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[X86][SSE] getFauxShuffle - ignore undemanded sources for PACKSS/PACKUS faux…

Authored by RKSimon on Sat, Jul 25, 2:50 AM.

Description

[X86][SSE] getFauxShuffle - ignore undemanded sources for PACKSS/PACKUS faux shuffles

If we don't care about an entire LHS/RHS of the PACK op, then can just treat it the same as undef (we don't care if it saturates) and is safe to treat as a shuffle.

This can happen if we attempt to decode as a faux shuffle before SimplifyDemandedVectorElts has been called on the PACK which should replace the source with UNDEF entirely.

Details

Committed
RKSimonSat, Jul 25, 2:51 AM
Parents
rG6c25fc35e096: [ADT] Add a range-based version of std::move
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