[Possible bug] fails when array.end() iterator is passed as a function parameter

[ETatuzova]

On this example:

#include <nil/crypto3/algebra/curves/pallas.hpp>

using namespace nil::crypto3::algebra::curves;

int f(std::array<int,5>::iterator it_begin, std::array<int,5>::iterator it_end) {
    return *it_begin;
}

[[circuit]] int field_for_example() {
    std::array<int, 5> v = {1, 2, 3, 4, 5};

    return f(v.begin(), v.end());
}

assigner fails with undef_type->isAggregateType() error.

[akokoshn]

Fail happens on processing parameters of call:

%5 = call noundef i32 @_Z1fPiS_(ptr noundef %3, ptr poison)

'v.end()' is special llvm constant poison which is UndefValue and not AggregateType, so we have no it in frame of stack. It means now end iterator can't be used as parameter of instruction. But valid expressions based on end iterator is ok: *(v.en() - 1)

[akokoshn]

possible solution - process poison value as undefined integer constant:

if (undef_type->isIntegerTy() || undef_type->isFieldTy() || llvm::isa<llvm::PoisonValue>(c)) {

[akokoshn]

Fix: https://github.com/NilFoundation/zkllvm-assigner/pull/179