winch(aarch64): Simplify constant handling, part 1/N #10888
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This commit is the first step toward simplifying constant handling, particularly for the aarch64 backend. The main highlights in this patch are: * Introduction of `ConstantPool` implemenetation on top of Cranlift primitives. The implemettaion is identical to the existing for x64, however, it's abstracted so that it can be easily consumed from any existing backend. * Usage of the constant pool from aarch64, which simplifies the loading of constants, particularly floating point constants. The main motivation behind this change is to _eventually_ detach the implicit usage of the scatch register from constant loading as much as possible, reducing the possibility of subtle bugs (like the one described in bytecodealliance#10829). Note that I have a work-in-progress branch from where all these changes are cherry picked from, to make everything easier to review. A side effect of this change, is the improvement to the code generation involving floating point constants. Prior to this change, multiple moves were involved, with this patch, at most 1 move is required and at worst one load is required.
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This commit is the first step toward simplifying constant handling,
particularly for the aarch64 backend.
The main highlights in this patch are:
ConstantPoolimplemenetation on top of Cranliftprimitives. The implemettaion is identical to the existing for x64,
however, it's abstracted so that it can be easily consumed from any
existing backend.
loading of constants, particularly floating point constants.
The main motivation behind this change is to eventually detach the
implicit usage of the scatch register from constant loading as much as
possible, reducing the possibility of subtle bugs (like the one
described in #10829).
Note that I have a work-in-progress branch from where all these
changes are cherry picked from, to make everything easier to review.
A side effect of this change, is the improvement to the code
generation involving floating point constants. Prior to this change,
multiple moves were involved, with this patch, at most 1 move is
required and at worst one load is required.