爱特每羊队
81 lines
2.6 KiB
Rust
81 lines
2.6 KiB
Rust
//! Pass 4：exit 哨兵收尾 + succs 反推 preds。
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use crate::{BasicBlock, Cfg};
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/// 追加 exit 哨兵块（`0..0`，置末尾），从各块 succs 反推 preds。
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pub(super) fn finalize(mut blocks: Vec<BasicBlock>, exit_id: usize) -> Cfg {
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blocks.push(BasicBlock {
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inst_range: 0..0,
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preds: Vec::new(),
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succs: Vec::new(),
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});
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let mut succs_total = 0usize;
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let mut preds_total = 0usize;
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for i in 0..blocks.len() {
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succs_total += blocks[i].succs.len();
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let targets: Vec<crate::BBId> = blocks[i].succs.iter().map(|&(t, _)| t).collect();
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for target in targets {
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blocks[target].preds.push(i);
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preds_total += 1;
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}
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}
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debug_assert_eq!(succs_total, preds_total, "succs/preds 不对称（Pitfall 4）");
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Cfg {
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blocks,
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entry: 0,
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exit: exit_id,
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}
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}
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#[cfg(test)]
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mod tests {
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use super::*;
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use crate::{BasicBlock, EdgeKind};
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/// exit 哨兵恒在 blocks 末尾（空块 0..0），preds 反推正确。
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#[test]
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fn exit_sentinel_appended_with_preds_reversed() {
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let blocks_in = vec![
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BasicBlock {
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inst_range: 0..1,
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preds: Vec::new(),
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succs: vec![(1, EdgeKind::Jump)],
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},
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BasicBlock {
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inst_range: 1..2,
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preds: Vec::new(),
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succs: vec![(2, EdgeKind::Fallthrough)],
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},
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];
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let cfg = finalize(blocks_in, 2);
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assert_eq!(cfg.blocks.len(), 3, "2 实块 + exit 哨兵");
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assert_eq!(cfg.entry, 0);
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assert_eq!(cfg.exit, 2);
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assert_eq!(cfg.blocks[2].inst_range, 0..0, "exit 是空块");
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assert_eq!(cfg.blocks[1].preds, vec![0], "块 1 preds 反推自块 0 的 Jump 边");
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assert_eq!(cfg.blocks[2].preds, vec![1], "exit preds 反推自块 1 的 Fallthrough 边");
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}
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/// succs/preds 对称：total 边数一致（防御性约束）。
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#[test]
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fn preds_and_succs_symmetric() {
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let blocks_in = vec![
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BasicBlock {
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inst_range: 0..1,
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preds: Vec::new(),
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succs: vec![(1, EdgeKind::Jump)],
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},
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BasicBlock {
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inst_range: 1..2,
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preds: Vec::new(),
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succs: vec![(2, EdgeKind::Fallthrough)],
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},
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];
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let cfg = finalize(blocks_in, 2);
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let succs_total: usize = cfg.blocks.iter().map(|b| b.succs.len()).sum();
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let preds_total: usize = cfg.blocks.iter().map(|b| b.preds.len()).sum();
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assert_eq!(succs_total, preds_total, "succs/preds 对称");
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}
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}
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