[libc] Remove workarounds for lack of functional NVPTX linker (#96972)

Summary:
Currently we have several hacks to work around the fact that the NVPTX
linker, 'nvlink', does not support static libraries or LTO linking.
The patch in #96561 introduces
a wrapper in the toolchain that allows us to use a standard `ld.lld`
like interface. This means all the divergence with this target can be
removed.

Depends on #96561

Author: jhuber6

libc/cmake/modules/LLVMLibCObjectRules.cmake

@@ -65,25 +65,6 @@ function(create_object_library fq_target_name)
   target_include_directories(${fq_target_name} PRIVATE ${LIBC_SOURCE_DIR})
   target_compile_options(${fq_target_name} PRIVATE ${compile_options})
 
-  # The NVPTX target is installed as LLVM-IR but the internal testing toolchain
-  # cannot handle it natively. Make a separate internal target for testing.
-  if(LIBC_TARGET_ARCHITECTURE_IS_NVPTX AND NOT LIBC_GPU_TESTS_DISABLED)
-    add_library(
-      ${internal_target_name}
-      EXCLUDE_FROM_ALL
-      OBJECT
-      ${ADD_OBJECT_SRCS}
-      ${ADD_OBJECT_HDRS}
-    )
-    target_include_directories(${internal_target_name} SYSTEM PRIVATE ${LIBC_INCLUDE_DIR})
-    target_include_directories(${internal_target_name} PRIVATE ${LIBC_SOURCE_DIR})
-    target_compile_options(${internal_target_name} PRIVATE ${compile_options}
-                           -fno-lto -march=${LIBC_GPU_TARGET_ARCHITECTURE})
-    set_target_properties(${internal_target_name}
-                          PROPERTIES
-                          CXX_STANDARD ${ADD_OBJECT_CXX_STANDARD})
-  endif()
-
   if(SHOW_INTERMEDIATE_OBJECTS)
     message(STATUS "Adding object library ${fq_target_name}")
     if(${SHOW_INTERMEDIATE_OBJECTS} STREQUAL "DEPS")
@@ -283,12 +264,6 @@ function(create_entrypoint_object fq_target_name)
   add_dependencies(${internal_target_name} ${full_deps_list})
   target_link_libraries(${internal_target_name} ${full_deps_list})
 
-  # The NVPTX target cannot use LTO for the internal targets used for testing.
-  if(LIBC_TARGET_ARCHITECTURE_IS_NVPTX)
-    target_compile_options(${internal_target_name} PRIVATE
-                           -fno-lto -march=${LIBC_GPU_TARGET_ARCHITECTURE})
-  endif()
-
   add_library(
     ${fq_target_name}
     # We want an object library as the objects will eventually get packaged into

libc/cmake/modules/LLVMLibCTestRules.cmake

@@ -453,8 +453,6 @@ function(add_integration_test test_name)
   add_executable(
     ${fq_build_target_name}
     EXCLUDE_FROM_ALL
-    # The NVIDIA 'nvlink' linker does not currently support static libraries.
-    $<$<BOOL:${LIBC_TARGET_ARCHITECTURE_IS_NVPTX}>:${link_object_files}>
     ${INTEGRATION_TEST_SRCS}
     ${INTEGRATION_TEST_HDRS}
   )
@@ -473,8 +471,6 @@ function(add_integration_test test_name)
       "-Wl,-mllvm,-amdgpu-lower-global-ctor-dtor=0" -nostdlib -static
       "-Wl,-mllvm,-amdhsa-code-object-version=${LIBC_GPU_CODE_OBJECT_VERSION}")
   elseif(LIBC_TARGET_ARCHITECTURE_IS_NVPTX)
-    # We need to use the internal object versions for NVPTX.
-    set(internal_suffix ".__internal__")
     target_link_options(${fq_build_target_name} PRIVATE
       ${LIBC_COMPILE_OPTIONS_DEFAULT} -Wno-multi-gpu
       "-Wl,--suppress-stack-size-warning"
@@ -490,10 +486,9 @@ function(add_integration_test test_name)
   endif()
   target_link_libraries(
     ${fq_build_target_name}
-    # The NVIDIA 'nvlink' linker does not currently support static libraries.
-    $<$<NOT:$<BOOL:${LIBC_TARGET_ARCHITECTURE_IS_NVPTX}>>:${fq_target_name}.__libc__>
-    libc.startup.${LIBC_TARGET_OS}.crt1${internal_suffix}
-    libc.test.IntegrationTest.test${internal_suffix}
+    ${fq_target_name}.__libc__
+    libc.startup.${LIBC_TARGET_OS}.crt1
+    libc.test.IntegrationTest.test
   )
   add_dependencies(${fq_build_target_name}
                    libc.test.IntegrationTest.test
@@ -628,8 +623,6 @@ function(add_libc_hermetic test_name)
   add_executable(
     ${fq_build_target_name}
     EXCLUDE_FROM_ALL
-    # The NVIDIA 'nvlink' linker does not currently support static libraries.
-    $<$<BOOL:${LIBC_TARGET_ARCHITECTURE_IS_NVPTX}>:${link_object_files}>
     ${HERMETIC_TEST_SRCS}
     ${HERMETIC_TEST_HDRS}
   )
@@ -656,13 +649,12 @@ function(add_libc_hermetic test_name)
 
   if(LIBC_TARGET_ARCHITECTURE_IS_AMDGPU)
     target_link_options(${fq_build_target_name} PRIVATE
-      ${LIBC_COMPILE_OPTIONS_DEFAULT}
-      -mcpu=${LIBC_GPU_TARGET_ARCHITECTURE} -flto -Wno-multi-gpu
+      ${LIBC_COMPILE_OPTIONS_DEFAULT} -Wno-multi-gpu
+      -mcpu=${LIBC_GPU_TARGET_ARCHITECTURE} -flto
+      "-Wl,-asdfasdfasdf"
       "-Wl,-mllvm,-amdgpu-lower-global-ctor-dtor=0" -nostdlib -static
       "-Wl,-mllvm,-amdhsa-code-object-version=${LIBC_GPU_CODE_OBJECT_VERSION}")
   elseif(LIBC_TARGET_ARCHITECTURE_IS_NVPTX)
-    # We need to use the internal object versions for NVPTX.
-    set(internal_suffix ".__internal__")
     target_link_options(${fq_build_target_name} PRIVATE
       ${LIBC_COMPILE_OPTIONS_DEFAULT} -Wno-multi-gpu
       "-Wl,--suppress-stack-size-warning"
@@ -679,11 +671,10 @@ function(add_libc_hermetic test_name)
   target_link_libraries(
     ${fq_build_target_name}
     PRIVATE
-      libc.startup.${LIBC_TARGET_OS}.crt1${internal_suffix}
+      libc.startup.${LIBC_TARGET_OS}.crt1
       ${link_libraries}
       LibcHermeticTestSupport.hermetic
-      # The NVIDIA 'nvlink' linker does not currently support static libraries.
-      $<$<NOT:$<BOOL:${LIBC_TARGET_ARCHITECTURE_IS_NVPTX}>>:${fq_target_name}.__libc__>)
+      ${fq_target_name}.__libc__)
   add_dependencies(${fq_build_target_name}
                    LibcTest.hermetic
                    libc.test.UnitTest.ErrnoSetterMatcher

libc/config/gpu/entrypoints.txt

@@ -1,3 +1,13 @@
+if(LIBC_TARGET_ARCHITECTURE_IS_AMDGPU)
+  set(extra_entrypoints
+      # stdio.h entrypoints
+      libc.src.stdio.snprintf
+      libc.src.stdio.sprintf
+      libc.src.stdio.vsnprintf
+      libc.src.stdio.vsprintf
+  )
+endif()
+
 set(TARGET_LIBC_ENTRYPOINTS
     # assert.h entrypoints
     libc.src.assert.__assert_fail
@@ -176,16 +186,13 @@ set(TARGET_LIBC_ENTRYPOINTS
     libc.src.errno.errno
 
     # stdio.h entrypoints
+    ${extra_entrypoints}
     libc.src.stdio.clearerr
     libc.src.stdio.fclose
     libc.src.stdio.printf
     libc.src.stdio.vprintf
     libc.src.stdio.fprintf
     libc.src.stdio.vfprintf
-    libc.src.stdio.sprintf
-    libc.src.stdio.snprintf
-    libc.src.stdio.vsprintf
-    libc.src.stdio.vsnprintf
     libc.src.stdio.feof
     libc.src.stdio.ferror
     libc.src.stdio.fflush

libc/test/UnitTest/CMakeLists.txt

@@ -11,17 +11,10 @@ function(add_unittest_framework_library name)
                         "header only libraries, use 'add_header_library'")
   endif()
 
-  # The Nvidia 'nvlink' linker does not support static libraries.
-  if(LIBC_TARGET_ARCHITECTURE_IS_NVPTX)
-    set(library_type OBJECT)
-  else()
-    set(library_type STATIC)
-  endif()
-
   foreach(lib IN ITEMS ${name}.unit ${name}.hermetic)
     add_library(
       ${lib}
-      ${library_type}
+      STATIC
       EXCLUDE_FROM_ALL
       ${TEST_LIB_SRCS}
       ${TEST_LIB_HDRS}