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perf: calculate capacity of generated Wasm module code (#992)
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100_000 iterations of `test_render_js_wasm_module`

Before: 400.4625ms
After: 239.3486ms
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@dsherret
dsherret authored Dec 9, 2024
1 parent e897ce2 commit eefb5c0
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14 changes: 12 additions & 2 deletions Cargo.lock
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1 change: 1 addition & 0 deletions core/Cargo.toml
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Original file line number Diff line number Diff line change
Expand Up @@ -29,6 +29,7 @@ bincode.workspace = true
bit-set.workspace = true
bit-vec.workspace = true
bytes.workspace = true
capacity_builder = "0.1.0"
cooked-waker.workspace = true
deno_core_icudata = { workspace = true, optional = true }
deno_ops.workspace = true
Expand Down
178 changes: 100 additions & 78 deletions core/modules/map.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -35,6 +35,7 @@ use crate::ModuleSourceCode;
use crate::ModuleSpecifier;
use anyhow::bail;
use anyhow::Error;
use capacity_builder::StringBuilder;
use futures::future::FutureExt;
use futures::stream::FuturesUnordered;
use futures::stream::StreamFuture;
Expand Down Expand Up @@ -1996,100 +1997,118 @@ pub fn script_origin<'a>(
}

fn render_js_wasm_module(specifier: &str, wasm_deps: WasmDeps) -> String {
// NOTE(bartlomieju): it's unlikely the generated file will have more lines,
// but it's better to overallocate than to have to mem copy.
let mut src = Vec::with_capacity(512);
struct ImportInfo {
key_escaped: String,
escaped_named_imports: Vec<String>,
}

fn aggregate_wasm_module_imports(
imports: &[wasm_dep_analyzer::Import],
) -> IndexMap<String, Vec<String>> {
let mut imports_map = IndexMap::default();
fn aggregate_wasm_module_imports<'a>(
imports: &'a [wasm_dep_analyzer::Import],
) -> IndexMap<&'a str, ImportInfo> {
let mut imports_map = IndexMap::with_capacity(imports.len());

for import in imports.iter().filter(|i| {
matches!(i.import_type, wasm_dep_analyzer::ImportType::Function(..))
}) {
let entry = imports_map
.entry(import.module.to_string())
.or_insert(vec![]);
entry.push(import.name.to_string());
let entry =
imports_map
.entry(import.module)
.or_insert_with(|| ImportInfo {
key_escaped: import.module.escape_default().to_string(),
escaped_named_imports: Vec::new(),
});
entry
.escaped_named_imports
.push(import.name.escape_default().to_string());
}

imports_map
}

src.push(format!(
r#"import wasmMod from "{}" with {{ type: "$$deno-core-internal-wasm-module" }};"#,
specifier,
));

if !wasm_deps.imports.is_empty() {
let aggregated_imports = aggregate_wasm_module_imports(&wasm_deps.imports);

for (i, (key, names)) in aggregated_imports.iter().enumerate() {
src.push(format!(
r#"import {{ {} }} from "{}";"#,
names
.iter()
.enumerate()
// use a named import so that the error messages are good when
// an export can't be found on the module
.map(|(name_index, name)| format!(
"\"{}\" as import_{}_{}",
name.escape_default(),
i,
name_index
))
.collect::<Vec<_>>()
.join(", "),
key.escape_default(),
));
}

src.push("const importsObject = {".to_string());
let aggregated_imports = aggregate_wasm_module_imports(&wasm_deps.imports);
let escaped_export_names = wasm_deps
.exports
.iter()
.map(|e| {
if e.name == "default" {
Cow::Borrowed(e.name)
} else {
Cow::Owned(e.name.escape_default().to_string())
}
})
.collect::<Vec<_>>();

StringBuilder::build(|builder| {
builder.append("import wasmMod from \"");
builder.append(specifier);
builder.append("\" with { type: \"$$deno-core-internal-wasm-module\" };\n");

if !aggregated_imports.is_empty() {
for (i, (_, import_info)) in aggregated_imports.iter().enumerate() {
builder.append("import { ");
for (name_index, named_import) in import_info.escaped_named_imports.iter().enumerate() {
if name_index > 0 {
builder.append(", ");
}
builder.append('"');
builder.append(named_import);
builder.append("\" as import_");
builder.append(i);
builder.append('_');
builder.append(name_index);
}
builder.append(" } from \"");
builder.append(&import_info.key_escaped);
builder.append("\";\n");
}

for (i, (key, names)) in aggregated_imports.iter().enumerate() {
src.push(format!(" \"{}\": {{", key.escape_default()).to_string());
builder.append("const importsObject = {\n");

for (i, (_, import_info)) in aggregated_imports.iter().enumerate() {
builder.append(" \"");
builder.append(&import_info.key_escaped);
builder.append("\": {\n");

for (name_index, named_import) in import_info.escaped_named_imports.iter().enumerate() {
builder.append(" \"");
builder.append(named_import);
builder.append("\": import_");
builder.append(i);
builder.append('_');
builder.append(name_index);
builder.append(",\n");
}

for (name_index, name) in names.iter().enumerate() {
src.push(format!(
" \"{0}\": import_{1}_{2},",
name.escape_default(),
i,
name_index
));
builder.append(" },\n");
}

src.push(" },".to_string());
}
builder.append("};\n");

src.push("};".to_string());

src.push(
"const modInstance = new import.meta.WasmInstance(wasmMod, importsObject);".to_string(),
)
} else {
src.push(
"const modInstance = new import.meta.WasmInstance(wasmMod);".to_string(),
)
}
builder.append("const modInstance = new import.meta.WasmInstance(wasmMod, importsObject);\n");
} else {
builder.append(
"const modInstance = new import.meta.WasmInstance(wasmMod);\n"
);
}

if !wasm_deps.exports.is_empty() {
for (idx, export_desc) in wasm_deps.exports.iter().enumerate() {
if export_desc.name == "default" {
src.push(format!(
"export default modInstance.exports.{};",
export_desc.name
));
for (idx, escaped_name) in escaped_export_names.iter().enumerate() {
if escaped_name == "default" {
builder.append("export default modInstance.exports.");
builder.append(escaped_name);
builder.append(";\n");
} else {
let escaped_name = export_desc.name.escape_default();
src.push(format!(
"const export{idx} = modInstance.exports[\"{escaped_name}\"];\nexport {{ export{idx} as \"{escaped_name}\" }};",
));
builder.append("const export");
builder.append(idx);
builder.append(" = modInstance.exports[\"");
builder.append(escaped_name);
builder.append("\"];\nexport { export");
builder.append(idx);
builder.append(" as \"");
builder.append(escaped_name);
builder.append("\" };\n");
}
}
}

src.join("\n")
}).unwrap()
}

#[test]
Expand All @@ -2102,7 +2121,8 @@ fn test_render_js_wasm_module() {
pretty_assertions::assert_eq!(
rendered,
r#"import wasmMod from "./foo.wasm" with { type: "$$deno-core-internal-wasm-module" };
const modInstance = new import.meta.WasmInstance(wasmMod);"#,
const modInstance = new import.meta.WasmInstance(wasmMod);
"#,
);

let deps = WasmDeps {
Expand Down Expand Up @@ -2214,7 +2234,8 @@ const export4 = modInstance.exports["export5"];
export { export4 as "export5" };
const export5 = modInstance.exports["export6"];
export { export5 as "export6" };
export default modInstance.exports.default;"#,
export default modInstance.exports.default;
"#,
);

let deps = WasmDeps {
Expand Down Expand Up @@ -2246,6 +2267,7 @@ const importsObject = {
};
const modInstance = new import.meta.WasmInstance(wasmMod, importsObject);
const export0 = modInstance.exports["\n"];
export { export0 as "\n" };"#,
export { export0 as "\n" };
"#,
);
}

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