Cranelift: Add a new backend for emitting Pulley bytecode #9089
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alexcrichton
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| if let Ok(offset) = i8::try_from(offset) { | ||
| enc::xconst8(sink, dst, offset); | ||
| } else if let Ok(offset) = i16::try_from(offset) { | ||
| enc::xconst16(sink, dst, offset); | ||
| } else if let Ok(offset) = i32::try_from(offset) { | ||
| enc::xconst32(sink, dst, offset); | ||
| } else { | ||
| enc::xconst64(sink, dst, offset); | ||
| } |
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I think I saw this as well in abi.rs as well as lower.isle perhaps, coul the Rust-side parts be deduplicated into a helper?
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The one in abi.rs is constructing MInst::Xconst* variants while this one is calling differentenc::xconst* functions, so there isn't a great way to dedupe this. We could make something that is abstract enough to handle both but that abstraction won't actually be any more concise, simpler, or easy to understand, unfortunately.
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This commit adds two new backends for Cranelift that emits 32- and 64-bit Pulley bytecode. The backends are both actually the same, with a common implementation living in `cranelift/codegen/src/isa/pulley_shared`. Each backend configures an ISA flag that determines the pointer size, and lowering inspects this flag's value when lowering memory accesses. To avoid multiple ISLE compilation units, and to avoid compiling duplicate copies of Pulley's generated `MInst`, I couldn't use `MInst` as the `MachInst` implementation directly. Instead, there is an `InstAndKind` type that is a newtype over the generated `MInst` but which also carries a phantom type parameter that implements the `PulleyTargetKind` trait. There are two implementations of this trait, a 32- and 64-bit version. This is necessary because there are various static trait methods for the mach backend which we must implement, and which return the pointer width, but don't have access to any `self`. Therefore, we are forced to monomorphize some amount of code. This type parameter is fairly infectious, and all the "big" backend types (`PulleyBackend<P>`, `PulleyABICallSite<P>`, etc...) are parameterized over it. Nonetheless, not everything is parameterized over a `PulleyTargetKind`, and we manage to avoid duplicate `MInst` definitions and lowering code. Note that many methods are still stubbed out with `todo!`s. It is expected that we will fill in those implementations as the work on Pulley progresses.
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This commit adds two new backends for Cranelift that emits 32- and 64-bit Pulley
bytecode. The backends are both actually the same, with a common implementation
living in
cranelift/codegen/src/isa/pulley_shared. Each backend configures anISA flag that determines the pointer size, and lowering inspects this flag's
value when lowering memory accesses.
To avoid multiple ISLE compilation units, and to avoid compiling duplicate
copies of Pulley's generated
MInst, I couldn't useMInstas theMachInstimplementation directly. Instead, there is an
InstAndKindtype that is anewtype over the generated
MInstbut which also carries a phantom typeparameter that implements the
PulleyTargetKindtrait. There are twoimplementations of this trait, a 32- and 64-bit version. This is necessary
because there are various static trait methods for the mach backend which we
must implement, and which return the pointer width, but don't have access to any
self. Therefore, we are forced to monomorphize some amount of code. This typeparameter is fairly infectious, and all the "big" backend
types (
PulleyBackend<P>,PulleyABICallSite<P>, etc...) are parameterizedover it. Nonetheless, not everything is parameterized over a
PulleyTargetKind,and we manage to avoid duplicate
MInstdefinitions and lowering code.Note that many methods are still stubbed out with
todo!s. It is expected thatwe will fill in those implementations as the work on Pulley progresses.
The first commit is #9085; this depends on that PR.