[New offloading model][SPIR-V backend] Add SPIR-V backend support inside clang-sycl-linker

buildbot/configure.py

@@ -46,7 +46,7 @@ def do_configure(args):
     xptifw_dir = os.path.join(abs_src_dir, "xptifw")
     libdevice_dir = os.path.join(abs_src_dir, "libdevice")
     jit_dir = os.path.join(abs_src_dir, "sycl-jit")
-    llvm_targets_to_build = args.host_target
+    llvm_targets_to_build = "SPIRV;" + args.host_target
     llvm_enable_projects = "clang;" + llvm_external_projects
     libclc_build_native = "OFF"
     libclc_targets_to_build = ""

clang/include/clang/Driver/Options.td

@@ -6919,6 +6919,10 @@ def fsycl_host_only : Flag<["-"], "fsycl-host-only">,
 def sycl_link : Flag<["--"], "sycl-link">, Flags<[HelpHidden]>,
   HelpText<"Perform link through clang-sycl-linker via the target "
   "offloading toolchain.">;
+def sycl_use_spirv_backend
+    : Flag<["--"], "sycl-use-spirv-backend">,
+      Flags<[HelpHidden]>,
+      HelpText<"Use SPIR-V backend for LLVM to SPIR-V translation.">;
 defm sycl_early_optimizations :
   OptOutCC1FFlag<"sycl-early-optimizations", "Enable", "Disable", " standard "
                  "optimization pipeline for SYCL device compiler",

clang/lib/Driver/ToolChains/SPIRV.cpp

@@ -137,6 +137,8 @@ void SPIRV::Linker::ConstructJob(Compilation &C, const JobAction &JA,
 
   CmdArgs.push_back("-o");
   CmdArgs.push_back(Output.getFilename());
+  if (Args.hasArg(options::OPT_sycl_use_spirv_backend))
+    CmdArgs.push_back("-use-spirv-backend");
 
   // Use of --sycl-link will call the clang-sycl-linker instead of
   // the default linker (spirv-link).

clang/test/Driver/clang-sycl-linker-test.cpp

@@ -46,3 +46,8 @@
 // RUN: clang-sycl-linker --dry-run -triple spirv64  %t_1.bc %t_2.bc -o a.spv 2>&1 \
 // RUN:   | FileCheck %s --check-prefix=LLVMOPTSLIN
 // LLVMOPTSLIN: -spirv-debug-info-version=nonsemantic-shader-200 -spirv-allow-unknown-intrinsics=llvm.genx. -spirv-ext=
+
+// Test if SPIR-V backend is called when -use-spirv-backend is specified.
+// RUN: clang-sycl-linker --dry-run -use-spirv-backend %t_1.bc -o a.spv 2>&1 \
+// RUN:   | FileCheck %s --check-prefix=SPV-BACKEND
+// SPV-BACKEND: LLVM-SPIRV-Backend: input: {{.*}}, output: {{.*}}

clang/test/Driver/sycl-link-spirv-target.cpp

@@ -7,3 +7,8 @@
 // RUN:   -Xlinker --library-path=/tmp -Xlinker --device-libs=lib1.bc,lib2.bc %t.bc 2>&1 \
 // RUN:   | FileCheck %s -check-prefix=XLINKEROPTS
 // XLINKEROPTS: "{{.*}}clang-sycl-linker{{.*}}" "--llvm-spirv-path=/tmp" "--library-path=/tmp" "--device-libs=lib1.bc,lib2.bc" "{{.*}}.bc" "-o" "a.out"
+
+// Test that -use-spirv-backend option is being passed to clang-sycl-linker, when -sycl-use-spirv-backend is specified.
+// RUN: %clangxx -### --target=spirv64 --sycl-link --sycl-use-spirv-backend %t.bc 2>&1 \
+// RUN:   | FileCheck %s -check-prefix=SPIRV_BACKEND
+// SPIRV_BACKEND: "{{.*}}clang-sycl-linker{{.*}}" "{{.*}}.bc" "-o" "a.out" "-use-spirv-backend"

clang/tools/clang-sycl-linker/ClangSYCLLinker.cpp

@@ -16,6 +16,7 @@
 
 #include "clang/Basic/Version.h"
 
+#include "../../llvm/lib/Target/SPIRV/SPIRVAPI.h"
 #include "llvm/ADT/StringExtras.h"
 #include "llvm/BinaryFormat/Magic.h"
 #include "llvm/Bitcode/BitcodeWriter.h"
@@ -423,6 +424,63 @@ static Expected<StringRef> runLLVMToSPIRVTranslation(StringRef File,
   return OutputFile;
 }
 
+/// Run LLVM to SPIR-V translation.
+/// Converts 'File' from LLVM bitcode to SPIR-V format using SPIR-V backend,
+/// 'Args' encompasses all arguments required for linking device code and will
+/// be parsed to generate options required to be passed into the backend.
+static Expected<StringRef> runLLVMSPIRVBackend(StringRef File,
+                                               const ArgList &Args) {
+  llvm::TimeTraceScope TimeScope("LLVMToSPIRVTranslationViaSPIRVBackend");
+  std::vector<std::string> ExtNames, Opts;
+  if (Verbose || DryRun) {
+    errs() << formatv("LLVM-SPIRV-Backend: input: {0}, output: {1}\n", File,
+                      OutputFile);
+    if (DryRun)
+      return OutputFile;
+  }
+  SMDiagnostic Err;
+  LLVMContext C;
+  std::unique_ptr<Module> M = parseIRFile(File, Err, C);
+  if (!M)
+    return createStringError(inconvertibleErrorCode(), Err.getMessage());
+
+  static const std::string DefaultTriple = "spirv64v1.6-unknown-unknown";
+
+  // Correct the Triple value if needed
+  // TODO: Remove this correction once we start using spirv64/spirv32 triples
+  // everywhere.
+  Triple TargetTriple(M->getTargetTriple());
+  if (TargetTriple.isSPIR()) {
+    TargetTriple.setArch(TargetTriple.getArch() == Triple::spir64
+                             ? Triple::spirv64
+                             : Triple::spirv32,
+                         TargetTriple.getSubArch());
+    M->setTargetTriple(TargetTriple.str());
+    // We need to reset Data Layout to conform with the TargetMachine
+    M->setDataLayout("");
+  }
+  if (TargetTriple.getTriple().empty())
+    TargetTriple.setTriple(DefaultTriple);
+  TargetTriple.setArch(TargetTriple.getArch(), Triple::SPIRVSubArch_v16);
+  M->setTargetTriple(TargetTriple.str());
+
+  int FD = -1;
+  if (std::error_code EC = sys::fs::openFileForWrite(OutputFile, FD))
+    return errorCodeToError(EC);
+  auto OS = std::make_unique<llvm::raw_fd_ostream>(FD, true);
+
+  std::string Result, ErrMsg;
+  // List of allowed extensions. Currently, all extensions are allowed.
+  // TODO: Update list of allowed extensions for SYCL compilation flow.
+  static const std::vector<std::string> AllowExtNames{"all"};
+  // Translate the Module into SPIR-V
+  if (!SPIRVTranslateModule(M.release(), Result, ErrMsg, AllowExtNames, {}))
+    return createStringError(
+        "SPIRVTranslation: SPIRV translation failed with " + ErrMsg);
+  *OS << Result;
+  return OutputFile;
+}
+
 Error runSYCLLink(ArrayRef<std::string> Files, const ArgList &Args) {
   llvm::TimeTraceScope TimeScope("SYCLDeviceLink");
   // First llvm-link step
@@ -436,7 +494,9 @@ Error runSYCLLink(ArrayRef<std::string> Files, const ArgList &Args) {
     reportError(DeviceLinkedFile.takeError());
 
   // LLVM to SPIR-V translation step
-  auto SPVFile = runLLVMToSPIRVTranslation(*DeviceLinkedFile, Args);
+  auto SPVFile = Args.hasArg(OPT_use_spirv_backend)
+                     ? runLLVMSPIRVBackend(*DeviceLinkedFile, Args)
+                     : runLLVMToSPIRVTranslation(*DeviceLinkedFile, Args);
   if (!SPVFile)
     return SPVFile.takeError();
   return Error::success();

clang/tools/clang-sycl-linker/SYCLLinkOpts.td

@@ -50,3 +50,9 @@ def llvm_spirv_path_EQ : Joined<["--"], "llvm-spirv-path=">,
 def llvm_spirv_options_EQ : Joined<["--", "-"], "llvm-spirv-options=">,
   Flags<[LinkerOnlyOption]>,
   HelpText<"Options that will control llvm-spirv step">;
+
+// TODO: Option will be removed when llvm-spirv translator is removed
+def use_spirv_backend : Flag<["--", "-"], "use-spirv-backend">,
+                        Flags<[LinkerOnlyOption]>,
+                        HelpText<"Use the SPIR-V backend for LLVM to SPIR-V "
+                                 "translation. Off by default">;

sycl/CMakeLists.txt

@@ -378,6 +378,7 @@ add_custom_target(sycl-compiler
           clang-offload-extract
           clang-offload-packager
           clang-linker-wrapper
+          clang-sycl-linker
           file-table-tform
           llc
           llvm-ar
@@ -461,6 +462,7 @@ set( SYCL_TOOLCHAIN_DEPLOY_COMPONENTS
      clang-offload-extract
      clang-offload-packager
      clang-linker-wrapper
+     clang-sycl-linker
      file-table-tform
      llc
      llvm-ar