[all-commits] [llvm/llvm-project] a87782: Revert "[DAG] Create fptosi.sat from clamped fptosi"

[Hans via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: a87782c34d667d1c1a18fe82a9a7abfc72fd345b
      https://github.com/llvm/llvm-project/commit/a87782c34d667d1c1a18fe82a9a7abfc72fd345b
  Author: Hans Wennborg <hans at chromium.org>
  Date:   2021-11-30 (Tue, 30 Nov 2021)

  Changed paths:
    M llvm/include/llvm/CodeGen/TargetLowering.h
    M llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
    M llvm/lib/Target/AArch64/AArch64ISelLowering.cpp
    M llvm/lib/Target/AArch64/AArch64ISelLowering.h
    M llvm/lib/Target/ARM/ARMISelLowering.cpp
    M llvm/lib/Target/ARM/ARMISelLowering.h
    M llvm/lib/Target/RISCV/RISCVISelLowering.cpp
    M llvm/lib/Target/RISCV/RISCVISelLowering.h
    M llvm/test/CodeGen/AArch64/fpclamptosat.ll
    M llvm/test/CodeGen/AArch64/fpclamptosat_vec.ll
    M llvm/test/CodeGen/ARM/fpclamptosat.ll
    M llvm/test/CodeGen/RISCV/fpclamptosat.ll
    M llvm/test/CodeGen/Thumb2/mve-fpclamptosat_vec.ll
    M llvm/test/CodeGen/WebAssembly/fpclamptosat.ll
    M llvm/test/CodeGen/WebAssembly/fpclamptosat_vec.ll
    M llvm/test/CodeGen/X86/fpclamptosat.ll

  Log Message:
  -----------
  Revert "[DAG] Create fptosi.sat from clamped fptosi"

It causes builds to fail with this assert:

llvm/include/llvm/ADT/APInt.h:990:
bool llvm::APInt::operator==(const llvm::APInt &) const:
Assertion `BitWidth == RHS.BitWidth && "Comparison requires equal bit widths"' failed.

See comment on the code review.

> This adds a fold in DAGCombine to create fptosi_sat from sequences for
> smin(smax(fptosi(x))) nodes, where the min/max saturate the output of
> the fp convert to a specific bitwidth (say INT_MIN and INT_MAX). Because
> it is dealing with smin(/smax) in DAG they may currently be ISD::SMIN,
> ISD::SETCC/ISD::SELECT, ISD::VSELECT or ISD::SELECT_CC nodes which need
> to be handled similarly.
>
> A shouldConvertFpToSat method was added to control when converting may
> be profitable. The original fptosi will have a less strict semantics
> than the fptosisat, with less values that need to produce defined
> behaviour.
>
> This especially helps on ARM/AArch64 where the vcvt instructions
> naturally saturate the result.
>
> Differential Revision: https://reviews.llvm.org/D111976

This reverts commit 52ff3b009388f1bef4854f1b6470b4ec19d10b0e.