[compiler-rt][CMake] Multiarch build of XRay libraries

[ilammy]

Summary

Instead of dumping all sources into RTXray object library with a weird
special case for x86, handle multiarch builds better. Build a separate
object library for each arch with its arch-specific sources, then link
in all those libraries.

This fixes the build on platforms that produce fat binaries, such as new
macOS which expects both x86_64 and aarch64 objects in the same library
since Apple Silicon is a thing.

This only enables building XRay support for Apple Silicon. It does not
actually work yet on macOS, neither on Intel nor on Apple Silicon CPUs.
Thus the tests are still disabled.

[MaskRay]

I don't know enough about CMake, so I wish that an expert can look into this.

If you can test arm64-apple-darwin, I wonder whether the following all work:

• unset CMAKE_OSX_ARCHITECTURES
• -DCMAKE_OSX_ARCHITECTURES='arm64;x86_64'
• -DCMAKE_OSX_ARCHITECTURES='x86_64'

compiler-rt/lib/xray/CMakeLists.txt

82

sort alphabetically

[MaskRay]

In a build not setting CMAKE_OSX_ARCHITECTURES on an arm64-apple-darwin machine, I cannot find RTXray_aarch64.osx or RTXray_arm64.osx. I don't know what's wrong...

% ninja -C out/release -t targets | grep RTXray
RTXray.osx: phony
RTXrayBASIC.osx: phony
RTXrayFDR.osx: phony
RTXrayPROFILING.osx: phony
RTXray_x86_64.osx: phony

[phosek]

Ideally we would use CMAKE_OSX_ARCHITECTURES which is the native CMake solution, but that's not currently supported in compiler-rt which implements its own crude version. We should eventually migrate to CMAKE_OSX_ARCHITECTURES, but I'm fine with this change as an interim solution.

[MaskRay]

I'll land this. I don't get RTXray_arm64.osx on an Apple M1, but this looks like a step forward. Thanks!

[MaskRay]

sort

compiler-rt/cmake/Modules/AllSupportedArchDefs.cmake

set(ALL_UBSAN_SUPPORTED_ARCH ${X86} ${X86_64} ${ARM32} ${ARM64} ${RISCV64}
     ${LOONGARCH64})
 set(ALL_SAFESTACK_SUPPORTED_ARCH ${X86} ${X86_64} ${ARM64} ${MIPS32} ${MIPS64}
     ${HEXAGON} ${LOONGARCH64})
 set(ALL_CFI_SUPPORTED_ARCH ${X86} ${X86_64} ${ARM32} ${ARM64} ${MIPS64}
     ${HEXAGON})
 set(ALL_SCUDO_STANDALONE_SUPPORTED_ARCH ${X86} ${X86_64} ${ARM32} ${ARM64}
     ${MIPS32} ${MIPS64} ${PPC64} ${HEXAGON} ${LOONGARCH64} ${RISCV64})
 if(APPLE)
-set(ALL_XRAY_SUPPORTED_ARCH ${X86_64})
+set(ALL_XRAY_SUPPORTED_ARCH ${X86_64} ${ARM64})
 else()
 set(ALL_XRAY_SUPPORTED_ARCH ${X86_64} ${ARM32} ${ARM64} ${MIPS32} ${MIPS64}
     powerpc64le ${HEXAGON})
 endif()
 set(ALL_SHADOWCALLSTACK_SUPPORTED_ARCH ${ARM64})
 
 if (UNIX)
 set(ALL_ORC_SUPPORTED_ARCH ${X86_64} ${ARM64} ${ARM32})
 endif()
 
 if (WIN32)
   set(ALL_ORC_SUPPORTED_ARCH ${X86_64})
 endif()

compiler-rt/lib/xray/CMakeLists.txt

set(powerpc64le_SOURCES
   xray_trampoline_powerpc64_asm.S
   )
 
 set(hexagon_SOURCES
   xray_hexagon.cpp
   xray_trampoline_hexagon.S
   )
 
+set(XRAY_SOURCE_ARCHS
+  arm
+  armhf
+  aarch64
+  hexagon
+  mips
+  mipsel
+  mips64
+  mips64el
+  powerpc64le
+  x86_64
+  )
+
 set(XRAY_IMPL_HEADERS
   xray_allocator.h
   xray_basic_flags.h
   xray_basic_flags.inc
   xray_basic_logging.h
   xray_buffer_queue.h
   xray_defs.h
   xray_fdr_controller.h
set(XRAY_COMMON_RUNTIME_OBJECT_LIBS
     RTSanitizerCommonLibc)
 
 # XRay uses C++ standard library headers.
 if (TARGET cxx-headers OR HAVE_LIBCXX)
   set(XRAY_DEPS cxx-headers)
 endif()
 
 if (APPLE)
-  set(XRAY_ASM_SOURCES xray_trampoline_x86_64.S)
-
   add_weak_symbols("sanitizer_common" WEAK_SYMBOL_LINK_FLAGS)
   add_weak_symbols("xray" WEAK_SYMBOL_LINK_FLAGS)
 
   add_compiler_rt_object_libraries(RTXray
     OS ${XRAY_SUPPORTED_OS}
     ARCHS ${XRAY_SUPPORTED_ARCH}
-    SOURCES ${XRAY_SOURCES} ${x86_64_SOURCES}
+    SOURCES ${XRAY_SOURCES}
+    ADDITIONAL_HEADERS ${XRAY_IMPL_HEADERS}
+    CFLAGS ${XRAY_CFLAGS}
+    DEFS ${XRAY_COMMON_DEFINITIONS}
+    DEPS ${XRAY_DEPS})
+  set(XRAY_RTXRAY_ARCH_LIBS "")
+  foreach(arch ${XRAY_SUPPORTED_ARCH})
+    if(NOT ${arch} IN_LIST XRAY_SOURCE_ARCHS)
+      continue()
+    endif()
+    add_compiler_rt_object_libraries(RTXray_${arch}
+      OS ${XRAY_SUPPORTED_OS}
+      ARCHS ${arch}
+      SOURCES ${${arch}_SOURCES}
       ADDITIONAL_HEADERS ${XRAY_IMPL_HEADERS}
       CFLAGS ${XRAY_CFLAGS}
       DEFS ${XRAY_COMMON_DEFINITIONS}
       DEPS ${XRAY_DEPS})
+    list(APPEND XRAY_RTXRAY_ARCH_LIBS RTXray_${arch})
+  endforeach()
   add_compiler_rt_object_libraries(RTXrayFDR
     OS ${XRAY_SUPPORTED_OS}
     ARCHS ${XRAY_SUPPORTED_ARCH}
     SOURCES ${XRAY_FDR_MODE_SOURCES}
     ADDITIONAL_HEADERS ${XRAY_IMPL_HEADERS}
     CFLAGS ${XRAY_CFLAGS}
     DEFS ${XRAY_COMMON_DEFINITIONS}
     DEPS ${XRAY_DEPS})
add_compiler_rt_object_libraries(RTXrayPROFILING
     DEFS ${XRAY_COMMON_DEFINITIONS}
     DEPS ${XRAY_DEPS})
 
   # We only support running on osx for now.
   add_compiler_rt_runtime(clang_rt.xray
     STATIC
     OS ${XRAY_SUPPORTED_OS}
     ARCHS ${XRAY_SUPPORTED_ARCH}
-    OBJECT_LIBS RTXray
-                RTSanitizerCommon
-                RTSanitizerCommonLibc
+    OBJECT_LIBS ${XRAY_COMMON_RUNTIME_OBJECT_LIBS} RTXray ${XRAY_RTXRAY_ARCH_LIBS}
     CFLAGS ${XRAY_CFLAGS}
     DEFS ${XRAY_COMMON_DEFINITIONS}
     LINK_FLAGS ${XRAY_LINK_FLAGS} ${WEAK_SYMBOL_LINK_FLAGS}
     LINK_LIBS ${XRAY_LINK_LIBS}
     PARENT_TARGET xray)
   add_compiler_rt_runtime(clang_rt.xray-fdr
     STATIC
     OS ${XRAY_SUPPORTED_OS}