hakorune/src/backend/llvm/compiler/codegen/instructions/arith.rs

use std::collections::HashMap;

use inkwell::values::BasicValueEnum;

use crate::backend::llvm::context::CodegenContext;
use crate::mir::{function::MirFunction, CompareOp, ValueId};

/// Compare lowering: return the resulting BasicValueEnum (i1)
pub(in super::super) fn lower_compare<'ctx>(
    codegen: &CodegenContext<'ctx>,
    func: &MirFunction,
    vmap: &HashMap<ValueId, BasicValueEnum<'ctx>>,
    op: &CompareOp,
    lhs: &ValueId,
    rhs: &ValueId,
) -> Result<BasicValueEnum<'ctx>, String> {
    use crate::backend::llvm::compiler::helpers::{as_float, as_int};
    let lv = *vmap
        .get(lhs)
        .ok_or_else(|| format!("lhs missing: {}", lhs.as_u32()))?;
    let rv = *vmap
        .get(rhs)
        .ok_or_else(|| format!("rhs missing: {}", rhs.as_u32()))?;
    // String equality/inequality by content when annotated as String/StringBox
    if matches!(op, CompareOp::Eq | CompareOp::Ne) {
        let l_is_str = match func.metadata.value_types.get(lhs) {
            Some(crate::mir::MirType::String) => true,
            Some(crate::mir::MirType::Box(b)) if b == "StringBox" => true,
            _ => false,
        };
        let r_is_str = match func.metadata.value_types.get(rhs) {
            Some(crate::mir::MirType::String) => true,
            Some(crate::mir::MirType::Box(b)) if b == "StringBox" => true,
            _ => false,
        };
        if l_is_str && r_is_str {
            let i64t = codegen.context.i64_type();
            // Convert both sides to handles if needed
            let to_handle = |v: BasicValueEnum<'ctx>| -> Result<inkwell::values::IntValue<'ctx>, String> {
                match v {
                    BasicValueEnum::IntValue(iv) => {
                        if iv.get_type() == i64t { Ok(iv) } else { codegen.builder.build_int_s_extend(iv, i64t, "i2i64").map_err(|e| e.to_string()) }
                    }
                    BasicValueEnum::PointerValue(pv) => {
                        let fnty = i64t.fn_type(&[codegen.context.ptr_type(inkwell::AddressSpace::from(0)).into()], false);
                        let callee = codegen
                            .module
                            .get_function("nyash.box.from_i8_string")
                            .unwrap_or_else(|| codegen.module.add_function("nyash.box.from_i8_string", fnty, None));
                        let call = codegen
                            .builder
                            .build_call(callee, &[pv.into()], "str_ptr_to_handle_cmp")
                            .map_err(|e| e.to_string())?;
                        let rv = call
                            .try_as_basic_value()
                            .left()
                            .ok_or("from_i8_string returned void".to_string())?;
                        Ok(rv.into_int_value())
                    }
                    _ => Err("unsupported value for string compare".to_string()),
                }
            };
            let lh = to_handle(lv)?;
            let rh = to_handle(rv)?;
            let fnty = i64t.fn_type(&[i64t.into(), i64t.into()], false);
            let callee = codegen
                .module
                .get_function("nyash.string.eq_hh")
                .unwrap_or_else(|| codegen.module.add_function("nyash.string.eq_hh", fnty, None));
            let call = codegen
                .builder
                .build_call(callee, &[lh.into(), rh.into()], "str_eq_hh")
                .map_err(|e| e.to_string())?;
            let iv = call
                .try_as_basic_value()
                .left()
                .ok_or("eq_hh returned void".to_string())?
                .into_int_value();
            let zero = i64t.const_zero();
            let pred = if matches!(op, CompareOp::Eq) {
                inkwell::IntPredicate::NE
            } else {
                inkwell::IntPredicate::EQ
            };
            let b = codegen
                .builder
                .build_int_compare(pred, iv, zero, "str_eq_to_bool")
                .map_err(|e| e.to_string())?;
            return Ok(b.into());
        }
    }
    let out = if let (Some(li), Some(ri)) = (as_int(lv), as_int(rv)) {
        use CompareOp as C;
        let pred = match op {
            C::Eq => inkwell::IntPredicate::EQ,
            C::Ne => inkwell::IntPredicate::NE,
            C::Lt => inkwell::IntPredicate::SLT,
            C::Le => inkwell::IntPredicate::SLE,
            C::Gt => inkwell::IntPredicate::SGT,
            C::Ge => inkwell::IntPredicate::SGE,
        };
        codegen
            .builder
            .build_int_compare(pred, li, ri, "icmp")
            .map_err(|e| e.to_string())?
            .into()
    } else if let (Some(lf), Some(rf)) = (as_float(lv), as_float(rv)) {
        use CompareOp as C;
        let pred = match op {
            C::Eq => inkwell::FloatPredicate::OEQ,
            C::Ne => inkwell::FloatPredicate::ONE,
            C::Lt => inkwell::FloatPredicate::OLT,
            C::Le => inkwell::FloatPredicate::OLE,
            C::Gt => inkwell::FloatPredicate::OGT,
            C::Ge => inkwell::FloatPredicate::OGE,
        };
        codegen
            .builder
            .build_float_compare(pred, lf, rf, "fcmp")
            .map_err(|e| e.to_string())?
            .into()
    } else if let (BasicValueEnum::PointerValue(lp), BasicValueEnum::PointerValue(rp)) = (lv, rv) {
        // Support pointer equality/inequality comparisons
        use CompareOp as C;
        match op {
            C::Eq | C::Ne => {
                let i64t = codegen.context.i64_type();
                let li = codegen
                    .builder
                    .build_ptr_to_int(lp, i64t, "pi_l")
                    .map_err(|e| e.to_string())?;
                let ri = codegen
                    .builder
                    .build_ptr_to_int(rp, i64t, "pi_r")
                    .map_err(|e| e.to_string())?;
                let pred = if matches!(op, C::Eq) {
                    inkwell::IntPredicate::EQ
                } else {
                    inkwell::IntPredicate::NE
                };
                codegen
                    .builder
                    .build_int_compare(pred, li, ri, "pcmp")
                    .map_err(|e| e.to_string())?
                    .into()
            }
            _ => return Err("unsupported pointer comparison (only Eq/Ne)".to_string()),
        }
    } else if let (BasicValueEnum::PointerValue(lp), BasicValueEnum::IntValue(ri)) = (lv, rv) {
        use CompareOp as C;
        let i64t = codegen.context.i64_type();
        let li = codegen
            .builder
            .build_ptr_to_int(lp, i64t, "pi_l")
            .map_err(|e| e.to_string())?;
        let pred = match op {
            C::Eq => inkwell::IntPredicate::EQ,
            C::Ne => inkwell::IntPredicate::NE,
            C::Lt => inkwell::IntPredicate::SLT,
            C::Le => inkwell::IntPredicate::SLE,
            C::Gt => inkwell::IntPredicate::SGT,
            C::Ge => inkwell::IntPredicate::SGE,
        };
        codegen
            .builder
            .build_int_compare(pred, li, ri, "pcmpi")
            .map_err(|e| e.to_string())?
            .into()
    } else if let (BasicValueEnum::IntValue(li), BasicValueEnum::PointerValue(rp)) = (lv, rv) {
        use CompareOp as C;
        let i64t = codegen.context.i64_type();
        let ri = codegen
            .builder
            .build_ptr_to_int(rp, i64t, "pi_r")
            .map_err(|e| e.to_string())?;
        let pred = match op {
            C::Eq => inkwell::IntPredicate::EQ,
            C::Ne => inkwell::IntPredicate::NE,
            C::Lt => inkwell::IntPredicate::SLT,
            C::Le => inkwell::IntPredicate::SLE,
            C::Gt => inkwell::IntPredicate::SGT,
            C::Ge => inkwell::IntPredicate::SGE,
        };
        codegen
            .builder
            .build_int_compare(pred, li, ri, "pcmpi")
            .map_err(|e| e.to_string())?
            .into()
    } else {
        return Err("compare type mismatch".to_string());
    };
    Ok(out)
}