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//
// wasm intepreter for asm2wasm output, in a js environment. receives asm.js,
// generates a runnable module suitable as a polyfill.
//
// this polyfills an emscripten --separate-asm *.asm.js file, as a drop-in
// replacement. it writes the wasm module to Module.asm, and sets Module.buffer.
//
#include <emscripten.h>
#include "asm2wasm.h"
#include "wasm-interpreter.h"
using namespace cashew;
using namespace wasm;
ModuleInstance* instance = nullptr;
// receives asm.js code, parses into wasm and returns an instance handle.
// this creates a module, an external interface, 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
// emcc --separate-asm modules look like
//
// Module["asm"] = (function(global, env, buffer) {
// ..
// });
//
// we need to clean that up.
size_t num = strlen(input);
assert(*input == 'M');
while (*input != 'f') {
input++;
num--;
}
char *end = input + num - 1;
while (*end != '}') {
*end = 0;
end--;
}
int debug = 0;
if (debug) std::cerr << "parsing...\n";
cashew::Parser<Ref, DotZeroValueBuilder> builder;
Ref asmjs = builder.parseToplevel(input);
Module* wasm = new Module();
if (debug) std::cerr << "wasming...\n";
Asm2WasmBuilder asm2wasm(*wasm);
asm2wasm.processAsm(asmjs);
if (debug) std::cerr << "optimizing...\n";
asm2wasm.optimize();
if (debug) std::cerr << "generating exports...\n";
EM_ASM({
Module['asmExports'] = {};
});
for (auto& curr : wasm->exports) {
EM_ASM_({
var name = Pointer_stringify($0);
Module['asmExports'][name] = function() {
Module['tempArguments'] = Array.prototype.slice.call(arguments);
return Module['_call_from_js']($0);
};
}, curr.name.str);
}
if (debug) std::cerr << "creating instance...\n";
struct JSExternalInterface : ModuleInstance::ExternalInterface {
Literal callImport(Import *import, ModuleInstance::LiteralList& arguments) override {
EM_ASM({
Module['tempArguments'] = [];
});
for (auto& argument : arguments) {
if (argument.type == i32) {
EM_ASM_({ Module['tempArguments'].push($0) }, argument.geti32());
} else if (argument.type == f64) {
EM_ASM_({ Module['tempArguments'].push($0) }, argument.getf64());
} else {
abort();
}
}
return Literal(EM_ASM_DOUBLE({
var mod = Pointer_stringify($0);
var base = Pointer_stringify($1);
var tempArguments = Module['tempArguments'];
Module['tempArguments'] = null;
return Module['instance'][mod][base].apply(null, tempArguments);
}, import->module.str, import->base.str));
}
Literal load(Load* load, Literal ptr) override {
size_t addr = ptr.geti32();
assert(load->align == load->bytes);
if (!load->float_) {
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] }, addr));
} else {
return Literal(EM_ASM_INT({ return Module['info'].parent['HEAPU16'][$0] }, addr));
}
} else if (load->bytes == 4) {
if (load->signed_) {
return Literal(EM_ASM_INT({ return Module['info'].parent['HEAP32'][$0] }, addr));
} else {
return Literal(EM_ASM_INT({ return Module['info'].parent['HEAPU32'][$0] }, addr));
}
}
abort();
} else {
if (load->bytes == 4) {
return Literal(EM_ASM_DOUBLE({ return Module['info'].parent['HEAPF32'][$0] }, addr));
} else if (load->bytes == 8) {
return Literal(EM_ASM_DOUBLE({ return Module['info'].parent['HEAPF64'][$0] }, addr));
}
abort();
}
}
void store(Store* store, Literal ptr, Literal value) override {
size_t addr = ptr.geti32();
assert(store->align == store->bytes);
if (!store->float_) {
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 }, addr, value.geti32());
} else if (store->bytes == 4) {
EM_ASM_INT({ Module['info'].parent['HEAP32'][$0] = $1 }, addr, value.geti32());
}
abort();
} else {
if (store->bytes == 4) {
EM_ASM_DOUBLE({ Module['info'].parent['HEAPF32'][$0] = $1 }, addr, value.getf64());
} else if (store->bytes == 8) {
EM_ASM_DOUBLE({ Module['info'].parent['HEAPF64'][$0] = $1 }, addr, value.getf64());
}
abort();
}
}
};
instance = new ModuleInstance(*wasm, new JSExternalInterface());
}
// Does a call from js into an export of the module.
extern "C" double EMSCRIPTEN_KEEPALIVE call_from_js(const char *target) {
IString name(target);
assert(instance->functions.find(name) != instance->functions.end());
Function *function = instance->functions[name];
size_t num = EM_ASM_INT_V({ return Module['tempArguments'].length });
assert(num == function->params.size()); // TODO: fake missing/extra args?
ModuleInstance::LiteralList arguments;
for (size_t i = 0; i < num; i++) {
WasmType type = function->params[i].type;
if (type == i32) {
arguments.push_back(Literal(EM_ASM_INT({ return Module['tempArguments'][$0] }, i)));
} else if (type == f64) {
arguments.push_back(Literal(EM_ASM_DOUBLE({ return Module['tempArguments'][$0] }, i)));
} else {
abort();
}
}
Literal ret = instance->callFunction(name, arguments);
if (ret.type == i32) return ret.i32;
if (ret.type == f64) return ret.f64;
abort();
}
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