e59b47c41a
When an instruction can't be encoded, provide a viable legalization action in the form of a Legalize enum.
133 lines
4.5 KiB
Rust
133 lines
4.5 KiB
Rust
//! Instruction Set Architectures.
|
|
//!
|
|
//! The `isa` module provides a `TargetIsa` trait which provides the behavior specialization needed
|
|
//! by the ISA-independent code generator. The sub-modules of this module provide definitions for
|
|
//! the instruction sets that Cretonne can target. Each sub-module has it's own implementation of
|
|
//! `TargetIsa`.
|
|
//!
|
|
//! # Constructing a `TargetIsa` instance
|
|
//!
|
|
//! The target ISA is built from the following information:
|
|
//!
|
|
//! - The name of the target ISA as a string. Cretonne is a cross-compiler, so the ISA to target
|
|
//! can be selected dynamically. Individual ISAs can be left out when Cretonne is compiled, so a
|
|
//! string is used to identify the proper sub-module.
|
|
//! - Values for settings that apply to all ISAs. This is represented by a `settings::Flags`
|
|
//! instance.
|
|
//! - Values for ISA-specific settings.
|
|
//!
|
|
//! The `isa::lookup()` function is the main entry point which returns an `isa::Builder`
|
|
//! appropriate for the requested ISA:
|
|
//!
|
|
//! ```
|
|
//! use cretonne::settings::{self, Configurable};
|
|
//! use cretonne::isa;
|
|
//!
|
|
//! let shared_builder = settings::builder();
|
|
//! let shared_flags = settings::Flags::new(&shared_builder);
|
|
//!
|
|
//! match isa::lookup("riscv") {
|
|
//! None => {
|
|
//! // The RISC-V target ISA is not available.
|
|
//! }
|
|
//! Some(mut isa_builder) => {
|
|
//! isa_builder.set("supports_m", "on");
|
|
//! let isa = isa_builder.finish(shared_flags);
|
|
//! }
|
|
//! }
|
|
//! ```
|
|
//!
|
|
//! The configured target ISA trait object is a `Box<TargetIsa>` which can be used for multiple
|
|
//! concurrent function compilations.
|
|
|
|
pub use isa::encoding::Encoding;
|
|
use settings;
|
|
use ir::{InstructionData, DataFlowGraph};
|
|
|
|
pub mod riscv;
|
|
mod encoding;
|
|
mod enc_tables;
|
|
|
|
/// Look for a supported ISA with the given `name`.
|
|
/// Return a builder that can create a corresponding `TargetIsa`.
|
|
pub fn lookup(name: &str) -> Option<Builder> {
|
|
match name {
|
|
"riscv" => riscv_builder(),
|
|
_ => None,
|
|
}
|
|
}
|
|
|
|
// Make a builder for RISC-V.
|
|
fn riscv_builder() -> Option<Builder> {
|
|
Some(riscv::isa_builder())
|
|
}
|
|
|
|
/// Builder for a `TargetIsa`.
|
|
/// Modify the ISA-specific settings before creating the `TargetIsa` trait object with `finish`.
|
|
pub struct Builder {
|
|
setup: settings::Builder,
|
|
constructor: fn(settings::Flags, &settings::Builder) -> Box<TargetIsa>,
|
|
}
|
|
|
|
impl Builder {
|
|
/// Combine the ISA-specific settings with the provided ISA-independent settings and allocate a
|
|
/// fully configured `TargetIsa` trait object.
|
|
pub fn finish(self, shared_flags: settings::Flags) -> Box<TargetIsa> {
|
|
(self.constructor)(shared_flags, &self.setup)
|
|
}
|
|
}
|
|
|
|
impl settings::Configurable for Builder {
|
|
fn set(&mut self, name: &str, value: &str) -> settings::Result<()> {
|
|
self.setup.set(name, value)
|
|
}
|
|
|
|
fn set_bool(&mut self, name: &str, value: bool) -> settings::Result<()> {
|
|
self.setup.set_bool(name, value)
|
|
}
|
|
}
|
|
|
|
/// After determining that an instruction doesn't have an encoding, how should we proceed to
|
|
/// legalize it?
|
|
///
|
|
/// These actions correspond to the transformation groups defined in `meta/cretonne/legalize.py`.
|
|
#[derive(Clone, Copy, PartialEq, Eq, Debug)]
|
|
pub enum Legalize {
|
|
/// Legalize in terms of narrower types.
|
|
Narrow,
|
|
|
|
/// Expanding in terms of other instructions using the same types.
|
|
Expand,
|
|
}
|
|
|
|
/// Methods that are specialized to a target ISA.
|
|
pub trait TargetIsa {
|
|
/// Get the name of this ISA.
|
|
fn name(&self) -> &'static str;
|
|
|
|
/// Get the ISA-independent flags that were used to make this trait object.
|
|
fn flags(&self) -> &settings::Flags;
|
|
|
|
/// Encode an instruction after determining it is legal.
|
|
///
|
|
/// If `inst` can legally be encoded in this ISA, produce the corresponding `Encoding` object.
|
|
/// Otherwise, return `None`.
|
|
///
|
|
/// This is also the main entry point for determining if an instruction is legal.
|
|
fn encode(&self, dfg: &DataFlowGraph, inst: &InstructionData) -> Result<Encoding, Legalize>;
|
|
|
|
/// Get a static array of names associated with encoding recipes in this ISA. Encoding recipes
|
|
/// are numbered starting from 0, corresponding to indexes into th name array.
|
|
///
|
|
/// This is just used for printing and parsing encodings in the textual IL format.
|
|
fn recipe_names(&self) -> &'static [&'static str];
|
|
|
|
/// Create an object that can display an ISA-dependent encoding properly.
|
|
fn display_enc(&self, enc: Encoding) -> encoding::DisplayEncoding {
|
|
encoding::DisplayEncoding {
|
|
encoding: enc,
|
|
recipe_names: self.recipe_names(),
|
|
}
|
|
}
|
|
}
|