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//! A linear IR for optimizations. //! //! This IR is designed such that it should be easy to combine multiple linear //! optimizations into a single automata. //! //! See also `src/linearize.rs` for the AST to linear IR translation pass. use crate::cc::ConditionCode; use crate::integer_interner::{IntegerId, IntegerInterner}; use crate::operator::{Operator, UnquoteOperator}; use crate::paths::{PathId, PathInterner}; use crate::r#type::{BitWidth, Type}; use serde::{Deserialize, Serialize}; use std::num::NonZeroU32; /// A set of linear optimizations. #[derive(Debug)] pub struct Optimizations { /// The linear optimizations. pub optimizations: Vec<Optimization>, /// The de-duplicated paths referenced by these optimizations. pub paths: PathInterner, /// The integer literals referenced by these optimizations. pub integers: IntegerInterner, } /// A linearized optimization. #[derive(Clone, Debug, PartialEq, Eq)] pub struct Optimization { /// The chain of increments for this optimization. pub increments: Vec<Increment>, } /// Match any value. /// /// This can be used to create fallback, wildcard-style transitions between /// states. #[derive(Clone, Copy, Debug, PartialEq, Eq, PartialOrd, Ord, Hash, Serialize, Deserialize)] pub struct Else; /// The result of evaluating a `MatchOp`. /// /// This is either a specific non-zero `u32`, or a fallback that matches /// everything. pub type MatchResult = Result<NonZeroU32, Else>; /// Convert a boolean to a `MatchResult`. #[inline] pub fn bool_to_match_result(b: bool) -> MatchResult { let b = b as u32; unsafe { Ok(NonZeroU32::new_unchecked(b + 1)) } } /// A partial match of an optimization's LHS and partial construction of its /// RHS. /// /// An increment is a matching operation, the expected result from that /// operation to continue to the next increment, and the actions to take to /// build up the LHS scope and RHS instructions given that we got the expected /// result from this increment's matching operation. Each increment will /// basically become a state and a transition edge out of that state in the /// final automata. #[derive(Clone, Debug, PartialEq, Eq)] pub struct Increment { /// The matching operation to perform. pub operation: MatchOp, /// The expected result of our matching operation, that enables us to /// continue to the next increment, or `Else` for "don't care" /// wildcard-style matching. pub expected: MatchResult, /// Actions to perform, given that the operation resulted in the expected /// value. pub actions: Vec<Action>, } /// A matching operation to be performed on some Cranelift instruction as part /// of determining whether an optimization is applicable. #[derive(Clone, Copy, Debug, PartialEq, Eq, Hash, Deserialize, Serialize)] pub enum MatchOp { /// Switch on the opcode of an instruction. Opcode { /// The path to the instruction whose opcode we're switching on. path: PathId, }, /// Does an instruction have a constant value? IsConst { /// The path to the instruction (or immediate) that we're checking /// whether it is constant or not. path: PathId, }, /// Is the constant value a power of two? IsPowerOfTwo { /// The path to the instruction (or immediate) that we are checking /// whether it is a constant power of two or not. path: PathId, }, /// Switch on the bit width of a value. BitWidth { /// The path to the instruction (or immediate) whose result's bit width /// we are checking. path: PathId, }, /// Does the value fit in our target architecture's native word size? FitsInNativeWord { /// The path to the instruction (or immediate) whose result we are /// checking whether it fits in a native word or not. path: PathId, }, /// Are the instructions (or immediates) at the given paths the same? Eq { /// The path to the first instruction (or immediate). path_a: PathId, /// The path to the second instruction (or immediate). path_b: PathId, }, /// Switch on the constant integer value of an instruction. IntegerValue { /// The path to the instruction. path: PathId, }, /// Switch on the constant boolean value of an instruction. BooleanValue { /// The path to the instruction. path: PathId, }, /// Switch on a condition code. ConditionCode { /// The path to the condition code. path: PathId, }, /// No operation. Always evaluates to `None`. /// /// Exceedingly rare in real optimizations; nonetheless required to support /// corner cases of the DSL, such as a LHS pattern that is nothing but a /// variable pattern. Nop, } /// A canonicalized identifier for a left-hand side value that was bound in a /// pattern. #[derive(Clone, Copy, Debug, PartialEq, Eq, Hash, PartialOrd, Ord, Serialize, Deserialize)] pub struct LhsId(pub u16); /// A canonicalized identifier for a right-hand side value. #[derive(Clone, Copy, Debug, PartialEq, Eq, Hash, Serialize, Deserialize)] pub struct RhsId(pub u16); /// An action to perform when transitioning between states in the automata. /// /// When evaluating actions, the `i^th` action implicitly defines the /// `RhsId(i)`. #[derive(Clone, Copy, Debug, PartialEq, Eq, Hash, Serialize, Deserialize)] pub enum Action { /// Reuse something from the left-hand side. GetLhs { /// The path to the instruction or value. path: PathId, }, /// Perform compile-time evaluation. UnaryUnquote { /// The unquote operator. operator: UnquoteOperator, /// The constant operand to this unquote. operand: RhsId, }, /// Perform compile-time evaluation. BinaryUnquote { /// The unquote operator. operator: UnquoteOperator, /// The constant operands to this unquote. operands: [RhsId; 2], }, /// Create an integer constant. MakeIntegerConst { /// The constant integer value. value: IntegerId, /// The bit width of this constant. bit_width: BitWidth, }, /// Create a boolean constant. MakeBooleanConst { /// The constant boolean value. value: bool, /// The bit width of this constant. bit_width: BitWidth, }, /// Create a condition code. MakeConditionCode { /// The condition code. cc: ConditionCode, }, /// Make a unary instruction. MakeUnaryInst { /// The operand for this instruction. operand: RhsId, /// The type of this instruction's result. r#type: Type, /// The operator for this instruction. operator: Operator, }, /// Make a binary instruction. MakeBinaryInst { /// The opcode for this instruction. operator: Operator, /// The type of this instruction's result. r#type: Type, /// The operands for this instruction. operands: [RhsId; 2], }, /// Make a ternary instruction. MakeTernaryInst { /// The opcode for this instruction. operator: Operator, /// The type of this instruction's result. r#type: Type, /// The operands for this instruction. operands: [RhsId; 3], }, } #[cfg(test)] mod tests { use super::*; // These types all end up in the automaton, so we should take care that they // are small and don't fill up the data cache (or take up too much // serialized size). #[test] fn match_result_size() { assert_eq!(std::mem::size_of::<MatchResult>(), 4); } #[test] fn match_op_size() { assert_eq!(std::mem::size_of::<MatchOp>(), 6); } #[test] fn action_size() { assert_eq!(std::mem::size_of::<Action>(), 16); } }