Improve the lowering of CheckedInt32Div and CheckedUint32Div for the
case that the right hand side is a known (positive) power of two, as
in that case it's sufficient to just check the relevant bits on the
left hand side and then shift by the appropriate amount of bits.
This is significantly faster than what TurboFan is able to generate
from the general lowering, even with all the MachineOperatorReducer
magic (it even shows as a steady ~1.5% overall improvement on the
Kraken crypto ccm benchmark).
Also turn the general CheckedInt32Div lowering into readable code again,
and make sure that all the bailout cases are properly covered by mjsunit
tests (i.e. the "division by zero" bailout was not covered properly).
Bug: v8:8015
Change-Id: Ibfdd367a6ee5d70dcaa48801858042c5029b7004
Reviewed-on: https://chromium-review.googlesource.com/1236954
Reviewed-by: Sigurd Schneider <sigurds@chromium.org>
Commit-Queue: Benedikt Meurer <bmeurer@chromium.org>
Cr-Commit-Position: refs/heads/master@{#56115}
ce7ec6ef0a