[PATCH] D130151: [X86][FP16] Do not split FP64->FP16 to FP64->FP32->FP16

[Phoebe Wang via Phabricator via llvm-commits]

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Truncation from double to half is not always identical to truncating to float first and then to half. https://godbolt.org/z/56s9517hd

On the other hand, expanding to float and then to double is always identical to expanding to double directly. https://godbolt.org/z/Ye8vbYPnY


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D130151

Files:
  llvm/lib/Target/X86/X86ISelLowering.cpp
  llvm/test/CodeGen/X86/cvt16.ll
  llvm/test/CodeGen/X86/fastmath-float-half-conversion.ll
  llvm/test/CodeGen/X86/fp-strict-scalar-fp16.ll
  llvm/test/CodeGen/X86/half-constrained.ll
  llvm/test/CodeGen/X86/half.ll
  llvm/test/CodeGen/X86/vector-half-conversions.ll

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