[apple clang] disable in-process CC1 to preserve crashlog compatibility

[arphaman]

Summary

The in-process CC1 currently doesn't interoperate with the macOS crash analytics, which we would like to keep enabled for Apple clang. This commit restores the out-of-process CC1 to the Apple clang CMake configuration for now.

[dexonsmith]

LGTM, but next we should get the crash reproductions working with in-process -cc1.

clang/cmake/caches/Apple-stage1.cmake

 set(LLVM_INCLUDE_DOCS OFF CACHE BOOL "")
 set(CLANG_INCLUDE_TESTS OFF CACHE BOOL "")
 set(COMPILER_RT_INCLUDE_TESTS OFF CACHE BOOL "")
 set(COMPILER_RT_BUILD_SANITIZERS OFF CACHE BOOL "")
 set(CMAKE_MACOSX_RPATH ON CACHE BOOL "")
 set(LLVM_ENABLE_ZLIB OFF CACHE BOOL "")
 set(LLVM_ENABLE_BACKTRACES OFF CACHE BOOL "")
 set(CLANG_PLUGIN_SUPPORT OFF CACHE BOOL "")
+set(CLANG_SPAWN_CC1 ON CACHE BOOL "")
 set(CLANG_BOOTSTRAP_PASSTHROUGH
   CMAKE_OSX_ARCHITECTURES
   CACHE STRING "")
 
 # Disabling embedded darwin compiler-rt on stage1 builds is required because we
 # don't build stage1 to support arm code generation.
 set(COMPILER_RT_ENABLE_IOS OFF CACHE BOOL "")
 set(COMPILER_RT_ENABLE_WATCHOS OFF CACHE BOOL "")

clang/cmake/caches/Apple-stage2.cmake

 set(CLANG_TOOL_SCAN_VIEW_BUILD OFF CACHE BOOL "")
 set(CLANG_LINKS_TO_CREATE clang++ cc c++ CACHE STRING "")
 set(CMAKE_MACOSX_RPATH ON CACHE BOOL "")
 set(LLVM_ENABLE_ZLIB ON CACHE BOOL "")
 set(LLVM_ENABLE_BACKTRACES OFF CACHE BOOL "")
 set(LLVM_ENABLE_MODULES ON CACHE BOOL "")
 set(LLVM_EXTERNALIZE_DEBUGINFO ON CACHE BOOL "")
 set(CLANG_PLUGIN_SUPPORT OFF CACHE BOOL "")
+set(CLANG_SPAWN_CC1 ON CACHE BOOL "")
 set(BUG_REPORT_URL "http://developer.apple.com/bugreporter/" CACHE STRING "")
 
 set(LLVM_BUILD_EXTERNAL_COMPILER_RT ON CACHE BOOL "Build Compiler-RT with just-built clang")
 set(COMPILER_RT_ENABLE_IOS ON CACHE BOOL "Build iOS Compiler-RT libraries")
 
 set(LLVM_CREATE_XCODE_TOOLCHAIN ON CACHE BOOL "Generate targets to create and install an Xcode compatible toolchain")
 
 # Make unit tests (if present) part of the ALL target

clang/test/Driver/apple-clang-defaults.c

+// RUN: %clang -c %s -### 2>&1 | FileCheck %s --check-prefix=APPLE-CLANG
+// RUN: %clang -fintegrated-cc1 -c %s -### 2>&1 | FileCheck %s --check-prefix=EXPLICIT-IN-PROCESS
+
+// REQUIRES: clang-vendor=com.apple.clang
+
+// APPLE-CLANG-NOT: (in-process)
+// EXPLICIT-IN-PROCESS: (in-process)

clang/test/lit.cfg.py

 if macOSSDKVersion is not None:
     config.available_features.add('macos-sdk-' + str(macOSSDKVersion))
 
 if os.path.exists('/etc/gentoo-release'):
     config.available_features.add('gentoo')
 
 if config.enable_shared:
     config.available_features.add("enable_shared")
+
+# Add a vendor-specific feature.
+if config.clang_vendor_uti:
+    config.available_features.add('clang-vendor=' + config.clang_vendor_uti)

clang/test/lit.site.cfg.py.in

 config.enable_shared = @ENABLE_SHARED@
 config.enable_backtrace = @ENABLE_BACKTRACES@
 config.enable_experimental_new_pass_manager = @ENABLE_EXPERIMENTAL_NEW_PASS_MANAGER@
 config.enable_threads = @LLVM_ENABLE_THREADS@
 config.host_arch = "@HOST_ARCH@"
 config.python_executable = "@Python3_EXECUTABLE@"
 config.use_z3_solver = lit_config.params.get('USE_Z3_SOLVER', "@USE_Z3_SOLVER@")
 config.has_plugins = @LLVM_ENABLE_PLUGINS@
+config.clang_vendor_uti = "@CLANG_VENDOR_UTI@"
 
 # Support substitution of the tools and libs dirs with user parameters. This is
 # used when we can't determine the tool dir at configuration time.
 try:
     config.clang_tools_dir = config.clang_tools_dir % lit_config.params
     config.llvm_tools_dir = config.llvm_tools_dir % lit_config.params
     config.llvm_shlib_dir = config.llvm_shlib_dir % lit_config.params
     config.llvm_libs_dir = config.llvm_libs_dir % lit_config.params