Precompute fields in VMOffsets
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This commit updates the implementation of `VMOffsets` to frontload all checked arithmetic on construction of the `VMOffsets` which allows eliding all checked arithmetic when accessing the fields of `VMOffsets`. For testing and such this adds a new constructor as well from a new `VMOffsetsFields` structure which is a clone of the old definition. This should help speed up some profile hot spots I've been seeing where with all the checked arithmetic on field sizes this was slowing down the various accessors during instantiation (which uses `VMOffsets` to initialize various fields of the `VMContext`).
alexcrichton
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peterhuene
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Apr 8, 2021
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This commit updates the implementation of
VMOffsetsto frontload allchecked arithmetic on construction of the
VMOffsetswhich allowseliding all checked arithmetic when accessing the fields of
VMOffsets.For testing and such this adds a new constructor as well from a new
VMOffsetsFieldsstructure which is a clone of the old definition.This should help speed up some profile hot spots I've been seeing where
with all the checked arithmetic on field sizes this was slowing down the
various accessors during instantiation (which uses
VMOffsetstoinitialize various fields of the
VMContext).