[Darwin] Limit parallelism for sanitizer tests that use shadow memory on AS

On Darwin, we want to limit the parallelism during test execution for
sanitizer tests that use shadow memory.  The reason is explained by this
existing comment:

> Only run up to 3 processes that require shadow memory simultaneously
> on 64-bit Darwin. Using more scales badly and hogs the system due to
> inefficient handling of large mmap'd regions (terabytes) by the
> kernel.

Previously we detected 3 cases:
* on-device: limit to 1 process
* 64-bit: macOS & simulators, limit to 3 processes
* others (32-bit): no limitation

We checked for the 64-bit case like this: `if arch in ['x86_64',
'x86_64h']` which misses macOS running on AS. Additionally, we don't
care about 32-bit anymore, so I've simplified this to 2 cases: on-device
and everything else.

Differential Revision: https://reviews.llvm.org/D122751

compiler-rt/test/asan/Unit/lit.site.cfg.py.in

@@ -62,5 +62,5 @@ if config.enable_per_target_runtime_dir and config.target_arch != config.host_ar
 # Set LD_LIBRARY_PATH to pick dynamic runtime up properly.
 push_ld_library_path(config, config.compiler_rt_libdir)
 
-if config.host_os == 'Darwin':
-  config.parallelism_group = config.darwin_sanitizer_parallelism_group_func
+if not config.parallelism_group:
+  config.parallelism_group = 'shadow-memory'

compiler-rt/test/lit.common.cfg.py

@@ -613,8 +613,8 @@ if platform.system() == 'Darwin':
   # Only run up to 3 processes that require shadow memory simultaneously on
   # 64-bit Darwin. Using more scales badly and hogs the system due to
   # inefficient handling of large mmap'd regions (terabytes) by the kernel.
-  elif config.target_arch in ['x86_64', 'x86_64h']:
-    lit_config.warning('Throttling sanitizer tests that require shadow memory on Darwin 64bit')
+  else:
+    lit_config.warning('Throttling sanitizer tests that require shadow memory on Darwin')
     lit_config.parallelism_groups['shadow-memory'] = 3
 
 # Multiple substitutions are necessary to support multiple shared objects used

compiler-rt/test/sanitizer_common/Unit/lit.site.cfg.py.in

@@ -13,5 +13,5 @@ config.test_exec_root = os.path.join("@COMPILER_RT_BINARY_DIR@", "lib",
                                      "sanitizer_common", "tests")
 config.test_source_root = config.test_exec_root
 
-if config.host_os == 'Darwin':
-  config.parallelism_group = config.darwin_sanitizer_parallelism_group_func
+if not config.parallelism_group:
+  config.parallelism_group = 'shadow-memory'

compiler-rt/test/tsan/Unit/lit.site.cfg.py.in

@@ -12,9 +12,10 @@ config.name = 'ThreadSanitizer-Unit'
 config.test_exec_root = "@COMPILER_RT_BINARY_DIR@/lib/tsan/tests"
 config.test_source_root = config.test_exec_root
 
-if config.host_os == 'Darwin':
-  config.parallelism_group = config.darwin_sanitizer_parallelism_group_func
+if not config.parallelism_group:
+  config.parallelism_group = 'shadow-memory'
 
+if config.host_os == 'Darwin':
   # On Darwin, we default to ignore_noninstrumented_modules=1, which also
   # suppresses some races the tests are supposed to find.  See tsan/lit.cfg.py.
   if 'TSAN_OPTIONS' in config.environment:

compiler-rt/unittests/lit.common.unit.cfg.py

@@ -50,13 +50,3 @@ if config.host_os == 'Darwin':
   #
   # rdar://80086125
   config.environment['MallocNanoZone'] = '0'
-
-  # The test config gets pickled and sent to multiprocessing workers, and that
-  # only works for code if it is stored at the top level of some module.
-  # Therefore, we have to put the code in a .py file, add it to path, and import
-  # it to store it in the config.
-  import site
-  site.addsitedir(os.path.dirname(__file__))
-  import lit_unittest_cfg_utils
-  config.darwin_sanitizer_parallelism_group_func = \
-    lit_unittest_cfg_utils.darwin_sanitizer_parallelism_group_func

compiler-rt/unittests/lit_unittest_cfg_utils.py

@@ -1,4 +0,0 @@
-# Put all 64-bit tests in the shadow-memory parallelism group. We throttle those
-# in our common lit config (lit.common.unit.cfg.py).
-def darwin_sanitizer_parallelism_group_func(test):
-  return "shadow-memory" if "x86_64" in test.file_path else None