Use host's executable suffix for clang when cross-compiling compiler-rt

[broadwaylamb]

Summary

When cross-compiling compiler-rt as part of LLVM e. g. for Linux on
a Windows host and using the just-built clang as cross-compiler, we set
the -DBUILTINS_CMAKE_ARGS="-DCMAKE_SYSTEM_NAME=Linux" flag in top-level
cmake invocation, which causes CMAKE_EXECUTABLE_SUFFIX to be an empty
string in the nested cmake invocation for building builtins.

But the compiler for compiling test cases is meant to be run on host,
therefore it may have the '.exe' suffix.

Handle this by asking cmake about the host system.

[rnk]

lgtm

[broadwaylamb]

In D67401#1665548, @rnk wrote:

lgtm

I don't have commit access, can I ask you to commit this for me? Or is there anything else that needs to be done?

[rnk]

In D67401#1666357, @broadwaylamb wrote:

In D67401#1665548, @rnk wrote:

lgtm

I don't have commit access, can I ask you to commit this for me? Or is there anything else that needs to be done?

Sure, I landed it in r371754. I actually tested it on Windows before landing, and check-asan seemed to work.

compiler-rt/cmake/base-config-ix.cmake

if (LLVM_TREE_AVAILABLE)
   # Setup the paths where compiler-rt runtimes and headers should be stored.
   set(COMPILER_RT_OUTPUT_DIR ${LLVM_LIBRARY_OUTPUT_INTDIR}/clang/${CLANG_VERSION})
   set(COMPILER_RT_EXEC_OUTPUT_DIR ${LLVM_RUNTIME_OUTPUT_INTDIR})
   set(COMPILER_RT_INSTALL_PATH lib${LLVM_LIBDIR_SUFFIX}/clang/${CLANG_VERSION})
   option(COMPILER_RT_INCLUDE_TESTS "Generate and build compiler-rt unit tests."
          ${LLVM_INCLUDE_TESTS})
   option(COMPILER_RT_ENABLE_WERROR "Fail and stop if warning is triggered"
          ${LLVM_ENABLE_WERROR})
+  
   # Use just-built Clang to compile/link tests on all platforms.
+  if(CMAKE_CROSSCOMPILING)
+    if(CMAKE_HOST_WIN32)
+      set(_host_executable_suffix ".exe")
+    else()
+      set(_host_executable_suffix "")
+    endif()
+  else()
+    set(_host_executable_suffix ${CMAKE_EXECUTABLE_SUFFIX})
+  endif()
   set(COMPILER_RT_TEST_COMPILER
-    ${LLVM_RUNTIME_OUTPUT_INTDIR}/clang${CMAKE_EXECUTABLE_SUFFIX})
+    ${LLVM_RUNTIME_OUTPUT_INTDIR}/clang${_host_executable_suffix})
   set(COMPILER_RT_TEST_CXX_COMPILER
-    ${LLVM_RUNTIME_OUTPUT_INTDIR}/clang++${CMAKE_EXECUTABLE_SUFFIX})
+    ${LLVM_RUNTIME_OUTPUT_INTDIR}/clang++${_host_executable_suffix})
 else()
     # Take output dir and install path from the user.
   set(COMPILER_RT_OUTPUT_DIR ${CMAKE_CURRENT_BINARY_DIR} CACHE PATH
     "Path where built compiler-rt libraries should be stored.")
   set(COMPILER_RT_EXEC_OUTPUT_DIR ${CMAKE_CURRENT_BINARY_DIR}/bin CACHE PATH
     "Path where built compiler-rt executables should be stored.")
   set(COMPILER_RT_INSTALL_PATH ${CMAKE_INSTALL_PREFIX} CACHE PATH
     "Path where built compiler-rt libraries should be installed.")