide and sqrt used in "
   "the program source are correctly rounded (HIP device compilation only)">>,
   ShouldParseIf<hip.KeyPath>;
+def hipspv_pass_plugin_EQ : Joined<["--"], "hipspv-pass-plugin=">,
+  Group<Link_Group>, MetaVarName<"<dsopath>">,
+  HelpText<"path to a pass plugin for HIP to SPIR-V passes.">;
 defm gpu_allow_device_init : BoolFOption<"gpu-allow-device-init",
   LangOpts<"GPUAllowDeviceInit">, DefaultFalse,
   PosFlag<SetTrue, [CC1Option], "Allow">, NegFlag<SetFalse, [], "Don't allow">,
   BothFlags<[], " device side init function in HIP (experimental)">>,
   ShouldParseIf<hip.KeyPath>;
 defm gpu_defer_diag : BoolFOption<"gpu-defer-diag",
   LangOpts<"GPUDeferDiag">, DefaultFalse,
   PosFlag<SetTrue, [CC1Option], "Defer">, NegFlag<SetFalse, [], "Don't defer">,

 def no_integrated_cpp : Flag<["-", "--"], "no-integrated-cpp">, Flags<[NoXarchOption]>;
 def no_pedantic : Flag<["-", "--"], "no-pedantic">, Group<pedantic_Group>;
 def no__dead__strip__inits__and__terms : Flag<["-"], "no_dead_strip_inits_and_terms">;
 def nobuiltininc : Flag<["-"], "nobuiltininc">, Flags<[CC1Option, CoreOption]>,
   HelpText<"Disable builtin #include directories">,
   MarshallingInfoNegativeFlag<HeaderSearchOpts<"UseBuiltinIncludes">>;
 def nogpuinc : Flag<["-"], "nogpuinc">, HelpText<"Do not add include paths for CUDA/HIP and"
   " do not include the default CUDA/HIP wrapper headers">;
+def nohipwrapperinc : Flag<["-"], "nohipwrapperinc">,
+  HelpText<"Do not include the default HIP wrapper headers and include paths">;
 def : Flag<["-"], "nocudainc">, Alias<nogpuinc>;
 def nogpulib : Flag<["-"], "nogpulib">,
   HelpText<"Do not link device library for CUDA/HIP device compilation">;
 def : Flag<["-"], "nocudalib">, Alias<nogpulib>;
 def nodefaultlibs : Flag<["-"], "nodefaultlibs">;
 def nofixprebinding : Flag<["-"], "nofixprebinding">;
 def nolibc : Flag<["-"], "nolibc">;
 def nomultidefs : Flag<["-"], "nomultidefs">;

clang/lib/Driver/CMakeLists.txt

add_clang_library(clangDriver
   ToolChains/DragonFly.cpp
   ToolChains/Flang.cpp
   ToolChains/FreeBSD.cpp
   ToolChains/Fuchsia.cpp
   ToolChains/Gnu.cpp
   ToolChains/Haiku.cpp
   ToolChains/HIPUtility.cpp
   ToolChains/HIPAMD.cpp
+  ToolChains/HIPSPV.cpp
   ToolChains/Hexagon.cpp
   ToolChains/Hurd.cpp
   ToolChains/Linux.cpp
   ToolChains/MipsLinux.cpp
   ToolChains/MinGW.cpp
   ToolChains/Minix.cpp
   ToolChains/MSP430.cpp
   ToolChains/MSVC.cpp

clang/lib/Driver/ToolChains/AMDGPU.cpp

 void RocmInstallationDetector::print(raw_ostream &OS) const {
   if (hasHIPRuntime())
     OS << "Found HIP installation: " << InstallPath << ", version "
        << DetectedVersion << '\n';
 }
 
 void RocmInstallationDetector::AddHIPIncludeArgs(const ArgList &DriverArgs,
                                                  ArgStringList &CC1Args) const {
-  bool UsesRuntimeWrapper = VersionMajorMinor > llvm::VersionTuple(3, 5);
+  bool UsesRuntimeWrapper = VersionMajorMinor > llvm::VersionTuple(3, 5) &&
+                            !DriverArgs.hasArg(options::OPT_nohipwrapperinc);
 
   if (!DriverArgs.hasArg(options::OPT_nobuiltininc)) {
     // HIP header includes standard library wrapper headers under clang
     // cuda_wrappers directory. Since these wrapper headers include_next
     // standard C++ headers, whereas libc++ headers include_next other clang
     // headers. The include paths have to follow this order:
     // - wrapper include path
     // - standard C++ include path

clang/lib/Driver/ToolChains/HIPSPV.h

+//===--- HIPSPV.h - HIP ToolChain Implementations ---------------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_CLANG_LIB_DRIVER_TOOLCHAINS_HIPSPV_H
+#define LLVM_CLANG_LIB_DRIVER_TOOLCHAINS_HIPSPV_H
+
+#include "SPIRV.h"
+#include "clang/Driver/Tool.h"
+#include "clang/Driver/ToolChain.h"
+
+namespace clang {
+namespace driver {
+namespace tools {
+namespace HIPSPV {
+
+// Runs llvm-link/opt/llc/lld, which links multiple LLVM bitcode, together with
+// device library, then compiles it to SPIR-V in a shared object.
+class LLVM_LIBRARY_VISIBILITY Linker : public Tool {
+public:
+  Linker(const ToolChain &TC) : Tool("HIPSPV::Linker", "hipspv-link", TC) {}
+
+  bool hasIntegratedCPP() const override { return false; }
+
+  void ConstructJob(Compilation &C, const JobAction &JA,
+                    const InputInfo &Output, const InputInfoList &Inputs,
+                    const llvm::opt::ArgList &TCArgs,
+                    const char *LinkingOutput) const override;
+
+private:
+  void constructLinkAndEmitSpirvCommand(Compilation &C, const JobAction &JA,
+                                        const InputInfoList &Inputs,
+                                        const InputInfo &Output,
+                                        const llvm::opt::ArgList &Args) const;
+};
+
+} // namespace HIPSPV
+} // namespace tools
+
+namespace toolchains {
+
+class LLVM_LIBRARY_VISIBILITY HIPSPVToolChain final : public ToolChain {
+public:
+  HIPSPVToolChain(const Driver &D, const llvm::Triple &Triple,
+                  const ToolChain &HostTC, const llvm::opt::ArgList &Args);
+
+  const llvm::Triple *getAuxTriple() const override {
+    return &HostTC.getTriple();
+  }
+
+  void
+  addClangTargetOptions(const llvm::opt::ArgList &DriverArgs,
+                        llvm::opt::ArgStringList &CC1Args,
+                        Action::OffloadKind DeviceOffloadKind) const override;
+  void addClangWarningOptions(llvm::opt::ArgStringList &CC1Args) const override;
+  CXXStdlibType GetCXXStdlibType(const llvm::opt::ArgList &Args) const override;
+  void
+  AddClangSystemIncludeArgs(const llvm::opt::ArgList &DriverArgs,
+                            llvm::opt::ArgStringList &CC1Args) const override;
+  void AddClangCXXStdlibIncludeArgs(
+      const llvm::opt::ArgList &Args,
+      llvm::opt::ArgStringList &CC1Args) const override;
+  void AddIAMCUIncludeArgs(const llvm::opt::ArgList &DriverArgs,
+                           llvm::opt::ArgStringList &CC1Args) const override;
+  void AddHIPIncludeArgs(const llvm::opt::ArgList &DriverArgs,
+                         llvm::opt::ArgStringList &CC1Args) const override;
+  llvm::SmallVector<BitCodeLibraryInfo, 12>
+  getHIPDeviceLibs(const llvm::opt::ArgList &Args) const override;
+
+  SanitizerMask getSupportedSanitizers() const override;
+
+  VersionTuple
+  computeMSVCVersion(const Driver *D,
+                     const llvm::opt::ArgList &Args) const override;
+
+  void adjustDebugInfoKind(codegenoptions::DebugInfoKind &DebugInfoKind,
+                           const llvm::opt::ArgList &Args) const override;
+  bool IsIntegratedAssemblerDefault() const override { return true; }
+  bool IsMathErrnoDefault() const override { return false; }
+  bool useIntegratedAs() const override { return true; }
+  bool isCrossCompiling() const override { return true; }
+  bool isPICDefault() const override { return false; }
+  bool isPIEDefault(const llvm::opt::ArgList &Args) const override {
+    return false;
+  }
+  bool isPICDefaultForced() const override { return false; }
+  bool SupportsProfiling() const override { return false; }
+
+  const ToolChain &HostTC;
+
+protected:
+  Tool *buildLinker() const override;
+};
+
+} // end namespace toolchains
+} // end namespace driver
+} // end namespace clang
+
+#endif // LLVM_CLANG_LIB_DRIVER_TOOLCHAINS_HIPSPV_H

clang/lib/Driver/ToolChains/HIPSPV.cpp

+//===--- HIPSPV.cpp - HIPSPV ToolChain Implementation -----------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "HIPSPV.h"
+#include "CommonArgs.h"
+#include "HIPUtility.h"
+#include "clang/Driver/Compilation.h"
+#include "clang/Driver/Driver.h"
+#include "clang/Driver/DriverDiagnostic.h"
+#include "clang/Driver/InputInfo.h"
+#include "clang/Driver/Options.h"
+#include "llvm/Support/FileSystem.h"
+#include "llvm/Support/Path.h"
+
+using namespace clang::driver;
+using namespace clang::driver::toolchains;
+using namespace clang::driver::tools;
+using namespace clang;
+using namespace llvm::opt;
+
+// Convenience function for creating temporary file for both modes of
+// isSaveTempsEnabled().
+static const char *getTempFile(Compilation &C, StringRef Prefix,
+                               StringRef Extension) {
+  if (C.getDriver().isSaveTempsEnabled()) {
+    return C.getArgs().MakeArgString(Prefix + "." + Extension);
+  }
+  auto TmpFile = C.getDriver().GetTemporaryPath(Prefix, Extension);
+  return C.addTempFile(C.getArgs().MakeArgString(TmpFile));
+}
+
+// Locates HIP pass plugin.
+static std::string findPassPlugin(const Driver &D,
+                                  const llvm::opt::ArgList &Args) {
+  StringRef Path = Args.getLastArgValue(options::OPT_hipspv_pass_plugin_EQ);
+  if (!Path.empty()) {
+    if (llvm::sys::fs::exists(Path))
+      return Path.str();
+    D.Diag(diag::err_drv_no_such_file) << Path;
+  }
+
+  StringRef hipPath = Args.getLastArgValue(options::OPT_hip_path_EQ);
+  if (!hipPath.empty()) {
+    SmallString<128> PluginPath(hipPath);
+    llvm::sys::path::append(PluginPath, "lib", "libLLVMHipSpvPasses.so");
+    if (llvm::sys::fs::exists(PluginPath))
+      return PluginPath.str().str();
+    PluginPath.assign(hipPath);
+    llvm::sys::path::append(PluginPath, "lib", "llvm",
+                            "libLLVMHipSpvPasses.so");
+    if (llvm::sys::fs::exists(PluginPath))
+      return PluginPath.str().str();
+  }
+
+  return std::string();
+}
+
+void HIPSPV::Linker::constructLinkAndEmitSpirvCommand(
+    Compilation &C, const JobAction &JA, const InputInfoList &Inputs,
+    const InputInfo &Output, const llvm::opt::ArgList &Args) const {
+
+  assert(!Inputs.empty() && "Must have at least one input.");
+  std::string Name = std::string(llvm::sys::path::stem(Output.getFilename()));
+  const char *TempFile = getTempFile(C, Name + "-link", "bc");
+
+  // Link LLVM bitcode.
+  ArgStringList LinkArgs{};
+  for (auto Input : Inputs)
+    LinkArgs.push_back(Input.getFilename());
+  LinkArgs.append({"-o", TempFile});
+  const char *LlvmLink =
+      Args.MakeArgString(getToolChain().GetProgramPath("llvm-link"));
+  C.addCommand(std::make_unique<Command>(JA, *this, ResponseFileSupport::None(),
+                                         LlvmLink, LinkArgs, Inputs, Output));
+
+  // Post-link HIP lowering.
+
+  // Run LLVM IR passes to lower/expand/emulate HIP code that does not translate
+  // to SPIR-V (E.g. dynamic shared memory).
+  auto PassPluginPath = findPassPlugin(C.getDriver(), Args);
+  if (!PassPluginPath.empty()) {
+    const char *PassPathCStr = C.getArgs().MakeArgString(PassPluginPath);
+    const char *OptOutput = getTempFile(C, Name + "-lower", "bc");
+    ArgStringList OptArgs{TempFile,     "-load-pass-plugin",
+                          PassPathCStr, "-passes=hip-post-link-passes",
+                          "-o",         OptOutput};
+    const char *Opt = Args.MakeArgString(getToolChain().GetProgramPath("opt"));
+    C.addCommand(std::make_unique<Command>(
+        JA, *this, ResponseFileSupport::None(), Opt, OptArgs, Inputs, Output));
+    TempFile = OptOutput;
+  }
+
+  // Emit SPIR-V binary.
+
+  llvm::opt::ArgStringList TrArgs{"--spirv-max-version=1.1",
+                                  "--spirv-ext=+all"};
+  InputInfo TrInput = InputInfo(types::TY_LLVM_BC, TempFile, "");
+  SPIRV::constructTranslateCommand(C, *this, JA, Output, TrInput, TrArgs);
+}
+
+void HIPSPV::Linker::ConstructJob(Compilation &C, const JobAction &JA,
+                                  const InputInfo &Output,
+                                  const InputInfoList &Inputs,
+                                  const ArgList &Args,
+                                  const char *LinkingOutput) const {
+  if (Inputs.size() > 0 && Inputs[0].getType() == types::TY_Image &&
+      JA.getType() == types::TY_Object)
+    return HIP::constructGenerateObjFileFromHIPFatBinary(C, Output, Inputs,
+                                                         Args, JA, *this);
+
+  if (JA.getType() == types::TY_HIP_FATBIN)
+    return HIP::constructHIPFatbinCommand(C, JA, Output.getFilename(), Inputs,
+                                          Args, *this);
+
+  constructLinkAndEmitSpirvCommand(C, JA, Inputs, Output, Args);
+}
+
+HIPSPVToolChain::HIPSPVToolChain(const Driver &D, const llvm::Triple &Triple,
+                                 const ToolChain &HostTC, const ArgList &Args)
+    : ToolChain(D, Triple, Args), HostTC(HostTC) {
+  // Lookup binaries into the driver directory, this is used to
+  // discover the clang-offload-bundler executable.
+  getProgramPaths().push_back(getDriver().Dir);
+}
+
+void HIPSPVToolChain::addClangTargetOptions(
+    const llvm::opt::ArgList &DriverArgs, llvm::opt::ArgStringList &CC1Args,
+    Action::OffloadKind DeviceOffloadingKind) const {
+  HostTC.addClangTargetOptions(DriverArgs, CC1Args, DeviceOffloadingKind);
+
+  assert(DeviceOffloadingKind == Action::OFK_HIP &&
+         "Only HIP offloading kinds are supported for GPUs.");
+
+  CC1Args.append(
+      {"-fcuda-is-device", "-fcuda-allow-variadic-functions",
+       // A crude workaround for llvm-spirv which does not handle the
+       // autovectorized code well (vector reductions, non-i{8,16,32,64} types).
+       // TODO: Allow autovectorization when SPIR-V backend arrives.
+       "-mllvm", "-vectorize-loops=false", "-mllvm", "-vectorize-slp=false"});
+
+  if (DriverArgs.hasFlag(options::OPT_fcuda_approx_transcendentals,
+                         options::OPT_fno_cuda_approx_transcendentals, false))
+    CC1Args.push_back("-fcuda-approx-transcendentals");
+
+  // Default to "hidden" visibility, as object level linking will not be
+  // supported for the foreseeable future.
+  if (!DriverArgs.hasArg(options::OPT_fvisibility_EQ,
+                         options::OPT_fvisibility_ms_compat))
+    CC1Args.append(
+        {"-fvisibility", "hidden", "-fapply-global-visibility-to-externs"});
+
+  llvm::for_each(getHIPDeviceLibs(DriverArgs),
+                 [&](const BitCodeLibraryInfo &BCFile) {
+                   CC1Args.append({"-mlink-builtin-bitcode",
+                                   DriverArgs.MakeArgString(BCFile.Path)});
+                 });
+}
+
+Tool *HIPSPVToolChain::buildLinker() const {
+  assert(getTriple().getArch() == llvm::Triple::spirv64);
+  return new tools::HIPSPV::Linker(*this);
+}
+
+void HIPSPVToolChain::addClangWarningOptions(ArgStringList &CC1Args) const {
+  HostTC.addClangWarningOptions(CC1Args);
+}
+
+ToolChain::CXXStdlibType
+HIPSPVToolChain::GetCXXStdlibType(const ArgList &Args) const {
+  return HostTC.GetCXXStdlibType(Args);
+}
+
+void HIPSPVToolChain::AddClangSystemIncludeArgs(const ArgList &DriverArgs,
+                                                ArgStringList &CC1Args) const {
+  HostTC.AddClangSystemIncludeArgs(DriverArgs, CC1Args);
+}
+
+void HIPSPVToolChain::AddClangCXXStdlibIncludeArgs(
+    const ArgList &Args, ArgStringList &CC1Args) const {
+  HostTC.AddClangCXXStdlibIncludeArgs(Args, CC1Args);
+}
+
+void HIPSPVToolChain::AddIAMCUIncludeArgs(const ArgList &Args,
+                                          ArgStringList &CC1Args) const {
+  HostTC.AddIAMCUIncludeArgs(Args, CC1Args);
+}
+
+void HIPSPVToolChain::AddHIPIncludeArgs(const ArgList &DriverArgs,
+                                        ArgStringList &CC1Args) const {
+  if (DriverArgs.hasArg(options::OPT_nogpuinc))
+    return;
+
+  StringRef hipPath = DriverArgs.getLastArgValue(options::OPT_hip_path_EQ);
+  if (hipPath.empty()) {
+    getDriver().Diag(diag::err_drv_hipspv_no_hip_path) << 1 << "'-nogpuinc'";
+    return;
+  }
+  SmallString<128> P(hipPath);
+  llvm::sys::path::append(P, "include");
+  CC1Args.append({"-isystem", DriverArgs.MakeArgString(P)});
+}
+
+llvm::SmallVector<ToolChain::BitCodeLibraryInfo, 12>
+HIPSPVToolChain::getHIPDeviceLibs(const llvm::opt::ArgList &DriverArgs) const {
+  llvm::SmallVector<ToolChain::BitCodeLibraryInfo, 12> BCLibs;
+  if (DriverArgs.hasArg(options::OPT_nogpulib))
+    return {};
+
+  ArgStringList LibraryPaths;
+  // Find device libraries in --hip-device-lib-path and HIP_DEVICE_LIB_PATH.
+  auto HipDeviceLibPathArgs = DriverArgs.getAllArgValues(
+      // --hip-device-lib-path is alias to this option.
+      clang::driver::options::OPT_rocm_device_lib_path_EQ);
+  for (auto Path : HipDeviceLibPathArgs)
+    LibraryPaths.push_back(DriverArgs.MakeArgString(Path));
+
+  StringRef HipPath = DriverArgs.getLastArgValue(options::OPT_hip_path_EQ);
+  if (!HipPath.empty()) {
+    SmallString<128> Path(HipPath);
+    llvm::sys::path::append(Path, "lib", "hip-device-lib");
+    LibraryPaths.push_back(DriverArgs.MakeArgString(Path));
+  }
+
+  addDirectoryList(DriverArgs, LibraryPaths, "", "HIP_DEVICE_LIB_PATH");
+
+  // Maintain compatability with --hip-device-lib.
+  auto BCLibArgs = DriverArgs.getAllArgValues(options::OPT_hip_device_lib_EQ);
+  if (!BCLibArgs.empty()) {
+    llvm::for_each(BCLibArgs, [&](StringRef BCName) {
+      StringRef FullName;
+      for (std::string LibraryPath : LibraryPaths) {
+        SmallString<128> Path(LibraryPath);
+        llvm::sys::path::append(Path, BCName);
+        FullName = Path;
+        if (llvm::sys::fs::exists(FullName)) {
+          BCLibs.emplace_back(FullName.str());
+          return;
+        }
+      }
+      getDriver().Diag(diag::err_drv_no_such_file) << BCName;
+    });
+  } else {
+    // Search device library named as 'hipspv-<triple>.bc'.
+    auto TT = getTriple().normalize();
+    std::string BCName = "hipspv-" + TT + ".bc";
+    for (auto *LibPath : LibraryPaths) {
+      SmallString<128> Path(LibPath);
+      llvm::sys::path::append(Path, BCName);
+      if (llvm::sys::fs::exists(Path)) {
+        BCLibs.emplace_back(Path.str().str());
+        return BCLibs;
+      }
+    }
+    getDriver().Diag(diag::err_drv_no_hipspv_device_lib)
+        << 1 << ("'" + TT + "' target");
+    return {};
+  }
+
+  return BCLibs;
+}
+
+SanitizerMask HIPSPVToolChain::getSupportedSanitizers() const {
+  // The HIPSPVToolChain only supports sanitizers in the sense that it allows
+  // sanitizer arguments on the command line if they are supported by the host
+  // toolchain. The HIPSPVToolChain will actually ignore any command line
+  // arguments for any of these "supported" sanitizers. That means that no
+  // sanitization of device code is actually supported at this time.
+  //
+  // This behavior is necessary because the host and device toolchains
+  // invocations often share the command line, so the device toolchain must
+  // tolerate flags meant only for the host toolchain.
+  return HostTC.getSupportedSanitizers();
+}
+
+VersionTuple HIPSPVToolChain::computeMSVCVersion(const Driver *D,
+                                                 const ArgList &Args) const {
+  return HostTC.computeMSVCVersion(D, Args);
+}
+
+void HIPSPVToolChain::adjustDebugInfoKind(
+    codegenoptions::DebugInfoKind &DebugInfoKind,
+    const llvm::opt::ArgList &Args) const {
+  // Debug info generation is disabled for SPIRV-LLVM-Translator
+  // which currently aborts on the presence of DW_OP_LLVM_convert.
+  // TODO: Enable debug info when the SPIR-V backend arrives.
+  DebugInfoKind = codegenoptions::NoDebugInfo;
+}