1 files changed, 18 insertions, 1 deletions
diff --git a/scripts/fuzz_opt.py b/scripts/fuzz_opt.py
index 145a2c543..4f35a1a77 100755
--- a/scripts/fuzz_opt.py
+++ b/scripts/fuzz_opt.py
@@ -118,6 +118,7 @@ FUZZ_OPTS = None
 NANS = None
 OOB = None
 LEGALIZE = None
+ORIGINAL_V8_OPTS = shared.V8_OPTS[:]
 
 
 def randomize_fuzz_settings():
@@ -138,7 +139,23 @@ def randomize_fuzz_settings():
         FUZZ_OPTS += ['--legalize-js-interface']
     else:
         LEGALIZE = False
-    print('randomized settings (NaNs, OOB, legalize):', NANS, OOB, LEGALIZE)
+    extra_v8_opts = []
+    # 50% of the time test v8 normally, that is, the same way it runs in
+    # production (which as of 07/15/2020 means baseline, then tier up to
+    # optimizing, but that may change in the future).
+    if random.random() < 0.5:
+        # test either the optimizing compiler or the baseline compiler, with
+        # equal probability. it's useful to do this because the normal tier-up
+        # mode does not check them both equally (typically baseline does not get
+        # enough testing, as we quickly leave it), and also because the tiering
+        # up is nondeterministic (when optimized code becomes ready, we switch
+        # to it)
+        if random.random() < 0.5:
+            extra_v8_opts += ['--no-liftoff']
+        else:
+            extra_v8_opts += ['--liftoff', '--no-wasm-tier-up']
+    shared.V8_OPTS = ORIGINAL_V8_OPTS + extra_v8_opts
+    print('randomized settings (NaNs, OOB, legalize, extra V8_OPTS):', NANS, OOB, LEGALIZE, extra_v8_opts)
 
 
 # Test outputs we want to ignore are marked this way.