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[Windows] Autolink with basenames and add libdir to libpath

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Prior to this change, for a few compiler-rt libraries such as ubsan and
the profile library, Clang would embed "-defaultlib:path/to/rt-arch.lib"
into the .drective section of every object compiled with
-finstr-profile-generate or -fsanitize=ubsan as appropriate.

These paths assume that the link step will run from the same working
directory as the compile step. There is also evidence that sometimes the
paths become absolute, such as when clang is run from a different drive
letter from the current working directory. This is fragile, and I'd like
to get away from having paths embedded in the object if possible. Long
ago it was suggested that we use this for ASan, and apparently I felt
the same way back then:
https://reviews.llvm.org/D4428#56536

This is also consistent with how all other autolinking usage works for
PS4, Mac, and Windows: they all use basenames, not paths.

To keep things working for people using the standard GCC driver
workflow, the driver now adds the resource directory to the linker
library search path when it calls the linker. This is enough to make
check-ubsan pass, and seems like a generally good thing.

Users that invoke the linker directly (most clang-cl users) will have to
add clang's resource library directory to their linker search path in
their build system. I'm not sure where I can document this. Ideally I'd
also do it in the MSBuild files, but I can't figure out where they go.
I'd like to start with this for now.

Reviewed By: hans

Differential Revision: https://reviews.llvm.org/D65543
This commit is contained in:
Reid Kleckner 2019-07-31 14:52:00 -07:00
parent 7453a1bd1f
commit 6c8b4bb2b1
1 changed files with 21 additions and 0 deletions
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21
cmake/modules/HandleLLVMOptions.cmake
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@ -886,6 +886,27 @@ if (LLVM_BUILD_INSTRUMENTED)
endif()
endif()
# When using clang-cl with an instrumentation-based tool, add clang's library
# resource directory to the library search path. Because cmake invokes the
# linker directly, it isn't sufficient to pass -fsanitize=* to the linker.
if (CLANG_CL AND (LLVM_BUILD_INSTRUMENTED OR LLVM_USE_SANITIZER))
execute_process(
COMMAND ${CMAKE_CXX_COMPILER} /clang:-print-resource-dir
OUTPUT_VARIABLE clang_resource_dir
ERROR_VARIABLE clang_cl_stderr
OUTPUT_STRIP_TRAILING_WHITESPACE
ERROR_STRIP_TRAILING_WHITESPACE
RESULT_VARIABLE clang_cl_exit_code)
if (NOT "${clang_cl_exit_code}" STREQUAL "0")
message(FATAL_ERROR
"Unable to invoke clang-cl to find resource dir: ${clang_cl_stderr}")
endif()
file(TO_CMAKE_PATH "${clang_resource_dir}" clang_resource_dir)
append("/libpath:${clang_resource_dir}/lib/windows"
CMAKE_EXE_LINKER_FLAGS
CMAKE_SHARED_LINKER_FLAGS)
endif()
if(LLVM_PROFDATA_FILE AND EXISTS ${LLVM_PROFDATA_FILE})
if ("${CMAKE_CXX_COMPILER_ID}" MATCHES "Clang" )
append("-fprofile-instr-use=\"${LLVM_PROFDATA_FILE}\""