ADR 0090: Conversion range results

Context

The public contract records undefined hardware overflow where CPU simulation may saturate, and backend paths expose non-saturating wrap and target-specific control combinations. Review must choose a deterministic result or a bounded implementation-defined result set for every source, destination, rounding, saturation, NaN, infinity, and out-of-range combination.

The proposal under review requires every conversion cross-product to have one deterministic result, an enumerated profile-specific allowed-result set, or pre-effect rejection. Public undefined-overflow wording and CPU-only saturation cannot remain architectural outcomes.

Affected domains

• scalar-fp-convert
• scalar-fp-to-integer
• scalar-integer-to-fp
• tile-convert
• tile-dequantize
• tile-quantize

Alternatives considered

• portable normative rules;
• named target-profile rules;
• implementation-defined rules with explicit allowed sets; and
• unsupported-in-profile dispositions.

Blockers

• Complete the source/destination/rounding/saturation cross-product.
• Resolve the public CPU-saturation versus implementation default-OFF conflict.
• Choose overflow, NaN, and infinity results.
• Define non-saturating narrowing, wrap behavior, and omitted-saturation defaults per profile/type pair.

Acceptance obligations

• A complete conversion cross-product.
• Minimum, maximum, one-past, NaN, and infinity vectors.
• Saturation-off wrap vectors.

Decision

No conversion range result is accepted by this draft.