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//
// WebAssembly intepreter for asm2wasm output, in a js environment.
//
// Receives asm.js, generates a runnable module that executes the code in a WebAssembly
// interpreter. This is suitable as a polyfill for WebAssembly support in browsers.
//
#include <emscripten.h>
#include "asm2wasm.h"
#include "wasm-interpreter.h"
using namespace cashew;
using namespace wasm;
// global singletons
Asm2WasmBuilder* asm2wasm = nullptr;
ModuleInstance* instance = nullptr;
AllocatingModule* module = nullptr;
bool wasmJSDebug = false;
// receives asm.js code, parses into wasm and returns an instance handle.
// this creates a module, an external interface, a builder, and a module instance,
// all of which are then the responsibility of the caller to free.
// note: this modifies the input.
extern "C" void EMSCRIPTEN_KEEPALIVE load_asm(char *input) {
assert(instance == nullptr); // singleton
#if WASM_JS_DEBUG
wasmJSDebug = 1;
#else
wasmJSDebug = EM_ASM_INT_V({ return !!Module['outside']['WASM_JS_DEBUG'] }); // Set WASM_JS_DEBUG on the outside Module to get debugging
#endif
Asm2WasmPreProcessor pre;
input = pre.process(input);
// proceed to parse and wasmify
if (wasmJSDebug) std::cerr << "parsing...\n";
cashew::Parser<Ref, DotZeroValueBuilder> builder;
Ref asmjs = builder.parseToplevel(input);
module = new AllocatingModule();
module->memory.initial = EM_ASM_INT_V({
return Module['providedTotalMemory']; // we receive the size of memory from emscripten
});
module->memory.max = pre.memoryGrowth ? -1 : module->memory.initial;
if (wasmJSDebug) std::cerr << "wasming...\n";
asm2wasm = new Asm2WasmBuilder(*module, pre.memoryGrowth);
asm2wasm->processAsm(asmjs);
if (wasmJSDebug) std::cerr << "optimizing...\n";
asm2wasm->optimize();
if (wasmJSDebug) std::cerr << *module << '\n';
if (wasmJSDebug) std::cerr << "generating exports...\n";
EM_ASM({
Module['asmExports'] = {};
});
for (auto& pair : module->exportsMap) {
auto& curr = pair.second;
EM_ASM_({
var name = Pointer_stringify($0);
Module['asmExports'][name] = function() {
Module['tempArguments'] = Array.prototype.slice.call(arguments);
Module['_call_from_js']($0);
return Module['tempReturn'];
};
}, curr->name.str);
}
if (wasmJSDebug) std::cerr << "creating instance...\n";
struct JSExternalInterface : ModuleInstance::ExternalInterface {
Literal callImport(Import *import, ModuleInstance::LiteralList& arguments) override {
if (wasmJSDebug) std::cout << "calling import " << import->name.str << '\n';
EM_ASM({
Module['tempArguments'] = [];
});
for (auto& argument : arguments) {
if (argument.type == i32) {
EM_ASM_({ Module['tempArguments'].push($0) }, argument.geti32());
} else if (argument.type == f32) {
EM_ASM_({ Module['tempArguments'].push($0) }, argument.getf32());
} else if (argument.type == f64) {
EM_ASM_({ Module['tempArguments'].push($0) }, argument.getf64());
} else {
abort();
}
}
double ret = EM_ASM_DOUBLE({
var mod = Pointer_stringify($0);
var base = Pointer_stringify($1);
var tempArguments = Module['tempArguments'];
Module['tempArguments'] = null;
var lookup = Module['lookupImport'](mod, base);
return lookup.apply(null, tempArguments);
}, import->module.str, import->base.str);
if (wasmJSDebug) std::cout << "calling import returning " << ret << '\n';
switch (import->type.result) {
case none: return Literal(0);
case i32: return Literal((int32_t)ret);
case f32: return Literal((float)ret);
case f64: return Literal((double)ret);
default: abort();
}
}
Literal load(Load* load, size_t addr) override {
assert(load->align == load->bytes);
if (!isWasmTypeFloat(load->type)) {
if (load->bytes == 1) {
if (load->signed_) {
return Literal(EM_ASM_INT({ return Module['info'].parent['HEAP8'][$0] }, addr));
} else {
return Literal(EM_ASM_INT({ return Module['info'].parent['HEAPU8'][$0] }, addr));
}
} else if (load->bytes == 2) {
if (load->signed_) {
return Literal(EM_ASM_INT({ return Module['info'].parent['HEAP16'][$0 >> 1] }, addr));
} else {
return Literal(EM_ASM_INT({ return Module['info'].parent['HEAPU16'][$0 >> 1] }, addr));
}
} else if (load->bytes == 4) {
if (load->signed_) {
return Literal(EM_ASM_INT({ return Module['info'].parent['HEAP32'][$0 >> 2] }, addr));
} else {
return Literal(EM_ASM_INT({ return Module['info'].parent['HEAPU32'][$0 >> 2] }, addr));
}
}
abort();
} else {
if (load->bytes == 4) {
return Literal((float)EM_ASM_DOUBLE({ return Module['info'].parent['HEAPF32'][$0 >> 2] }, addr));
} else if (load->bytes == 8) {
return Literal(EM_ASM_DOUBLE({ return Module['info'].parent['HEAPF64'][$0 >> 3] }, addr));
}
abort();
}
}
void store(Store* store, size_t addr, Literal value) override {
assert(store->align == store->bytes);
if (!isWasmTypeFloat(store->type)) {
if (store->bytes == 1) {
EM_ASM_INT({ Module['info'].parent['HEAP8'][$0] = $1 }, addr, value.geti32());
} else if (store->bytes == 2) {
EM_ASM_INT({ Module['info'].parent['HEAP16'][$0 >> 1] = $1 }, addr, value.geti32());
} else if (store->bytes == 4) {
EM_ASM_INT({ Module['info'].parent['HEAP32'][$0 >> 2] = $1 }, addr, value.geti32());
} else {
abort();
}
} else {
if (store->bytes == 4) {
EM_ASM_DOUBLE({ Module['info'].parent['HEAPF32'][$0 >> 2] = $1 }, addr, value.getf32());
} else if (store->bytes == 8) {
EM_ASM_DOUBLE({ Module['info'].parent['HEAPF64'][$0 >> 3] = $1 }, addr, value.getf64());
} else {
abort();
}
}
}
void growMemory(size_t oldSize, size_t newSize) override {
EM_ASM_({
var size = $0;
var buffer;
try {
buffer = new ArrayBuffer(size);
} catch(e) {
// fail to grow memory. post.js notices this since the buffer is unchanged
return;
}
var oldHEAP8 = Module['outside']['HEAP8'];
var temp = new Int8Array(buffer);
temp.set(oldHEAP8);
Module['outside']['buffer'] = buffer;
}, newSize);
}
void trap(const char* why) override {
EM_ASM_({
abort("wasm trap: " + Pointer_stringify($0));
}, why);
}
};
instance = new ModuleInstance(*module, new JSExternalInterface());
}
// Ready the provided imported globals, copying them to their mapped locations.
extern "C" void EMSCRIPTEN_KEEPALIVE load_mapped_globals() {
for (auto& pair : asm2wasm->mappedGlobals) {
auto name = pair.first;
auto& global = pair.second;
if (!global.import) continue; // non-imports are initialized to zero in the typed array anyhow, so nothing to do here
double value = EM_ASM_DOUBLE({ return Module['lookupImport'](Pointer_stringify($0), Pointer_stringify($1)) }, global.module.str, global.base.str);
unsigned address = global.address;
switch (global.type) {
case i32: EM_ASM_({ Module['info'].parent['HEAP32'][$0 >> 2] = $1 }, address, value); break;
case f32: EM_ASM_({ Module['info'].parent['HEAPF32'][$0 >> 2] = $1 }, address, value); break;
case f64: EM_ASM_({ Module['info'].parent['HEAPF64'][$0 >> 3] = $1 }, address, value); break;
default: abort();
}
}
}
// Does a call from js into an export of the module.
extern "C" void EMSCRIPTEN_KEEPALIVE call_from_js(const char *target) {
if (wasmJSDebug) std::cout << "call_from_js " << target << '\n';
IString exportName(target);
IString functionName = instance->wasm.exportsMap[exportName]->value;
Function *function = instance->wasm.functionsMap[functionName];
assert(function);
size_t seen = EM_ASM_INT_V({ return Module['tempArguments'].length });
size_t actual = function->params.size();
ModuleInstance::LiteralList arguments;
for (size_t i = 0; i < actual; i++) {
WasmType type = function->params[i].type;
// add the parameter, with a zero value if JS did not provide it.
if (type == i32) {
arguments.push_back(Literal(i < seen ? EM_ASM_INT({ return Module['tempArguments'][$0] }, i) : (int32_t)0));
} else if (type == f32) {
arguments.push_back(Literal(i < seen ? (float)EM_ASM_DOUBLE({ return Module['tempArguments'][$0] }, i) : (float)0.0));
} else if (type == f64) {
arguments.push_back(Literal(i < seen ? EM_ASM_DOUBLE({ return Module['tempArguments'][$0] }, i) : (double)0.0));
} else {
abort();
}
}
Literal ret = instance->callExport(exportName, arguments);
if (wasmJSDebug) std::cout << "call_from_js returning " << ret << '\n';
if (ret.type == none) EM_ASM({ Module['tempReturn'] = undefined });
else if (ret.type == i32) EM_ASM_({ Module['tempReturn'] = $0 }, ret.i32);
else if (ret.type == f32) EM_ASM_({ Module['tempReturn'] = $0 }, ret.f32);
else if (ret.type == f64) EM_ASM_({ Module['tempReturn'] = $0 }, ret.f64);
else abort();
}
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