Struct DataFlowAnalyzer 

pub struct DataFlowAnalyzer;

Data flow analyzer for building def-use chains and performing live variable analysis.

Implementations

impl DataFlowAnalyzer

pub fn build_def_use_chains( instructions: &[DecodedInstruction], ) -> HashMap<u8, DefUseChain>

Build definition-use chains for all registers.

Algorithm

Scans all instructions to identify:

• Definitions: Instructions that write to registers (destination operands)
• Uses: Instructions that read from registers (source operands)

Arguments

• instructions - Sequence of decoded PowerPC instructions

Returns

HashMap<u8, DefUseChain> - Map from register number to def-use chain

Examples

let instructions = vec![/* decoded instructions */];
let chains = DataFlowAnalyzer::build_def_use_chains(&instructions);
if let Some(chain) = chains.get(&3) {
    println!("Register r3 has {} definitions and {} uses", 
             chain.definitions.len(), chain.uses.len());
}

pub fn live_variable_analysis(cfg: &ControlFlowGraph) -> LiveVariableAnalysis

Perform live variable analysis on a control flow graph.

Algorithm

Uses iterative data flow analysis (worklist algorithm):

1. Initialize all blocks with empty live sets
2. Iterate until fixed point:
   • Live at exit = union of live at entry of all successors
   • Live at entry = (Live at exit - Killed) ∪ Generated
     • Killed: Registers defined in this block
     • Generated: Registers used in this block

Arguments

• cfg - Control flow graph to analyze

Returns

LiveVariableAnalysis - Live variable sets at entry and exit of each block

Examples

let live_analysis = DataFlowAnalyzer::live_variable_analysis(&cfg);
if let Some(live) = live_analysis.live_at_entry.get(&0) {
    println!("Block 0 has {} live variables at entry", live.count_ones());
}

pub fn eliminate_dead_code( instructions: &[DecodedInstruction], _live_analysis: &LiveVariableAnalysis, ) -> Vec<DecodedInstruction>

Eliminate dead code using live variable analysis.

Algorithm

Removes instructions that define registers that are never used. This is a simple implementation - a full implementation would need to track uses across basic blocks using live variable analysis.

Arguments

• instructions - Sequence of decoded PowerPC instructions
• live_analysis - Live variable analysis results

Returns

Vec<DecodedInstruction> - Optimized instruction sequence with dead code removed

Examples

let optimized = DataFlowAnalyzer::eliminate_dead_code(&instructions, &live_analysis);
println!("Removed {} dead instructions", instructions.len() - optimized.len());