[X86][SSE] Improve recognition of uitofp conversions that can be performed as sitofp
With D24253 we can now use SelectionDAG::SignBitIsZero with vector operations.
This patch uses SelectionDAG::SignBitIsZero to recognise that a zero sign bit means that we can use a sitofp instead of a uitofp (which is not directly support on pre-AVX512 hardware).
While AVX512 does provide support for uitofp, the conversion to sitofp should not cause any regressions.
Differential Revision: https://reviews.llvm.org/D24343
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@281852 91177308-0d34-0410-b5e6-96231b3b80d8
6 files changed