Change the meaning of --interpreter option in testing scripts.

Previously --interpreter used to run the tests on the slow C++
switch-interpreter (the analogue of -Xint option to dalvikvm). Now it
runs the tests on the fast assembly interpreter, Nterp (the analogue of
-Xusefit:false option to dalvikvm).

--interp-ac can stil be used to run tests on the switch interpreter.

Bug: 271573990

Test: `art/test.py --host -r 001-HelloWorld` with the following
    modifications that ensure ART runs in the intended mode:
      - no modifications: 10/10 tests pass
      - deliberaly break Nterp: 2/10 tests pass (only --interp-ac ones)
      - deliberately break JIT: 8/10 tests pass (only --jit tests fail)
Change-Id: If2ec1df96b65c7e2dd7e81dff3ee0378bde62751
diff --git a/test/default_run.py b/test/default_run.py
index 7e28dfc..6fcaa16 100755
--- a/test/default_run.py
+++ b/test/default_run.py
@@ -73,6 +73,7 @@
   argp.add_argument("--image", default=True, action=opt_bool)
   argp.add_argument("--instruction-set-features", default="")
   argp.add_argument("--interpreter", action="store_true")
+  argp.add_argument("--switch-interpreter", action="store_true")
   argp.add_argument("--invoke-with", default=[], action="append")
   argp.add_argument("--jit", action="store_true")
   argp.add_argument("--jvm", action="store_true")
@@ -277,6 +278,7 @@
   USE_EXTRACTED_ZIPAPEX = (args.runtime_extracted_zipapex != "")
   EXTRACTED_ZIPAPEX_LOC = args.runtime_extracted_zipapex
   INTERPRETER = args.interpreter
+  SWITCH_INTERPRETER = args.switch_interpreter
   JIT = args.jit
   INVOKE_WITH = " ".join(args.invoke_with)
   USE_JVMTI = args.jvmti
@@ -655,15 +657,20 @@
       GDB = "gdb"
       GDB_ARGS += f" -d '{ANDROID_BUILD_TOP}' --args {DALVIKVM}"
 
-  if INTERPRETER:
+  if SWITCH_INTERPRETER:
+    # run on the slow switch-interpreter enabled with -Xint
     INT_OPTS += " -Xint"
 
+  if INTERPRETER:
+    # run on Nterp the fast interpreter, not the slow switch-interpreter enabled with -Xint
+    INT_OPTS += " -Xusejit:false"
+
   if JIT:
     INT_OPTS += " -Xusejit:true"
   else:
     INT_OPTS += " -Xusejit:false"
 
-  if INTERPRETER or JIT:
+  if INTERPRETER or SWITCH_INTERPRETER or JIT:
     if VERIFY == "y":
       INT_OPTS += " -Xcompiler-option --compiler-filter=verify"
       COMPILE_FLAGS += " --compiler-filter=verify"
diff --git a/test/run-test b/test/run-test
index 2760db9..9565ebb 100755
--- a/test/run-test
+++ b/test/run-test
@@ -409,6 +409,9 @@
     elif arg == "--interpreter":
       run_args += ["--interpreter"]
       shift()
+    elif arg == "--switch-interpreter":
+      run_args += ["--switch-interpreter"]
+      shift()
     elif arg == "--jit":
       run_args += ["--jit"]
       shift()
diff --git a/test/testrunner/testrunner.py b/test/testrunner/testrunner.py
index 247a6aa..6a348dc 100755
--- a/test/testrunner/testrunner.py
+++ b/test/testrunner/testrunner.py
@@ -535,7 +535,7 @@
       elif compiler == 'interpreter':
         args_test += ['--interpreter']
       elif compiler == 'interp-ac':
-        args_test += ['--interpreter', '--verify-soft-fail']
+        args_test += ['--switch-interpreter', '--verify-soft-fail']
       elif compiler == 'jit':
         args_test += ['--jit']
       elif compiler == 'jit-on-first-use':