ristretto_jit 0.31.0

JVM JIT Compiler
Documentation 
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use crate::Error::InternalError;
use crate::Result;
use crate::instruction::{ThrowContext, emit_bci, emit_pending_exception_check};
use crate::operand_stack::OperandStack;
use crate::runtime_helpers::RuntimeHelpers;
use cranelift::codegen::ir::{FuncRef, Value};
use cranelift::prelude::{FunctionBuilder, InstBuilder, types};
use ristretto_classfile::{ConstantPool, JavaStr};

/// Describes how a field value is represented in JIT code.
#[derive(Clone, Copy)]
pub(crate) enum FieldKind {
    Int,
    Long,
    Float,
    Double,
    Object,
}

impl FieldKind {
    pub(crate) fn from_descriptor(descriptor: &JavaStr) -> Result<Self> {
        let bytes = descriptor.as_bytes();
        let first = bytes
            .first()
            .copied()
            .ok_or_else(|| InternalError(format!("empty field descriptor: {descriptor}")))?;
        Ok(match first {
            b'B' | b'C' | b'S' | b'Z' | b'I' => FieldKind::Int,
            b'J' => FieldKind::Long,
            b'F' => FieldKind::Float,
            b'D' => FieldKind::Double,
            b'L' | b'[' => FieldKind::Object,
            _ => {
                return Err(InternalError(format!(
                    "unsupported field descriptor: {descriptor}"
                )));
            }
        })
    }
}

/// Resolves the field descriptor string for a `CONSTANT_Fieldref_info` entry.
pub(crate) fn resolve_field_descriptor<'a>(
    constant_pool: &'a ConstantPool,
    cp_field_ref_index: u16,
) -> Result<&'a JavaStr> {
    let (_class_index, name_and_type_index) =
        constant_pool.try_get_field_ref(cp_field_ref_index)?;
    let (_name_index, descriptor_index) =
        constant_pool.try_get_name_and_type(*name_and_type_index)?;
    Ok(constant_pool.try_get_utf8(*descriptor_index)?)
}

/// # References
///
/// - [JVMS §6.5.getfield](https://docs.oracle.com/javase/specs/jvms/se25/html/jvms-6.html#jvms-6.5.getfield)
pub(crate) fn getfield(
    constant_pool: &ConstantPool,
    function_builder: &mut FunctionBuilder,
    stack: &mut OperandStack,
    helpers: &RuntimeHelpers,
    context_pointer: Value,
    throw_context: &ThrowContext<'_>,
    cp_field_ref_index: u16,
) -> Result<()> {
    let descriptor = resolve_field_descriptor(constant_pool, cp_field_ref_index)?;
    let kind = FieldKind::from_descriptor(descriptor)?;
    let object = stack.pop_object(function_builder)?;
    crate::instruction::emit_null_check(
        function_builder,
        stack,
        helpers,
        context_pointer,
        throw_context,
        object,
    )?;
    let field_ref = function_builder
        .ins()
        .iconst(types::I32, i64::from(cp_field_ref_index));
    let bci = emit_bci(function_builder, throw_context);

    let helper: FuncRef = match kind {
        FieldKind::Int => helpers.getfield_int,
        FieldKind::Long => helpers.getfield_long,
        FieldKind::Float => helpers.getfield_float,
        FieldKind::Double => helpers.getfield_double,
        FieldKind::Object => helpers.getfield_object,
    };
    let call = function_builder
        .ins()
        .call(helper, &[context_pointer, bci, field_ref, object]);
    let result = function_builder.inst_results(call)[0];
    match kind {
        FieldKind::Int => stack.push_int(function_builder, result)?,
        FieldKind::Long => stack.push_long(function_builder, result)?,
        FieldKind::Float => stack.push_float(function_builder, result)?,
        FieldKind::Double => stack.push_double(function_builder, result)?,
        FieldKind::Object => stack.push_object(function_builder, result)?,
    }
    emit_pending_exception_check(
        function_builder,
        stack,
        helpers,
        context_pointer,
        throw_context,
    )
}

/// # References
///
/// - [JVMS §6.5.putfield](https://docs.oracle.com/javase/specs/jvms/se25/html/jvms-6.html#jvms-6.5.putfield)
pub(crate) fn putfield(
    constant_pool: &ConstantPool,
    function_builder: &mut FunctionBuilder,
    stack: &mut OperandStack,
    helpers: &RuntimeHelpers,
    context_pointer: Value,
    throw_context: &ThrowContext<'_>,
    cp_field_ref_index: u16,
) -> Result<()> {
    let descriptor = resolve_field_descriptor(constant_pool, cp_field_ref_index)?;
    let kind = FieldKind::from_descriptor(descriptor)?;
    let value = match kind {
        FieldKind::Int => stack.pop_int(function_builder)?,
        FieldKind::Long => stack.pop_long(function_builder)?,
        FieldKind::Float => stack.pop_float(function_builder)?,
        FieldKind::Double => stack.pop_double(function_builder)?,
        FieldKind::Object => stack.pop_object(function_builder)?,
    };
    let object = stack.pop_object(function_builder)?;
    crate::instruction::emit_null_check(
        function_builder,
        stack,
        helpers,
        context_pointer,
        throw_context,
        object,
    )?;
    let field_ref = function_builder
        .ins()
        .iconst(types::I32, i64::from(cp_field_ref_index));
    let bci = emit_bci(function_builder, throw_context);
    let helper: FuncRef = match kind {
        FieldKind::Int => helpers.putfield_int,
        FieldKind::Long => helpers.putfield_long,
        FieldKind::Float => helpers.putfield_float,
        FieldKind::Double => helpers.putfield_double,
        FieldKind::Object => helpers.putfield_object,
    };
    function_builder
        .ins()
        .call(helper, &[context_pointer, bci, field_ref, object, value]);
    emit_pending_exception_check(
        function_builder,
        stack,
        helpers,
        context_pointer,
        throw_context,
    )
}