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Merged
merged 11 commits into from
Oct 10, 2025
Merged

[wasm-split] Do multi-split at once #7956

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9bfbbe6
[wasm-split] Do multi-split at once
aheejin Sep 24, 2025
7de862e
Misc fixes
aheejin Oct 8, 2025
4d2475e
Comment fix
aheejin Oct 8, 2025
566249c
Apply suggestions from code review
aheejin Oct 9, 2025
d071d5c
Fixing errors after apply suggestions
aheejin Oct 9, 2025
aece184
Make CallCollector calls one-liner
aheejin Oct 9, 2025
0c853c5
Use vector instead of map to store secondary modules
aheejin Oct 9, 2025
7e7fa66
Error out when there are duplicate module names
aheejin Oct 9, 2025
d275cc4
Example test fix after "Use vector instead of map to store secondary …
aheejin Oct 9, 2025
46c907f
Revert an accidental change
aheejin Oct 9, 2025
cef1155
Update src/tools/wasm-split/wasm-split.cpp
aheejin Oct 10, 2025
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440 changes: 248 additions & 192 deletions src/ir/module-splitting.cpp
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13 changes: 7 additions & 6 deletions src/ir/module-splitting.h
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Original file line number Diff line number Diff line change
Expand Up @@ -47,11 +47,12 @@ namespace wasm::ModuleSplitting {
static const Name LOAD_SECONDARY_MODULE("__load_secondary_module");

struct Config {
// The set of functions to split into the secondary module. All others are
// kept in the primary module. Must not include the start function if it
// exists. May or may not include imported functions, which are always kept in
// the primary module regardless.
std::set<Name> secondaryFuncs;
// A vector of set of functions to split into that secondary. Each function
// set belongs to a single secondary module. All others are kept in the
// primary module. Must not include the start function if it exists. May or
// may not include imported functions, which are always kept in the primary
// module regardless.
std::vector<std::set<Name>> secondaryFuncs;
// Whether to import placeholder functions into the primary module that will
// be called when a secondary function is called before the secondary module
// has been loaded.
Expand All @@ -76,7 +77,7 @@ struct Config {
};

struct Results {
std::unique_ptr<Module> secondary;
std::vector<std::unique_ptr<Module>> secondaries;
std::unordered_map<Name, std::map<size_t, Name>> placeholderMap;
};

Expand Down
51 changes: 26 additions & 25 deletions src/tools/wasm-split/wasm-split.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -329,7 +329,7 @@ void splitModule(const WasmSplitOptions& options) {

// Actually perform the splitting
ModuleSplitting::Config config;
config.secondaryFuncs = std::move(splitFuncs);
config.secondaryFuncs.push_back(std::move(splitFuncs));
if (options.importNamespace.size()) {
config.importNamespace = options.importNamespace;
}
Expand All @@ -343,7 +343,7 @@ void splitModule(const WasmSplitOptions& options) {
config.minimizeNewExportNames = !options.passOptions.debugInfo;
config.jspi = options.jspi;
auto splitResults = ModuleSplitting::splitFunctions(wasm, config);
auto& secondary = splitResults.secondary;
auto& secondary = *splitResults.secondaries.begin();

adjustTableSize(wasm, options.initialTableSize);
adjustTableSize(*secondary, options.initialTableSize, /*secondary=*/true);
Expand Down Expand Up @@ -389,27 +389,37 @@ void multiSplitModule(const WasmSplitOptions& options) {
Module wasm;
parseInput(wasm, options);

// Map module names to the functions that should be in the modules.
std::map<Name, std::unordered_set<Name>> moduleFuncs;
// The module for which we are currently parsing a set of functions.
Name currModule;
// The set of functions we are currently inserting into.
std::unordered_set<Name>* currFuncs = nullptr;
std::set<Name>* currFuncs = nullptr;
// Map functions to their modules to ensure no function is assigned to
// multiple modules.
std::unordered_map<Name, Name> funcModules;

ModuleSplitting::Config config;
std::string line;
bool newSection = true;
std::vector<Name> moduleNames;
std::unordered_set<Name> moduleNameSet;
while (std::getline(manifest, line)) {
if (line.empty()) {
newSection = true;
if (currFuncs->empty() && !options.quiet) {
std::cerr << "warning: Module " << currModule << " will be empty\n";
}
continue;
}
Name name = WasmBinaryReader::escape(line);
if (newSection) {
if (moduleNameSet.count(name)) {
Fatal() << "Module name " << name << " is listed more than once\n";
}
currModule = name;
currFuncs = &moduleFuncs[name];
moduleNameSet.insert(currModule);
moduleNames.push_back(currModule);
config.secondaryFuncs.emplace_back(std::set<Name>());
currFuncs = &config.secondaryFuncs.back();
newSection = false;
continue;
}
Expand All @@ -426,42 +436,33 @@ void multiSplitModule(const WasmSplitOptions& options) {
}
}

ModuleSplitting::Config config;
config.usePlaceholders = options.usePlaceholders;
config.importNamespace = options.importNamespace;
config.minimizeNewExportNames = !options.passOptions.debugInfo;
if (options.emitModuleNames && !wasm.name) {
wasm.name = Path::getBaseName(options.output);
}

std::unordered_map<Name, std::map<size_t, Name>> placeholderMap;
for (auto& [mod, funcs] : moduleFuncs) {
if (options.verbose) {
std::cerr << "Splitting module " << mod << '\n';
}
if (!options.quiet && funcs.empty()) {
std::cerr << "warning: Module " << mod << " will be empty\n";
}
config.secondaryFuncs = std::set<Name>(funcs.begin(), funcs.end());
auto splitResults = ModuleSplitting::splitFunctions(wasm, config);
auto moduleName = options.outPrefix + mod.toString() +
auto splitResults = ModuleSplitting::splitFunctions(wasm, config);
assert(moduleNames.size() == splitResults.secondaries.size());
for (Index i = 0, n = moduleNames.size(); i < n; i++) {
auto& secondary = *splitResults.secondaries[i];
auto moduleName = options.outPrefix + moduleNames[i].toString() +
(options.emitBinary ? ".wasm" : ".wast");
if (options.symbolMap) {
writeSymbolMap(*splitResults.secondary, moduleName + ".symbols");
}
if (options.placeholderMap) {
placeholderMap.merge(splitResults.placeholderMap);
writeSymbolMap(secondary, moduleName + ".symbols");
}
if (options.emitModuleNames) {
splitResults.secondary->name = Path::getBaseName(moduleName);
secondary.name = Path::getBaseName(moduleName);
}
writeModule(*splitResults.secondary, moduleName, options);
writeModule(secondary, moduleName, options);
}
if (options.symbolMap) {
writeSymbolMap(wasm, options.output + ".symbols");
}
if (options.placeholderMap) {
writePlaceholderMap(wasm, placeholderMap, options.output + ".placeholders");
writePlaceholderMap(
wasm, splitResults.placeholderMap, options.output + ".placeholders");
}
writeModule(wasm, options.output, options);
}
Expand Down
10 changes: 6 additions & 4 deletions test/example/module-splitting.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -51,9 +51,10 @@ void do_test(const std::set<Name>& keptFuncs, std::string&& module) {
std::cout << "\n";

ModuleSplitting::Config config;
config.secondaryFuncs = std::move(splitFuncs);
config.secondaryFuncs.push_back(std::move(splitFuncs));
config.newExportPrefix = "%";
auto secondary = splitFunctions(*primary, config).secondary;
auto results = splitFunctions(*primary, config);
auto& secondary = *results.secondaries.begin();

std::cout << "After:\n";
std::cout << *primary.get();
Expand Down Expand Up @@ -475,11 +476,12 @@ void test_minimized_exports() {
primary.addFunction(Builder::makeFunction("call", funcType, {}, callBody));

ModuleSplitting::Config config;
config.secondaryFuncs = {"call"};
config.secondaryFuncs.push_back({"call"});
config.newExportPrefix = "%";
config.minimizeNewExportNames = true;

auto secondary = splitFunctions(primary, config).secondary;
auto results = splitFunctions(primary, config);
auto& secondary = *results.secondaries.begin();
std::cout << "Minimized names primary:\n";
std::cout << primary << "\n";
std::cout << "Minimized names secondary:\n";
Expand Down
74 changes: 32 additions & 42 deletions test/lit/wasm-split/multi-split-escape-names.wast
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Original file line number Diff line number Diff line change
Expand Up @@ -7,11 +7,13 @@
;; RUN: wasm-dis %t3.wasm | filecheck %s --check-prefix=MOD3

(module
;; PRIMARY: (type $ret-i64 (func (result i64)))

;; PRIMARY: (type $ret-f32 (func (result f32)))

;; PRIMARY: (type $ret-i32 (func (result i32)))
(type $ret-i32 (func (result i32)))
;; PRIMARY: (type $ret-i64 (func (result i64)))
(type $ret-i64 (func (result i64)))
;; PRIMARY: (type $ret-f32 (func (result f32)))
(type $ret-f32 (func (result f32)))

;; MOD1: (type $0 (func (result f32)))
Expand All @@ -20,13 +22,13 @@

;; MOD1: (type $2 (func (result i32)))

;; MOD1: (import "" "table" (table $timport$0 1 funcref))
;; MOD1: (import "" "table" (table $timport$0 3 funcref))

;; MOD1: (import "" "std::operator<<\\28std::__2::basic_ostream<char\\2c\\20std::__2::char_traits<char>>&\\2c\\20wasm::Module&\\29" (func $std::operator<<\28std::__2::basic_ostream<char\2c\20std::__2::char_traits<char>>&\2c\20wasm::Module&\29 (result f32)))
;; MOD1: (import "" "trampoline_std::operator<<\\28std::__2::basic_ostream<char\\2c\\20std::__2::char_traits<char>>&\\2c\\20wasm::Module&\\29" (func $trampoline_std::operator<<\28std::__2::basic_ostream<char\2c\20std::__2::char_traits<char>>&\2c\20wasm::Module&\29 (result f32)))

;; MOD1: (import "" "wasm::Literal::Literal\\28std::__2::array<wasm::Literal\\2c\\204ul>\\20const&\\29" (func $wasm::Literal::Literal\28std::__2::array<wasm::Literal\2c\204ul>\20const&\29 (result i64)))
;; MOD1: (import "" "trampoline_wasm::Literal::Literal\\28std::__2::array<wasm::Literal\\2c\\204ul>\\20const&\\29" (func $trampoline_wasm::Literal::Literal\28std::__2::array<wasm::Literal\2c\204ul>\20const&\29 (result i64)))

;; MOD1: (elem $0 (i32.const 0) $wasm::Type::getFeatures\28\29\20const)
;; MOD1: (elem $0 (i32.const 2) $wasm::Type::getFeatures\28\29\20const)

;; MOD1: (func $wasm::Type::getFeatures\28\29\20const (result i32)
;; MOD1-NEXT: (drop
Expand All @@ -36,12 +38,12 @@
;; MOD1-NEXT: )
;; MOD1-NEXT: (drop
;; MOD1-NEXT: (call_ref $1
;; MOD1-NEXT: (ref.func $wasm::Literal::Literal\28std::__2::array<wasm::Literal\2c\204ul>\20const&\29)
;; MOD1-NEXT: (ref.func $trampoline_wasm::Literal::Literal\28std::__2::array<wasm::Literal\2c\204ul>\20const&\29)
;; MOD1-NEXT: )
;; MOD1-NEXT: )
;; MOD1-NEXT: (drop
;; MOD1-NEXT: (call_ref $0
;; MOD1-NEXT: (ref.func $std::operator<<\28std::__2::basic_ostream<char\2c\20std::__2::char_traits<char>>&\2c\20wasm::Module&\29)
;; MOD1-NEXT: (ref.func $trampoline_std::operator<<\28std::__2::basic_ostream<char\2c\20std::__2::char_traits<char>>&\2c\20wasm::Module&\29)
;; MOD1-NEXT: )
;; MOD1-NEXT: )
;; MOD1-NEXT: (i32.const 0)
Expand Down Expand Up @@ -71,9 +73,9 @@

;; MOD2: (type $2 (func (result i64)))

;; MOD2: (import "" "table_4" (table $timport$0 1 funcref))
;; MOD2: (import "" "table" (table $timport$0 3 funcref))

;; MOD2: (import "" "std::operator<<\\28std::__2::basic_ostream<char\\2c\\20std::__2::char_traits<char>>&\\2c\\20wasm::Module&\\29" (func $std::operator<<\28std::__2::basic_ostream<char\2c\20std::__2::char_traits<char>>&\2c\20wasm::Module&\29 (result f32)))
;; MOD2: (import "" "trampoline_std::operator<<\\28std::__2::basic_ostream<char\\2c\\20std::__2::char_traits<char>>&\\2c\\20wasm::Module&\\29" (func $trampoline_std::operator<<\28std::__2::basic_ostream<char\2c\20std::__2::char_traits<char>>&\2c\20wasm::Module&\29 (result f32)))

;; MOD2: (import "" "trampoline_wasm::Type::getFeatures\\28\\29\\20const" (func $trampoline_wasm::Type::getFeatures\28\29\20const (result i32)))

Expand All @@ -92,7 +94,7 @@
;; MOD2-NEXT: )
;; MOD2-NEXT: (drop
;; MOD2-NEXT: (call_ref $0
;; MOD2-NEXT: (ref.func $std::operator<<\28std::__2::basic_ostream<char\2c\20std::__2::char_traits<char>>&\2c\20wasm::Module&\29)
;; MOD2-NEXT: (ref.func $trampoline_std::operator<<\28std::__2::basic_ostream<char\2c\20std::__2::char_traits<char>>&\2c\20wasm::Module&\29)
;; MOD2-NEXT: )
;; MOD2-NEXT: )
;; MOD2-NEXT: (i64.const 0)
Expand Down Expand Up @@ -122,13 +124,13 @@

;; MOD3: (type $2 (func (result f32)))

;; MOD3: (import "" "table_5" (table $timport$0 1 funcref))
;; MOD3: (import "" "table" (table $timport$0 3 funcref))

;; MOD3: (import "" "wasm::Literal::Literal\\28std::__2::array<wasm::Literal\\2c\\204ul>\\20const&\\29" (func $trampoline_wasm::Literal::Literal\28std::__2::array<wasm::Literal\2c\204ul>\20const&\29 (result i64)))
;; MOD3: (import "" "trampoline_wasm::Literal::Literal\\28std::__2::array<wasm::Literal\\2c\\204ul>\\20const&\\29" (func $trampoline_wasm::Literal::Literal\28std::__2::array<wasm::Literal\2c\204ul>\20const&\29 (result i64)))

;; MOD3: (import "" "trampoline_wasm::Type::getFeatures\\28\\29\\20const" (func $trampoline_wasm::Type::getFeatures\28\29\20const (result i32)))

;; MOD3: (elem $0 (i32.const 0) $std::operator<<\28std::__2::basic_ostream<char\2c\20std::__2::char_traits<char>>&\2c\20wasm::Module&\29)
;; MOD3: (elem $0 (i32.const 1) $std::operator<<\28std::__2::basic_ostream<char\2c\20std::__2::char_traits<char>>&\2c\20wasm::Module&\29)

;; MOD3: (func $std::operator<<\28std::__2::basic_ostream<char\2c\20std::__2::char_traits<char>>&\2c\20wasm::Module&\29 (result f32)
;; MOD3-NEXT: (drop
Expand Down Expand Up @@ -167,50 +169,38 @@
(f32.const 0)
)
)
;; PRIMARY: (import "placeholder" "0" (func $placeholder_0 (result i32)))
;; PRIMARY: (import "placeholder" "0" (func $placeholder_0 (result i64)))

;; PRIMARY: (import "placeholder" "0" (func $placeholder_0_4 (result i64)))
;; PRIMARY: (import "placeholder" "1" (func $placeholder_1 (result f32)))

;; PRIMARY: (import "placeholder" "0" (func $placeholder_0_5 (result f32)))
;; PRIMARY: (import "placeholder" "2" (func $placeholder_2 (result i32)))

;; PRIMARY: (table $0 1 funcref)
;; PRIMARY: (table $0 3 funcref)

;; PRIMARY: (table $1 1 funcref)
;; PRIMARY: (elem $0 (i32.const 0) $placeholder_0 $placeholder_1 $placeholder_2)

;; PRIMARY: (table $2 1 funcref)
;; PRIMARY: (export "trampoline_std::operator<<\\28std::__2::basic_ostream<char\\2c\\20std::__2::char_traits<char>>&\\2c\\20wasm::Module&\\29" (func $trampoline_std::operator<<\28std::__2::basic_ostream<char\2c\20std::__2::char_traits<char>>&\2c\20wasm::Module&\29))

;; PRIMARY: (elem $0 (table $0) (i32.const 0) func $placeholder_0)

;; PRIMARY: (elem $1 (table $1) (i32.const 0) func $placeholder_0_4)

;; PRIMARY: (elem $2 (table $2) (i32.const 0) func $placeholder_0_5)

;; PRIMARY: (export "std::operator<<\\28std::__2::basic_ostream<char\\2c\\20std::__2::char_traits<char>>&\\2c\\20wasm::Module&\\29" (func $trampoline_std::operator<<\28std::__2::basic_ostream<char\2c\20std::__2::char_traits<char>>&\2c\20wasm::Module&\29))

;; PRIMARY: (export "wasm::Literal::Literal\\28std::__2::array<wasm::Literal\\2c\\204ul>\\20const&\\29" (func $trampoline_wasm::Literal::Literal\28std::__2::array<wasm::Literal\2c\204ul>\20const&\29))

;; PRIMARY: (export "table" (table $0))
;; PRIMARY: (export "trampoline_wasm::Literal::Literal\\28std::__2::array<wasm::Literal\\2c\\204ul>\\20const&\\29" (func $trampoline_wasm::Literal::Literal\28std::__2::array<wasm::Literal\2c\204ul>\20const&\29))

;; PRIMARY: (export "trampoline_wasm::Type::getFeatures\\28\\29\\20const" (func $trampoline_wasm::Type::getFeatures\28\29\20const))

;; PRIMARY: (export "table_4" (table $1))

;; PRIMARY: (export "table_5" (table $2))
;; PRIMARY: (export "table" (table $0))

;; PRIMARY: (func $trampoline_wasm::Type::getFeatures\28\29\20const (result i32)
;; PRIMARY-NEXT: (call_indirect (type $ret-i32)
;; PRIMARY: (func $trampoline_wasm::Literal::Literal\28std::__2::array<wasm::Literal\2c\204ul>\20const&\29 (result i64)
;; PRIMARY-NEXT: (call_indirect (type $ret-i64)
;; PRIMARY-NEXT: (i32.const 0)
;; PRIMARY-NEXT: )
;; PRIMARY-NEXT: )

;; PRIMARY: (func $trampoline_wasm::Literal::Literal\28std::__2::array<wasm::Literal\2c\204ul>\20const&\29 (result i64)
;; PRIMARY-NEXT: (call_indirect $1 (type $ret-i64)
;; PRIMARY-NEXT: (i32.const 0)
;; PRIMARY: (func $trampoline_std::operator<<\28std::__2::basic_ostream<char\2c\20std::__2::char_traits<char>>&\2c\20wasm::Module&\29 (result f32)
;; PRIMARY-NEXT: (call_indirect (type $ret-f32)
;; PRIMARY-NEXT: (i32.const 1)
;; PRIMARY-NEXT: )
;; PRIMARY-NEXT: )

;; PRIMARY: (func $trampoline_std::operator<<\28std::__2::basic_ostream<char\2c\20std::__2::char_traits<char>>&\2c\20wasm::Module&\29 (result f32)
;; PRIMARY-NEXT: (call_indirect $2 (type $ret-f32)
;; PRIMARY-NEXT: (i32.const 0)
;; PRIMARY: (func $trampoline_wasm::Type::getFeatures\28\29\20const (result i32)
;; PRIMARY-NEXT: (call_indirect (type $ret-i32)
;; PRIMARY-NEXT: (i32.const 2)
;; PRIMARY-NEXT: )
;; PRIMARY-NEXT: )
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