regalloc: Count excess callee registers once

625eabb9efb2e0b94045cd2a546ce66ee33ecbc4fa712501d12c7bf239f47309 
Compute the excess callee-class count once and select all spills with
one iterator. This avoids repeated bitset scans while preserving the
ascending register order and the global callee-saved register limit.

Assisted-by: Codex:gpt-6-astra
Alexis Sellier committed ago 1 parent e0c7ad6c
lib/std/lang/gen/regalloc/spill.rad +9 -6
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    // Phase 3: Enforce global callee-class limit.
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    // The per-call-site limit may leave the callee-class set larger than
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    // `numCalleeSaved` when different call sites keep different subsets.
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    // Spill excess values to guarantee the assignment phase always finds
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    // a callee-saved register for cross-call values.
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    while bitset::count(&calleeClass) > numCalleeSaved {
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    let calleeCount = bitset::count(&calleeClass);
157 + 
    if calleeCount > numCalleeSaved {
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        let mut it = bitset::iter(&calleeClass);
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        if let reg = bitset::iterNext(&mut it) {
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            bitset::clear(&mut calleeClass, reg);
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            bitset::put(&mut spilled, reg);
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        } else {
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            panic "spill: count > 0 but no set bits found";
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        for _ in 0..(calleeCount - numCalleeSaved) {
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            if let reg = bitset::iterNext(&mut it) {
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                bitset::clear(&mut calleeClass, reg);
162 + 
                bitset::put(&mut spilled, reg);
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            } else {
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                panic "spill: count > 0 but no set bits found";
165 + 
            }
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        }
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    }
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    // Phase 4: Assign stack slots to spilled values.

    

  
    

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    let mut frameSize: i32 = 0;