"Warning: unknown flag --turbo."

Sounds like the config needs some change?

Yep, as discussed offline with machenbach@, the flag is gone. There already is a CL in flight that adapts the foozzie configuration ...

https://chromium-review.googlesource.com/c/565398/

We ignore wrong flags anyways. The issue here is something else. Reduced repro:

function __f_0() { return Reflect.getPrototypeOf(""); }
try {
 __f_0();
} catch(e) {}
%OptimizeFunctionOnNextCall(__f_0);
__f_0();

OK, thanks! Will take a look. Wrong analysis, right owner nonetheless. :)

Fix is in flight: https://chromium-review.googlesource.com/c/565295/

The following revision refers to this bug:
  https://chromium.googlesource.com/v8/v8.git/+/933a874e1d7e67e7c9502adacd216f52b2839276

commit 933a874e1d7e67e7c9502adacd216f52b2839276
Author: Michael Starzinger <mstarzinger@chromium.org>
Date: Tue Jul 11 12:45:12 2017

[turbofan] Fix Reflect.getPrototypeOf on primitives.

This fixes the lowering of Reflect.getPrototypeOf and friends to not
perform a [[ToObject]] coercion, but bailout instead. We ensure to
exclude primitive values from the lowering. This makes the lowering
uniform between "Reflect.getPrototypeOf" and "Object.getPrototypeOf".

R=bmeurer@chromium.org
TEST=mjsunit/regress/regress-crbug-740116
BUG= chromium:740116 

Change-Id: If986ee2a3ae4e8f1fd227bdeb4668f523b0dea84
Reviewed-on: https://chromium-review.googlesource.com/565295
Reviewed-by: Benedikt Meurer <bmeurer@chromium.org>
Commit-Queue: Michael Starzinger <mstarzinger@chromium.org>
Cr-Commit-Position: refs/heads/master@{#46556}
[modify] https://crrev.com/933a874e1d7e67e7c9502adacd216f52b2839276/src/compiler/js-call-reducer.cc
[add] https://crrev.com/933a874e1d7e67e7c9502adacd216f52b2839276/test/mjsunit/regress/regress-crbug-740116.js

ClusterFuzz has detected this issue as fixed in range 46555:46556.

Detailed report: https://clusterfuzz.com/testcase?key=4541730828582912

Fuzzer: foozzie_js_mutation
Job Type: v8_foozzie
Platform Id: linux

Crash Type: V8 correctness failure
Crash Address: 
Crash State:
  configs: x64,ignition:x64,ignition_turbo
  sources: 24e
  
Sanitizer: address (ASAN)

Regressed: V8: 44787:44788
Fixed: V8: 46555:46556

Reproducer Testcase: https://clusterfuzz.com/download?testcase_id=4541730828582912


See https://dev.chromium.org/Home/chromium-security/bugs/reproducing-clusterfuzz-bugs for more information.

If you suspect that the result above is incorrect, try re-doing that job on the test case report page.