`e51d444`

Make o2_removes_dead_seed test unroll-tolerant: check store-of-const-zero pattern

Authored by mfwolffe <wolffemf@dukes.jmu.edu> 1 week ago

SHA: e51d4449747d592c9c2bce9d14139d830756b5de
Parents: 8f2a8dd
Tree: cf30195

1 changed file

Status	File	+	-
M	`tests/gvn_dse_audit_29_11.rs`	37	3

tests/gvn_dse_audit_29_11.rsmodified

          "raw loop body should still contain the seed store and the real fill store:\n{}",
          raw_body
      );
 +    // Detect "seed-zero" pattern: a store whose value is a `const_int 0`.
 +    // This invariant is robust to loop transformations like partial
 +    // unrolling that multiply store counts — DSE removing the dead
 +    // seed eliminates the const-zero feeding any store.
 +    fn count_store_of_zero(func_section: &str) -> usize {
 +        use std::collections::HashSet;
 +        // Collect every value id defined as `const_int 0`.
 +        let zeros: HashSet<&str> = func_section
 +            .lines()
 +            .filter_map(|l| {
 +                let t = l.trim();
 +                let after_eq = t.strip_prefix("%")?;
 +                let (id, rest) = after_eq.split_once(" = const_int 0 ")?;
 +                let _ = rest;
 +                Some(id)
 +            })
 +            .collect();
 +        // Count `store %ID, ...` where %ID is one of those.
 +        func_section
 +            .lines()
 +            .filter_map(|l| l.trim().strip_prefix("store %"))
 +            .filter(|rest| {
 +                let id = rest.split(',').next().unwrap_or("").trim();
 +                zeros.contains(id)
 +            })
 +            .count()
 +    }
 +    let raw_zeros = count_store_of_zero(raw_fill);
 +    let opt_zeros = count_store_of_zero(opt_fill);
      assert!(
 -        opt_body.matches("store ").count() < raw_body.matches("store ").count(),
 -        "O2 should remove the dead seed store while keeping the real fill:\n{}",
 -        opt_body
 +        raw_zeros >= 1,
 +        "raw seed_and_fill should have at least one store-of-zero (the dead seed):\n{}",
 +        raw_fill
 +    );
 +    assert_eq!(
 +        opt_zeros, 0,
 +        "O2 DSE should remove the dead store-of-zero (raw had {}):\n{}",
 +        raw_zeros, opt_fill
      );
+ }