[all-commits] [llvm/llvm-project] eecaeb: [FPEnv] Intrinsics for access to FP environment

[Serge Pavlov via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: eecaeb6f100a328e93dee4e35e34731cdef04d6d
      https://github.com/llvm/llvm-project/commit/eecaeb6f100a328e93dee4e35e34731cdef04d6d
  Author: Serge Pavlov <sepavloff at gmail.com>
  Date:   2023-06-05 (Mon, 05 Jun 2023)

  Changed paths:
    M llvm/docs/LangRef.rst
    M llvm/include/llvm/CodeGen/ISDOpcodes.h
    M llvm/include/llvm/CodeGen/SelectionDAG.h
    M llvm/include/llvm/CodeGen/SelectionDAGNodes.h
    M llvm/include/llvm/IR/Intrinsics.td
    M llvm/include/llvm/IR/RuntimeLibcalls.def
    M llvm/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp
    M llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
    M llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
    M llvm/lib/CodeGen/SelectionDAG/SelectionDAGDumper.cpp
    M llvm/lib/CodeGen/TargetLoweringBase.cpp
    M llvm/test/CodeGen/ARM/fpenv.ll
    M llvm/test/CodeGen/X86/fpenv.ll

  Log Message:
  -----------
  [FPEnv] Intrinsics for access to FP environment

The change implements intrinsics 'get_fpenv', 'set_fpenv' and 'reset_fpenv'.
They are used to read floating-point environment, set it or reset to
some default state. They do the same actions as C library functions
'fegetenv' and 'fesetenv'. By default these intrinsics are lowered to calls
to these functions.

The new intrinsics specify FP environment as a value of integer type, it
is convenient of most targets where the FP state is a content of some
register. Some targets however use long representations. On X86 the size
of FP environment is 256 bits, and even half of this size is not a legal
ibteger type. To facilitate legalization in such cases, two sets of DAG
nodes is used. Nodes GET_FPENV and SET_FPENV are used when FP
environment may be represented by a legal integer type. Nodes
GET_FPENV_MEM and SET_FPENV_MEM consider FP environment as a region in
memory, much like `fesetenv` and `fegetenv` do. They are used when
target has long representation for floationg-point state.

Differential Revision: https://reviews.llvm.org/D71742