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Leszek Swirski authored
Add a new CRTP StaticCallInterfaceDescriptor class, which provides static constexpr getters for a descriptor's registers, parameter counts, and so on. Each CallInterfaceDescriptor subclass is changed to extend StaticCallInterfaceDescriptor, with StaticCallInterfaceDescriptor itself extending CallInterfaceDescriptor to still provide a dynamic lookup where needed. StaticCallInterfaceDescriptor provides a couple of customisation points, where it reads its CRTP derived descriptor's static fields and functions, with default fallbacks where appropriate. With these customisation points, the definition of CallInterfaceDescriptor subclasses is simplified to: a) Providing parameter names (as before) b) Providing parameter types (as before) c) Optionally setting flags (like kNoContext or kAllowVarArgs) as static booleans on the class. d) Optionally providing a `registers()` method that returns a std::array<Register, N> of registers that may be used for parameters (if not provided, this defaults to the implementation specific default register set). Parameter registers (and register count) are automagically set based on the number of parameters and number of given registers, with extra magic to ignore no_reg registers (to reduce ia32 special casing). The CallInterfaceDescriptorData is initialized based on these static functions, rather than manual per-descriptor initializers. This allows us to skip loading descriptors dynamically for CallBuiltin in Sparkplug, and instead lets us use a bit of template magic to statically set up arguments for the calls. Any other users of statically known descriptors will also benefit, thanks to C++ picking the static methods over the dynamic methods on the base class when available. Because we can remove various virtual functions and trigger heavier inlining of constantly known values, binary size slightly decreases with this change. Note that torque-generated descriptors are changed to use the same magic, rather than having Torque-specific magic, for consistency. Bug: v8:11420 Change-Id: Icc5e238b6313a08734feb564204a13226b450c22 Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2814518 Auto-Submit: Leszek Swirski <leszeks@chromium.org> Reviewed-by: Nico Hartmann <nicohartmann@chromium.org> Reviewed-by: Clemens Backes <clemensb@chromium.org> Reviewed-by: Igor Sheludko <ishell@chromium.org> Reviewed-by: Jakob Gruber <jgruber@chromium.org> Commit-Queue: Clemens Backes <clemensb@chromium.org> Cr-Commit-Position: refs/heads/master@{#73996}
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