If the SimplifyMultipleUseDemandedBits calls BITCASTs that peek through back to the original type then we can remove the BITCASTs entirely.
Differential Revision: https://reviews.llvm.org/D79572
This patch attempts to peek through vectors based on the demanded bits/elt of a particular ISD::EXTRACT_VECTOR_ELT node, allowing us to avoid dependencies on ops that have no impact on the extract.
In particular this helps remove some unnecessary scalar->vector->scalar patterns.
The wasm shift patterns are annoying - @tlively has indicated that the wasm vector shift codegen are to be refactored in the near-term and isn't considered a major issue.
Reapplied after reversion at rL368660 due to PR42982 which was fixed at rGca7fdd41bda0.
Differential Revision: https://reviews.llvm.org/D65887
During legalisation we can end up with some pretty strange nodes, like shifts
of 0. We need to make sure we don't try to make long shifts of these, ending up
with invalid assembly instructions. A long shift with a zero immediate actually
encodes a shift by 32.
Differential Revision: https://reviews.llvm.org/D67664
llvm-svn: 372839
Simon Pilgrim