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feat(SR-25): fix resource handle translation in cross-component adapters #28

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Merged
avrabe merged 1 commit into from
Mar 15, 2026
Merged

feat(SR-25): fix resource handle translation in cross-component adapters #28

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197 changes: 147 additions & 50 deletions meld-core/src/adapter/fact.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -40,6 +40,27 @@ fn alignment_for_encoding(encoding: StringEncoding) -> i32 {
}
}

/// Build a lookup from `(module, field)` → merged function index for resource imports.
///
/// Scans the merged module's imports to find `[resource-rep]` function imports
/// and records their merged function indices.
fn build_resource_import_map(
merged: &MergedModule,
) -> std::collections::HashMap<(String, String), u32> {
use wasm_encoder::EntityType;
let mut map = std::collections::HashMap::new();
let mut func_idx = 0u32;
for imp in &merged.imports {
if matches!(imp.entity_type, EntityType::Function(_)) {
if imp.name.starts_with("[resource-rep]") {
map.insert((imp.module.clone(), imp.name.clone()), func_idx);
}
func_idx += 1;
}
}
map
}

/// FACT-style adapter generator
pub struct FactStyleGenerator {
#[allow(dead_code)]
Expand All @@ -58,22 +79,23 @@ impl FactStyleGenerator {
site: &AdapterSite,
merged: &MergedModule,
_adapter_idx: usize,
resource_imports: &std::collections::HashMap<(String, String), u32>,
) -> Result<AdapterFunction> {
let name = format!(
"$adapter_{}_{}_to_{}_{}",
site.from_component, site.from_module, site.to_component, site.to_module
);

// Determine adapter options based on call site
let options = self.analyze_call_site(site, merged);
let options = self.analyze_call_site(site, merged, resource_imports);

// Generate the adapter function body
let (type_idx, body) = if site.crosses_memory && options.needs_transcoding() {
self.generate_transcoding_adapter(site, merged, &options)?
} else if site.crosses_memory {
self.generate_memory_copy_adapter(site, merged, &options)?
} else {
self.generate_direct_adapter(site, merged)?
self.generate_direct_adapter(site, merged, &options)?
};

Ok(AdapterFunction {
Expand All @@ -89,7 +111,12 @@ impl FactStyleGenerator {
}

/// Analyze a call site to determine adapter options
fn analyze_call_site(&self, site: &AdapterSite, merged: &MergedModule) -> AdapterOptions {
fn analyze_call_site(
&self,
site: &AdapterSite,
merged: &MergedModule,
resource_imports: &std::collections::HashMap<(String, String), u32>,
) -> AdapterOptions {
let mut options = AdapterOptions::default();

// Determine memory indices
Expand Down Expand Up @@ -162,6 +189,35 @@ impl FactStyleGenerator {
options.callee_post_return = Some(merged_pr_idx);
}

// Resolve resource BORROW params → [resource-rep] merged function indices.
//
// Per the canonical ABI spec, `borrow<T>` params where T is defined by
// the callee receive the representation (raw pointer), not the handle.
// The adapter must call resource.rep(handle) → rep for these.
//
// `own<T>` params receive the handle directly — the callee's core
// function calls from_handle/resource.rep internally, so the adapter
// must NOT convert them (that would cause double conversion).
//
// Results are never converted — own results have resource.new called
// by the callee's core function, and borrows cannot appear in results.
for op in &site.requirements.resource_params {
if op.is_owned {
continue; // own<T>: callee handles conversion internally
}
if let Some(&func_idx) =
resource_imports.get(&(op.import_module.clone(), op.import_field.clone()))
{
options.resource_rep_calls.push((op.flat_idx, func_idx));
} else {
log::debug!(
"Resource rep import not found: ({}, {})",
op.import_module,
op.import_field
);
}
}

options
}

Expand All @@ -170,9 +226,9 @@ impl FactStyleGenerator {
&self,
site: &AdapterSite,
merged: &MergedModule,
options: &AdapterOptions,
) -> Result<(u32, Function)> {
let target_func = self.resolve_target_function(site, merged)?;
let options = self.analyze_call_site(site, merged);

// Find the target function's type (convert wasm index to array position)
let type_idx = merged
Expand All @@ -186,36 +242,45 @@ impl FactStyleGenerator {
let result_types: Vec<wasm_encoder::ValType> =
func_type.map(|t| t.results.clone()).unwrap_or_default();

// If post-return is specified, we need scratch locals to save results
let has_post_return = options.callee_post_return.is_some();
let has_resource_ops = !options.resource_rep_calls.is_empty();

if has_post_return && result_count > 0 {
// Need locals to save results across the post-return call
let locals: Vec<(u32, wasm_encoder::ValType)> =
result_types.iter().map(|t| (1u32, *t)).collect();
let mut func = Function::new(locals);
if has_resource_ops || (has_post_return && result_count > 0) {
let mut locals: Vec<(u32, wasm_encoder::ValType)> = Vec::new();
let result_base = param_count as u32;

// Load all parameters and call target
for i in 0..param_count {
func.instruction(&Instruction::LocalGet(i as u32));
if has_post_return && result_count > 0 {
locals.extend(result_types.iter().map(|t| (1u32, *t)));
}
func.instruction(&Instruction::Call(target_func));
let mut func = Function::new(locals);

// Save results to locals (pop in reverse order)
for i in (0..result_count).rev() {
func.instruction(&Instruction::LocalSet(result_base + i as u32));
// Phase 0: Convert borrow resource handles → representations
for &(param_idx, rep_func) in &options.resource_rep_calls {
func.instruction(&Instruction::LocalGet(param_idx));
func.instruction(&Instruction::Call(rep_func));
func.instruction(&Instruction::LocalSet(param_idx));
}

// Call post-return with the saved results
for i in 0..result_count {
func.instruction(&Instruction::LocalGet(result_base + i as u32));
for i in 0..param_count {
func.instruction(&Instruction::LocalGet(i as u32));
}
func.instruction(&Instruction::Call(options.callee_post_return.unwrap()));
func.instruction(&Instruction::Call(target_func));

// Push saved results back onto stack
for i in 0..result_count {
func.instruction(&Instruction::LocalGet(result_base + i as u32));
if has_post_return && result_count > 0 {
// Save results to locals (pop in reverse order)
for i in (0..result_count).rev() {
func.instruction(&Instruction::LocalSet(result_base + i as u32));
}
// Call post-return with saved results
for i in 0..result_count {
func.instruction(&Instruction::LocalGet(result_base + i as u32));
}
func.instruction(&Instruction::Call(options.callee_post_return.unwrap()));
// Push saved results back onto stack
for i in 0..result_count {
func.instruction(&Instruction::LocalGet(result_base + i as u32));
}
} else if has_post_return {
func.instruction(&Instruction::Call(options.callee_post_return.unwrap()));
}

func.instruction(&Instruction::End);
Expand All @@ -230,7 +295,6 @@ impl FactStyleGenerator {
func.instruction(&Instruction::Call(target_func));

if has_post_return {
// No results to save, just call post-return
func.instruction(&Instruction::Call(options.callee_post_return.unwrap()));
}

Expand Down Expand Up @@ -324,33 +388,41 @@ impl FactStyleGenerator {
// If memories are the same, just do direct call (with post-return if needed)
if options.caller_memory == options.callee_memory {
let has_post_return = options.callee_post_return.is_some();
let has_resource_ops = !options.resource_rep_calls.is_empty();

if has_post_return && result_count > 0 {
// Need scratch locals to save results across post-return call
let locals: Vec<(u32, wasm_encoder::ValType)> =
result_types.iter().map(|t| (1u32, *t)).collect();
let mut func = Function::new(locals);
if has_resource_ops || (has_post_return && result_count > 0) {
let mut locals: Vec<(u32, wasm_encoder::ValType)> = Vec::new();
let result_base = param_count as u32;

for i in 0..param_count {
func.instruction(&Instruction::LocalGet(i as u32));
if has_post_return && result_count > 0 {
locals.extend(result_types.iter().map(|t| (1u32, *t)));
}
func.instruction(&Instruction::Call(target_func));
let mut func = Function::new(locals);

// Save results to locals (pop in reverse order)
for i in (0..result_count).rev() {
func.instruction(&Instruction::LocalSet(result_base + i as u32));
// Phase 0: Convert borrow resource handles → representations
for &(param_idx, rep_func) in &options.resource_rep_calls {
func.instruction(&Instruction::LocalGet(param_idx));
func.instruction(&Instruction::Call(rep_func));
func.instruction(&Instruction::LocalSet(param_idx));
}

// Call post-return with saved results
for i in 0..result_count {
func.instruction(&Instruction::LocalGet(result_base + i as u32));
for i in 0..param_count {
func.instruction(&Instruction::LocalGet(i as u32));
}
func.instruction(&Instruction::Call(options.callee_post_return.unwrap()));
func.instruction(&Instruction::Call(target_func));

// Push saved results back onto stack
for i in 0..result_count {
func.instruction(&Instruction::LocalGet(result_base + i as u32));
if has_post_return && result_count > 0 {
for i in (0..result_count).rev() {
func.instruction(&Instruction::LocalSet(result_base + i as u32));
}
for i in 0..result_count {
func.instruction(&Instruction::LocalGet(result_base + i as u32));
}
func.instruction(&Instruction::Call(options.callee_post_return.unwrap()));
for i in 0..result_count {
func.instruction(&Instruction::LocalGet(result_base + i as u32));
}
} else if has_post_return {
func.instruction(&Instruction::Call(options.callee_post_return.unwrap()));
}

func.instruction(&Instruction::End);
Expand All @@ -363,7 +435,6 @@ impl FactStyleGenerator {
func.instruction(&Instruction::Call(target_func));

if has_post_return {
// No results to save, just call post-return
func.instruction(&Instruction::Call(options.callee_post_return.unwrap()));
}

Expand All @@ -390,16 +461,19 @@ impl FactStyleGenerator {
let needs_post_return_save =
!needs_result_copy && options.callee_post_return.is_some() && result_count > 0;

// We need result-save locals for post-return AND/OR conditional result copy
// We need result-save locals for post-return or conditional result copy.
let needs_result_save =
(needs_post_return_save || needs_conditional_result_copy) && result_count > 0;

// If no copying and no post-return save needed, direct call
let has_resource_ops = !options.resource_rep_calls.is_empty();

// If no copying, no post-return save, and no resource ops needed, direct call
if !needs_outbound_copy
&& !needs_conditional_copy
&& !needs_result_copy
&& !needs_conditional_result_copy
&& !needs_post_return_save
&& !has_resource_ops
{
let mut func = Function::new([]);
for i in 0..param_count {
Expand Down Expand Up @@ -443,6 +517,13 @@ impl FactStyleGenerator {

let mut func = Function::new(local_decls);

// Phase 0: Convert borrow resource handles → representations
for &(param_idx, rep_func) in &options.resource_rep_calls {
func.instruction(&Instruction::LocalGet(param_idx));
func.instruction(&Instruction::Call(rep_func));
func.instruction(&Instruction::LocalSet(param_idx));
}

// Assign scratch local indices (after params)
let base = param_count as u32;
// For outbound copy:
Expand Down Expand Up @@ -655,7 +736,7 @@ impl FactStyleGenerator {
func.instruction(&Instruction::LocalGet(callee_ret_len_local));
}

// Post-return and/or conditional result copy for non-result-copy case
// Post-return and/or conditional result copy
if !needs_result_copy
&& (needs_conditional_result_copy || options.callee_post_return.is_some())
{
Expand Down Expand Up @@ -814,6 +895,13 @@ impl FactStyleGenerator {
let local_decls = vec![(scratch_count, wasm_encoder::ValType::I32)];
let mut func = Function::new(local_decls);

// Phase 0: Convert borrow resource handles → representations
for &(param_idx, rep_func) in &options.resource_rep_calls {
func.instruction(&Instruction::LocalGet(param_idx));
func.instruction(&Instruction::Call(rep_func));
func.instruction(&Instruction::LocalSet(param_idx));
}

// --- Phase 1: Outbound copy of ALL pointer pairs (caller → callee) ---
if let Some(callee_realloc) = options
.callee_realloc
Expand Down Expand Up @@ -953,6 +1041,7 @@ impl FactStyleGenerator {
// load/store instructions based on the canonical ABI memory layout.
let result_layouts = &site.requirements.result_copy_layouts;
let return_area_slots = &site.requirements.return_area_slots;

if let Some(caller_realloc) = options
.caller_realloc
.filter(|_| !result_ptr_offsets.is_empty())
Expand Down Expand Up @@ -1462,6 +1551,13 @@ impl FactStyleGenerator {
}
let mut func = Function::new(local_decls);

// Phase 0: Convert borrow resource handles → representations
for &(param_idx, rep_func) in &options.resource_rep_calls {
func.instruction(&Instruction::LocalGet(param_idx));
func.instruction(&Instruction::Call(rep_func));
func.instruction(&Instruction::LocalSet(param_idx));
}

// Generate transcoding logic based on encoding pair

match (
Expand Down Expand Up @@ -2350,10 +2446,11 @@ impl AdapterGenerator for FactStyleGenerator {
merged: &MergedModule,
graph: &DependencyGraph,
) -> Result<Vec<AdapterFunction>> {
let resource_imports = build_resource_import_map(merged);
let mut adapters = Vec::new();

for (idx, site) in graph.adapter_sites.iter().enumerate() {
let adapter = self.generate_adapter(site, merged, idx)?;
let adapter = self.generate_adapter(site, merged, idx, &resource_imports)?;
adapters.push(adapter);
}

Expand Down
20 changes: 20 additions & 0 deletions meld-core/src/adapter/mod.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -123,6 +123,25 @@ pub struct AdapterOptions {
/// Post-return function index in merged module (if any).
/// Called after results have been copied back, to allow callee cleanup.
pub callee_post_return: Option<u32>,

/// Resource borrow params needing handle→representation conversion.
/// Each entry: `(flat_param_idx, merged_func_idx of [resource-rep])`.
///
/// Per the canonical ABI spec, `borrow<T>` params where T is defined by
/// the callee receive the **representation** (raw pointer), not the handle.
/// The `lower_borrow` function has `if cx.inst is t.rt.impl: return rep`.
/// So the adapter must call `[resource-rep]R(handle)` to convert before
/// forwarding to the callee's core function.
///
/// `own<T>` params always receive a **handle** (table index) because
/// `lower_own` unconditionally creates a handle entry. The callee's core
/// function calls `from_handle` / `[resource-rep]` internally, so the
/// adapter must NOT convert own params.
///
/// Results are never converted by the adapter — the callee's core function
/// already calls `[resource-new]R` internally for own results, and borrows
/// cannot appear in results.
pub resource_rep_calls: Vec<(u32, u32)>,
}

impl Default for AdapterOptions {
Expand All @@ -136,6 +155,7 @@ impl Default for AdapterOptions {
callee_realloc: None,
returns_pointer_pair: false,
callee_post_return: None,
resource_rep_calls: Vec::new(),
}
}
}
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