Add a `%darwin_min_target_with_tls_support` lit substitution.

[delcypher]

Summary

This substitution expands to the appropriate minimum deployment target
flag where thread local storage (TLS) was first introduced on Darwin
platforms. For all other platforms the substitution expands to an empty
string.

E.g. for macOS the substitution expands to -mmacosx-version-min=10.12

This patch adds support for the substitution (and future substitutions)
by doing a minor refactor and then uses the substitution in the relevant
TSan tests.

rdar://problem/59568956

[yln]

LGTM.

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

 if config.can_symbolize:
   config.available_features.add('can-symbolize')
 
 if config.gwp_asan:
   config.available_features.add('gwp_asan')
 
 lit.util.usePlatformSdkOnDarwin(config, lit_config)
 
+# Maps a lit substitution name for the minimum target OS flag
+# to the macOS version that first contained the relevant feature.
+darwin_min_deployment_target_substitutions = {
+  '%macos_min_target_10_11': '10.11',
+  # rdar://problem/22207160
+  '%darwin_min_target_with_full_runtime_arc_support': '10.11',
+  '%darwin_min_target_with_tls_support': '10.12',
+}
+
 if config.host_os == 'Darwin':
   def get_apple_platform_version_aligned_with(macos_version, apple_platform):
     """
       Given a macOS version (`macos_version`) returns the corresponding version for
       the specified Apple platform if it exists.
 
       `macos_version` - The macOS version as a string.
       `apple_platform` - The Apple platform name as a string.
try:
     output_re = re.match("^hw.cpusubtype: ([0-9]+)$", output)
     if output_re:
       cpu_subtype = int(output_re.group(1))
       if cpu_subtype == 8: # x86_64h
         config.available_features.add('x86_64h')
   except:
     pass
 
-  min_os_aligned_with_osx_10_11 = get_apple_platform_version_aligned_with('10.11', config.apple_platform)
-  min_os_aligned_with_osx_10_11_flag = ''
-  if min_os_aligned_with_osx_10_11:
-    min_os_aligned_with_osx_10_11_flag = '{flag}={version}'.format(
+  def get_apple_min_deploy_target_flag_aligned_with_osx(version):
+    min_os_aligned_with_osx_v = get_apple_platform_version_aligned_with(version, config.apple_platform)
+    min_os_aligned_with_osx_v_flag = ''
+    if min_os_aligned_with_osx_v:
+      min_os_aligned_with_osx_v_flag = '{flag}={version}'.format(
         flag=config.apple_platform_min_deployment_target_flag,
-      version=min_os_aligned_with_osx_10_11)
+        version=min_os_aligned_with_osx_v)
     else:
-    lit_config.warning('Could not find a version of {} that corresponds with macOS 10.11'.format(config.apple_platform))
-  config.substitutions.append( ("%macos_min_target_10_11", min_os_aligned_with_osx_10_11_flag) )
-  # rdar://problem/22207160
-  config.substitutions.append( ("%darwin_min_target_with_full_runtime_arc_support", min_os_aligned_with_osx_10_11_flag) )
+      lit_config.warning('Could not find a version of {} that corresponds with macOS {}'.format(
+        config.apple_platform,
+        version))
+    return min_os_aligned_with_osx_v_flag
+
+  for substitution, osx_version in darwin_min_deployment_target_substitutions.items():
+    config.substitutions.append( (substitution, get_apple_min_deploy_target_flag_aligned_with_osx(osx_version)) )
 
   # 32-bit iOS simulator is deprecated and removed in latest Xcode.
   if config.apple_platform == "iossim":
     if config.target_arch == "i386":
       config.unsupported = True
 else:
-  config.substitutions.append( ("%macos_min_target_10_11", "") )
-  config.substitutions.append( ("%darwin_min_target_with_full_runtime_arc_support", "") )
+  for substitution in darwin_min_deployment_target_substitutions.keys():
+    config.substitutions.append( (substitution, "") )
 
 if config.android:
   env = os.environ.copy()
   if config.android_serial:
     env['ANDROID_SERIAL'] = config.android_serial
     config.environment['ANDROID_SERIAL'] = config.android_serial
 
   adb = os.environ.get('ADB', 'adb')

compiler-rt/test/tsan/dtls.c

-// RUN: %clang_tsan %s -o %t
-// RUN: %clang_tsan %s -DBUILD_SO -fPIC -o %t-so.so -shared
+// RUN: %clang_tsan %darwin_min_target_with_tls_support %s -o %t
+// RUN: %clang_tsan %darwin_min_target_with_tls_support %s -DBUILD_SO -fPIC -o \
+// RUN:   %t-so.so -shared
 // RUN: %run %t 2>&1 | FileCheck %s
 // XFAIL: netbsd
 
 // Test that tsan cleans up dynamic TLS memory between reuse.
 
 #include "test.h"
 
 #ifndef BUILD_SO

compiler-rt/test/tsan/mutexset7.cpp

-// RUN: %clangxx_tsan -O1 %s -o %t && %deflake %run %t | FileCheck %s
+// RUN: %clangxx_tsan %darwin_min_target_with_tls_support -O1 %s -o %t && \
+// RUN:   %deflake %run %t | FileCheck %s
 #include "test.h"
 
 int Global;
 __thread int huge[1024*1024];
 
 void *Thread1(void *x) {
   barrier_wait(&barrier);
   Global++;

compiler-rt/test/tsan/tls_race.cpp

-// RUN: %clangxx_tsan -O1 %s -o %t && %deflake %run %t | FileCheck %s --check-prefix=CHECK-%os --check-prefix=CHECK
+// RUN: %clangxx_tsan %darwin_min_target_with_tls_support -O1 %s -o %t && \
+// RUN:   %deflake %run %t | \
+// RUN:   FileCheck %s --check-prefix=CHECK-%os --check-prefix=CHECK
 #include "test.h"
 
 void *Thread(void *a) {
   barrier_wait(&barrier);
   *(int*)a = 43;
   return 0;
 }
 

compiler-rt/test/tsan/tls_race2.cpp

-// RUN: %clangxx_tsan -O1 %s -o %t && %deflake %run %t | FileCheck %s --check-prefix=CHECK-%os --check-prefix=CHECK
+// RUN: %clangxx_tsan %darwin_min_target_with_tls_support -O1 %s -o %t && \
+// RUN:   %deflake %run %t | \
+// RUN:   FileCheck %s --check-prefix=CHECK-%os --check-prefix=CHECK
 #include "test.h"
 
 void *Thread2(void *a) {
   barrier_wait(&barrier);
   *(int*)a = 43;
   return 0;
 }