73 lines
2.7 KiB
Rust
73 lines
2.7 KiB
Rust
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/*!
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* Loop Builder Facade (Minimal API)
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*
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* Goal: Decouple loop construction from concrete MirBuilder types by exposing
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* a small trait that both legacy (mir::builder::MirBuilder) and modularized
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* builders can implement. This enables shared helpers and gradual migration.
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*
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* Note: Only legacy MirBuilder is wired for now to keep WIP modularized code
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* out of the main build. The modularized builder can implement this trait
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* later without changing callers.
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*/
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use super::{BasicBlockId, MirInstruction, ValueId};
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/// Minimal API for constructing loops and emitting instructions
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pub trait LoopBuilderApi {
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/// Allocate a new basic block id
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fn new_block(&mut self) -> BasicBlockId;
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/// Get current block id
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fn current_block(&self) -> Result<BasicBlockId, String>;
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/// Switch current block, creating it if needed
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fn start_new_block(&mut self, block: BasicBlockId) -> Result<(), String>;
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/// Emit an instruction to the current block
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fn emit(&mut self, inst: MirInstruction) -> Result<(), String>;
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/// Allocate a new SSA value id
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fn new_value(&mut self) -> ValueId;
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}
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/// Helper: simplified loop lowering usable by any LoopBuilderApi implementor
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pub fn build_simple_loop<L: LoopBuilderApi>(
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lb: &mut L,
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condition: ValueId,
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build_body: &mut dyn FnMut(&mut L) -> Result<(), String>,
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) -> Result<ValueId, String> {
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let header = lb.new_block();
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let body = lb.new_block();
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let after = lb.new_block();
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// Jump to header
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lb.emit(MirInstruction::Jump { target: header })?;
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// Header: branch on provided condition
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lb.start_new_block(header)?;
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lb.emit(MirInstruction::Branch { condition, then_bb: body, else_bb: after })?;
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// Body
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lb.start_new_block(body)?;
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build_body(lb)?;
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lb.emit(MirInstruction::Jump { target: header })?;
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// After: return void value
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lb.start_new_block(after)?;
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let void_id = lb.new_value();
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lb.emit(MirInstruction::Const { dst: void_id, value: super::instruction::ConstValue::Void })?;
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Ok(void_id)
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}
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// === Legacy wiring: implement LoopBuilderApi for mir::builder::MirBuilder ===
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impl LoopBuilderApi for super::builder::MirBuilder {
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fn new_block(&mut self) -> BasicBlockId { self.block_gen.next() }
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fn current_block(&self) -> Result<BasicBlockId, String> {
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self.current_block.ok_or_else(|| "No current block".to_string())
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}
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fn start_new_block(&mut self, block: BasicBlockId) -> Result<(), String> {
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super::builder::MirBuilder::start_new_block(self, block)
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}
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fn emit(&mut self, inst: MirInstruction) -> Result<(), String> {
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super::builder::MirBuilder::emit_instruction(self, inst)
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}
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fn new_value(&mut self) -> ValueId { self.value_gen.next() }
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}
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