[NFC] Generalize flags for linking in shared objects in compiler-rt tests to support using multiple shared objects at once

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

 
 # The current implementation of the tools in sanitizer_common/ios_comamnds
 # do not support parallel execution so force sequential execution of the
 # tests on iOS devices.
 if config.host_os == 'Darwin' and config.ios and not config.iossim:
   lit_config.warning("iOS device test cases being run sequentially")
   lit_config.parallelism_groups["darwin-ios-device-sanitizer"] = 1
 
-
+# Multiple substitutions are necessary to support multiple shared objects used
+# at once.
+# Note that substitutions with numbers have to be defined first to avoid
+# being subsumed by substitutions with smaller postfix.
+for postfix in ["2", "1", ""]:
   if config.host_os == 'Darwin':
-  config.substitutions.append( ("%ld_flags_rpath_exe", '-Wl,-rpath,@executable_path/ %dynamiclib') )
-  config.substitutions.append( ("%ld_flags_rpath_so", '-install_name @rpath/`basename %dynamiclib`') )
+    config.substitutions.append( ("%ld_flags_rpath_exe" + postfix, '-Wl,-rpath,@executable_path/ %dynamiclib' + postfix) )
+    config.substitutions.append( ("%ld_flags_rpath_so" + postfix, '-install_name @rpath/`basename %dynamiclib{}`'.format(postfix)) )
   elif config.host_os == 'FreeBSD' or config.host_os == 'NetBSD':
-  config.substitutions.append( ("%ld_flags_rpath_exe", "-Wl,-z,origin -Wl,-rpath,\$ORIGIN -L%T -l%xdynamiclib_namespec") )
-  config.substitutions.append( ("%ld_flags_rpath_so", '') )
+    config.substitutions.append( ("%ld_flags_rpath_exe" + postfix, "-Wl,-z,origin -Wl,-rpath,\$ORIGIN -L%T -l%xdynamiclib_namespec" + postfix) )
+    config.substitutions.append( ("%ld_flags_rpath_so" + postfix, '') )
   elif config.host_os == 'Linux':
-  config.substitutions.append( ("%ld_flags_rpath_exe", "-Wl,-rpath,\$ORIGIN -L%T -l%xdynamiclib_namespec") )
-  config.substitutions.append( ("%ld_flags_rpath_so", '') )
+    config.substitutions.append( ("%ld_flags_rpath_exe" + postfix, "-Wl,-rpath,\$ORIGIN -L%T -l%xdynamiclib_namespec" + postfix) )
+    config.substitutions.append( ("%ld_flags_rpath_so" + postfix, '') )
   elif config.host_os == 'SunOS':
-  config.substitutions.append( ("%ld_flags_rpath_exe", "-Wl,-R\$ORIGIN -L%T -l%xdynamiclib_namespec") )
-  config.substitutions.append( ("%ld_flags_rpath_so", '') )
+    config.substitutions.append( ("%ld_flags_rpath_exe" + postfix, "-Wl,-R\$ORIGIN -L%T -l%xdynamiclib_namespec" + postfix) )
+    config.substitutions.append( ("%ld_flags_rpath_so" + postfix, '') )
+
+  # Must be defined after the substitutions that use %dynamiclib.
+  config.substitutions.append( ("%dynamiclib" + postfix, '%T/%xdynamiclib_filename' + postfix) )
+  config.substitutions.append( ("%xdynamiclib_filename" + postfix, 'lib%xdynamiclib_namespec{}.so'.format(postfix)) )
+  config.substitutions.append( ("%xdynamiclib_namespec", '%basename_t.dynamic') )
 
 # Provide a substituion that can be used to tell Clang to use a static libstdc++.
 # The substitution expands to nothing on non Linux platforms.
 # FIXME: This should check the target OS, not the host OS.
 if config.host_os == 'Linux':
   config.substitutions.append( ("%linux_static_libstdcplusplus", "-stdlib=libstdc++ -static-libstdc++") )
 else:
   config.substitutions.append( ("%linux_static_libstdcplusplus", "") )
 
-# Must be defined after the substitutions that use %dynamiclib.
-config.substitutions.append( ("%dynamiclib", '%T/%xdynamiclib_filename') )
-config.substitutions.append( ("%xdynamiclib_filename", 'lib%xdynamiclib_namespec.so') )
-config.substitutions.append( ("%xdynamiclib_namespec", '%basename_t.dynamic') )
-
 config.default_sanitizer_opts = []
 if config.host_os == 'Darwin':
   # On Darwin, we default to `abort_on_error=1`, which would make tests run
   # much slower. Let's override this and run lit tests with 'abort_on_error=0'.
   config.default_sanitizer_opts += ['abort_on_error=0']
   config.default_sanitizer_opts += ['log_to_syslog=0']
 elif config.android:
   config.default_sanitizer_opts += ['abort_on_error=0']