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sebmarkbage
03205d9bd9
At some point this trick was added to initialize the value first to NaN and then replace them with zeros and negative ones. This is to address the issue noted in https://github.com/facebook/react/issues/14365 where these hidden classes can be initialized to SMIs at first and then deopt when we realize they're actually doubles. However, this fix has been long broken and has deopted the profiling build for years because closure compiler optimizes out the first write. I'm not sure because I haven't A/B-tested this in the JIT yet but I think we can use negative zero and -1.1 as the initial values instead since they're not simple integers. Negative zero `===` zero (but not Object.is) so is the same as far as our code is concerned. The negative value is just `< 0` comparisons. DiffTrain build for commit https://github.com/facebook/react/commit/94e4acaa1477e65cac02ba86058cde0afe4c8f1f.