Attempt to replace `inttoptr` with a direct call

description.md

I'm trying to replace inttoptr uses that happen when ccalls are generated. I've gotten as far as drilling down to the operand with inttoptr, but I can't figure out the next step.

using LLVM
ctx = Context()

mod = parse(LLVM.Module,  """
    define double @fun() {
    top:
      %0 = call double inttoptr (i32 -137186077 to double ()*)()
      ret double %0
    }
    """, ctx)

inst = first(instructions(first(blocks(functions(mod)["fun"]))))
ops = operands(inst)
op = first(ops)

There are not many methods that can operate on the operand, and I don't see any way to check that it is an inttoptr.

julia> inst = first(instructions(first(blocks(functions(mod)["fun"]))))
  %0 = call double inttoptr (i32 -137186077 to double ()*)()

julia> ops = operands(inst)
LLVM.UserOperandSet(  %0 = call double inttoptr (i32 -137186077 to double ()*)())

julia> op = first(ops)
double ()* inttoptr (i32 -137186077 to double ()*)

julia> filter!(s->!occursin("builder", s), string.(methodswith(typeof(op),supertypes=true)))
14-element Array{String,1}:
 "condition!(br::Instruction, cond::Value) in LLVM at /home/tshort/.julia/packages/LLVM/ViliQ/src/core/instructions.jl:153"
 "context(val::Value) in LLVM at /home/tshort/.julia/packages/LLVM/ViliQ/src/core/value.jl:54"
 "initializer!(gv::GlobalVariable, val::LLVM.Constant) in LLVM at /home/tshort/.julia/packages/LLVM/ViliQ/src/core/value/constant.jl:223"
 "isconstant(val::Value) in LLVM at /home/tshort/.julia/packages/LLVM/ViliQ/src/core/value.jl:50"
 "isnull(val::Value) in LLVM at /home/tshort/.julia/packages/LLVM/ViliQ/src/core/value/constant.jl:7"
 "isundef(val::Value) in LLVM at /home/tshort/.julia/packages/LLVM/ViliQ/src/core/value.jl:52"
 "llvmtype(val::Value) in LLVM at /home/tshort/.julia/packages/LLVM/ViliQ/src/core/value.jl:36"
 "name(val::Value) in LLVM at /home/tshort/.julia/packages/LLVM/ViliQ/src/core/value.jl:38"
 "name!(val::Value, name::String) in LLVM at /home/tshort/.julia/packages/LLVM/ViliQ/src/core/value.jl:39"
 "operands(user::LLVM.User) in LLVM at /home/tshort/.julia/packages/LLVM/ViliQ/src/core/value/user.jl:13"
 "replace_uses!(old::Value, new::Value) in LLVM at /home/tshort/.julia/packages/LLVM/ViliQ/src/core/value.jl:46"
 "show(io::IO, val::Value) in LLVM at /home/tshort/.julia/packages/LLVM/ViliQ/src/core/value.jl:42"
 "uses(val::Value) in LLVM at /home/tshort/.julia/packages/LLVM/ViliQ/src/core/value.jl:87"
 "setindex!(iter::LLVM.UserOperandSet, val::Value, i) in LLVM at /home/tshort/.julia/packages/LLVM/ViliQ/src/core/value/user.jl:20"

I can get the address of the pointer with, but I can't tell how to check whether it's an inttoptr.

julia> first(operands(op))
i32 -137186077

There is LLVM.IntToPtrInst, but that is an instruction, and what I'm trying to detect is part of an operand.

Tim pointed me to the following code that used string to check:

https://github.com/JuliaGPU/CUDAnative.jl/blob/84126dcb8ba6cbf250ee289a1aac3ef67ba4647a/src/compiler/validation.jl#L254

Another way is with opcode(x) == LLVM.API.LLVMIntToPtr.