From:  Lars Hansen <>
Date:  19 Aug 2017 00:07:42 Hong Kong Time

Wasm: Tiered compilation enabled in the JS shell


Just a quick heads-up for those of you working on Webassembly.  I just
landed a set of patches for tiered wasm compilation (fast baseline + slower
ion in the background); this is enabled by default in the shell but not yet
in the browser.  You should expect benchmark results to change (for now)
and there may be bugs, of course.  Over the next few weeks we'll tune
tiering further to kick in where most appropriate but right now everything
is compiled tiered.  Very large programs may suffer from (quiet) OOM during
Ion compilation and may run more slowly on 32-bit systems if there's only
space for the results from the baseline compilation.

The shell accepts new switches, --no-wasm-baseline and --no-wasm-ion, that
disable the respective compilers.  The old switch --wasm-always-baseline is