Jonas Paulsson ef7aad0db4 [SystemZ] Improve handling of ZERO_EXTEND_VECTOR_INREG. ...

Instead of doing multiple unpacks when zero extending vectors (e.g. v2i16 ->
v2i64), benchmarks have shown that it is better to do a VPERM (vector
permute) since that is only one sequential instruction on the critical path.

This patch achieves this by

1. Expand ZERO_EXTEND_VECTOR_INREG into a vector shuffle with a zero vector
   instead of (multiple) unpacks.

2. Improve SystemZ::GeneralShuffle to perform a single unpack as the last
   operation if Bytes matches it.

Review: Ulrich Weigand
Differential Revision: https://reviews.llvm.org/D78486

2020-06-30 09:08:10 +02:00

3.7 KiB

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