Files
wasmtime/lib/frontend/src/lib.rs
2018-07-13 09:15:16 -07:00

160 lines
5.1 KiB
Rust

//! Cranelift IR builder library.
//!
//! Provides a straightforward way to create a Cranelift IR function and fill it with instructions
//! translated from another language. Contains an SSA construction module that lets you translate
//! your non-SSA variables into SSA Cranelift IR values via `use_var` and `def_var` calls.
//!
//! To get started, create an [`FunctionBuilderContext`](struct.FunctionBuilderContext.html) and
//! pass it as an argument to a [`FunctionBuilder`](struct.FunctionBuilder.html).
//!
//! # Example
//!
//! Here is a pseudo-program we want to transform into Cranelift IR:
//!
//! ```clif
//! function(x) {
//! x, y, z : i32
//! block0:
//! y = 2;
//! z = x + y;
//! jump block1
//! block1:
//! z = z + y;
//! brnz y, block2;
//! z = z - x;
//! return y
//! block2:
//! y = y - x
//! jump block1
//! }
//! ```
//!
//! Here is how you build the corresponding Cranelift IR function using `FunctionBuilderContext`:
//!
//! ```rust
//! extern crate cranelift_codegen;
//! extern crate cranelift_frontend;
//!
//! use cranelift_codegen::entity::EntityRef;
//! use cranelift_codegen::ir::{ExternalName, Function, Signature, AbiParam, InstBuilder};
//! use cranelift_codegen::ir::types::*;
//! use cranelift_codegen::settings::{self, CallConv};
//! use cranelift_frontend::{FunctionBuilderContext, FunctionBuilder, Variable};
//! use cranelift_codegen::verifier::verify_function;
//!
//! fn main() {
//! let mut sig = Signature::new(CallConv::SystemV);
//! sig.returns.push(AbiParam::new(I32));
//! sig.params.push(AbiParam::new(I32));
//! let mut fn_builder_ctx = FunctionBuilderContext::<Variable>::new();
//! let mut func = Function::with_name_signature(ExternalName::user(0, 0), sig);
//! {
//! let mut builder = FunctionBuilder::<Variable>::new(&mut func, &mut fn_builder_ctx);
//!
//! let block0 = builder.create_ebb();
//! let block1 = builder.create_ebb();
//! let block2 = builder.create_ebb();
//! let x = Variable::new(0);
//! let y = Variable::new(1);
//! let z = Variable::new(2);
//! builder.declare_var(x, I32);
//! builder.declare_var(y, I32);
//! builder.declare_var(z, I32);
//! builder.append_ebb_params_for_function_params(block0);
//!
//! builder.switch_to_block(block0);
//! builder.seal_block(block0);
//! {
//! let tmp = builder.ebb_params(block0)[0]; // the first function parameter
//! builder.def_var(x, tmp);
//! }
//! {
//! let tmp = builder.ins().iconst(I32, 2);
//! builder.def_var(y, tmp);
//! }
//! {
//! let arg1 = builder.use_var(x);
//! let arg2 = builder.use_var(y);
//! let tmp = builder.ins().iadd(arg1, arg2);
//! builder.def_var(z, tmp);
//! }
//! builder.ins().jump(block1, &[]);
//!
//! builder.switch_to_block(block1);
//! {
//! let arg1 = builder.use_var(y);
//! let arg2 = builder.use_var(z);
//! let tmp = builder.ins().iadd(arg1, arg2);
//! builder.def_var(z, tmp);
//! }
//! {
//! let arg = builder.use_var(y);
//! builder.ins().brnz(arg, block2, &[]);
//! }
//! {
//! let arg1 = builder.use_var(z);
//! let arg2 = builder.use_var(x);
//! let tmp = builder.ins().isub(arg1, arg2);
//! builder.def_var(z, tmp);
//! }
//! {
//! let arg = builder.use_var(y);
//! builder.ins().return_(&[arg]);
//! }
//!
//! builder.switch_to_block(block2);
//! builder.seal_block(block2);
//!
//! {
//! let arg1 = builder.use_var(y);
//! let arg2 = builder.use_var(x);
//! let tmp = builder.ins().isub(arg1, arg2);
//! builder.def_var(y, tmp);
//! }
//! builder.ins().jump(block1, &[]);
//! builder.seal_block(block1);
//!
//! builder.finalize();
//! }
//!
//! let flags = settings::Flags::new(settings::builder());
//! let res = verify_function(&func, &flags);
//! println!("{}", func.display(None));
//! match res {
//! Ok(_) => {}
//! Err(err) => panic!("{}", err),
//! }
//! }
//! ```
#![deny(missing_docs, trivial_numeric_casts, unused_extern_crates)]
#![warn(unused_import_braces)]
#![cfg_attr(feature = "std", warn(unstable_features))]
#![cfg_attr(feature = "cargo-clippy", allow(new_without_default))]
#![cfg_attr(
feature = "cargo-clippy",
warn(
float_arithmetic, mut_mut, nonminimal_bool, option_map_unwrap_or, option_map_unwrap_or_else,
print_stdout, unicode_not_nfc, use_self
)
)]
#![cfg_attr(not(feature = "std"), no_std)]
#![cfg_attr(not(feature = "std"), feature(alloc))]
extern crate cranelift_codegen;
pub use frontend::{FunctionBuilder, FunctionBuilderContext};
pub use variable::Variable;
mod frontend;
mod ssa;
mod variable;
#[cfg(not(feature = "std"))]
mod std {
extern crate alloc;
pub use self::alloc::vec;
pub use core::*;
}