[compiler-rt] Allow override of 'emulator' value from lit_config.

Currently the 'emulator' value is fixed at build time. This patch allows changing the emulator at testing time and enables us to run the tests on different board or simulators without needing to run CMake again to change the value of emulator. With this patch in place, the value of 'emulator' can be changed at test time from the command line like this: $ llvm-lit --param=emulator="..." Reviewed By: delcypher Differential Revision: https://reviews.llvm.org/D84708

Author: abidh

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

@@ -132,9 +132,21 @@
 else:
  config.substitutions.append( ('%run_nomprotect', '%run') )
 
+# Copied from libcxx's config.py
+def get_lit_conf(name, default=None):
+ # Allow overriding on the command line using --param=<name>=<val>
+ val = lit_config.params.get(name, None)
+ if val is None:
+ val = getattr(config, name, None)
+ if val is None:
+ val = default
+ return val
+
+emulator = get_lit_conf('emulator', None)
+
 # Allow tests to be executed on a simulator or remotely.
-if config.emulator:
- config.substitutions.append( ('%run', config.emulator) )
+if emulator:
+ config.substitutions.append( ('%run', emulator) )
  config.substitutions.append( ('%env ', "env ") )
  # TODO: Implement `%device_rm` to perform removal of files in the emulator.
  # For now just make it a no-op.