106 lines
3.6 KiB
Rust
106 lines
3.6 KiB
Rust
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use super::{
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lower_expr_with_vars, lower_stmt_list_with_vars, new_block, BridgeEnv, LoopContext,
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};
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use crate::mir::{BasicBlockId, MirFunction, MirInstruction, ValueId};
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use std::collections::HashMap;
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use super::super::ast::StmtV0;
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use super::super::ast::ExprV0;
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pub(super) fn lower_loop_stmt(
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f: &mut MirFunction,
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cur_bb: BasicBlockId,
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cond: &ExprV0,
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body: &[StmtV0],
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vars: &mut HashMap<String, ValueId>,
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loop_stack: &mut Vec<LoopContext>,
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env: &BridgeEnv,
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) -> Result<BasicBlockId, String> {
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let cond_bb = new_block(f);
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let body_bb = new_block(f);
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let exit_bb = new_block(f);
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if let Some(bb) = f.get_block_mut(cur_bb) {
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if !bb.is_terminated() {
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bb.add_instruction(MirInstruction::Jump { target: cond_bb });
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}
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}
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let no_phi = env.mir_no_phi;
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let base_vars = vars.clone();
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let orig_names: Vec<String> = base_vars.keys().cloned().collect();
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let mut phi_map: HashMap<String, ValueId> = HashMap::new();
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for name in &orig_names {
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if let Some(&bval) = base_vars.get(name) {
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let dst = f.next_value_id();
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if no_phi {
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if let Some(bb) = f.get_block_mut(cur_bb) {
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bb.add_instruction(MirInstruction::Copy { dst, src: bval });
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}
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} else if let Some(bb) = f.get_block_mut(cond_bb) {
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bb.insert_instruction_after_phis(MirInstruction::Phi {
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dst,
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inputs: vec![(cur_bb, bval)],
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});
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}
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phi_map.insert(name.clone(), dst);
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}
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}
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for (name, &phi) in &phi_map {
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vars.insert(name.clone(), phi);
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}
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let (cval, _cend) = lower_expr_with_vars(env, f, cond_bb, cond, vars)?;
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if let Some(bb) = f.get_block_mut(cond_bb) {
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bb.set_terminator(MirInstruction::Branch {
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condition: cval,
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then_bb: body_bb,
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else_bb: exit_bb,
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});
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}
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let mut body_vars = vars.clone();
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loop_stack.push(LoopContext { cond_bb, exit_bb });
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let bend_res = lower_stmt_list_with_vars(f, body_bb, body, &mut body_vars, loop_stack, env);
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loop_stack.pop();
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let bend = bend_res?;
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if let Some(bb) = f.get_block_mut(bend) {
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if !bb.is_terminated() {
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bb.set_terminator(MirInstruction::Jump { target: cond_bb });
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}
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}
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let backedge_to_cond = matches!(
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f.blocks
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.get(&bend)
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.and_then(|bb| bb.terminator.as_ref()),
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Some(MirInstruction::Jump { target, .. }) if *target == cond_bb
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);
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if backedge_to_cond {
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if no_phi {
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for (name, &phi_dst) in &phi_map {
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if let Some(&latch_val) = body_vars.get(name) {
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if let Some(bb) = f.get_block_mut(bend) {
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bb.add_instruction(MirInstruction::Copy {
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dst: phi_dst,
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src: latch_val,
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});
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}
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}
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}
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} else if let Some(bb) = f.get_block_mut(cond_bb) {
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for (name, &phi_dst) in &phi_map {
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if let Some(&latch_val) = body_vars.get(name) {
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for inst in &mut bb.instructions {
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if let MirInstruction::Phi { dst, inputs } = inst {
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if *dst == phi_dst {
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inputs.push((bend, latch_val));
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break;
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}
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}
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}
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}
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}
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}
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}
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for (name, &phi) in &phi_map {
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vars.insert(name.clone(), phi);
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}
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Ok(exit_bb)
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}
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