llvm.ldexp.f128 lowering hits assertion failure on arm64 windows

[efriedma-quic]

$ llc -mtriple=aarch64-windows-msvc
define void @f7(ptr %p, i32 %a) {
  %val = load fp128, ptr %p
  %call = tail call fast fp128 @llvm.ldexp.f128(fp128 %val, i32 %a)
  store fp128 %call, ptr %p
  ret void
}

        .def    "@feat.00";
        .scl    3;
        .type   0;
        .endef
        .globl  "@feat.00"
"@feat.00" = 0
        .file   "<stdin>"
llc: [...]llvm/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp:985: void (anonymous namespace)::SelectionDAGLegalize::LegalizeOp(llvm::SDNode *): Assertion `(TLI.getTypeAction(*DAG.getContext(), Op.getValueType()) == TargetLowering::TypeLegal || Op.getOpcode() == ISD::TargetConstant || Op.getOpcode() == ISD::Register) && "Unexpected illegal type!"' failed.
PLEASE submit a bug report to https://github.com/llvm/llvm-project/issues/ and include the crash backtrace.

[llvmbot]

@llvm/issue-subscribers-backend-aarch64

Author: Eli Friedman (efriedma-quic)

``` $ llc -mtriple=aarch64-windows-msvc define void @f7(ptr %p, i32 %a) { %val = load fp128, ptr %p %call = tail call fast fp128 @llvm.ldexp.f128(fp128 %val, i32 %a) store fp128 %call, ptr %p ret void }

    .def    "@<!-- -->feat.00";
    .scl    3;
    .type   0;
    .endef
    .globl  "@<!-- -->feat.00"

"@feat.00" = 0
.file "<stdin>"
llc: [...]llvm/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp:985: void (anonymous namespace)::SelectionDAGLegalize::LegalizeOp(llvm::SDNode *): Assertion `(TLI.getTypeAction(*DAG.getContext(), Op.getValueType()) == TargetLowering::TypeLegal || Op.getOpcode() == ISD::TargetConstant || Op.getOpcode() == ISD::Register) && "Unexpected illegal type!"' failed.
PLEASE submit a bug report to https://github.com/llvm/llvm-project/issues/ and include the crash backtrace.

</details>