This CL adds the simplest version of a trap handler fallback. At
instantiation time, we check whether the module was compiled to use
trap handlers and the memory is guarded. If the memory is not guarded
but the module is supposed to use trap handlers, we recompile the
module with bounds checks so that we can use an unguarded memory.
The compiled module is replaced with a bounds checking version, meaning
future instances from this module will also use bounds checks.
Some likely desirable features that are current missing but can be
added future CLs include:
* Disabling trap handler mode entirely.
* Recompiling all old instances so that trap handler and bounds checked
code does not coexist in the same process.
Bug: v8:7143
Change-Id: I161fc0d544133b07dc4a93cc6af813369aaf3efe
Reviewed-on: https://chromium-review.googlesource.com/1018182
Commit-Queue: Eric Holk <eholk@chromium.org>
Reviewed-by: Michael Starzinger <mstarzinger@chromium.org>
Reviewed-by: Andreas Haas <ahaas@chromium.org>
Cr-Commit-Position: refs/heads/master@{#53566}
