Struct MinimumCodeGenerationUnlimitedRegisters 

pub struct MinimumCodeGenerationUnlimitedRegisters { /* private fields */ }

Minimum Code Generation with Unlimited Registers.

Given a directed acyclic graph G = (V, A) with maximum out-degree 2, where arcs are partitioned into left (L) and right (R) operand sets, leaves (out-degree 0) are input values each in its own register, internal vertices are 2-address operations (the left operand’s register is overwritten by the result), and roots (in-degree 0) are values to compute, find a program of minimum instructions using OP and LOAD (copy).

Representation

The configuration is a permutation of internal (non-leaf) vertices giving their evaluation order. config[i] is the evaluation position for internal vertex i (0-indexed among internal vertices).

Example

use problemreductions::models::misc::MinimumCodeGenerationUnlimitedRegisters;
use problemreductions::{Problem, Solver, BruteForce, Min};

// 5 vertices: leaves {3,4}, internal {0,1,2}
// v1 = op(v3, v4), v2 = op(v3, v4), v0 = op(v1, v2)
let problem = MinimumCodeGenerationUnlimitedRegisters::new(
    5,
    vec![(1,3),(2,3),(0,1)],  // left arcs (child destroyed)
    vec![(1,4),(2,4),(0,2)],  // right arcs (child preserved)
);
let result = BruteForce::new().solve(&problem);
assert_eq!(result, Min(Some(4)));

Implementations

impl MinimumCodeGenerationUnlimitedRegisters

pub fn new( num_vertices: usize, left_arcs: Vec<(usize, usize)>, right_arcs: Vec<(usize, usize)>, ) -> Self

Create a new instance.

Arguments

• num_vertices - Total number of vertices
• left_arcs - Left operand arcs (parent, child); child register is destroyed by OP
• right_arcs - Right operand arcs (parent, child); child register is preserved

Panics

Panics if any arc index is out of bounds, if any vertex has out-degree > 2, if left and right arcs for binary vertices are inconsistent, or if a vertex has a self-loop.

pub fn num_vertices(&self) -> usize

Get the number of vertices.

pub fn left_arcs(&self) -> &[(usize, usize)]

Get the left operand arcs.

pub fn right_arcs(&self) -> &[(usize, usize)]

Get the right operand arcs.

pub fn num_leaves(&self) -> usize

Get the number of leaf vertices (out-degree 0).

pub fn num_internal(&self) -> usize

Get the number of internal (non-leaf) vertices.

pub fn simulate(&self, config: &[usize]) -> Option<usize>

Simulate the unlimited-register machine for a given evaluation order of internal vertices and return the instruction count, or None if the ordering is invalid (not a permutation or violates dependencies).

With unlimited registers:

• Each leaf starts in its own register
• OP v: computes v, result overwrites the left operand’s register
• LOAD: copies a register value (needed when a left operand is still needed later and would be destroyed)
• Cost = num_OPs + num_LOADs

Trait Implementations

impl Clone for MinimumCodeGenerationUnlimitedRegisters

fn clone(&self) -> MinimumCodeGenerationUnlimitedRegisters

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for MinimumCodeGenerationUnlimitedRegisters

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl<'de> Deserialize<'de> for MinimumCodeGenerationUnlimitedRegisters

fn deserialize<__D>(__deserializer: __D) -> Result<Self, __D::Error>

where __D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer.

impl Problem for MinimumCodeGenerationUnlimitedRegisters

const NAME: &'static str = "MinimumCodeGenerationUnlimitedRegisters"

Base name of this problem type (e.g., “MaximumIndependentSet”).

type Value = Min<usize>

The evaluation value type.

fn variant() -> Vec<(&'static str, &'static str)>

Returns variant attributes derived from type parameters.

fn dims(&self) -> Vec<usize>

Configuration space dimensions. Each entry is the cardinality of that variable.

fn evaluate(&self, config: &[usize]) -> Min<usize>

Evaluate the problem on a configuration.

fn num_variables(&self) -> usize

Number of variables (derived from dims).

fn problem_type() -> ProblemType

Look up this problem’s catalog entry.

impl ReduceTo<MinimumCodeGenerationUnlimitedRegisters> for MinimumFeedbackVertexSet<i32>

type Result = ReductionFVSToCodeGen

The reduction result type.

fn reduce_to(&self) -> Self::Result

Reduce this problem to the target problem type.

impl Serialize for MinimumCodeGenerationUnlimitedRegisters

fn serialize<__S>(&self, __serializer: __S) -> Result<__S::Ok, __S::Error>

where __S: Serializer,

Serialize this value into the given Serde serializer.

impl DeclaredVariant for MinimumCodeGenerationUnlimitedRegisters