[SCEV] Propagate nuw/nsw flags from or disjoint (#197236) The Scalar Evolution analysis converts the `or disjoint` instruction into a synthetic add with the `IsNSW` and `IsNUW` flags set, but the real instruction reference set to `nullptr`. The flags propagation logic only reads the real instruction flags, when the instruction reference is present. This behavior silently ignores the flags for the synthetic add, which can lead to missed optimization opportunities. This patch inserts the pointer to the actual instruction into the `BinaryOp` object created for the synthetic add. It also adjust the flags handling logic to threat the `disjoint` flag as both `nuw` and `nsw` as if they were set on the `add` instruction. Assisted-by: Claude Opus 4.6 <noreply@anthropic.com>
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