[PATCH] D43463: [SelectionDAG] ComputeKnownBits - add support for SMIN+SMAX clamp patterns

[Simon Pilgrim via Phabricator via llvm-commits]

RKSimon created this revision.
RKSimon added reviewers: craig.topper, spatel, zvi.

If we have a clamp pattern, SMIN(SMAX(X, LO),HI) or SMAX(SMIN(X, HI),LO) then we can deduce that the number of signbits (zeros/ones) will be at least the minimum of the LO and HI constants.

ComputeKnownBits equivalent of https://reviews.llvm.org/D43338.


Repository:
  rL LLVM

https://reviews.llvm.org/D43463

Files:
  lib/CodeGen/SelectionDAG/SelectionDAG.cpp
  test/CodeGen/X86/vector-trunc-packus.ll

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