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, 5 insertions, 5 deletions

diff --git a/test/passes/emit-js-wrapper=a.js.wast.js b/test/passes/emit-js-wrapper=a.js.wast.js
index 9e8578781..2e127d189 100644
--- a/test/passes/emit-js-wrapper=a.js.wast.js
+++ b/test/passes/emit-js-wrapper=a.js.wast.js
@@ -51,33 +51,33 @@ try {
   console.log('[fuzz-exec] calling $add');
   console.log('[fuzz-exec] note result: $add => ' + literal(instance.exports.add(0, 0), 'i32'));
 } catch (e) {
-  console.log('exception: ' + e);
+  console.log('exception!' /* + e */);
 }
 if (instance.exports.hangLimitInitializer) instance.exports.hangLimitInitializer();
 try {
   console.log('[fuzz-exec] calling $no_return');
   instance.exports.no_return(0);
 } catch (e) {
-  console.log('exception: ' + e);
+  console.log('exception!' /* + e */);
 }
 if (instance.exports.hangLimitInitializer) instance.exports.hangLimitInitializer();
 try {
   console.log('[fuzz-exec] calling $types');
   instance.exports.types(0, 0, 0, 0, 0);
 } catch (e) {
-  console.log('exception: ' + e);
+  console.log('exception!' /* + e */);
 }
 if (instance.exports.hangLimitInitializer) instance.exports.hangLimitInitializer();
 try {
   console.log('[fuzz-exec] calling $types2');
   instance.exports.types2(0, 0, 0);
 } catch (e) {
-  console.log('exception: ' + e);
+  console.log('exception!' /* + e */);
 }
 if (instance.exports.hangLimitInitializer) instance.exports.hangLimitInitializer();
 try {
   console.log('[fuzz-exec] calling $types3');
   console.log('[fuzz-exec] note result: $types3 => ' + literal(instance.exports.types3(0, 0, 0), 'i32'));
 } catch (e) {
-  console.log('exception: ' + e);
+  console.log('exception!' /* + e */);
 }