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honey/source/interpreter/interpreter.hon
T

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import "@std/mem"
import "@std/arraylist"
import "@source/ir"
import "@source/diagnostics"
Outcome :: struct {
value ir.Value = ir.Value{}
trap ?diagnostics.DiagnosticId = null
}
@hide:file
Slot :: struct {
initialized bool = false
value ir.Value = ir.Value{}
}
@hide:file
GlobalStatus :: enum { uninitialized, initializing, ready }
@hide:file
GlobalState :: struct {
status GlobalStatus = .uninitialized
value ir.Value = ir.Value{}
}
@hide:file
Frame :: struct {
function ir.FunctionId
block ir.BlockId
next_instruction usize = 0
destination ir.ValueId = ir.no_value
global ?usize = null
locals []mut Slot
values []mut ir.Value
}
#! executes only typed IR; invocation and global state are temporary and released on every exit.
#! returned string IDs resolve through `module`; runtime source errors are traps, not infrastructure errors.
run proc(
allocator mem.Allocator,
module @ir.Module,
diagnostic_store @mut diagnostics.Store,
) Outcome ! (mem.AllocError | diagnostics.CapacityError) {
entry ir.FunctionId := ir.FunctionId(0)
if module.entry |function| {
entry = function
} else {
return Outcome{ trap = module.entry_diagnostic }
}
globals :: try mem.alloc(GlobalState, allocator, module.globals.items.len)
defer mem.free(allocator, globals)
mem.set(globals, GlobalState{})
frames := arraylist.init(Frame, allocator)
defer {
for (frames.items) |frame| free_frame(allocator, frame)
arraylist.deinit(&frames)
}
try push_frame(allocator, module, &frames, entry, ir.no_value, null)
while frames.items.len != 0 {
frame_index :: frames.items.len - 1
function :: &module.functions.items[usize(frames.items[frame_index].function)]
block :: &function.blocks.items[usize(frames.items[frame_index].block)]
instruction_index :: frames.items[frame_index].next_instruction
if instruction_index == block.instructions.items.len {
terminator :: block.terminator
if (terminator.kind == .trap) return Outcome{ trap = terminator.diagnostic }
if (terminator.kind == .jump or terminator.kind == .branch) {
target := terminator.target
if (terminator.kind == .branch) {
condition :: frames.items[frame_index].values[usize(terminator.value)]
if (!condition.data.boolean) target = terminator.alternative
}
frames.items[frame_index].block = target
frames.items[frame_index].next_instruction = 0
continue
}
value := ir.Value{}
if terminator.value != ir.no_value {
value = frames.items[frame_index].values[usize(terminator.value)]
}
completed :: frames.items[frame_index]
_ = arraylist.pop(&frames)
free_frame(allocator, completed)
if completed.global |global_index| {
globals[global_index].value = value
globals[global_index].status = .ready
}
if (frames.items.len == 0) return Outcome{ value = value }
if completed.destination != ir.no_value {
frames.items[frames.items.len - 1].values[usize(completed.destination)] = value
}
continue
}
instruction :: &block.instructions.items[instruction_index]
frames.items[frame_index].next_instruction += 1
value := ir.Value{}
match instruction.op {
.constant: value = instruction.constant
.load_local: {
local :: &frames.items[frame_index].locals[usize(instruction.slot)]
if !local.initialized {
return try runtime_trap(diagnostic_store, .read_before_initialization, instruction.span)
}
value = local.value
}
.store_local: {
frames.items[frame_index].locals[usize(instruction.slot)] = Slot{
initialized = true,
value = frames.items[frame_index].values[usize(instruction.left)],
}
continue
}
.assign_local: {
local :: &frames.items[frame_index].locals[usize(instruction.slot)]
if (!local.initialized) {
return try runtime_trap(diagnostic_store, .write_before_initialization, instruction.span)
}
local.value = frames.items[frame_index].values[usize(instruction.left)]
continue
}
.reset_local: {
frames.items[frame_index].locals[usize(instruction.slot)].initialized = false
continue
}
.load_global: {
global_index :: usize(instruction.slot)
match globals[global_index].status {
.ready: value = globals[global_index].value
.initializing: {
return try runtime_trap(diagnostic_store, .initialization_cycle, instruction.span)
}
.uninitialized: {
try push_frame(
allocator,
module,
&frames,
module.globals.items[global_index].initializer,
instruction.destination,
global_index,
)
globals[global_index].status = .initializing
continue
}
}
}
.call: {
callee :: frames.items[frame_index].values[usize(instruction.left)].data.function
try push_frame(allocator, module, &frames, callee, instruction.destination, null)
# frame indices survive stack growth; pointers into frames.items do not.
for (0..instruction.arguments_count) |argument_index| {
argument :: block.arguments.items[instruction.arguments_start + argument_index]
frames.items[frame_index + 1].locals[argument_index] = Slot{
initialized = true,
value = frames.items[frame_index].values[usize(argument)],
}
}
continue
}
.negate: {
operand :: frames.items[frame_index].values[usize(instruction.left)]
if instruction.type == .float {
value = ir.Value{ type = .float, data = ir.ValueData{ real = -operand.data.real } }
} else {
if operand.data.integer == minval!(i64) {
return try runtime_trap(diagnostic_store, .integer_overflow, instruction.span)
}
value = ir.Value{ type = .int, data = ir.ValueData{ integer = -operand.data.integer } }
}
}
.add, .subtract, .multiply, .divide: {
left :: frames.items[frame_index].values[usize(instruction.left)]
right :: frames.items[frame_index].values[usize(instruction.right)]
if instruction.type == .float {
result f64 := 0
match instruction.op {
.add: result = left.data.real + right.data.real
.subtract: result = left.data.real - right.data.real
.multiply: result = left.data.real * right.data.real
.divide: result = left.data.real / right.data.real
else: unreachable
}
value = ir.Value{ type = .float, data = ir.ValueData{ real = result } }
} else {
result :: checked_integer(instruction.op, left.data.integer, right.data.integer)
if result |result_integer| {
value = ir.Value{ type = .int, data = ir.ValueData{ integer = result_integer } }
} else {
return try runtime_trap(diagnostic_store, .integer_overflow, instruction.span)
}
}
}
.equal, .not_equal, .less, .less_equal, .greater, .greater_equal: {
left :: frames.items[frame_index].values[usize(instruction.left)]
right :: frames.items[frame_index].values[usize(instruction.right)]
result := false
match left.type {
.int: result = match instruction.op {
.equal: left.data.integer == right.data.integer
.not_equal: left.data.integer != right.data.integer
.less: left.data.integer < right.data.integer
.less_equal: left.data.integer <= right.data.integer
.greater: left.data.integer > right.data.integer
.greater_equal: left.data.integer >= right.data.integer
else: unreachable
}
.float: result = match instruction.op {
.equal: left.data.real == right.data.real
.not_equal: left.data.real != right.data.real
.less: left.data.real < right.data.real
.less_equal: left.data.real <= right.data.real
.greater: left.data.real > right.data.real
.greater_equal: left.data.real >= right.data.real
else: unreachable
}
.bool: result = match instruction.op {
.equal: left.data.boolean == right.data.boolean
.not_equal: left.data.boolean != right.data.boolean
else: unreachable
}
else: unreachable
}
value = ir.Value{ type = .bool, data = ir.ValueData{ boolean = result } }
}
}
if instruction.destination != ir.no_value {
frames.items[frame_index].values[usize(instruction.destination)] = value
}
}
unreachable
}
@hide:file
push_frame proc(
allocator mem.Allocator,
module @ir.Module,
frames @mut arraylist.ArrayList(Frame),
function ir.FunctionId,
destination ir.ValueId,
global ?usize,
) void ! mem.AllocError {
signature :: &module.functions.items[usize(function)]
locals :: try mem.alloc(Slot, allocator, signature.locals.items.len)
errdefer mem.free(allocator, locals)
mem.set(locals, Slot{})
values :: try mem.alloc(ir.Value, allocator, signature.value_count)
errdefer mem.free(allocator, values)
# typed IR assigns each temporary before use; only local slots need initialization flags.
try arraylist.append(frames, Frame{
function = function,
block = signature.entry,
destination = destination,
global = global,
locals = locals,
values = values,
})
}
@hide:file
free_frame proc(allocator mem.Allocator, frame Frame) void {
mem.free(allocator, frame.locals)
mem.free(allocator, frame.values)
}
@hide:file
runtime_trap proc(
diagnostic_store @mut diagnostics.Store,
code diagnostics.Code,
span diagnostics.Span,
) Outcome ! (mem.AllocError | diagnostics.CapacityError) {
return Outcome{ trap = try diagnostics.add(diagnostic_store, code, span) }
}
@hide:file
checked_integer proc(op ir.Op, left i64, right i64) ?i64 {
minimum :: minval!(i64)
maximum :: maxval!(i64)
match op {
.add: {
if (right > 0 and left > maximum - right) return null
if (right < 0 and left < minimum - right) return null
return left + right
}
.subtract: {
if (right > 0 and left < minimum + right) return null
if (right < 0 and left > maximum + right) return null
return left - right
}
.multiply: {
if left > 0 {
if (right > 0 and left > divtrunc!(maximum, right)) return null
if (right < 0 and right < divtrunc!(minimum, left)) return null
} else if left < 0 {
if (right > 0 and left < divtrunc!(minimum, right)) return null
if (right < 0 and left < divtrunc!(maximum, right)) return null
}
return left * right
}
else: unreachable
}
}