[PATCH] D76853: [DAGCombiner] Use rsqrt to estimate sqrt only when ninf flag set

[Qiu Chaofan via Phabricator via llvm-commits]

qiucf created this revision.
qiucf added reviewers: PowerPC, hfinkel, jsji, nemanjai, spatel, evandro, craig.scott, jlebar.
Herald added subscribers: llvm-commits, hiraditya, jholewinski.
Herald added a project: LLVM.

Currently we use `rsqrt` to build estimation of `sqrt`. But this would produce wrong result (`NaN`) when x is +infinity.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D76853

Files:
  llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
  llvm/test/CodeGen/NVPTX/fast-math.ll
  llvm/test/CodeGen/NVPTX/sqrt-approx.ll
  llvm/test/CodeGen/PowerPC/fmf-propagation.ll
  llvm/test/CodeGen/X86/sqrt-fastmath-mir.ll
  llvm/test/CodeGen/X86/sqrt-fastmath.ll

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