[SYCL][Driver][libdevice] Link libspirv in -fsycl-device-only mode (#19136)

<!-- start git-machete generated -->

# Based on PR #19135

## Chain of upstream PRs as of 2025-06-25

* PR #19130

  * PR #19131

    * PR #19134

      * PR #19135

        * **PR #19136 (THIS ONE)**

<!-- end git-machete generated -->

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

@@ -210,11 +210,6 @@ 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

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

@@ -95,13 +95,13 @@ set(full_build_archs)
 if ("NVPTX" IN_LIST LLVM_TARGETS_TO_BUILD)
   list(APPEND full_build_archs 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 full_build_archs 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()
 
@@ -435,7 +435,8 @@ if("native_cpu" IN_LIST SYCL_ENABLE_BACKENDS)
   # libsycl-nativecpu_utils is only needed as BC file by NativeCPU.
   add_custom_command(
     OUTPUT ${bc_binary_dir}/nativecpu_utils.bc
-    COMMAND ${clang_exe} ${compile_opts} ${bc_device_compile_opts} -fsycl-targets=native_cpu
+    COMMAND ${clang_exe} ${compile_opts} ${bc_device_compile_opts}
+      -fsycl-targets=native_cpu -fno-sycl-libspirv -Wno-unsafe-libspirv-not-linked
       -I ${PROJECT_BINARY_DIR}/include -I ${NATIVE_CPU_DIR}
       ${CMAKE_CURRENT_SOURCE_DIR}/nativecpu_utils.cpp
       -o ${bc_binary_dir}/nativecpu_utils.bc

sycl/test/check_device_code/math-builtins/cmath-spirv-mapping.cpp

@@ -2,7 +2,8 @@
 // Note: This isn't really target specific and should be switched to spir when
 // it's enabled for it.
 
-// RUN: %clangxx -fsycl -fsycl-targets=nvptx64-nvidia-cuda -S -Xclang -emit-llvm -fsycl-device-only %s -o - | FileCheck %s
+// RUN: %clangxx -fsycl -fsycl-targets=nvptx64-nvidia-cuda -S -Xclang -emit-llvm \
+// RUN:   -fsycl-device-only -fno-sycl-libspirv -Wno-unsafe-libspirv-not-linked %s -o - | FileCheck %s
 
 #include <cmath>
 

sycl/test/check_device_code/native_cpu/kernelhandler-scalar.cpp

@@ -1,4 +1,4 @@
-// RUN: %clangxx -fsycl-device-only  -fsycl-targets=native_cpu -Xclang -sycl-std=2020 -mllvm -sycl-opt -S -emit-llvm  -o %t_temp.ll %s
+// RUN: %clangxx -fsycl-device-only -fno-sycl-libspirv -Wno-unsafe-libspirv-not-linked  -fsycl-targets=native_cpu -Xclang -sycl-std=2020 -mllvm -sycl-opt -S -emit-llvm  -o %t_temp.ll %s
 // RUN: %clangxx -mllvm -sycl-native-cpu-backend -S -emit-llvm -o - %t_temp.ll | FileCheck %s
 #include <sycl/sycl.hpp>
 

sycl/test/check_device_code/native_cpu/native_cpu_subhandler.cpp

@@ -1,4 +1,4 @@
-// RUN: %clangxx -fsycl-device-only -O2 -g -fexceptions  -fsycl-targets=native_cpu -Xclang -sycl-std=2020 -mllvm -sycl-opt -S -emit-llvm  -o %t_temp.ll %s
+// RUN: %clangxx -fsycl-device-only -fno-sycl-libspirv -Wno-unsafe-libspirv-not-linked -O2 -g -fexceptions  -fsycl-targets=native_cpu -Xclang -sycl-std=2020 -mllvm -sycl-opt -S -emit-llvm  -o %t_temp.ll %s
 // RUN: %clangxx -mllvm -sycl-native-cpu-backend -S -emit-llvm -o - %t_temp.ll | FileCheck %s
 
 // Checks that the subhandler is correctly emitted in the module

sycl/test/check_device_code/native_cpu/offload-wrapper.cpp

@@ -1,6 +1,6 @@
 // This test checks the output for the clang-offload-wrapper for the Native CPU
 // target:
-// RUN: %clangxx -fsycl-device-only -fsycl-targets=native_cpu %s -o %t.bc
+// RUN: %clangxx -fsycl-device-only -fno-sycl-libspirv -Wno-unsafe-libspirv-not-linked -fsycl-targets=native_cpu %s -o %t.bc
 // RUN: sycl-post-link -properties -emit-param-info -symbols -emit-exported-symbols -O2 -spec-const=native -device-globals -o %t.table %t.bc
 // RUN: clang-offload-wrapper -o=%t_wrap.bc -host=x86_64-unknown-linux-gnu -target=native_cpu -kind=sycl -batch %t.table
 // RUN: llvm-dis %t_wrap.bc -o - | FileCheck %s