[SYCL][Driver][libdevice] Link libspirv in -fsycl-device-only mode

Previously, the `-fsycl-device-only` mode disabled linking libspirv.

`-fsycl-device-only` should produce the same LLVM-IR as `-fsycl` would,
but without any host actions.

Libdevice is the likely reason why this was done as is, but it should
not be the default. This patch changes libdevice options to disable
libspirv linking there, and enables linking by default in
`-fsycl-device-only` mode.

Author: Maetveis

clang/lib/Driver/ToolChains/SYCL.cpp

@@ -209,11 +209,6 @@ const char *SYCLInstallationDetector::findLibspirvPath(
 void SYCLInstallationDetector::addLibspirvLinkArgs(
     const llvm::Triple &DeviceTriple, const llvm::opt::ArgList &DriverArgs,
     const llvm::Triple &HostTriple, llvm::opt::ArgStringList &CC1Args) const {
-  DriverArgs.claimAllArgs(options::OPT_fno_sycl_libspirv);
-
-  if (D.offloadDeviceOnly())
-    return;
-
   if (DriverArgs.hasArg(options::OPT_fno_sycl_libspirv)) {
     // -fno-sycl-libspirv flag is reserved for very unusual cases where the
     // libspirv library is not linked when required by the device: so output appropriate

clang/test/Driver/sycl-libspirv-toolchain.cpp

@@ -21,8 +21,7 @@
 //
 // RUN: %clang -### -fsycl -fsycl-device-only -fsycl-targets=nvptx64-nvidia-cuda -nocudalib %s 2>&1 \
 // RUN: | FileCheck %s --check-prefixes=CHECK-DEVICE-ONLY
-// CHECK-DEVICE-ONLY: "-cc1"{{.*}} "-fsycl-is-device"
-// CHECK-DEVICE-ONLY-NOT: "-mlink-builtin-bitcode" "{{.*}}.libspirv-{{.*}}.bc"
+// CHECK-DEVICE-ONLY: "-cc1"{{.*}} "-fsycl-is-device"{{.*}} "-mlink-builtin-bitcode" "{{.*[\\/]}}remangled-{{.*}}.libspirv-nvptx64-nvidia-cuda.bc"
 //
 // Only link libspirv in SYCL language mode, `-fno-sycl-libspirv` should result in a warning
 // RUN: %clang -### -x cu -fno-sycl-libspirv -nocudainc -nocudalib %s 2>&1 | FileCheck %s --check-prefixes=CHECK-CUDA

libdevice/cmake/modules/SYCLLibdevice.cmake

@@ -82,13 +82,13 @@ set(devicelib_arch)
 if ("NVPTX" IN_LIST LLVM_TARGETS_TO_BUILD)
   list(APPEND devicelib_arch nvptx64-nvidia-cuda)
   set(compile_opts_nvptx64-nvidia-cuda "-fsycl-targets=nvptx64-nvidia-cuda"
-  "-Xsycl-target-backend" "--cuda-gpu-arch=sm_50" "-nocudalib")
+  "-Xsycl-target-backend" "--cuda-gpu-arch=sm_50" "-nocudalib" "-fno-sycl-libspirv" "-Wno-unsafe-libspirv-not-linked")
   set(opt_flags_nvptx64-nvidia-cuda "-O3" "--nvvm-reflect-enable=false")
 endif()
 if("AMDGPU" IN_LIST LLVM_TARGETS_TO_BUILD)
   list(APPEND devicelib_arch amdgcn-amd-amdhsa)
   set(compile_opts_amdgcn-amd-amdhsa "-nogpulib" "-fsycl-targets=amdgcn-amd-amdhsa"
-  "-Xsycl-target-backend" "--offload-arch=gfx942")
+  "-Xsycl-target-backend" "--offload-arch=gfx942" "-fno-sycl-libspirv" "-Wno-unsafe-libspirv-not-linked")
   set(opt_flags_amdgcn-amd-amdhsa "-O3" "--amdgpu-oclc-reflect-enable=false")
 endif()