Enumerator |
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Legal | The operation is expected to be selectable directly by the target, and no transformation is necessary.
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NarrowScalar | The operation should be synthesized from multiple instructions acting on a narrower scalar base-type.
For example a 64-bit add might be implemented in terms of 32-bit add-with-carry.
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WidenScalar | The operation should be implemented in terms of a wider scalar base-type.
For example a <2 x s8> add could be implemented as a <2 x s32> add (ignoring the high bits).
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FewerElements | The (vector) operation should be implemented by splitting it into sub-vectors where the operation is legal.
For example a <8 x s64> add might be implemented as 4 separate <2 x s64> adds.
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MoreElements | The (vector) operation should be implemented by widening the input vector and ignoring the lanes added by doing so.
For example <2 x i8> is rarely legal, but you might perform an <8 x i8> and then only look at the first two results.
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Lower | The operation itself must be expressed in terms of simpler actions on this target.
E.g. a SREM replaced by an SDIV and subtraction.
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Libcall | The operation should be implemented as a call to some kind of runtime support library.
For example this usually happens on machines that don't support floating-point operations natively.
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Custom | The target wants to do something special with this combination of operand and type.
A callback will be issued when it is needed.
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Unsupported | This operation is completely unsupported on the target.
A programming error has occurred.
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NotFound | Sentinel value for when no action was found in the specified table.
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UseLegacyRules | Fall back onto the old rules.
TODO: Remove this once we've migrated
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