[XRay] [compiler-rt] reformat and clarify CMakeLists.txt [NFC]

[pelikan]

Summary

• last change (+ the Apple support change) missed a lot of indentation
• shorten architecture SOURCES definitions as most fit 1 line/arch
• comment in English what's where, and where the different .a come from (using only the word "runtime" in the comment isn't useful, since the CMake primitive itself says "runtime" in its name)
• skip unsupported architectures quickly, to avoid extra indentation

[kpw]

Thanks for the cleanup.

[pelikan]

sync & commit

lib/xray/CMakeLists.txt

-# Build for the XRay runtime support library.
+# Build for all components of the XRay runtime support library.
 
 # XRay runtime library implementation files.
 set(XRAY_SOURCES
   xray_init.cc
   xray_flags.cc
   xray_interface.cc
   xray_log_interface.cc
   xray_utils.cc)
 
-# XRay mode implementation files.
+# Implementation files for all XRay modes.
 set(XRAY_FDR_MODE_SOURCES
   xray_buffer_queue.cc
   xray_fdr_logging.cc)
 
 set(XRAY_BASIC_MODE_SOURCES
   xray_inmemory_log.cc)
 
-set(x86_64_SOURCES
-    xray_x86_64.cc
-    xray_trampoline_x86_64.S)
-
-set(arm_SOURCES
-    xray_arm.cc
-    xray_trampoline_arm.S)
-
-set(armhf_SOURCES
-    ${arm_SOURCES})
-
-set(aarch64_SOURCES
-  xray_AArch64.cc
-  xray_trampoline_AArch64.S)
-
-set(mips_SOURCES
-    xray_mips.cc
-    xray_trampoline_mips.S)
-
-set(mipsel_SOURCES
-    xray_mips.cc
-    xray_trampoline_mips.S)
-
-set(mips64_SOURCES
-    xray_mips64.cc
-    xray_trampoline_mips64.S)
-
-set(mips64el_SOURCES
-    xray_mips64.cc
-    xray_trampoline_mips64.S)
-
+# Implementation files for all XRay architectures.
+set(aarch64_SOURCES xray_AArch64.cc xray_trampoline_AArch64.S)
+set(arm_SOURCES xray_arm.cc xray_trampoline_arm.S)
+set(armhf_SOURCES ${arm_SOURCES})
+set(mips_SOURCES xray_mips.cc xray_trampoline_mips.S)
+set(mipsel_SOURCES xray_mips.cc xray_trampoline_mips.S)
+set(mips64_SOURCES xray_mips64.cc xray_trampoline_mips64.S)
+set(mips64el_SOURCES xray_mips64.cc xray_trampoline_mips64.S)
 set(powerpc64le_SOURCES
     xray_powerpc64.cc
     xray_trampoline_powerpc64.cc
     xray_trampoline_powerpc64_asm.S)
+set(x86_64_SOURCES xray_x86_64.cc xray_trampoline_x86_64.S)
 
+# Now put it all together...
 include_directories(..)
 include_directories(../../include)
 
 set(XRAY_CFLAGS ${SANITIZER_COMMON_CFLAGS})
 set(XRAY_COMMON_DEFINITIONS XRAY_HAS_EXCEPTIONS=1)
 append_list_if(
   COMPILER_RT_HAS_XRAY_COMPILER_FLAG XRAY_SUPPORTED=1 XRAY_COMMON_DEFINITIONS)
 append_list_if(
add_compiler_rt_runtime(clang_rt.xray-basic
     OS ${XRAY_SUPPORTED_OS}
     ARCHS ${XRAY_SUPPORTED_ARCH}
     OBJECT_LIBS RTXrayBASIC
     CFLAGS ${XRAY_CFLAGS}
     DEFS ${XRAY_COMMON_DEFINITIONS}
     LINK_FLAGS ${SANITIZER_COMMON_LINK_FLAGS} ${WEAK_SYMBOL_LINK_FLAGS}
     LINK_LIBS ${XRAY_LINK_LIBS}
     PARENT_TARGET xray)
-else()
+else() # not Apple
   foreach(arch ${XRAY_SUPPORTED_ARCH})
-  if(CAN_TARGET_${arch})
+    if(NOT CAN_TARGET_${arch})
+      continue()
+    endif()
     add_compiler_rt_object_libraries(RTXray
       ARCHS ${arch}
       SOURCES ${XRAY_SOURCES} ${${arch}_SOURCES} CFLAGS ${XRAY_CFLAGS}
       DEFS ${XRAY_COMMON_DEFINITIONS})
     add_compiler_rt_object_libraries(RTXrayFDR
       ARCHS ${arch}
       SOURCES ${XRAY_FDR_MODE_SOURCES} CFLAGS ${XRAY_CFLAGS}
       DEFS ${XRAY_COMMON_DEFINITIONS})
     add_compiler_rt_object_libraries(RTXrayBASIC
       ARCHS ${arch}
       SOURCES ${XRAY_BASIC_MODE_SOURCES} CFLAGS ${XRAY_CFLAGS}
       DEFS ${XRAY_COMMON_DEFINITIONS})
 
+    # Common XRay archive for instrumented binaries.
     add_compiler_rt_runtime(clang_rt.xray
      STATIC
      ARCHS ${arch}
      CFLAGS ${XRAY_CFLAGS}
      DEFS ${XRAY_COMMON_DEFINITIONS}
      OBJECT_LIBS ${XRAY_COMMON_RUNTIME_OBJECT_LIBS} RTXray
      PARENT_TARGET xray)
-   # FDR Mode runtime
+    # FDR mode runtime archive (addon for clang_rt.xray)
     add_compiler_rt_runtime(clang_rt.xray-fdr
       STATIC
       ARCHS ${arch}
       CFLAGS ${XRAY_CFLAGS}
       DEFS ${XRAY_COMMON_DEFINITIONS}
       OBJECT_LIBS RTXrayFDR
       PARENT_TARGET xray)
-   # Basic Mode runtime
+    # Basic mode runtime archive (addon for clang_rt.xray)
     add_compiler_rt_runtime(clang_rt.xray-basic
       STATIC
       ARCHS ${arch}
       CFLAGS ${XRAY_CFLAGS}
       DEFS ${XRAY_COMMON_DEFINITIONS}
       OBJECT_LIBS RTXrayBASIC
       PARENT_TARGET xray)
-  endif()
   endforeach()
-endif()
+endif() # not Apple
 
 if(COMPILER_RT_INCLUDE_TESTS)
   add_subdirectory(tests)
 endif()