[libc] Can build amdgpu libc even if rocm is missing

[JonChesterfield]

Summary

Clang defaults to failing to build if it can't find rocm device libs

[jhuber6]

This should be present in _get_common_compile_options and always passed in. Which scenario is it not present?

[JonChesterfield]

• more

[jhuber6]

LG after addressing comments.

Never caught this because if you can build the tests you presumably had HSA. But we definitely don't want vendor libraries for these builds, thanks.

libc/cmake/modules/LLVMLibCObjectRules.cmake

154 ↗

(On Diff #533734)

Redundant.

libc/cmake/modules/LLVMLibCTestRules.cmake

578

Add here as well for NVPTX.

[JonChesterfield]

• drop first attempt

[JonChesterfield]

• nvptx as well

[JonChesterfield]

This shows up if you've built / installed HSA but rocm device libs is refusing to build with trunk and you've chosen against trying to patch it up locally.

[JonChesterfield]

• more

libc/cmake/modules/LLVMLibCTestRules.cmake

PRIVATE
       ${LIBC_BUILD_DIR}
       ${LIBC_BUILD_DIR}/include
   )
   target_compile_options(${fq_build_target_name}
       PRIVATE -fpie -ffreestanding -fno-exceptions -fno-rtti ${INTEGRATION_TEST_COMPILE_OPTIONS})
   # The GPU build requires overriding the default CMake triple and architecture.
   if(LIBC_GPU_TARGET_ARCHITECTURE_IS_AMDGPU)
     target_compile_options(${fq_build_target_name} PRIVATE
-                           -mcpu=${LIBC_GPU_TARGET_ARCHITECTURE}
+                           -nogpulib -mcpu=${LIBC_GPU_TARGET_ARCHITECTURE}
                            -flto --target=${LIBC_GPU_TARGET_TRIPLE})
   elseif(LIBC_GPU_TARGET_ARCHITECTURE_IS_NVPTX)
     get_nvptx_compile_options(nvptx_options ${LIBC_GPU_TARGET_ARCHITECTURE})
     target_compile_options(${fq_build_target_name} PRIVATE
-                           ${nvptx_options} -fno-use-cxa-atexit
+                           -nogpulib ${nvptx_options} -fno-use-cxa-atexit
                            --target=${LIBC_GPU_TARGET_TRIPLE})
   endif()
 
   target_link_options(${fq_build_target_name} PRIVATE -nostdlib -static)
   target_link_libraries(
     ${fq_build_target_name}
     # The NVIDIA 'nvlink' linker does not currently support static libraries.
     $<$<NOT:$<BOOL:${LIBC_GPU_TARGET_ARCHITECTURE_IS_NVPTX}>>:${fq_target_name}.__libc__>
function(add_integration_test test_name)
   add_dependencies(${INTEGRATION_TEST_SUITE} ${fq_target_name})
 endfunction(add_integration_test)
 
 set(LIBC_HERMETIC_TEST_COMPILE_OPTIONS ${LIBC_COMPILE_OPTIONS_DEFAULT}
     -fpie -ffreestanding -fno-exceptions -fno-rtti)
 # The GPU build requires overriding the default CMake triple and architecture.
 if(LIBC_GPU_TARGET_ARCHITECTURE_IS_AMDGPU)
   list(APPEND LIBC_HERMETIC_TEST_COMPILE_OPTIONS
-       -mcpu=${LIBC_GPU_TARGET_ARCHITECTURE} -flto --target=${LIBC_GPU_TARGET_TRIPLE})
+       -nogpulib -mcpu=${LIBC_GPU_TARGET_ARCHITECTURE} -flto --target=${LIBC_GPU_TARGET_TRIPLE})
 elseif(LIBC_GPU_TARGET_ARCHITECTURE_IS_NVPTX)
   get_nvptx_compile_options(nvptx_options ${LIBC_GPU_TARGET_ARCHITECTURE})
   list(APPEND LIBC_HERMETIC_TEST_COMPILE_OPTIONS
-       ${nvptx_options} -fno-use-cxa-atexit --target=${LIBC_GPU_TARGET_TRIPLE})
+       -nogpulib ${nvptx_options} -fno-use-cxa-atexit --target=${LIBC_GPU_TARGET_TRIPLE})
 endif()
 
 # Rule to add a hermetic test. A hermetic test is one whose executable is fully
 # statically linked and consists of pieces drawn only from LLVM's libc. Nothing,
 # including the startup objects, come from the system libc.
 #
 # Usage:
 #   add_libc_hermetic_test(