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Optimize DO/LOOP: index/limit in WASM locals, J as IR primitive

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Two-path DO/LOOP codegen based on static analysis of the loop body:

- Fast path (no calls, no >R/R> in body): index and limit live purely
  in WASM locals with zero return stack traffic per iteration. RFetch (I)
  and LoopJ (J) resolve to local.get instead of memory access.

- Slow path (body has calls or explicit RS ops): locals still used for
  loop control, but synced to return stack for LEAVE/UNLOOP compatibility.

Also converts J from a host function (WASM→Rust roundtrip per call) to
an IR primitive (IrOp::LoopJ) that compiles to local.get of the outer
loop's index local.

Performance impact (vs gforth, all opts enabled):
- Factorial: 1.02x → 0.94x (now faster than gforth)
- NestedLoops: 717x → 543x (24% faster, still bottlenecked by data stack)
- Fibonacci, GCD, Collatz: unchanged (don't use DO/LOOP)
This commit is contained in:
Oleksandr Kozachuk
2026-04-09 17:13:31 +02:00
parent 1e2ede58ac
commit 4feeaeb0ba
3 changed files with 319 additions and 156 deletions
Download Patch File Download Diff File Expand all files Collapse all files
crates/core/src/codegen.rs
+304 -106
View File
@@ -225,13 +225,22 @@ fn bool_to_forth_flag(f: &mut Function, tmp: u32) {
// Float stack helpers
// ---------------------------------------------------------------------------
/// Carries f64 scratch local indices for float codegen.
/// Carries context for WASM code emission.
struct EmitCtx {
f64_local_0: u32,
f64_local_1: u32,
/// Base WASM local index for Forth locals ({: ... :}).
/// Forth local N maps to WASM local `forth_local_base + N`.
forth_local_base: u32,
/// Base WASM local index for DO/LOOP index/limit local pairs.
/// Each nested loop uses 2 locals: (index, limit).
loop_local_base: u32,
/// Stack of (index_local, limit_local) for active DO/LOOP nesting.
/// Innermost loop is last. Used to compile `J` as local.get.
loop_locals: Vec<(u32, u32)>,
/// Nesting depth of DO/LOOPs that use the fast path (no RS sync).
/// When > 0, `RFetch` (I) reads from the loop local instead of rpeek.
fast_loop_depth: u32,
}
/// Decrement the FSP global by 8 (allocate space for one f64).
@@ -318,7 +327,7 @@ fn emit_float_cmp(f: &mut Function, ctx: &EmitCtx, wasm_cmp: &Instruction<'_>) {
// ---------------------------------------------------------------------------
/// Emit all IR operations in `ops` into the WASM function body `f`.
fn emit_body(f: &mut Function, ops: &[IrOp], ctx: &EmitCtx) {
fn emit_body(f: &mut Function, ops: &[IrOp], ctx: &mut EmitCtx) {
for op in ops {
emit_op(f, op, ctx);
}
@@ -326,7 +335,7 @@ fn emit_body(f: &mut Function, ops: &[IrOp], ctx: &EmitCtx) {
/// Emit a single IR operation.
#[allow(clippy::too_many_lines)]
fn emit_op(f: &mut Function, op: &IrOp, ctx: &EmitCtx) {
fn emit_op(f: &mut Function, op: &IrOp, ctx: &mut EmitCtx) {
match op {
// -- Literals -------------------------------------------------------
IrOp::PushI32(n) => push_const(f, *n),
@@ -685,9 +694,34 @@ fn emit_op(f: &mut Function, op: &IrOp, ctx: &EmitCtx) {
}
IrOp::RFetch => {
// In a fast-path DO/LOOP (no >R/R>/calls), R@ == loop index local.
// In slow-path or outside loops, read from the return stack.
if ctx.fast_loop_depth > 0 {
let (index_local, _) = *ctx.loop_locals.last().expect("fast loop without locals");
f.instruction(&Instruction::LocalGet(index_local));
push_via_local(f, SCRATCH_BASE);
} else {
rpeek(f);
push_via_local(f, SCRATCH_BASE);
}
}
IrOp::LoopJ => {
// Read outer loop index: use loop locals if available,
// otherwise fall back to reading rsp+8.
if ctx.loop_locals.len() >= 2 {
let (outer_index, _) = ctx.loop_locals[ctx.loop_locals.len() - 2];
f.instruction(&Instruction::LocalGet(outer_index));
push_via_local(f, SCRATCH_BASE);
} else {
// Fallback: read from return stack (rsp + 2*CELL_SIZE)
f.instruction(&Instruction::GlobalGet(RSP))
.instruction(&Instruction::I32Const(2 * CELL_SIZE as i32))
.instruction(&Instruction::I32Add)
.instruction(&Instruction::I32Load(MEM4));
push_via_local(f, SCRATCH_BASE);
}
}
// -- I/O ------------------------------------------------------------
IrOp::Emit => {
@@ -892,41 +926,59 @@ fn emit_cmp(f: &mut Function, cmp: &Instruction<'_>) {
push_via_local(f, SCRATCH_BASE + 3);
}
/// Emit a DO...LOOP / DO...+LOOP construct.
fn emit_do_loop(f: &mut Function, body: &[IrOp], is_plus_loop: bool, ctx: &EmitCtx) {
/// Emit a DO...LOOP / DO...+LOOP construct using WASM locals for index/limit.
///
/// Two paths:
/// - **Fast path**: Body has no calls, no return stack ops. Index/limit live
/// purely in WASM locals — zero return stack traffic per iteration.
/// - **Slow path**: Body uses calls or return stack. Index/limit still in locals
/// but synced to return stack for LEAVE/UNLOOP/J/I compatibility.
fn emit_do_loop(f: &mut Function, body: &[IrOp], is_plus_loop: bool, ctx: &mut EmitCtx) {
let loop_depth = ctx.loop_locals.len() as u32;
let index_local = ctx.loop_local_base + loop_depth * 2;
let limit_local = ctx.loop_local_base + loop_depth * 2 + 1;
let needs_rs = body_needs_return_stack(body);
// DO ( limit index -- )
pop_to(f, SCRATCH_BASE); // index
pop_to(f, SCRATCH_BASE + 1); // limit
pop_to(f, index_local);
pop_to(f, limit_local);
// Push limit then index to return stack
f.instruction(&Instruction::LocalGet(SCRATCH_BASE + 1));
rpush_via_local(f, SCRATCH_BASE + 2);
f.instruction(&Instruction::LocalGet(SCRATCH_BASE));
rpush_via_local(f, SCRATCH_BASE + 2);
if needs_rs {
// Push to return stack for I/J/LEAVE/UNLOOP
f.instruction(&Instruction::LocalGet(limit_local));
rpush_via_local(f, SCRATCH_BASE);
f.instruction(&Instruction::LocalGet(index_local));
rpush_via_local(f, SCRATCH_BASE);
}
ctx.loop_locals.push((index_local, limit_local));
if !needs_rs {
ctx.fast_loop_depth += 1;
}
// block $exit
// loop $continue
// <body>
// -- update index, check, branch
// end
// end
f.instruction(&Instruction::Block(BlockType::Empty));
f.instruction(&Instruction::Loop(BlockType::Empty));
if needs_rs {
// Sync index local to return stack before body (so I/R@ reads current value)
rpop(f);
f.instruction(&Instruction::Drop);
f.instruction(&Instruction::LocalGet(index_local));
rpush_via_local(f, SCRATCH_BASE);
}
emit_body(f, body, ctx);
// Pop current index from return stack into scratch local
rpop(f);
if needs_rs {
// Reload index from return stack (LEAVE may have modified it)
rpeek(f);
f.instruction(&Instruction::LocalSet(index_local));
}
if is_plus_loop {
// +LOOP: Forth 2012 termination check.
// Exit when (old_index - limit) XOR (new_index - limit) is negative,
// or when the LEAVE flag is set (LEAVE sets index=limit, but +LOOP with
// step=0 would loop forever without this flag check).
f.instruction(&Instruction::LocalSet(SCRATCH_BASE));
pop_to(f, SCRATCH_BASE + 2); // step from data stack
// Check leave flag first — if set, clear it and exit immediately
// Check leave flag — if set, clear it and exit immediately
f.instruction(&Instruction::I32Const(SYSVAR_LEAVE_FLAG as i32))
.instruction(&Instruction::I32Load(MEM4))
.instruction(&Instruction::If(BlockType::Empty))
@@ -936,40 +988,28 @@ fn emit_do_loop(f: &mut Function, body: &[IrOp], is_plus_loop: bool, ctx: &EmitC
.instruction(&Instruction::Br(2)) // exit: If(0) → Loop(1) → Block(2)
.instruction(&Instruction::End);
// Peek limit from return stack
rpeek(f);
f.instruction(&Instruction::LocalSet(SCRATCH_BASE + 1));
// Compute old_index - limit
// SCRATCH_BASE+3 = old_index - limit
f.instruction(&Instruction::LocalGet(SCRATCH_BASE))
.instruction(&Instruction::LocalGet(SCRATCH_BASE + 1))
// old_index - limit
f.instruction(&Instruction::LocalGet(index_local))
.instruction(&Instruction::LocalGet(limit_local))
.instruction(&Instruction::I32Sub)
.instruction(&Instruction::LocalSet(SCRATCH_BASE + 3));
// new_index = old_index + step
f.instruction(&Instruction::LocalGet(SCRATCH_BASE))
f.instruction(&Instruction::LocalGet(index_local))
.instruction(&Instruction::LocalGet(SCRATCH_BASE + 2))
.instruction(&Instruction::I32Add)
.instruction(&Instruction::LocalSet(SCRATCH_BASE));
// Push updated index to return stack (use SCRATCH_BASE+4 as temp to preserve step)
f.instruction(&Instruction::LocalGet(SCRATCH_BASE));
rpush_via_local(f, SCRATCH_BASE + 4);
.instruction(&Instruction::LocalSet(index_local));
// Forth 2012 +LOOP termination:
// exit = ((old-limit) XOR (new-limit)) AND ((old-limit) XOR step) < 0
// xor1 = (old-limit) XOR (new-limit)
f.instruction(&Instruction::LocalGet(SCRATCH_BASE + 3)) // old - limit
.instruction(&Instruction::LocalGet(SCRATCH_BASE)) // new_index
.instruction(&Instruction::LocalGet(SCRATCH_BASE + 1)) // limit
.instruction(&Instruction::LocalGet(index_local)) // new_index
.instruction(&Instruction::LocalGet(limit_local)) // limit
.instruction(&Instruction::I32Sub) // new - limit
.instruction(&Instruction::I32Xor); // xor1
// xor2 = (old-limit) XOR step
f.instruction(&Instruction::LocalGet(SCRATCH_BASE + 3)) // old - limit
.instruction(&Instruction::LocalGet(SCRATCH_BASE + 2)) // step (preserved!)
.instruction(&Instruction::LocalGet(SCRATCH_BASE + 2)) // step
.instruction(&Instruction::I32Xor); // xor2
// exit = (xor1 AND xor2) < 0
f.instruction(&Instruction::I32And)
.instruction(&Instruction::I32Const(0))
.instruction(&Instruction::I32LtS)
@@ -979,21 +1019,26 @@ fn emit_do_loop(f: &mut Function, body: &[IrOp], is_plus_loop: bool, ctx: &EmitC
.instruction(&Instruction::End); // end block
} else {
// LOOP: simple increment by 1
f.instruction(&Instruction::I32Const(1))
f.instruction(&Instruction::LocalGet(index_local))
.instruction(&Instruction::I32Const(1))
.instruction(&Instruction::I32Add)
.instruction(&Instruction::LocalSet(SCRATCH_BASE));
.instruction(&Instruction::LocalSet(index_local));
// Peek limit from return stack
rpeek(f);
f.instruction(&Instruction::LocalSet(SCRATCH_BASE + 1));
// Push updated index back to return stack
f.instruction(&Instruction::LocalGet(SCRATCH_BASE));
rpush_via_local(f, SCRATCH_BASE + 2);
// Check leave flag (needed even for simple LOOP since LEAVE is a host function)
if needs_rs {
f.instruction(&Instruction::I32Const(SYSVAR_LEAVE_FLAG as i32))
.instruction(&Instruction::I32Load(MEM4))
.instruction(&Instruction::If(BlockType::Empty))
.instruction(&Instruction::I32Const(SYSVAR_LEAVE_FLAG as i32))
.instruction(&Instruction::I32Const(0))
.instruction(&Instruction::I32Store(MEM4))
.instruction(&Instruction::Br(2)) // exit: If→Loop→Block
.instruction(&Instruction::End);
}
// if index >= limit, exit
f.instruction(&Instruction::LocalGet(SCRATCH_BASE))
.instruction(&Instruction::LocalGet(SCRATCH_BASE + 1))
f.instruction(&Instruction::LocalGet(index_local))
.instruction(&Instruction::LocalGet(limit_local))
.instruction(&Instruction::I32GeS)
.instruction(&Instruction::BrIf(1)) // break to $exit
.instruction(&Instruction::Br(0)) // continue loop
@@ -1001,11 +1046,17 @@ fn emit_do_loop(f: &mut Function, body: &[IrOp], is_plus_loop: bool, ctx: &EmitC
.instruction(&Instruction::End); // end block
}
// Clean up: pop index and limit from return stack, clear leave flag
if !needs_rs {
ctx.fast_loop_depth -= 1;
}
ctx.loop_locals.pop();
if needs_rs {
rpop(f);
f.instruction(&Instruction::Drop);
rpop(f);
f.instruction(&Instruction::Drop);
}
f.instruction(&Instruction::I32Const(SYSVAR_LEAVE_FLAG as i32))
.instruction(&Instruction::I32Const(0))
.instruction(&Instruction::I32Store(MEM4));
@@ -1672,6 +1723,117 @@ fn needs_f64_locals(ops: &[IrOp]) -> bool {
false
}
/// Check if a DO/LOOP body needs return stack access.
///
/// When false, the loop can use pure WASM locals for index/limit without
/// syncing to the return stack. This is safe when the body has no calls
/// (which might be LEAVE/J/UNLOOP) and no explicit return stack ops.
fn body_needs_return_stack(ops: &[IrOp]) -> bool {
for op in ops {
match op {
IrOp::Call(_) | IrOp::TailCall(_) | IrOp::Execute => return true,
IrOp::ToR | IrOp::FromR => return true,
// RFetch (I) is handled by loop locals in the fast path — not a problem.
// LoopJ is also handled by loop locals.
// Only explicit >R / R> / calls force the slow path.
IrOp::If {
then_body,
else_body,
} => {
if body_needs_return_stack(then_body) {
return true;
}
if let Some(eb) = else_body {
if body_needs_return_stack(eb) {
return true;
}
}
}
IrOp::DoLoop { body, .. }
| IrOp::BeginUntil { body }
| IrOp::BeginAgain { body } => {
if body_needs_return_stack(body) {
return true;
}
}
IrOp::BeginWhileRepeat { test, body } => {
if body_needs_return_stack(test) || body_needs_return_stack(body) {
return true;
}
}
IrOp::BeginDoubleWhileRepeat {
outer_test,
inner_test,
body,
after_repeat,
else_body,
} => {
if body_needs_return_stack(outer_test)
|| body_needs_return_stack(inner_test)
|| body_needs_return_stack(body)
|| body_needs_return_stack(after_repeat)
{
return true;
}
if let Some(eb) = else_body {
if body_needs_return_stack(eb) {
return true;
}
}
}
_ => {}
}
}
false
}
/// Count the maximum DO/LOOP nesting depth in an IR body.
/// Each nesting level needs 2 WASM locals (index, limit).
fn count_loop_depth(ops: &[IrOp]) -> u32 {
let mut max: u32 = 0;
for op in ops {
match op {
IrOp::DoLoop { body, .. } => {
max = max.max(1 + count_loop_depth(body));
}
IrOp::If {
then_body,
else_body,
} => {
max = max.max(count_loop_depth(then_body));
if let Some(eb) = else_body {
max = max.max(count_loop_depth(eb));
}
}
IrOp::BeginUntil { body }
| IrOp::BeginAgain { body } => {
max = max.max(count_loop_depth(body));
}
IrOp::BeginWhileRepeat { test, body } => {
max = max.max(count_loop_depth(test)).max(count_loop_depth(body));
}
IrOp::BeginDoubleWhileRepeat {
outer_test,
inner_test,
body,
after_repeat,
else_body,
} => {
max = max
.max(count_loop_depth(outer_test))
.max(count_loop_depth(inner_test))
.max(count_loop_depth(body))
.max(count_loop_depth(after_repeat));
if let Some(eb) = else_body {
max = max.max(count_loop_depth(eb));
}
}
_ => {}
}
}
max
}
/// Estimate scratch locals a function body needs (not counting cached DSP).
fn count_scratch_locals(ops: &[IrOp]) -> u32 {
let mut max: u32 = 4; // baseline scratch space (indices SCRATCH_BASE..SCRATCH_BASE+3)
@@ -1850,13 +2012,15 @@ pub fn compile_word(
let promoted = config.stack_to_local_promotion && is_promotable(body);
let scratch_count = count_scratch_locals(body);
let forth_local_count = count_forth_locals(body);
let loop_depth = count_loop_depth(body);
let loop_local_count = loop_depth * 2; // 2 locals per nesting level (index, limit)
let num_locals = if promoted {
let (preload, _) = compute_stack_needs(body);
let promoted_count = count_promoted_locals(body, preload);
// 1 (cached DSP) + promoted locals (scratch locals not needed in promoted path)
1 + promoted_count + forth_local_count
1 + promoted_count + forth_local_count + loop_local_count
} else {
1 + scratch_count + forth_local_count
1 + scratch_count + forth_local_count + loop_local_count
};
let has_floats = needs_f64_locals(body);
let num_f64: u32 = if has_floats { 2 } else { 0 };
@@ -1872,10 +2036,14 @@ pub fn compile_word(
} else {
1 + scratch_count
};
let ctx = EmitCtx {
let loop_local_base = forth_local_base + forth_local_count;
let mut ctx = EmitCtx {
f64_local_0: num_locals,
f64_local_1: num_locals + 1,
forth_local_base,
loop_local_base,
loop_locals: Vec::new(),
fast_loop_depth: 0,
};
// Prologue: cache $dsp global into local 0
@@ -1892,7 +2060,7 @@ pub fn compile_word(
}
emit_promoted_epilogue(&mut func, &mut sim);
} else {
emit_body(&mut func, body, &ctx);
emit_body(&mut func, body, &mut ctx);
}
// Epilogue: write cached DSP back to the $dsp global
@@ -1928,7 +2096,7 @@ fn emit_consolidated_body(
f: &mut Function,
ops: &[IrOp],
local_fn_map: &HashMap<WordId, u32>,
ctx: &EmitCtx,
ctx: &mut EmitCtx,
) {
for op in ops {
emit_consolidated_op(f, op, local_fn_map, ctx);
@@ -1944,7 +2112,7 @@ fn emit_consolidated_op(
f: &mut Function,
op: &IrOp,
local_fn_map: &HashMap<WordId, u32>,
ctx: &EmitCtx,
ctx: &mut EmitCtx,
) {
match op {
IrOp::Call(word_id) => {
@@ -2068,65 +2236,76 @@ fn emit_consolidated_op(
}
/// Emit a DO...LOOP / DO...+LOOP with consolidated call support for the body.
/// Same fast/slow path logic as `emit_do_loop`.
fn emit_consolidated_do_loop(
f: &mut Function,
body: &[IrOp],
is_plus_loop: bool,
local_fn_map: &HashMap<WordId, u32>,
ctx: &EmitCtx,
ctx: &mut EmitCtx,
) {
// DO ( limit index -- )
pop_to(f, SCRATCH_BASE); // index
pop_to(f, SCRATCH_BASE + 1); // limit
let loop_depth = ctx.loop_locals.len() as u32;
let index_local = ctx.loop_local_base + loop_depth * 2;
let limit_local = ctx.loop_local_base + loop_depth * 2 + 1;
let needs_rs = body_needs_return_stack(body);
// Push limit then index to return stack
f.instruction(&Instruction::LocalGet(SCRATCH_BASE + 1));
rpush_via_local(f, SCRATCH_BASE + 2);
f.instruction(&Instruction::LocalGet(SCRATCH_BASE));
rpush_via_local(f, SCRATCH_BASE + 2);
pop_to(f, index_local);
pop_to(f, limit_local);
if needs_rs {
f.instruction(&Instruction::LocalGet(limit_local));
rpush_via_local(f, SCRATCH_BASE);
f.instruction(&Instruction::LocalGet(index_local));
rpush_via_local(f, SCRATCH_BASE);
}
ctx.loop_locals.push((index_local, limit_local));
if !needs_rs {
ctx.fast_loop_depth += 1;
}
f.instruction(&Instruction::Block(BlockType::Empty));
f.instruction(&Instruction::Loop(BlockType::Empty));
if needs_rs {
rpop(f);
f.instruction(&Instruction::Drop);
f.instruction(&Instruction::LocalGet(index_local));
rpush_via_local(f, SCRATCH_BASE);
}
emit_consolidated_body(f, body, local_fn_map, ctx);
// Pop current index from return stack into scratch local
rpop(f);
if needs_rs {
rpeek(f);
f.instruction(&Instruction::LocalSet(index_local));
}
if is_plus_loop {
f.instruction(&Instruction::LocalSet(SCRATCH_BASE));
pop_to(f, SCRATCH_BASE + 2); // step from data stack
pop_to(f, SCRATCH_BASE + 2); // step
// Check leave flag — if set, clear it and exit immediately
f.instruction(&Instruction::I32Const(SYSVAR_LEAVE_FLAG as i32))
.instruction(&Instruction::I32Load(MEM4))
.instruction(&Instruction::If(BlockType::Empty))
.instruction(&Instruction::I32Const(SYSVAR_LEAVE_FLAG as i32))
.instruction(&Instruction::I32Const(0))
.instruction(&Instruction::I32Store(MEM4))
.instruction(&Instruction::Br(2)) // exit: If(0) → Loop(1) → Block(2)
.instruction(&Instruction::Br(2))
.instruction(&Instruction::End);
rpeek(f);
f.instruction(&Instruction::LocalSet(SCRATCH_BASE + 1));
f.instruction(&Instruction::LocalGet(SCRATCH_BASE))
.instruction(&Instruction::LocalGet(SCRATCH_BASE + 1))
f.instruction(&Instruction::LocalGet(index_local))
.instruction(&Instruction::LocalGet(limit_local))
.instruction(&Instruction::I32Sub)
.instruction(&Instruction::LocalSet(SCRATCH_BASE + 3));
f.instruction(&Instruction::LocalGet(SCRATCH_BASE))
f.instruction(&Instruction::LocalGet(index_local))
.instruction(&Instruction::LocalGet(SCRATCH_BASE + 2))
.instruction(&Instruction::I32Add)
.instruction(&Instruction::LocalSet(SCRATCH_BASE));
.instruction(&Instruction::LocalSet(index_local));
f.instruction(&Instruction::LocalGet(SCRATCH_BASE));
rpush_via_local(f, SCRATCH_BASE + 4);
// Forth 2012: ((old-limit) XOR (new-limit)) AND ((old-limit) XOR step) < 0
f.instruction(&Instruction::LocalGet(SCRATCH_BASE + 3))
.instruction(&Instruction::LocalGet(SCRATCH_BASE))
.instruction(&Instruction::LocalGet(SCRATCH_BASE + 1))
.instruction(&Instruction::LocalGet(index_local))
.instruction(&Instruction::LocalGet(limit_local))
.instruction(&Instruction::I32Sub)
.instruction(&Instruction::I32Xor);
f.instruction(&Instruction::LocalGet(SCRATCH_BASE + 3))
@@ -2140,18 +2319,24 @@ fn emit_consolidated_do_loop(
.instruction(&Instruction::End)
.instruction(&Instruction::End);
} else {
f.instruction(&Instruction::I32Const(1))
f.instruction(&Instruction::LocalGet(index_local))
.instruction(&Instruction::I32Const(1))
.instruction(&Instruction::I32Add)
.instruction(&Instruction::LocalSet(SCRATCH_BASE));
.instruction(&Instruction::LocalSet(index_local));
rpeek(f);
f.instruction(&Instruction::LocalSet(SCRATCH_BASE + 1));
if needs_rs {
f.instruction(&Instruction::I32Const(SYSVAR_LEAVE_FLAG as i32))
.instruction(&Instruction::I32Load(MEM4))
.instruction(&Instruction::If(BlockType::Empty))
.instruction(&Instruction::I32Const(SYSVAR_LEAVE_FLAG as i32))
.instruction(&Instruction::I32Const(0))
.instruction(&Instruction::I32Store(MEM4))
.instruction(&Instruction::Br(2))
.instruction(&Instruction::End);
}
f.instruction(&Instruction::LocalGet(SCRATCH_BASE));
rpush_via_local(f, SCRATCH_BASE + 2);
f.instruction(&Instruction::LocalGet(SCRATCH_BASE))
.instruction(&Instruction::LocalGet(SCRATCH_BASE + 1))
f.instruction(&Instruction::LocalGet(index_local))
.instruction(&Instruction::LocalGet(limit_local))
.instruction(&Instruction::I32GeS)
.instruction(&Instruction::BrIf(1))
.instruction(&Instruction::Br(0))
@@ -2159,11 +2344,17 @@ fn emit_consolidated_do_loop(
.instruction(&Instruction::End);
}
// Clean up: pop index and limit from return stack, clear leave flag
if !needs_rs {
ctx.fast_loop_depth -= 1;
}
ctx.loop_locals.pop();
if needs_rs {
rpop(f);
f.instruction(&Instruction::Drop);
rpop(f);
f.instruction(&Instruction::Drop);
}
f.instruction(&Instruction::I32Const(SYSVAR_LEAVE_FLAG as i32))
.instruction(&Instruction::I32Const(0))
.instruction(&Instruction::I32Store(MEM4));
@@ -2321,7 +2512,9 @@ fn compile_multi_word_module(
for (_word_id, body) in words {
let scratch_count = count_scratch_locals(body);
let forth_local_count = count_forth_locals(body);
let num_locals = 1 + scratch_count + forth_local_count;
let loop_depth = count_loop_depth(body);
let loop_local_count = loop_depth * 2;
let num_locals = 1 + scratch_count + forth_local_count + loop_local_count;
let has_floats = needs_f64_locals(body);
let num_f64: u32 = if has_floats { 2 } else { 0 };
let mut locals_decl = vec![(num_locals, ValType::I32)];
@@ -2329,10 +2522,15 @@ fn compile_multi_word_module(
locals_decl.push((num_f64, ValType::F64));
}
let mut func = Function::new(locals_decl);
let ctx = EmitCtx {
let forth_local_base = 1 + scratch_count;
let loop_local_base = forth_local_base + forth_local_count;
let mut ctx = EmitCtx {
f64_local_0: num_locals,
f64_local_1: num_locals + 1,
forth_local_base: 1 + scratch_count,
forth_local_base,
loop_local_base,
loop_locals: Vec::new(),
fast_loop_depth: 0,
};
// Prologue: cache $dsp global into local 0
@@ -2340,7 +2538,7 @@ fn compile_multi_word_module(
.instruction(&Instruction::LocalSet(CACHED_DSP_LOCAL));
// Body with consolidated call support
emit_consolidated_body(&mut func, body, local_fn_map, &ctx);
emit_consolidated_body(&mut func, body, local_fn_map, &mut ctx);
// Epilogue: write cached DSP back to the $dsp global
func.instruction(&Instruction::LocalGet(CACHED_DSP_LOCAL))
crates/core/src/ir.rs
+3
View File
@@ -119,6 +119,9 @@ pub enum IrOp {
FromR,
/// Copy from return stack: ( -- x ) ( R: x -- x )
RFetch,
/// Read outer DO/LOOP index (J): ( -- n )
/// Compiled to local.get when loop locals are available.
LoopJ,
// -- Forth locals (from {: ... :} syntax) --
/// Get Forth local variable N: ( -- x )
crates/core/src/outer.rs
+2 -40
View File
@@ -2255,8 +2255,8 @@ impl ForthVM {
// -- Priority 1: Loop support --
// I -- push loop index (top of return stack)
self.register_primitive("I", false, vec![IrOp::RFetch])?;
// J -- outer loop counter (third item on return stack)
self.register_j()?;
// J -- outer loop counter
self.register_primitive("J", false, vec![IrOp::LoopJ])?;
// UNLOOP -- remove loop parameters from return stack
self.register_primitive(
"UNLOOP",
@@ -2515,44 +2515,6 @@ impl ForthVM {
// Priority 1: Loop support host functions
// -----------------------------------------------------------------------
/// Register J (outer loop counter) as a host function.
/// During nested DO loops the return stack looks like:
/// ... `outer_limit` `outer_index` `inner_limit` `inner_index` (`inner_index` on top)
/// J reads the outer index = rsp + 8 (skip inner index and inner limit).
fn register_j(&mut self) -> anyhow::Result<()> {
let memory = self.memory;
let dsp = self.dsp;
let rsp = self.rsp;
let func = Func::new(
&mut self.store,
FuncType::new(&self.engine, [], []),
move |mut caller, _params, _results| {
let rsp_val = rsp.get(&mut caller).unwrap_i32() as u32;
// rsp points to inner_index, rsp+4 = inner_limit, rsp+8 = outer_index
let addr = (rsp_val + 8) as usize;
let data = memory.data(&caller);
let b: [u8; 4] = data[addr..addr + 4].try_into().unwrap();
let value = i32::from_le_bytes(b);
// Push onto data stack
let sp = dsp.get(&mut caller).unwrap_i32() as u32;
let mem_len = memory.data(&caller).len() as u32;
if sp < CELL_SIZE || sp > mem_len {
return Err(wasmtime::Error::msg("data stack overflow in J"));
}
let new_sp = sp - CELL_SIZE;
let data = memory.data_mut(&mut caller);
let bytes = value.to_le_bytes();
data[new_sp as usize..new_sp as usize + 4].copy_from_slice(&bytes);
dsp.set(&mut caller, Val::I32(new_sp as i32))?;
Ok(())
},
);
self.register_host_primitive("J", false, func)?;
Ok(())
}
/// Register LEAVE as a host function.
/// Sets the loop index equal to the limit and sets the leave flag
/// so the loop exits on the next +LOOP/LOOP check.