[LLVM] Replace use of LLVM_RUNTIMES_TARGET with LLVM_DEFAULT_TARGET_TRIPLE (#188303)

Summary:
This PR primarily changes using `LLVM_RUNTIMES_TARGET` to
`LLVM_DEFAULT_TARGET_TRIPLE`. The reason is that the default target
triple is the true cross-compiling architecture we are using, while the
runtimes_target can contain multilib strings like `+debug` or similar.

Additionally add the proper path handling to the OpenMP / Offload
libraries.

flang-rt/CMakeLists.txt

@@ -139,7 +139,6 @@ cmake_path(NORMAL_PATH FLANG_RT_INSTALL_RESOURCE_LIB_PATH)
 # Important: flang-rt user options must be prefixed with "FLANG_RT_". Variables
 # with this prefix will be forwarded in bootstrap builds.
 
-
 # Provide an interface to link against the LLVM libc/libc++ projects directly.
 set(FLANG_RT_SUPPORTED_PROVIDERS system llvm)
 set(FLANG_RT_LIBC_PROVIDER "system" CACHE STRING "Specify C library to use. Supported values are ${FLANG_RT_SUPPORTED_PROVIDERS}.")
@@ -169,7 +168,7 @@ endif ()
 
 # TODO: Support tests for the GPU target.
 set(FLANG_RT_INCLUDE_TESTS_default ${LLVM_INCLUDE_TESTS})
-if ("${LLVM_RUNTIMES_TARGET}" MATCHES "^amdgcn|^nvptx")
+if ("${LLVM_DEFAULT_TARGET_TRIPLE}" MATCHES "^amdgcn|^nvptx")
   set(FLANG_RT_INCLUDE_TESTS_default OFF)
 elseif (NOT FLANG_RT_ENABLE_STATIC AND NOT FLANG_RT_ENABLE_SHARED)
   set(FLANG_RT_INCLUDE_TESTS_default OFF)
@@ -268,7 +267,7 @@ find_package(Threads)
 # FIXME: The NVPTX target will erroneously report it has backtrace support. This
 #        is caused by using "-c -flto" in the required flags to suppress CUDA
 #        tools from being required for the CMake flag checks to succeed.
-if (NOT "${LLVM_RUNTIMES_TARGET}" MATCHES "^nvptx")
+if (NOT "${LLVM_DEFAULT_TARGET_TRIPLE}" MATCHES "^nvptx")
   find_package(Backtrace)
 endif()
 set(HAVE_BACKTRACE ${Backtrace_FOUND})

flang-rt/README.md

@@ -112,11 +112,10 @@ The `CMAKE_Fortran_COMPILER_WORKS` parameter must be set because otherwise CMake
 will test whether the Fortran compiler can compile and link programs which will
 obviously fail without a runtime library available yet.
 
-Building Flang-RT for cross-compilation triple, the target triple can
-be selected using `LLVM_DEFAULT_TARGET_TRIPLE` AND `LLVM_RUNTIMES_TARGET`.
-Of course, Flang-RT can be built multiple times with different build
-configurations, but have to be located manually when using with the Flang
-driver using the `-L` option.
+Building Flang-RT for cross-compilation triple, the target triple can be
+selected using `LLVM_DEFAULT_TARGET_TRIPLE`. Of course, Flang-RT can be built
+multiple times with different build configurations, but have to be located
+manually when using with the Flang driver using the `-L` option.
 
 After configuration, build, test, and install the runtime via
 

flang-rt/cmake/modules/AddFlangRT.cmake

@@ -266,11 +266,11 @@ function (add_flangrt_library name)
     endif ()
 
     # Add target specific options if necessary.
-    if ("${LLVM_RUNTIMES_TARGET}" MATCHES "^amdgcn")
+    if ("${LLVM_DEFAULT_TARGET_TRIPLE}" MATCHES "^amdgcn")
       target_compile_options(${tgtname} PRIVATE
           $<$<COMPILE_LANGUAGE:CXX>:-nogpulib -flto -fvisibility=hidden>
         )
-    elseif ("${LLVM_RUNTIMES_TARGET}" MATCHES "^nvptx")
+    elseif ("${LLVM_DEFAULT_TARGET_TRIPLE}" MATCHES "^nvptx")
       target_compile_options(${tgtname} PRIVATE
           $<$<COMPILE_LANGUAGE:CXX>:-nogpulib -flto -fvisibility=hidden -Wno-unknown-cuda-version --cuda-feature=+ptx63>
         )

flang-rt/lib/runtime/CMakeLists.txt

@@ -188,7 +188,7 @@ if (TARGET FortranFloat128MathILib)
   endif ()
 endif ()
 
-if ("${LLVM_RUNTIMES_TARGET}" MATCHES "^amdgcn|^nvptx")
+if ("${LLVM_DEFAULT_TARGET_TRIPLE}" MATCHES "^amdgcn|^nvptx")
   set(sources ${gpu_sources})
 elseif(FLANG_RT_EXPERIMENTAL_OFFLOAD_SUPPORT STREQUAL "CUDA")
   set(sources ${supported_sources})

libc/cmake/modules/LLVMLibCArchitectures.cmake

@@ -98,21 +98,22 @@ string(SUBSTRING ${libc_compiler_target_info} 8 -1 libc_compiler_triple)
 # One should not set LLVM_RUNTIMES_TARGET and LIBC_TARGET_TRIPLE
 if(LLVM_RUNTIMES_TARGET AND LIBC_TARGET_TRIPLE)
   message(FATAL_ERROR
-          "libc build: Specify only LLVM_RUNTIMES_TARGET if you are doing a "
+          "libc build: Specify only LLVM_DEFAULT_TARGET_TRIPLE if you are doing a "
           "runtimes/bootstrap build. If you are doing a standalone build, "
           "specify only LIBC_TARGET_TRIPLE.")
 endif()
 
 set(explicit_target_triple)
 if(LLVM_RUNTIMES_TARGET)
-  set(explicit_target_triple ${LLVM_RUNTIMES_TARGET})
+  # LLVM_RUNTIMES_TARGET may contain multilib flags, use the clean triple.
+  set(explicit_target_triple ${LLVM_DEFAULT_TARGET_TRIPLE})
 elseif(LIBC_TARGET_TRIPLE)
   set(explicit_target_triple ${LIBC_TARGET_TRIPLE})
 endif()
 
 # The libc's target architecture and OS are set to match the compiler's default
 # target triple above. However, one can explicitly set LIBC_TARGET_TRIPLE or
-# LLVM_RUNTIMES_TARGET (for runtimes/bootstrap build). If one of them is set,
+# LLVM_DEFAULT_TARGET_TRIPLE (for runtimes/bootstrap build). If one of them is set,
 # then we will use that target triple to deduce libc's target OS and
 # architecture.
 if(explicit_target_triple)
@@ -124,7 +125,7 @@ if(explicit_target_triple)
   set(LIBC_TARGET_ARCHITECTURE ${libc_arch})
   set(LIBC_TARGET_OS ${libc_sys})
   # If the compiler target triple is not the same as the triple specified by
-  # LIBC_TARGET_TRIPLE or LLVM_RUNTIMES_TARGET, we will add a --target option
+  # LIBC_TARGET_TRIPLE or LLVM_DEFAULT_TARGET_TRIPLE, we will add a --target option
   # if the compiler is clang. If the compiler is GCC we just error out as there
   # is no equivalent of an option like --target.
   if(NOT libc_compiler_triple STREQUAL explicit_target_triple)
@@ -216,7 +217,7 @@ else()
 endif()
 
 # If the compiler target triple is not the same as the triple specified by
-# LIBC_TARGET_TRIPLE or LLVM_RUNTIMES_TARGET, we will add a --target option
+# LIBC_TARGET_TRIPLE or LLVM_DEFAULT_TARGET_TRIPLE, we will add a --target option
 # if the compiler is clang. If the compiler is GCC we just error out as there
 # is no equivalent of an option like --target.
 if(explicit_target_triple AND

llvm/cmake/modules/HandleLLVMOptions.cmake

@@ -1159,7 +1159,7 @@ if (UNIX AND
 endif()
 
 # lld doesn't print colored diagnostics when invoked from Ninja
-if (UNIX AND CMAKE_GENERATOR MATCHES "Ninja" AND NOT "${LLVM_RUNTIMES_TARGET}" MATCHES "^nvptx64")
+if (UNIX AND CMAKE_GENERATOR MATCHES "Ninja" AND NOT "${LLVM_DEFAULT_TARGET_TRIPLE}" MATCHES "^nvptx64")
   include(CheckLinkerFlag)
   check_linker_flag(CXX "-Wl,--color-diagnostics" LINKER_SUPPORTS_COLOR_DIAGNOSTICS)
   append_if(LINKER_SUPPORTS_COLOR_DIAGNOSTICS "-Wl,--color-diagnostics"

runtimes/CMakeLists.txt

@@ -191,7 +191,7 @@ if ("${CMAKE_CXX_COMPILER_ID}" MATCHES "Clang")
 endif()
 
 # The NVPTX target needs to override linking to pass compiler flag checks.
-if("${LLVM_RUNTIMES_TARGET}" MATCHES "^nvptx")
+if("${LLVM_DEFAULT_TARGET_TRIPLE}" MATCHES "^nvptx")
   set(CMAKE_REQUIRED_FLAGS "${CMAKE_REQUIRED_FLAGS} -flto -c")
 endif()