[Dexter] Remove the Windows dependency on lld from CMake

[Orlando]

Summary

Currently, lld is marked as a dependency on Windows in
cross-project-tests/CMakeLists.txt which means CMake will fail if lld isn't
enabled. The idea of the cross-project-tests is that tests that don't have
their dependencies met should just be unsupported.

Remove the depenency from the CMake step and check whether Dexter's
platform-specific dependencies have been met in
cross-project-tests/lit.cfg.py. If the dependencies are met then add 'dexter'
to the available_features, otherwise don't and the dexter tests will be
"UNSUPPORTED".

[Orlando]

I decided to (add and) have configure_dexter_substitutions return the dependencies rather than having the dependencies checked independently of the substitutions because I felt that keeping them close together in code (as they are really coupled) would help to keep things in sync.

[chrisjackson]

lgtm

[jhenderson]

cross-project-tests/CMakeLists.txt

58–61

Shouldn't this just be removing the "WIN32" part? If cross-project-tests and lld are both enabled, then check-cross-project-tests will run LLD-requiring tests (there may not be any right at this moment, but I wrote the code with the intention of them being possible). Without this dependency, there could a build-time race condition, whereby the LLD project doesn't finish building before starting the tests.

[Orlando]

+ Add lld as a dependency if lld is in LLVM_ENABLE_PROJECTS

[jhenderson]

LGTM!

[Orlando]

cross-project-tests/CMakeLists.txt

58–61

Good point - fixed.

[Orlando]

Thanks @jhenderson.

cross-project-tests/lit.cfg.py

147–151

These lines are repeated earlier so have been removed from my commit.

cross-project-tests/CMakeLists.txt

if(TARGET safestack)
     list(APPEND CROSS_PROJECT_TEST_DEPS safestack)
   endif()
 endif()
 # Many dexter tests depend on lldb.
 if("lldb" IN_LIST LLVM_ENABLE_PROJECTS)
   list(APPEND CROSS_PROJECT_TEST_DEPS lldb lldb-server)
 endif()
 
-# The Windows builder scripts pass -fuse-ld=lld.
-if (WIN32 OR "lld" IN_LIST LLVM_ENABLE_PROJECTS)
+if ("lld" IN_LIST LLVM_ENABLE_PROJECTS)
   list(APPEND CROSS_PROJECT_TEST_DEPS lld)
 endif()
 
 configure_lit_site_cfg(
   ${CMAKE_CURRENT_SOURCE_DIR}/lit.site.cfg.py.in
   ${CMAKE_CURRENT_BINARY_DIR}/lit.site.cfg.py
   MAIN_CONFIG
   ${CMAKE_CURRENT_SOURCE_DIR}/lit.cfg.py
   )
 

cross-project-tests/lit.cfg.py

if not hasattr(config, 'lld_src_dir'):
     config.lld_src_dir = ""
 llvm_config.use_lld(required=('lld' in config.llvm_enabled_projects))
 
 if config.llvm_use_sanitizer:
     # Propagate path to symbolizer for ASan/MSan.
     llvm_config.with_system_environment(
         ['ASAN_SYMBOLIZER_PATH', 'MSAN_SYMBOLIZER_PATH'])
 
-def add_host_triple(clang):
-  return '{} --target={}'.format(clang, config.host_triple)
-
-# The set of arches we can build.
-targets = set(config.targets_to_build)
-# Add aliases to the target set.
-if 'AArch64' in targets:
-  targets.add('arm64')
-if 'ARM' in config.targets_to_build:
-  targets.add('thumbv7')
-
-def can_target_host():
-  # Check if the targets set contains anything that looks like our host arch.
-  # The arch name in the triple and targets set may be spelled differently
-  # (e.g. x86 vs X86).
-  return any(config.host_triple.lower().startswith(x.lower())
-             for x in targets)
-
-# Dexter tests run on the host machine. If the host arch is supported add
-# 'dexter' as an available feature and force the dexter tests to use the host
-# triple.
-if can_target_host():
-  config.available_features.add('dexter')
-  if config.host_triple != config.target_triple:
-    print('Forcing dexter tests to use host triple {}.'.format(config.host_triple))
-  llvm_config.with_environment('PATHTOCLANG',
-                               add_host_triple(llvm_config.config.clang))
-  llvm_config.with_environment('PATHTOCLANGPP',
-                               add_host_triple(llvm_config.use_llvm_tool('clang++')))
-  llvm_config.with_environment('PATHTOCLANGCL',
-                               add_host_triple(llvm_config.use_llvm_tool('clang-cl')))
-else:
-  print('Host triple {} not supported. Skipping dexter tests in the '
-        'debuginfo-tests project.'.format(config.host_triple))
-
 # Check which debuggers are available:
 lldb_path = llvm_config.use_llvm_tool('lldb', search_env='LLDB')
 
 if lldb_path is not None:
     config.available_features.add('lldb')
 
+def configure_dexter_substitutions():
+  """Configure substitutions for host platform and return list of dependencies
+  """
   # Produce dexter path, lldb path, and combine into the %dexter substitution
   # for running a test.
   dexter_path = os.path.join(config.cross_project_tests_src_root,
                              'debuginfo-tests', 'dexter', 'dexter.py')
   dexter_test_cmd = '"{}" "{}" test'.format(sys.executable, dexter_path)
   if lldb_path is not None:
     dexter_test_cmd += ' --lldb-executable "{}"'.format(lldb_path)
   tools.append(ToolSubst('%dexter', dexter_test_cmd))
 
   # For testing other bits of dexter that aren't under the "test" subcommand,
   # have a %dexter_base substitution.
   dexter_base_cmd = '"{}" "{}"'.format(sys.executable, dexter_path)
   tools.append(ToolSubst('%dexter_base', dexter_base_cmd))
 
   # Set up commands for DexTer regression tests.
   # Builder, debugger, optimisation level and several other flags differ
   # depending on whether we're running a unix like or windows os.
-if platform.system() == 'Windows': 
+  if platform.system() == 'Windows':
+    # The Windows builder script uses lld.
+    dependencies = ['clang', 'lld-link']
     dexter_regression_test_builder = '--builder clang-cl_vs2015'
     dexter_regression_test_debugger = '--debugger dbgeng'
     dexter_regression_test_cflags = '--cflags "/Zi /Od"'
     dexter_regression_test_ldflags = '--ldflags "/Zi"'
   else:
+    # Use lldb as the debugger on non-Windows platforms.
+    dependencies = ['clang', 'lldb']
     dexter_regression_test_builder = '--builder clang'
     dexter_regression_test_debugger = "--debugger lldb"
     dexter_regression_test_cflags = '--cflags "-O0 -glldb"'
     dexter_regression_test_ldflags = ''
 
   # Typical command would take the form:
   # ./path_to_py/python.exe ./path_to_dex/dexter.py test --fail-lt 1.0 -w --builder clang --debugger lldb --cflags '-O0 -g'
   # Exclude build flags for %dexter_regression_base.
   dexter_regression_test_base = ' '.join(
     # "python", "dexter.py", test, fail_mode, builder, debugger, cflags, ldflags
     ['"{}"'.format(sys.executable),
     '"{}"'.format(dexter_path),
     'test',
     '--fail-lt 1.0 -w',
     dexter_regression_test_debugger])
   tools.append(ToolSubst('%dexter_regression_base', dexter_regression_test_base))
 
   # Include build flags for %dexter_regression_test.
   dexter_regression_test_build = ' '.join([
     dexter_regression_test_base,
     dexter_regression_test_builder,
     dexter_regression_test_cflags,
     dexter_regression_test_ldflags])
   tools.append(ToolSubst('%dexter_regression_test', dexter_regression_test_build))
+  return dependencies
+
+def add_host_triple(clang):
+  return '{} --target={}'.format(clang, config.host_triple)
+
+# The set of arches we can build.
+targets = set(config.targets_to_build)
+# Add aliases to the target set.
+if 'AArch64' in targets:
+  targets.add('arm64')
+if 'ARM' in config.targets_to_build:
+  targets.add('thumbv7')
+
+def can_target_host():
+  # Check if the targets set contains anything that looks like our host arch.
+  # The arch name in the triple and targets set may be spelled differently
+  # (e.g. x86 vs X86).
+  return any(config.host_triple.lower().startswith(x.lower())
+             for x in targets)
+
+# Dexter tests run on the host machine. If the host arch is supported add
+# 'dexter' as an available feature and force the dexter tests to use the host
+# triple.
+if can_target_host():
+  if config.host_triple != config.target_triple:
+    print('Forcing dexter tests to use host triple {}.'.format(config.host_triple))
+  dependencies = configure_dexter_substitutions()
+  if all(d in config.available_features for d in dependencies):
+    config.available_features.add('dexter')
+    llvm_config.with_environment('PATHTOCLANG',
+                                 add_host_triple(llvm_config.config.clang))
+    llvm_config.with_environment('PATHTOCLANGPP',
+                                 add_host_triple(llvm_config.use_llvm_tool('clang++')))
+    llvm_config.with_environment('PATHTOCLANGCL',
+                                 add_host_triple(llvm_config.use_llvm_tool('clang-cl')))
+else:
+  print('Host triple {} not supported. Skipping dexter tests in the '
+        'debuginfo-tests project.'.format(config.host_triple))
 
 tool_dirs = [config.llvm_tools_dir]
 
 llvm_config.add_tool_substitutions(tools, tool_dirs)
 
 lit.util.usePlatformSdkOnDarwin(config, lit_config)
 
 if platform.system() == 'Darwin':