NaN fuzzing improvements (#1913)

* make DE_NAN avoid creating nan literals in the first place
* add a reducer option `--denan` to not introduce nans in destructive reduction
* add a `Literal::isNaN()` method
* also remove the default exception logging from the fuzzer js glue, which is a source of non-useful VM differences (like nan nondeterminism)
* added an option `--no-fuzz-nans` to make it easy to avoid nans when fuzzing (without hacking the source and recompiling).

Background: trying to get fuzzing on jsc working despite this open issue: https://bugs.webkit.org/show_bug.cgi?id=175691

1 files changed, 1 insertions, 1 deletions

diff --git a/src/tools/js-wrapper.h b/src/tools/js-wrapper.h
index 765a638c5..433d6fc5a 100644
--- a/src/tools/js-wrapper.h
+++ b/src/tools/js-wrapper.h
@@ -103,7 +103,7 @@ static std::string generateJSWrapper(Module& wasm) {
     }
     ret += ";\n";
     ret += "} catch (e) {\n";
-    ret += "  console.log('exception: ' + e);\n";
+    ret += "  console.log('exception!' /* + e */);\n";
     ret += "}\n";
   }
   return ret;