[WIP][clang] Add a cmake flag for choosing to build clang-repl

[leonardchan]

Summary

Not all downstream users may want to build all tools shipped with clang. clang-repl for us in particular can sometimes lead to flaky builds when testing a toolchain built with LTO.

This is a WIP patch that demonstrates:

• Allowing clang-repl to be built (by default) as part of check-all. Note that this doesn't remove it as a build target. It just makes it so that it's not built by default.
• Only running tests that require clang-repl via a REQUIRES line.

[leonardchan]

clang/CMakeLists.txt

468

Apart from name bikeshedding, it's more likely we'll want this ON by default to match current upstream behavior, then downstream users like us can just set this to OFF in our configs.

[tstellar]

Not all downstream users may want to build all tools shipped with clang. clang-repl for us in particular can sometimes lead to flaky builds when testing a toolchain built with LTO.

Can we just fix clang-repl instead? I think there needs to be a more compelling case to add a new cmake options for this.

[phosek]

Rather than hardcoding this only for clang-repl, I'd prefer to use a more generic approach.

We already have LLVM_DISTRIBUTION_COMPONENTS so one possibility would be to set a lit feature for every component. For example, if LLVM_DISTRIBUTION_COMPONENTS=foo;bar we would set foo-distribution-component and bar-distribution-component. The challenge is handling the default case where you want to build and test everything. We might be able to use CMake properties for that purpose to get the list of all tools and define the corresponding features.

Alternative would be to iterate over the CLANG_TEST_DEPS list and check if each entry is in LLVM_DISTRIBUTION_COMPONENTS, and if so add it to the list of dependencies and set a feature for it. If LLVM_DISTRIBUTION_COMPONENTS is empty, then include everything.

clang/CMakeLists.txt

 
 option(CLANG_BUILD_TOOLS
   "Build the Clang tools. If OFF, just generate build targets." ON)
 
 option(CLANG_ENABLE_ARCMT "Build ARCMT." ON)
 option(CLANG_ENABLE_STATIC_ANALYZER
   "Include static analyzer in clang binary." ON)
 
+option(CLANG_BUILD_CLANG_REPL_DEFAULT "Build clang-repl by default." OFF)
+
 option(CLANG_ENABLE_PROTO_FUZZER "Build Clang protobuf fuzzer." OFF)
 
 option(CLANG_ROUND_TRIP_CC1_ARGS
   "Round-trip command line arguments in -cc1." ${LLVM_ENABLE_ASSERTIONS})
 
 if(NOT CLANG_ENABLE_STATIC_ANALYZER AND CLANG_ENABLE_ARCMT)
   message(FATAL_ERROR "Cannot disable static analyzer while enabling ARCMT or Z3")
 endif()

clang/test/CMakeLists.txt

 # Test runner infrastructure for Clang. This configures the Clang test trees
 # for use by Lit, and delegates to LLVM's lit test handlers.
 
 if (CMAKE_CFG_INTDIR STREQUAL ".")
   set(LLVM_BUILD_MODE ".")
 else ()
   set(LLVM_BUILD_MODE "%(build_mode)s")
 endif ()
 
 string(REPLACE ${CMAKE_CFG_INTDIR} ${LLVM_BUILD_MODE} CLANG_TOOLS_DIR ${LLVM_RUNTIME_OUTPUT_INTDIR})
 
 llvm_canonicalize_cmake_booleans(
   CLANG_BUILD_EXAMPLES
   CLANG_ENABLE_ARCMT
   CLANG_ENABLE_STATIC_ANALYZER
+  CLANG_BUILD_CLANG_REPL_DEFAULT
   CLANG_SPAWN_CC1
   ENABLE_BACKTRACES
   LLVM_ENABLE_NEW_PASS_MANAGER
   LLVM_ENABLE_ZLIB
   LLVM_ENABLE_PER_TARGET_RUNTIME_DIR
   LLVM_ENABLE_PLUGINS
   LLVM_ENABLE_THREADS)
 
list(APPEND CLANG_TEST_DEPS
   clang
   clang-resource-headers
   clang-format
   clang-tblgen
   clang-offload-bundler
   clang-import-test
   clang-rename
   clang-refactor
-  clang-repl
   clang-diff
   clang-scan-deps
   diagtool
   hmaptool
   )
-  
+if(CLANG_BUILD_CLANG_REPL_DEFAULT)
+  list(APPEND CLANG_TEST_DEPS clang-repl)
+endif()
+
 if(CLANG_ENABLE_STATIC_ANALYZER)
   list(APPEND CLANG_TEST_DEPS
     clang-check
     clang-extdef-mapping
     )
 endif()
 
 if (CLANG_ENABLE_ARCMT)

clang/test/Interpreter/execute.cpp

+// REQUIRES: clang-repl
+
 // RUN: clang-repl "int i = 10;" 'extern "C" int printf(const char*,...);' \
 // RUN:            'auto r1 = printf("i = %d\n", i);' | FileCheck --check-prefix=CHECK-DRIVER %s
 // REQUIRES: host-supports-jit
 // UNSUPPORTED: system-aix
 // CHECK-DRIVER: i = 10
 // RUN: cat %s | clang-repl | FileCheck %s
 extern "C" int printf(const char *, ...);
 int i = 42;
 auto r1 = printf("i = %d\n", i);
 // CHECK: i = 42
 
 struct S { float f = 1.0; S *m = nullptr;} s;
 
 auto r2 = printf("S[f=%f, m=0x%llx]\n", s.f, reinterpret_cast<unsigned long long>(s.m));
 // CHECK-NEXT: S[f=1.000000, m=0x0]
 quit

clang/test/Interpreter/sanity.c

+// REQUIRES: clang-repl
+
 // RUN: cat %s | \
 // RUN:   clang-repl -Xcc -fno-color-diagnostics -Xcc -Xclang -Xcc -ast-dump \
 // RUN:            -Xcc -Xclang -Xcc -ast-dump-filter -Xcc -Xclang -Xcc Test 2>&1| \
 // RUN:         FileCheck %s
 
 int TestVar = 12;
 // CHECK: Dumping TestVar:
 // CHECK-NEXT: VarDecl [[var_ptr:0x[0-9a-f]+]] <{{.*}} TestVar 'int' cinit

clang/test/lit.cfg.py

 
 # For each occurrence of a clang tool name, replace it with the full path to
 # the build directory holding that tool.  We explicitly specify the directories
 # to search to ensure that we get the tools just built and not some random
 # tools that might happen to be in the user's PATH.
 tool_dirs = [config.clang_tools_dir, config.llvm_tools_dir]
 
 tools = [
-    'apinotes-test', 'c-index-test', 'clang-diff', 'clang-format', 'clang-repl',
+    'apinotes-test', 'c-index-test', 'clang-diff', 'clang-format',
     'clang-tblgen', 'clang-scan-deps', 'opt', 'llvm-ifs', 'yaml2obj',
     ToolSubst('%clang_extdef_map', command=FindTool(
         'clang-extdef-mapping'), unresolved='ignore'),
 ]
 
 if config.clang_examples:
     config.available_features.add('examples')
     tools.append('clang-interpreter')
 
-def have_host_jit_support():
+def get_clang_repl():
     clang_repl_exe = lit.util.which('clang-repl', config.clang_tools_dir)
 
     if not clang_repl_exe:
+        return None
+
+    return clang_repl_exe
+
+clang_repl_exe = get_clang_repl()
+if clang_repl_exe is not None:
+    tools.append('clang-repl')
+    config.available_features.add('clang-repl')
+
+def have_host_jit_support():
+    if not clang_repl_exe:
         print('clang-repl not found')
         return False
 
     try:
         clang_repl_cmd = subprocess.Popen(
             [clang_repl_exe, '--host-supports-jit'], stdout=subprocess.PIPE)
     except OSError:
         print('could not exec clang-repl')

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

 config.host_cxx = "@CMAKE_CXX_COMPILER@"
 config.llvm_use_sanitizer = "@LLVM_USE_SANITIZER@"
 config.have_zlib = @LLVM_ENABLE_ZLIB@
 config.clang_arcmt = @CLANG_ENABLE_ARCMT@
 config.clang_default_cxx_stdlib = "@CLANG_DEFAULT_CXX_STDLIB@"
 config.clang_staticanalyzer = @CLANG_ENABLE_STATIC_ANALYZER@
 config.clang_staticanalyzer_z3 = "@LLVM_WITH_Z3@"
 config.clang_examples = @CLANG_BUILD_EXAMPLES@
+config.clang_repl = @CLANG_BUILD_CLANG_REPL_DEFAULT@
 config.enable_shared = @ENABLE_SHARED@
 config.enable_backtrace = @ENABLE_BACKTRACES@
 config.enable_experimental_new_pass_manager = @LLVM_ENABLE_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@