[all-commits] [llvm/llvm-project] 62e91b: [DAGCombine]: Fold X/Sqrt(X) to Sqrt(X)

[venkataramanankumar via All-commits]

  Branch: refs/heads/master
  Home:   https://github.com/llvm/llvm-project
  Commit: 62e91bf563337fff93be0059ecb1f4dae32d8980
      https://github.com/llvm/llvm-project/commit/62e91bf563337fff93be0059ecb1f4dae32d8980
  Author: Venkataramanan Kumar <venkataramanan.kumar.llvm at gmail.com>
  Date:   2020-08-24 (Mon, 24 Aug 2020)

  Changed paths:
    M llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
    M llvm/test/CodeGen/AArch64/sqrt-fastmath.ll
    M llvm/test/CodeGen/X86/sqrt-fastmath.ll

  Log Message:
  -----------
  [DAGCombine]: Fold X/Sqrt(X) to Sqrt(X)

With FMF ( "nsz" and " reassoc") fold X/Sqrt(X) to Sqrt(X).

This is done after targets have the chance to produce a
reciprocal sqrt estimate sequence because that expansion
is probably more efficient than an expansion of a
non-reciprocal sqrt. That is also why we deferred doing
this transform in IR (D85709).

Differential Revision: https://reviews.llvm.org/D86403