/*
* Copyright 2015 WebAssembly Community Group participants
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
//
// WebAssembly-to-JS code translator. Converts wasm functions into
// valid JavaScript (with a somewhat asm.js-ish flavor).
//
#ifndef wasm_wasm2js_h
#define wasm_wasm2js_h
#include <cmath>
#include <numeric>
#include "abi/js.h"
#include "asm_v_wasm.h"
#include "asmjs/asmangle.h"
#include "asmjs/shared-constants.h"
#include "emscripten-optimizer/optimizer.h"
#include "ir/branch-utils.h"
#include "ir/effects.h"
#include "ir/element-utils.h"
#include "ir/find_all.h"
#include "ir/import-utils.h"
#include "ir/load-utils.h"
#include "ir/module-utils.h"
#include "ir/names.h"
#include "ir/table-utils.h"
#include "ir/utils.h"
#include "mixed_arena.h"
#include "passes/passes.h"
#include "support/base64.h"
#include "support/file.h"
#include "wasm-builder.h"
#include "wasm-io.h"
#include "wasm-validator.h"
#include "wasm.h"
namespace wasm {
using namespace cashew;
static IString importObject("imports");
// Appends extra to block, flattening out if extra is a block as well
void flattenAppend(Ref ast, Ref extra) {
int index;
if (ast[0] == BLOCK || ast[0] == TOPLEVEL) {
index = 1;
} else if (ast[0] == DEFUN) {
index = 3;
} else {
abort();
}
if (extra->isArray() && extra[0] == BLOCK) {
for (size_t i = 0; i < extra[1]->size(); i++) {
ast[index]->push_back(extra[1][i]);
}
} else {
ast[index]->push_back(extra);
}
}
// Appends extra to a chain of sequence elements
void sequenceAppend(Ref& ast, Ref extra) {
if (!ast.get()) {
ast = extra;
return;
}
ast = ValueBuilder::makeSeq(ast, extra);
}
bool isTableExported(Module& wasm) {
if (wasm.tables.empty() || wasm.tables[0]->imported()) {
return false;
}
for (auto& ex : wasm.exports) {
if (ex->kind == ExternalKind::Table && ex->value == wasm.tables[0]->name) {
return true;
}
}
return false;
}
bool hasActiveSegments(Module& wasm) {
for (Index i = 0; i < wasm.dataSegments.size(); i++) {
if (!wasm.dataSegments[i]->isPassive) {
return true;
}
}
return false;
}
bool needsBufferView(Module& wasm) {
if (wasm.memories.empty()) {
return false;
}
// If there are any active segments, initActiveSegments needs access
// to bufferView.
if (hasActiveSegments(wasm)) {
return true;
}
// The special support functions are emitted as part of the JS glue, if we
// need them.
bool need = false;
ModuleUtils::iterImportedFunctions(wasm, [&](Function* import) {
if (ABI::wasm2js::isHelper(import->base)) {
need = true;
}
});
return need;
}
IString stringToIString(std::string str) { return IString(str.c_str(), false); }
// Used when taking a wasm name and generating a JS identifier. Each scope here
// is used to ensure that all names have a unique name but the same wasm name
// within a scope always resolves to the same symbol.
//
// Export: Export names
// Top: The main scope which contains functions and globals
// Local: Local variables in a function.
// Label: Label identifiers in a function
enum class NameScope {
Export,
Top,
Local,
Label,
Max,
};
//
// Wasm2JSBuilder - converts a WebAssembly module's functions into JS
//
// Wasm-to-JS is tricky because wasm doesn't distinguish
// statements and expressions, or in other words, things like `break` and `if`
// can show up in places where JS can't handle them, like inside an a loop's
// condition check. For that reason we use flat IR here.
// We do optimize it later, to allow some nesting, but we avoid
// non-JS-compatible nesting like block return values control flow in an if
// condition, etc.
//
class Wasm2JSBuilder {
public:
struct Flags {
// see wasm2js.cpp for details
bool debug = false;
bool pedantic = false;
bool allowAsserts = false;
bool emscripten = false;
bool deterministic = false;
std::string symbolsFile;
};
// Map data segment names to indices.
std::unordered_map<Name, Index> dataIndices;
Wasm2JSBuilder(Flags f, PassOptions options_) : flags(f), options(options_) {
// We don't try to model wasm's trapping precisely - if we did, each load
// and store would need to do a check. Given that, we can just ignore
// implicit traps like those when optimizing. (When not optimizing, it's
// nice to see codegen that matches wasm more precisely.)
// It is also important to prevent the optimizer from adding new things that
// require additional lowering, as we could hit a cycle.
if (options.optimizeLevel > 0) {
options.ignoreImplicitTraps = true;
options.targetJS = true;
}
}
Ref processWasm(Module* wasm, Name funcName = ASM_FUNC);
Ref processFunction(Module* wasm, Function* func, bool standalone = false);
Ref processStandaloneFunction(Module* wasm, Function* func) {
return processFunction(wasm, func, true);
}
// The second pass on an expression: process it fully, generating
// JS
Ref processExpression(Expression* curr,
Module* m,
Function* func = nullptr,
bool standalone = false);
Index getDataIndex(Name segment) {
auto it = dataIndices.find(segment);
assert(it != dataIndices.end());
return it->second;
}
// Get a temp var.
IString getTemp(Type type, Function* func) {
IString ret;
// TODO: handle tuples
assert(!type.isTuple() && "Unexpected tuple type");
if (frees[type].size() > 0) {
ret = frees[type].back();
frees[type].pop_back();
} else {
auto index = temps[type]++;
ret = IString((std::string("wasm2js_") + type.toString() + "$" +
std::to_string(index))
.c_str(),
false);
ret = fromName(ret, NameScope::Local);
}
if (func->localIndices.find(ret) == func->localIndices.end()) {
Builder::addVar(func, ret, type);
}
return ret;
}
// Free a temp var.
void freeTemp(Type type, IString temp) {
// TODO: handle tuples
assert(!type.isTuple() && "Unexpected tuple type");
frees[type].push_back(temp);
}
// Generates a mangled name from `name` within the specified scope.
//
// The goal of this function is to ensure that all identifiers in JS ar
// unique. Otherwise there can be clashes with locals and functions and cause
// unwanted name shadowing.
//
// The returned string from this function is constant for a particular `name`
// within a `scope`. Or in other words, the same `name` and `scope` pair will
// always return the same result. If `scope` changes, however, the return
// value may differ even if the same `name` is passed in.
IString fromName(Name name, NameScope scope) {
// TODO: checking names do not collide after mangling
// First up check our cached of mangled names to avoid doing extra work
// below
auto& map = wasmNameToMangledName[(int)scope];
auto it = map.find(name.str.data());
if (it != map.end()) {
return it->second;
}
// The mangled names in our scope.
auto& scopeMangledNames = mangledNames[(int)scope];
// In some cases (see below) we need to also check the Top scope.
auto& topMangledNames = mangledNames[int(NameScope::Top)];
// This is the first time we've seen the `name` and `scope` pair. Generate a
// globally unique name based on `name` and then register that in our cache
// and return it.
//
// Identifiers here generated are of the form `${name}_${n}` where `_${n}`
// is omitted if `n==0` and otherwise `n` is just looped over to find the
// next unused identifier.
IString ret;
for (int i = 0;; i++) {
std::ostringstream out;
out << name;
if (i > 0) {
out << "_" << i;
}
auto mangled = asmangle(out.str());
ret = stringToIString(mangled);
if (scopeMangledNames.count(ret)) {
// When export names collide things may be confusing, as this is
// observable externally by the person using the JS. Report a warning.
if (scope == NameScope::Export) {
std::cerr << "wasm2js: warning: export names colliding: " << mangled
<< '\n';
}
continue;
}
// The Local scope is special: a Local name must not collide with a Top
// name, as they are in a single namespace in JS and can conflict:
//
// function foo(bar) {
// var bar = 0;
// }
// function bar() { ..
if (scope == NameScope::Local && topMangledNames.count(ret)) {
continue;
}
// We found a good name, use it.
scopeMangledNames.insert(ret);
map[name.str.data()] = ret;
return ret;
}
}
private:
Flags flags;
PassOptions options;
// How many temp vars we need for each type (type => num).
std::unordered_map<Type, Index> temps;
// Which temp vars are currently free to use for each type (type => freelist).
std::unordered_map<Type, std::vector<IString>> frees;
// Mangled names cache by interned names.
// Utilizes the usually reused underlying cstring's pointer as the key.
std::unordered_map<const void*, IString>
wasmNameToMangledName[(int)NameScope::Max];
// Set of all mangled names in each scope.
std::unordered_set<IString> mangledNames[(int)NameScope::Max];
std::unordered_set<IString> seenModuleImports;
// If a function is callable from outside, we'll need to cast the inputs
// and our return value. Otherwise, internally, casts are only needed
// on operations.
std::unordered_set<Name> functionsCallableFromOutside;
void ensureModuleVar(Ref ast, const Importable& imp);
Ref getImportName(const Importable& imp);
void addBasics(Ref ast, Module* wasm);
void addFunctionImport(Ref ast, Function* import);
void addGlobalImport(Ref ast, Global* import);
void addTable(Ref ast, Module* wasm);
void addStart(Ref ast, Module* wasm);
void addExports(Ref ast, Module* wasm);
void addGlobal(Ref ast, Global* global, Module* module);
void addMemoryFuncs(Ref ast, Module* wasm);
void addMemoryGrowFunc(Ref ast, Module* wasm);
Wasm2JSBuilder() = delete;
Wasm2JSBuilder(const Wasm2JSBuilder&) = delete;
Wasm2JSBuilder& operator=(const Wasm2JSBuilder&) = delete;
};
Ref Wasm2JSBuilder::processWasm(Module* wasm, Name funcName) {
// Scan the wasm for important things.
for (auto& exp : wasm->exports) {
if (exp->kind == ExternalKind::Function) {
functionsCallableFromOutside.insert(exp->value);
}
}
ElementUtils::iterAllElementFunctionNames(
wasm, [&](Name name) { functionsCallableFromOutside.insert(name); });
// Collect passive data segment indices.
for (Index i = 0; i < wasm->dataSegments.size(); ++i) {
dataIndices[wasm->dataSegments[i]->name] = i;
}
// Ensure the scratch memory helpers.
// If later on they aren't needed, we'll clean them up.
ABI::wasm2js::ensureHelpers(wasm);
// Process the code, and optimize if relevant.
// First, do the lowering to a JS-friendly subset.
{
PassRunner runner(wasm, options);
// TODO: only legalize if necessary - emscripten would already do so, and
// likely other toolchains. but spec test suite needs that.
runner.add("legalize-js-interface");
// Before lowering non-JS operations we can optimize some instructions which
// may simplify next passes
if (options.optimizeLevel > 0) {
runner.add("optimize-for-js");
}
// First up remove as many non-JS operations we can, including things like
// 64-bit integer multiplication/division, `f32.nearest` instructions, etc.
// This may inject intrinsics which use i64 so it needs to be run before the
// i64-to-i32 lowering pass.
runner.add("remove-non-js-ops");
// Currently the i64-to-32 lowering pass requires that `flatten` be run
// before it to produce correct code. For some more details about this see
// #1480
runner.add("flatten");
runner.add("i64-to-i32-lowering");
runner.add("alignment-lowering");
// Next, optimize that as best we can. This should not generate
// non-JS-friendly things.
if (options.optimizeLevel > 0) {
// It is especially import to propagate constants after the lowering.
// However, this can be a slow operation, especially after flattening;
// some local simplification helps.
if (options.optimizeLevel >= 3 || options.shrinkLevel >= 1) {
runner.add("simplify-locals-nonesting");
runner.add("precompute-propagate");
// Avoiding reinterpretation is helped by propagation. We also run
// it later down as default optimizations help as well.
runner.add("avoid-reinterprets");
}
runner.addDefaultOptimizationPasses();
runner.add("avoid-reinterprets");
}
// Finally, get the code into the flat form we need for wasm2js itself, and
// optimize that a little in a way that keeps that property.
runner.add("flatten");
// Regardless of optimization level, run some simple optimizations to undo
// some of the effects of flattening.
runner.add("simplify-locals-notee-nostructure");
// Some operations can be very slow if we didn't run full optimizations
// earlier, so don't run them automatically.
if (options.optimizeLevel > 0) {
runner.add("remove-unused-names");
runner.add("merge-blocks");
runner.add("reorder-locals");
runner.add("coalesce-locals");
}
runner.add("reorder-locals");
runner.add("vacuum");
runner.add("remove-unused-module-elements");
// DCE at the end to make sure all IR nodes have valid types for conversion
// to JS, and not unreachable.
runner.add("dce");
runner.setDebug(flags.debug);
runner.run();
}
if (flags.symbolsFile.size() > 0) {
Output out(flags.symbolsFile, wasm::Flags::Text);
Index i = 0;
for (auto& func : wasm->functions) {
out.getStream() << i++ << ':' << func->name.str << '\n';
}
}
#ifndef NDEBUG
if (!WasmValidator().validate(*wasm)) {
std::cout << *wasm << '\n';
Fatal() << "error in validating wasm2js output";
}
#endif
Ref ret = ValueBuilder::makeToplevel();
Ref asmFunc = ValueBuilder::makeFunction(funcName);
ret[1]->push_back(asmFunc);
ValueBuilder::appendArgumentToFunction(asmFunc, importObject);
// add memory import
if (!wasm->memories.empty()) {
if (wasm->memories[0]->imported()) {
ensureModuleVar(asmFunc[3], *wasm->memories[0]);
// find memory and buffer in imports
Ref theVar = ValueBuilder::makeVar();
asmFunc[3]->push_back(theVar);
ValueBuilder::appendToVar(
theVar, "memory", getImportName(*wasm->memories[0]));
// Assign `buffer = memory.buffer`
Ref buf = ValueBuilder::makeVar();
asmFunc[3]->push_back(buf);
ValueBuilder::appendToVar(
buf,
BUFFER,
ValueBuilder::makeDot(ValueBuilder::makeName("memory"),
ValueBuilder::makeName("buffer")));
// If memory is growable, override the imported memory's grow method to
// ensure so that when grow is called from the output it works as expected
if (wasm->memories[0]->max > wasm->memories[0]->initial) {
asmFunc[3]->push_back(
ValueBuilder::makeStatement(ValueBuilder::makeBinary(
ValueBuilder::makeDot(ValueBuilder::makeName("memory"),
ValueBuilder::makeName("grow")),
SET,
ValueBuilder::makeName(WASM_MEMORY_GROW))));
}
} else {
Ref theVar = ValueBuilder::makeVar();
asmFunc[3]->push_back(theVar);
ValueBuilder::appendToVar(
theVar,
BUFFER,
ValueBuilder::makeNew(ValueBuilder::makeCall(
ValueBuilder::makeName("ArrayBuffer"),
ValueBuilder::makeInt(Address::address32_t(
wasm->memories[0]->initial.addr * Memory::kPageSize)))));
}
}
// add imported tables
ModuleUtils::iterImportedTables(*wasm, [&](Table* table) {
ensureModuleVar(asmFunc[3], *table);
Ref theVar = ValueBuilder::makeVar();
asmFunc[3]->push_back(theVar);
ValueBuilder::appendToVar(theVar, FUNCTION_TABLE, getImportName(*table));
});
// create heaps, etc
addBasics(asmFunc[3], wasm);
ModuleUtils::iterImportedFunctions(
*wasm, [&](Function* import) { addFunctionImport(asmFunc[3], import); });
ModuleUtils::iterImportedGlobals(
*wasm, [&](Global* import) { addGlobalImport(asmFunc[3], import); });
// Note the names of functions. We need to do this here as when generating
// mangled local names we need them not to conflict with these (see fromName)
// so we can't wait until we parse each function to note its name.
for (auto& f : wasm->functions) {
fromName(f->name, NameScope::Top);
}
// globals
bool generateFetchHighBits = false;
ModuleUtils::iterDefinedGlobals(*wasm, [&](Global* global) {
addGlobal(asmFunc[3], global, wasm);
if (flags.allowAsserts && global->name == INT64_TO_32_HIGH_BITS) {
generateFetchHighBits = true;
}
});
if (flags.emscripten) {
asmFunc[3]->push_back(
ValueBuilder::makeName("// EMSCRIPTEN_START_FUNCS\n"));
}
// functions
ModuleUtils::iterDefinedFunctions(*wasm, [&](Function* func) {
asmFunc[3]->push_back(processFunction(wasm, func));
});
if (generateFetchHighBits) {
Builder builder(*wasm);
asmFunc[3]->push_back(
processFunction(wasm,
wasm->addFunction(builder.makeFunction(
WASM_FETCH_HIGH_BITS,
Signature(Type::none, Type::i32),
{},
builder.makeReturn(builder.makeGlobalGet(
INT64_TO_32_HIGH_BITS, Type::i32))))));
auto e = new Export();
e->name = WASM_FETCH_HIGH_BITS;
e->value = WASM_FETCH_HIGH_BITS;
e->kind = ExternalKind::Function;
wasm->addExport(e);
}
if (flags.emscripten) {
asmFunc[3]->push_back(ValueBuilder::makeName("// EMSCRIPTEN_END_FUNCS\n"));
}
if (needsBufferView(*wasm)) {
asmFunc[3]->push_back(
ValueBuilder::makeBinary(ValueBuilder::makeName("bufferView"),
SET,
ValueBuilder::makeName(HEAPU8)));
}
if (hasActiveSegments(*wasm)) {
asmFunc[3]->push_back(
ValueBuilder::makeCall(ValueBuilder::makeName("initActiveSegments"),
ValueBuilder::makeName(importObject)));
}
addTable(asmFunc[3], wasm);
addStart(asmFunc[3], wasm);
addExports(asmFunc[3], wasm);
return ret;
}
void Wasm2JSBuilder::addBasics(Ref ast, Module* wasm) {
if (!wasm->memories.empty()) {
// heaps, var HEAP8 = new global.Int8Array(buffer); etc
auto addHeap = [&](IString name, IString view) {
Ref theVar = ValueBuilder::makeVar();
ast->push_back(theVar);
ValueBuilder::appendToVar(theVar,
name,
ValueBuilder::makeNew(ValueBuilder::makeCall(
view, ValueBuilder::makeName(BUFFER))));
};
addHeap(HEAP8, INT8ARRAY);
addHeap(HEAP16, INT16ARRAY);
addHeap(HEAP32, INT32ARRAY);
addHeap(HEAPU8, UINT8ARRAY);
addHeap(HEAPU16, UINT16ARRAY);
addHeap(HEAPU32, UINT32ARRAY);
addHeap(HEAPF32, FLOAT32ARRAY);
addHeap(HEAPF64, FLOAT64ARRAY);
}
// core asm.js imports
auto addMath = [&](IString name, IString base) {
Ref theVar = ValueBuilder::makeVar();
ast->push_back(theVar);
ValueBuilder::appendToVar(
theVar, name, ValueBuilder::makeDot(ValueBuilder::makeName(MATH), base));
};
addMath(MATH_IMUL, IMUL);
addMath(MATH_FROUND, FROUND);
addMath(MATH_ABS, ABS);
addMath(MATH_CLZ32, CLZ32);
addMath(MATH_MIN, MIN);
addMath(MATH_MAX, MAX);
addMath(MATH_FLOOR, FLOOR);
addMath(MATH_CEIL, CEIL);
addMath(MATH_TRUNC, TRUNC);
addMath(MATH_SQRT, SQRT);
}
static bool needsQuoting(Name name) {
auto mangled = asmangle(name.toString());
return mangled != name.str;
}
void Wasm2JSBuilder::ensureModuleVar(Ref ast, const Importable& imp) {
if (seenModuleImports.count(imp.module) > 0) {
return;
}
Ref theVar = ValueBuilder::makeVar();
ast->push_back(theVar);
Ref rhs;
if (needsQuoting(imp.module)) {
rhs = ValueBuilder::makeSub(ValueBuilder::makeName(importObject),
ValueBuilder::makeString(imp.module));
} else {
rhs = ValueBuilder::makeDot(ValueBuilder::makeName(importObject),
ValueBuilder::makeName(imp.module));
}
ValueBuilder::appendToVar(theVar, fromName(imp.module, NameScope::Top), rhs);
seenModuleImports.insert(imp.module);
}
Ref Wasm2JSBuilder::getImportName(const Importable& imp) {
if (needsQuoting(imp.base)) {
return ValueBuilder::makeSub(
ValueBuilder::makeName(fromName(imp.module, NameScope::Top)),
ValueBuilder::makeString(imp.base));
} else {
return ValueBuilder::makeDot(
ValueBuilder::makeName(fromName(imp.module, NameScope::Top)),
ValueBuilder::makeName(imp.base));
}
}
void Wasm2JSBuilder::addFunctionImport(Ref ast, Function* import) {
// The scratch memory helpers are emitted in the glue, see code and comments
// below.
if (ABI::wasm2js::isHelper(import->base)) {
return;
}
ensureModuleVar(ast, *import);
Ref theVar = ValueBuilder::makeVar();
ast->push_back(theVar);
ValueBuilder::appendToVar(
theVar, fromName(import->name, NameScope::Top), getImportName(*import));
}
void Wasm2JSBuilder::addGlobalImport(Ref ast, Global* import) {
ensureModuleVar(ast, *import);
Ref theVar = ValueBuilder::makeVar();
ast->push_back(theVar);
Ref value = getImportName(*import);
if (import->type == Type::i32) {
value = makeJsCoercion(value, JS_INT);
}
ValueBuilder::appendToVar(
theVar, fromName(import->name, NameScope::Top), value);
}
void Wasm2JSBuilder::addTable(Ref ast, Module* wasm) {
if (wasm->tables.size() == 0) {
return;
}
bool perElementInit = false;
// Emit a simple flat table as a JS array literal. Otherwise,
// emit assignments separately for each index.
Ref theArray = ValueBuilder::makeArray();
for (auto& table : wasm->tables) {
if (!table->type.isFunction()) {
Fatal() << "wasm2js doesn't support non-function tables\n";
}
if (!table->imported()) {
TableUtils::FlatTable flat(*wasm, *table);
if (flat.valid) {
for (auto& name : flat.names) {
if (name.is()) {
name = fromName(name, NameScope::Top);
} else {
name = NULL_;
}
ValueBuilder::appendToArray(theArray, ValueBuilder::makeName(name));
}
} else {
perElementInit = true;
Ref initial =
ValueBuilder::makeInt(Address::address32_t(table->initial.addr));
theArray = ValueBuilder::makeNew(
ValueBuilder::makeCall(IString("Array"), initial));
}
} else {
perElementInit = true;
}
if (isTableExported(*wasm)) {
// If the table is exported use a fake WebAssembly.Table object
// We don't handle the case where a table is both imported and exported.
if (table->imported()) {
Fatal() << "wasm2js doesn't support a table that is both imported and "
"exported\n";
}
Ref theVar = ValueBuilder::makeVar();
ast->push_back(theVar);
Ref table = ValueBuilder::makeCall(IString("Table"), theArray);
ValueBuilder::appendToVar(theVar, FUNCTION_TABLE, table);
} else if (!table->imported()) {
// Otherwise if the table is internal (neither imported not exported).
// Just use a plain array in this case, avoiding the Table.
Ref theVar = ValueBuilder::makeVar();
ast->push_back(theVar);
ValueBuilder::appendToVar(theVar, FUNCTION_TABLE, theArray);
}
if (perElementInit) {
// TODO: optimize for size
ModuleUtils::iterTableSegments(
*wasm, table->name, [&](ElementSegment* segment) {
auto offset = segment->offset;
ElementUtils::iterElementSegmentFunctionNames(
segment, [&](Name entry, Index i) {
Ref index;
if (auto* c = offset->dynCast<Const>()) {
index = ValueBuilder::makeInt(c->value.geti32() + i);
} else if (auto* get = offset->dynCast<GlobalGet>()) {
index = ValueBuilder::makeBinary(
ValueBuilder::makeName(
stringToIString(asmangle(get->name.toString()))),
PLUS,
ValueBuilder::makeNum(i));
} else {
WASM_UNREACHABLE("unexpected expr type");
}
ast->push_back(
ValueBuilder::makeStatement(ValueBuilder::makeBinary(
ValueBuilder::makeSub(ValueBuilder::makeName(FUNCTION_TABLE),
index),
SET,
ValueBuilder::makeName(fromName(entry, NameScope::Top)))));
});
});
}
}
}
void Wasm2JSBuilder::addStart(Ref ast, Module* wasm) {
if (wasm->start.is()) {
ast->push_back(
ValueBuilder::makeCall(fromName(wasm->start, NameScope::Top)));
}
}
void Wasm2JSBuilder::addExports(Ref ast, Module* wasm) {
Ref exports = ValueBuilder::makeObject();
for (auto& export_ : wasm->exports) {
switch (export_->kind) {
case ExternalKind::Function: {
ValueBuilder::appendToObjectWithQuotes(
exports,
fromName(export_->name, NameScope::Export),
ValueBuilder::makeName(fromName(export_->value, NameScope::Top)));
break;
}
case ExternalKind::Memory: {
Ref descs = ValueBuilder::makeObject();
Ref growDesc = ValueBuilder::makeObject();
ValueBuilder::appendToObjectWithQuotes(
descs, IString("grow"), growDesc);
if (wasm->memories[0]->max > wasm->memories[0]->initial) {
ValueBuilder::appendToObjectWithQuotes(
growDesc,
IString("value"),
ValueBuilder::makeName(WASM_MEMORY_GROW));
}
Ref bufferDesc = ValueBuilder::makeObject();
Ref bufferGetter = ValueBuilder::makeFunction(IString(""));
bufferGetter[3]->push_back(
ValueBuilder::makeReturn(ValueBuilder::makeName(BUFFER)));
ValueBuilder::appendToObjectWithQuotes(
bufferDesc, IString("get"), bufferGetter);
ValueBuilder::appendToObjectWithQuotes(
descs, IString("buffer"), bufferDesc);
Ref memory = ValueBuilder::makeCall(
ValueBuilder::makeDot(ValueBuilder::makeName(IString("Object")),
IString("create")),
ValueBuilder::makeDot(ValueBuilder::makeName(IString("Object")),
IString("prototype")));
ValueBuilder::appendToCall(memory, descs);
ValueBuilder::appendToObjectWithQuotes(
exports, fromName(export_->name, NameScope::Export), memory);
break;
}
case ExternalKind::Table: {
ValueBuilder::appendToObjectWithQuotes(
exports,
fromName(export_->name, NameScope::Export),
ValueBuilder::makeName(FUNCTION_TABLE));
break;
}
case ExternalKind::Global: {
Ref object = ValueBuilder::makeObject();
IString identName = fromName(export_->value, NameScope::Top);
// getter
{
Ref block = ValueBuilder::makeBlock();
block[1]->push_back(
ValueBuilder::makeReturn(ValueBuilder::makeName(identName)));
ValueBuilder::appendToObjectAsGetter(object, IString("value"), block);
}
// setter
{
std::ostringstream buffer;
buffer << '_' << identName;
auto setterParam = stringToIString(buffer.str());
auto block = ValueBuilder::makeBlock();
block[1]->push_back(
ValueBuilder::makeBinary(ValueBuilder::makeName(identName),
SET,
ValueBuilder::makeName(setterParam)));
ValueBuilder::appendToObjectAsSetter(
object, IString("value"), setterParam, block);
}
ValueBuilder::appendToObjectWithQuotes(
exports, fromName(export_->name, NameScope::Export), object);
break;
}
case ExternalKind::Tag:
case ExternalKind::Invalid:
Fatal() << "unsupported export type: " << export_->name << "\n";
}
}
if (!wasm->memories.empty()) {
addMemoryFuncs(ast, wasm);
}
ast->push_back(
ValueBuilder::makeStatement(ValueBuilder::makeReturn(exports)));
}
void Wasm2JSBuilder::addGlobal(Ref ast, Global* global, Module* module) {
Ref theVar = ValueBuilder::makeVar();
ast->push_back(theVar);
Ref init = processExpression(global->init, module);
ValueBuilder::appendToVar(
theVar, fromName(global->name, NameScope::Top), init);
}
Ref Wasm2JSBuilder::processFunction(Module* m,
Function* func,
bool standaloneFunction) {
if (standaloneFunction) {
// We are only printing a function, not a whole module. Prepare it for
// translation now (if there were a module, we'd have done this for all
// functions in parallel, earlier).
PassRunner runner(m);
// We only run a subset of all passes here. TODO: create a full valid module
// for each assertion body.
runner.add("flatten");
runner.add("simplify-locals-notee-nostructure");
runner.add("reorder-locals");
runner.add("remove-unused-names");
runner.add("vacuum");
runner.runOnFunction(func);
}
// We process multiple functions from a single Wasm2JSBuilder instance, so
// clean up the function-specific local state before each function.
frees.clear();
temps.clear();
// We will be symbolically referring to all variables in the function, so make
// sure that everything has a name and it's unique.
Names::ensureNames(func);
Ref ret = ValueBuilder::makeFunction(fromName(func->name, NameScope::Top));
// arguments
bool needCoercions = options.optimizeLevel == 0 || standaloneFunction ||
functionsCallableFromOutside.count(func->name);
for (Index i = 0; i < func->getNumParams(); i++) {
IString name = fromName(func->getLocalNameOrGeneric(i), NameScope::Local);
ValueBuilder::appendArgumentToFunction(ret, name);
if (needCoercions) {
auto jsType = wasmToJsType(func->getLocalType(i));
if (needsJsCoercion(jsType)) {
ret[3]->push_back(ValueBuilder::makeStatement(ValueBuilder::makeBinary(
ValueBuilder::makeName(name),
SET,
makeJsCoercion(ValueBuilder::makeName(name), jsType))));
}
}
}
Ref theVar = ValueBuilder::makeVar();
size_t theVarIndex = ret[3]->size();
ret[3]->push_back(theVar);
// body
flattenAppend(ret,
processExpression(func->body, m, func, standaloneFunction));
// vars, including new temp vars
for (Index i = func->getVarIndexBase(); i < func->getNumLocals(); i++) {
ValueBuilder::appendToVar(
theVar,
fromName(func->getLocalNameOrGeneric(i), NameScope::Local),
makeJsCoercedZero(wasmToJsType(func->getLocalType(i))));
}
if (theVar[1]->size() == 0) {
ret[3]->splice(theVarIndex, 1);
}
return ret;
}
Ref Wasm2JSBuilder::processExpression(Expression* curr,
Module* m,
Function* func,
bool standaloneFunction) {
// Switches are tricky to handle - in wasm they often come with
// massively-nested "towers" of blocks, which if naively translated
// to JS may exceed parse recursion limits of VMs. Therefore even when
// not optimizing we work hard to emit minimal and minimally-nested
// switches.
// We do so by pre-scanning for br_tables and noting which of their
// targets can be hoisted up into them, e.g.
//
// (block $a
// (block $b
// (block $c
// (block $d
// (block $e
// (br_table $a $b $c $d $e (..))
// )
// ;; code X (for block $e)
// ;; implicit fallthrough - can be done in the switch too
// )
// ;; code Y
// (br $c) ;; branch which is identical to a fallthrough
// )
// ;; code Z
// (br $a) ;; skip some blocks - can't do this in a switch!
// )
// ;; code W
// )
//
// Every branch we see is a potential hazard - all targets must not
// be optimized into the switch, since they must be reached normally,
// unless they happen to be right after us, in which case it's just
// a fallthrough anyhow.
struct SwitchProcessor : public ExpressionStackWalker<SwitchProcessor> {
// A list of expressions we don't need to emit, as we are handling them
// in another way.
std::set<Expression*> unneededExpressions;
struct SwitchCase {
Name target;
std::vector<Expression*> code;
SwitchCase(Name target) : target(target) {}
};
// The switch cases we found that we can hoist up.
std::map<Switch*, std::vector<SwitchCase>> hoistedSwitchCases;
void visitSwitch(Switch* brTable) {
Index i = expressionStack.size() - 1;
assert(expressionStack[i] == brTable);
// A set of names we must stop at, since we've seen branches to them.
std::set<Name> namesBranchedTo;
while (1) {
// Stop if we are at the top level.
if (i == 0) {
break;
}
i--;
auto* child = expressionStack[i + 1];
auto* curr = expressionStack[i];
// Stop if the current node is not a block with the child in the
// first position, i.e., the classic switch pattern.
auto* block = curr->dynCast<Block>();
if (!block || block->list[0] != child) {
break;
}
// Ignore the case of a name-less block for simplicity (merge-blocks
// would have removed it).
if (!block->name.is()) {
break;
}
// If we have already seen this block, stop here.
if (unneededExpressions.count(block)) {
// XXX FIXME we should probably abort the entire optimization
break;
}
auto& list = block->list;
if (child == brTable) {
// Nothing more to do here (we can in fact skip any code til
// the parent block).
continue;
}
// Ok, we are a block and our child in the first position is a
// block, and the neither is branched to - unless maybe the child
// branches to the parent, check that. Note how we treat the
// final element which may be a break that is a fallthrough.
Expression* unneededBr = nullptr;
for (Index j = 1; j < list.size(); j++) {
auto* item = list[j];
auto newBranches = BranchUtils::getExitingBranches(item);
if (auto* br = item->dynCast<Break>()) {
if (j == list.size() - 1) {
if (!br->condition && br->name == block->name) {
// This is a natural, unnecessary-to-emit fallthrough.
unneededBr = br;
break;
}
}
}
namesBranchedTo.insert(newBranches.begin(), newBranches.end());
}
if (namesBranchedTo.count(block->name)) {
break;
}
// We can move code after the child (reached by branching on the
// child) into the switch.
auto* childBlock = child->cast<Block>();
hoistedSwitchCases[brTable].emplace_back(childBlock->name);
SwitchCase& case_ = hoistedSwitchCases[brTable].back();
for (Index j = 1; j < list.size(); j++) {
auto* item = list[j];
if (item != unneededBr) {
case_.code.push_back(item);
}
}
list.resize(1);
// Finally, mark the block as unneeded outside the switch.
unneededExpressions.insert(childBlock);
}
}
};
struct ExpressionProcessor
: public OverriddenVisitor<ExpressionProcessor, Ref> {
Wasm2JSBuilder* parent;
IString result; // TODO: remove
Function* func;
Module* module;
bool standaloneFunction;
SwitchProcessor switchProcessor;
ExpressionProcessor(Wasm2JSBuilder* parent,
Module* m,
Function* func,
bool standaloneFunction)
: parent(parent), func(func), module(m),
standaloneFunction(standaloneFunction) {}
Ref process(Expression* curr) {
switchProcessor.walk(curr);
return visit(curr, NO_RESULT);
}
// A scoped temporary variable.
struct ScopedTemp {
Wasm2JSBuilder* parent;
Type type;
IString temp; // TODO: switch to indexes; avoid names
bool needFree;
// @param possible if provided, this is a variable we can use as our temp.
// it has already been allocated in a higher scope, and we
// can just assign to it as our result is going there
// anyhow.
ScopedTemp(Type type,
Wasm2JSBuilder* parent,
Function* func,
IString possible = NO_RESULT)
: parent(parent), type(type) {
assert(possible != EXPRESSION_RESULT);
if (possible == NO_RESULT) {
temp = parent->getTemp(type, func);
needFree = true;
} else {
temp = possible;
needFree = false;
}
}
~ScopedTemp() {
if (needFree) {
parent->freeTemp(type, temp);
}
}
IString getName() { return temp; }
Ref getAstName() { return ValueBuilder::makeName(temp); }
};
Ref visit(Expression* curr, IString nextResult) {
IString old = result;
result = nextResult;
Ref ret = OverriddenVisitor::visit(curr);
// keep it consistent for the rest of this frame, which may call visit on
// multiple children
result = old;
return ret;
}
Ref visit(Expression* curr, ScopedTemp& temp) {
return visit(curr, temp.temp);
}
Ref visitAndAssign(Expression* curr, IString result) {
assert(result != NO_RESULT);
Ref ret = visit(curr, result);
return ValueBuilder::makeStatement(
ValueBuilder::makeBinary(ValueBuilder::makeName(result), SET, ret));
}
Ref visitAndAssign(Expression* curr, ScopedTemp& temp) {
return visitAndAssign(curr, temp.getName());
}
// Expressions with control flow turn into a block, which we must
// then handle, even if we are an expression.
bool isBlock(Ref ast) { return !!ast && ast->isArray() && ast[0] == BLOCK; }
Ref blockify(Ref ast) {
if (isBlock(ast)) {
return ast;
}
Ref ret = ValueBuilder::makeBlock();
ret[1]->push_back(ValueBuilder::makeStatement(ast));
return ret;
}
// Breaks to the top of a loop should be emitted as continues, to that
// loop's main label
std::unordered_set<Name> continueLabels;
IString fromName(Name name, NameScope scope) {
return parent->fromName(name, scope);
}
// Visitors
Ref visitBlock(Block* curr) {
if (switchProcessor.unneededExpressions.count(curr)) {
// We have had our tail hoisted into a switch that is nested in our
// first position, so we don't need to emit that code again, or
// ourselves in fact.
return visit(curr->list[0], NO_RESULT);
}
Ref ret = ValueBuilder::makeBlock();
size_t size = curr->list.size();
for (size_t i = 0; i < size; i++) {
flattenAppend(
ret, ValueBuilder::makeStatement(visit(curr->list[i], NO_RESULT)));
}
if (curr->name.is()) {
ret =
ValueBuilder::makeLabel(fromName(curr->name, NameScope::Label), ret);
}
return ret;
}
Ref visitIf(If* curr) {
Ref condition = visit(curr->condition, EXPRESSION_RESULT);
Ref ifTrue = visit(curr->ifTrue, NO_RESULT);
Ref ifFalse;
if (curr->ifFalse) {
ifFalse = visit(curr->ifFalse, NO_RESULT);
}
return ValueBuilder::makeIf(condition, ifTrue, ifFalse); // simple if
}
Ref visitLoop(Loop* curr) {
Name asmLabel = curr->name;
if (!asmLabel) {
// This loop has no label, so it cannot be continued to. We can just
// emit the body.
return visit(curr->body, result);
}
continueLabels.insert(asmLabel);
Ref body = visit(curr->body, result);
// if we can reach the end of the block, we must leave the while (1) loop
if (curr->body->type != Type::unreachable) {
assert(curr->body->type == Type::none); // flat IR
body = blockify(body);
flattenAppend(
body, ValueBuilder::makeBreak(fromName(asmLabel, NameScope::Label)));
}
Ref ret = ValueBuilder::makeWhile(ValueBuilder::makeInt(1), body);
return ValueBuilder::makeLabel(fromName(asmLabel, NameScope::Label), ret);
}
Ref makeBreakOrContinue(Name name) {
if (continueLabels.count(name)) {
return ValueBuilder::makeContinue(fromName(name, NameScope::Label));
} else {
return ValueBuilder::makeBreak(fromName(name, NameScope::Label));
}
}
Ref visitBreak(Break* curr) {
if (curr->condition) {
// we need an equivalent to an if here, so use that code
Break fakeBreak = *curr;
fakeBreak.condition = nullptr;
If fakeIf;
fakeIf.condition = curr->condition;
fakeIf.ifTrue = &fakeBreak;
return visit(&fakeIf, result);
}
return makeBreakOrContinue(curr->name);
}
Expression* defaultBody = nullptr; // default must be last in asm.js
Ref visitSwitch(Switch* curr) {
// Even without optimizations, we work hard here to emit minimal and
// especially minimally-nested code, since otherwise we may get block
// nesting of a size that JS engines can't handle.
Ref condition = visit(curr->condition, EXPRESSION_RESULT);
Ref theSwitch =
ValueBuilder::makeSwitch(makeJsCoercion(condition, JS_INT));
// First, group the switch targets.
std::map<Name, std::vector<Index>> targetIndexes;
for (size_t i = 0; i < curr->targets.size(); i++) {
targetIndexes[curr->targets[i]].push_back(i);
}
// Emit first any hoisted groups.
auto& hoistedCases = switchProcessor.hoistedSwitchCases[curr];
std::set<Name> emittedTargets;
bool hoistedEndsWithUnreachable = false;
for (auto& case_ : hoistedCases) {
auto target = case_.target;
auto& code = case_.code;
emittedTargets.insert(target);
if (target != curr->default_) {
auto& indexes = targetIndexes[target];
for (auto i : indexes) {
ValueBuilder::appendCaseToSwitch(theSwitch,
ValueBuilder::makeNum(i));
}
} else {
ValueBuilder::appendDefaultToSwitch(theSwitch);
}
for (auto* c : code) {
ValueBuilder::appendCodeToSwitch(
theSwitch, blockify(visit(c, NO_RESULT)), false);
hoistedEndsWithUnreachable = c->type == Type::unreachable;
}
}
// After the hoisted cases, if any remain we must make sure not to
// fall through into them. If no code was hoisted, this is unnecessary,
// and if the hoisted code ended with an unreachable it also is not
// necessary.
bool stoppedFurtherFallthrough = false;
auto stopFurtherFallthrough = [&]() {
if (!stoppedFurtherFallthrough && !hoistedCases.empty() &&
!hoistedEndsWithUnreachable) {
stoppedFurtherFallthrough = true;
ValueBuilder::appendCodeToSwitch(
theSwitch, blockify(ValueBuilder::makeBreak(IString())), false);
}
};
// Emit any remaining groups by just emitting branches to their code,
// which will appear outside the switch.
for (auto& [target, indexes] : targetIndexes) {
if (emittedTargets.count(target)) {
continue;
}
stopFurtherFallthrough();
if (target != curr->default_) {
for (auto i : indexes) {
ValueBuilder::appendCaseToSwitch(theSwitch,
ValueBuilder::makeNum(i));
}
ValueBuilder::appendCodeToSwitch(
theSwitch, blockify(makeBreakOrContinue(target)), false);
} else {
// For the group going to the same place as the default, we can just
// emit the default itself, which we do at the end.
}
}
// TODO: if the group the default is in is not the largest, we can turn
// the largest into
// the default by using a local and a check on the range
if (!emittedTargets.count(curr->default_)) {
stopFurtherFallthrough();
ValueBuilder::appendDefaultToSwitch(theSwitch);
ValueBuilder::appendCodeToSwitch(
theSwitch, blockify(makeBreakOrContinue(curr->default_)), false);
}
return theSwitch;
}
Ref visitCall(Call* curr) {
if (curr->isReturn) {
Fatal() << "tail calls not yet supported in wasm2js";
}
Ref theCall =
ValueBuilder::makeCall(fromName(curr->target, NameScope::Top));
// For wasm => wasm calls, we don't need coercions. TODO: even imports
// might be safe?
bool needCoercions = parent->options.optimizeLevel == 0 ||
standaloneFunction ||
module->getFunction(curr->target)->imported();
for (auto operand : curr->operands) {
auto value = visit(operand, EXPRESSION_RESULT);
if (needCoercions) {
value = makeJsCoercion(value, wasmToJsType(operand->type));
}
theCall[2]->push_back(value);
}
if (needCoercions) {
theCall = makeJsCoercion(theCall, wasmToJsType(curr->type));
}
return theCall;
}
Ref visitCallIndirect(CallIndirect* curr) {
if (curr->isReturn) {
Fatal() << "tail calls not yet supported in wasm2js";
}
// If the target has effects that interact with the operands, we must
// reorder it to the start.
bool mustReorder = false;
EffectAnalyzer targetEffects(parent->options, *module, curr->target);
if (targetEffects.hasAnything()) {
for (auto* operand : curr->operands) {
if (targetEffects.invalidates(
EffectAnalyzer(parent->options, *module, operand))) {
mustReorder = true;
break;
}
}
}
// Ensure the function pointer is a number. In general in wasm2js we are
// ok with true/false being present, as they are immediately cast to a
// number anyhow on their use. However, FUNCTION_TABLE[true] is *not* the
// same as FUNCTION_TABLE[1], so we must cast. This is a rare exception
// because FUNCTION_TABLE is just a normal JS object, not a typed array
// or a mathematical operation (all of which coerce to a number for us).
auto target = visit(curr->target, EXPRESSION_RESULT);
target = makeJsCoercion(target, JS_INT);
if (mustReorder) {
Ref ret;
ScopedTemp idx(Type::i32, parent, func);
std::vector<ScopedTemp*> temps; // TODO: utility class, with destructor?
for (auto* operand : curr->operands) {
temps.push_back(new ScopedTemp(operand->type, parent, func));
IString temp = temps.back()->temp;
sequenceAppend(ret, visitAndAssign(operand, temp));
}
sequenceAppend(ret,
ValueBuilder::makeBinary(
ValueBuilder::makeName(idx.getName()), SET, target));
Ref theCall = ValueBuilder::makeCall(ValueBuilder::makeSub(
ValueBuilder::makeName(FUNCTION_TABLE), idx.getAstName()));
for (size_t i = 0; i < temps.size(); i++) {
IString temp = temps[i]->temp;
auto& operand = curr->operands[i];
theCall[2]->push_back(makeJsCoercion(ValueBuilder::makeName(temp),
wasmToJsType(operand->type)));
}
theCall = makeJsCoercion(theCall, wasmToJsType(curr->type));
sequenceAppend(ret, theCall);
for (auto temp : temps) {
delete temp;
}
return ret;
} else {
// Target has no side effects, emit simple code
Ref theCall = ValueBuilder::makeCall(ValueBuilder::makeSub(
ValueBuilder::makeName(FUNCTION_TABLE), target));
for (auto* operand : curr->operands) {
theCall[2]->push_back(visit(operand, EXPRESSION_RESULT));
}
theCall = makeJsCoercion(theCall, wasmToJsType(curr->type));
return theCall;
}
}
// TODO: remove
Ref makeSetVar(Expression* curr,
Expression* value,
Name name,
NameScope scope) {
return ValueBuilder::makeBinary(
ValueBuilder::makeName(fromName(name, scope)),
SET,
visit(value, EXPRESSION_RESULT));
}
Ref visitLocalGet(LocalGet* curr) {
return ValueBuilder::makeName(
fromName(func->getLocalNameOrGeneric(curr->index), NameScope::Local));
}
Ref visitLocalSet(LocalSet* curr) {
return makeSetVar(curr,
curr->value,
func->getLocalNameOrGeneric(curr->index),
NameScope::Local);
}
Ref visitGlobalGet(GlobalGet* curr) {
return ValueBuilder::makeName(fromName(curr->name, NameScope::Top));
}
Ref visitGlobalSet(GlobalSet* curr) {
return makeSetVar(curr, curr->value, curr->name, NameScope::Top);
}
Ref visitLoad(Load* curr) {
// Unaligned loads and stores must have been fixed up already.
assert(curr->align == 0 || curr->align == curr->bytes);
// normal load
Ref ptr = makePointer(curr->ptr, curr->offset);
Ref ret;
switch (curr->type.getBasic()) {
case Type::i32: {
switch (curr->bytes) {
case 1:
ret = ValueBuilder::makeSub(
ValueBuilder::makeName(
LoadUtils::isSignRelevant(curr) && curr->signed_ ? HEAP8
: HEAPU8),
ValueBuilder::makePtrShift(ptr, 0));
break;
case 2:
ret = ValueBuilder::makeSub(
ValueBuilder::makeName(
LoadUtils::isSignRelevant(curr) && curr->signed_ ? HEAP16
: HEAPU16),
ValueBuilder::makePtrShift(ptr, 1));
break;
case 4:
ret = ValueBuilder::makeSub(ValueBuilder::makeName(HEAP32),
ValueBuilder::makePtrShift(ptr, 2));
break;
default: {
Fatal() << "Unhandled number of bytes in i32 load: "
<< curr->bytes;
}
}
break;
}
case Type::f32:
ret = ValueBuilder::makeSub(ValueBuilder::makeName(HEAPF32),
ValueBuilder::makePtrShift(ptr, 2));
break;
case Type::f64:
ret = ValueBuilder::makeSub(ValueBuilder::makeName(HEAPF64),
ValueBuilder::makePtrShift(ptr, 3));
break;
default: {
Fatal() << "Unhandled type in load: " << curr->type;
}
}
if (curr->isAtomic) {
Ref call = ValueBuilder::makeCall(
ValueBuilder::makeDot(ValueBuilder::makeName(ATOMICS), LOAD));
ValueBuilder::appendToCall(call, ret[1]);
ValueBuilder::appendToCall(call, ret[2]);
ret = call;
}
// Coercions are not actually needed, as if the user reads beyond valid
// memory, it's undefined behavior anyhow, and so we don't care much about
// slowness of undefined values etc.
bool needCoercions =
parent->options.optimizeLevel == 0 || standaloneFunction;
if (needCoercions) {
ret = makeJsCoercion(ret, wasmToJsType(curr->type));
}
return ret;
}
Ref visitStore(Store* curr) {
if (!module->memories.empty() &&
module->memories[0]->initial < module->memories[0]->max &&
curr->type != Type::unreachable) {
// In JS, if memory grows then it is dangerous to write
// HEAP[f()] = ..
// or
// HEAP[..] = f()
// since if the call swaps HEAP (in a growth operation) then
// we will not actually write to the new version (since the
// semantics of JS mean we already looked at HEAP and have
// decided where to assign to).
if (!FindAll<Call>(curr->ptr).list.empty() ||
!FindAll<Call>(curr->value).list.empty() ||
!FindAll<CallIndirect>(curr->ptr).list.empty() ||
!FindAll<CallIndirect>(curr->value).list.empty() ||
!FindAll<MemoryGrow>(curr->ptr).list.empty() ||
!FindAll<MemoryGrow>(curr->value).list.empty()) {
Ref ret;
ScopedTemp ptr(Type::i32, parent, func);
sequenceAppend(ret, visitAndAssign(curr->ptr, ptr));
ScopedTemp value(curr->value->type, parent, func);
sequenceAppend(ret, visitAndAssign(curr->value, value));
LocalGet getPtr;
getPtr.index = func->getLocalIndex(ptr.getName());
getPtr.type = Type::i32;
LocalGet getValue;
getValue.index = func->getLocalIndex(value.getName());
getValue.type = curr->value->type;
Store fakeStore = *curr;
fakeStore.ptr = &getPtr;
fakeStore.value = &getValue;
sequenceAppend(ret, visitStore(&fakeStore));
return ret;
}
}
// FIXME if memory growth, store ptr cannot contain a function call
// also other stores to memory, check them, all makeSub's
// Unaligned loads and stores must have been fixed up already.
assert(curr->align == 0 || curr->align == curr->bytes);
// normal store
Ref ptr = makePointer(curr->ptr, curr->offset);
Ref value = visit(curr->value, EXPRESSION_RESULT);
Ref ret;
switch (curr->valueType.getBasic()) {
case Type::i32: {
switch (curr->bytes) {
case 1:
ret = ValueBuilder::makeSub(ValueBuilder::makeName(HEAP8),
ValueBuilder::makePtrShift(ptr, 0));
break;
case 2:
ret = ValueBuilder::makeSub(ValueBuilder::makeName(HEAP16),
ValueBuilder::makePtrShift(ptr, 1));
break;
case 4:
ret = ValueBuilder::makeSub(ValueBuilder::makeName(HEAP32),
ValueBuilder::makePtrShift(ptr, 2));
break;
default:
abort();
}
break;
}
case Type::f32:
ret = ValueBuilder::makeSub(ValueBuilder::makeName(HEAPF32),
ValueBuilder::makePtrShift(ptr, 2));
break;
case Type::f64:
ret = ValueBuilder::makeSub(ValueBuilder::makeName(HEAPF64),
ValueBuilder::makePtrShift(ptr, 3));
break;
default: {
Fatal() << "Unhandled type in store: " << curr->valueType;
}
}
if (curr->isAtomic) {
Ref call = ValueBuilder::makeCall(
ValueBuilder::makeDot(ValueBuilder::makeName(ATOMICS), STORE));
ValueBuilder::appendToCall(call, ret[1]);
ValueBuilder::appendToCall(call, ret[2]);
ValueBuilder::appendToCall(call, value);
return call;
}
return ValueBuilder::makeBinary(ret, SET, value);
}
Ref visitDrop(Drop* curr) { return visit(curr->value, NO_RESULT); }
Ref visitConst(Const* curr) {
switch (curr->type.getBasic()) {
case Type::i32:
return ValueBuilder::makeInt(curr->value.geti32());
// An i64 argument translates to two actual arguments to asm.js
// functions, so we do a bit of a hack here to get our one `Ref` to look
// like two function arguments.
case Type::i64: {
auto lo = (unsigned)curr->value.geti64();
auto hi = (unsigned)(curr->value.geti64() >> 32);
std::ostringstream out;
out << lo << "," << hi;
std::string os = out.str();
IString name(os.c_str(), false);
return ValueBuilder::makeName(name);
}
case Type::f32: {
Ref ret = ValueBuilder::makeCall(MATH_FROUND);
Const fake;
fake.value = Literal(double(curr->value.getf32()));
fake.type = Type::f64;
ret[2]->push_back(visitConst(&fake));
return ret;
}
case Type::f64: {
double d = curr->value.getf64();
if (d == 0 && std::signbit(d)) { // negative zero
return ValueBuilder::makeUnary(
PLUS,
ValueBuilder::makeUnary(MINUS, ValueBuilder::makeDouble(0)));
}
return ValueBuilder::makeUnary(
PLUS, ValueBuilder::makeDouble(curr->value.getf64()));
}
default:
Fatal() << "unknown const type";
}
}
Ref visitUnary(Unary* curr) {
// normal unary
switch (curr->type.getBasic()) {
case Type::i32: {
switch (curr->op) {
case ClzInt32: {
return ValueBuilder::makeCall(
MATH_CLZ32, visit(curr->value, EXPRESSION_RESULT));
}
case CtzInt32:
case PopcntInt32: {
WASM_UNREACHABLE("i32 unary should have been removed");
}
case EqZInt32: {
// XXX !x does change the type to bool, which is correct, but may
// be slower?
return ValueBuilder::makeUnary(
L_NOT, visit(curr->value, EXPRESSION_RESULT));
}
case ReinterpretFloat32: {
ABI::wasm2js::ensureHelpers(module,
ABI::wasm2js::SCRATCH_STORE_F32);
ABI::wasm2js::ensureHelpers(module,
ABI::wasm2js::SCRATCH_LOAD_I32);
Ref store =
ValueBuilder::makeCall(ABI::wasm2js::SCRATCH_STORE_F32,
visit(curr->value, EXPRESSION_RESULT));
// 32-bit scratch memory uses index 2, so that it does not
// conflict with indexes 0, 1 which are used for 64-bit, see
// comment where |scratchBuffer| is defined.
Ref load = ValueBuilder::makeCall(ABI::wasm2js::SCRATCH_LOAD_I32,
ValueBuilder::makeInt(2));
return ValueBuilder::makeSeq(store, load);
}
// generate (~~expr), what Emscripten does
case TruncSFloat32ToInt32:
case TruncSFloat64ToInt32:
case TruncSatSFloat32ToInt32:
case TruncSatSFloat64ToInt32: {
return ValueBuilder::makeUnary(
B_NOT,
ValueBuilder::makeUnary(B_NOT,
visit(curr->value, EXPRESSION_RESULT)));
}
// generate (~~expr >>> 0), what Emscripten does
case TruncUFloat32ToInt32:
case TruncUFloat64ToInt32:
case TruncSatUFloat32ToInt32:
case TruncSatUFloat64ToInt32: {
return ValueBuilder::makeBinary(
ValueBuilder::makeUnary(
B_NOT,
ValueBuilder::makeUnary(
B_NOT, visit(curr->value, EXPRESSION_RESULT))),
TRSHIFT,
ValueBuilder::makeNum(0));
}
case ExtendS8Int32: {
return ValueBuilder::makeBinary(
ValueBuilder::makeBinary(visit(curr->value, EXPRESSION_RESULT),
LSHIFT,
ValueBuilder::makeNum(24)),
RSHIFT,
ValueBuilder::makeNum(24));
}
case ExtendS16Int32: {
return ValueBuilder::makeBinary(
ValueBuilder::makeBinary(visit(curr->value, EXPRESSION_RESULT),
LSHIFT,
ValueBuilder::makeNum(16)),
RSHIFT,
ValueBuilder::makeNum(16));
}
default:
WASM_UNREACHABLE("unhandled unary");
}
}
case Type::f32:
case Type::f64: {
Ref ret;
switch (curr->op) {
case NegFloat32:
case NegFloat64:
ret = ValueBuilder::makeUnary(
MINUS, visit(curr->value, EXPRESSION_RESULT));
break;
case AbsFloat32:
case AbsFloat64:
ret = ValueBuilder::makeCall(
MATH_ABS, visit(curr->value, EXPRESSION_RESULT));
break;
case CeilFloat32:
case CeilFloat64:
ret = ValueBuilder::makeCall(
MATH_CEIL, visit(curr->value, EXPRESSION_RESULT));
break;
case FloorFloat32:
case FloorFloat64:
ret = ValueBuilder::makeCall(
MATH_FLOOR, visit(curr->value, EXPRESSION_RESULT));
break;
case TruncFloat32:
case TruncFloat64:
ret = ValueBuilder::makeCall(
MATH_TRUNC, visit(curr->value, EXPRESSION_RESULT));
break;
case SqrtFloat32:
case SqrtFloat64:
ret = ValueBuilder::makeCall(
MATH_SQRT, visit(curr->value, EXPRESSION_RESULT));
break;
case PromoteFloat32:
return makeJsCoercion(visit(curr->value, EXPRESSION_RESULT),
JS_DOUBLE);
case DemoteFloat64:
return makeJsCoercion(visit(curr->value, EXPRESSION_RESULT),
JS_FLOAT);
case ReinterpretInt32: {
ABI::wasm2js::ensureHelpers(module,
ABI::wasm2js::SCRATCH_STORE_I32);
ABI::wasm2js::ensureHelpers(module,
ABI::wasm2js::SCRATCH_LOAD_F32);
// 32-bit scratch memory uses index 2, so that it does not
// conflict with indexes 0, 1 which are used for 64-bit, see
// comment where |scratchBuffer| is defined.
Ref store =
ValueBuilder::makeCall(ABI::wasm2js::SCRATCH_STORE_I32,
ValueBuilder::makeNum(2),
visit(curr->value, EXPRESSION_RESULT));
Ref load = ValueBuilder::makeCall(ABI::wasm2js::SCRATCH_LOAD_F32);
return ValueBuilder::makeSeq(store, load);
}
// Coerce the integer to a float as emscripten does
case ConvertSInt32ToFloat32:
return makeJsCoercion(
makeJsCoercion(visit(curr->value, EXPRESSION_RESULT), JS_INT),
JS_FLOAT);
case ConvertSInt32ToFloat64:
return makeJsCoercion(
makeJsCoercion(visit(curr->value, EXPRESSION_RESULT), JS_INT),
JS_DOUBLE);
// Generate (expr >>> 0), followed by a coercion
case ConvertUInt32ToFloat32:
return makeJsCoercion(
ValueBuilder::makeBinary(visit(curr->value, EXPRESSION_RESULT),
TRSHIFT,
ValueBuilder::makeInt(0)),
JS_FLOAT);
case ConvertUInt32ToFloat64:
return makeJsCoercion(
ValueBuilder::makeBinary(visit(curr->value, EXPRESSION_RESULT),
TRSHIFT,
ValueBuilder::makeInt(0)),
JS_DOUBLE);
// TODO: more complex unary conversions
case NearestFloat32:
case NearestFloat64:
WASM_UNREACHABLE(
"operation should have been removed in previous passes");
default:
WASM_UNREACHABLE("unhandled unary float operator");
}
if (curr->type == Type::f32) { // doubles need much less coercing
return makeJsCoercion(ret, JS_FLOAT);
}
return ret;
}
default: {
Fatal() << "Unhandled type in unary: " << *curr;
}
}
}
Ref visitBinary(Binary* curr) {
// normal binary
Ref left = visit(curr->left, EXPRESSION_RESULT);
Ref right = visit(curr->right, EXPRESSION_RESULT);
Ref ret;
switch (curr->type.getBasic()) {
case Type::i32: {
switch (curr->op) {
case AddInt32:
ret = ValueBuilder::makeBinary(left, PLUS, right);
break;
case SubInt32:
ret = ValueBuilder::makeBinary(left, MINUS, right);
break;
case MulInt32: {
if (curr->type == Type::i32) {
// TODO: when one operand is a small int, emit a multiply
return ValueBuilder::makeCall(MATH_IMUL, left, right);
} else {
return ValueBuilder::makeBinary(left, MUL, right);
}
}
case DivSInt32:
ret = ValueBuilder::makeBinary(makeSigning(left, JS_SIGNED),
DIV,
makeSigning(right, JS_SIGNED));
break;
case DivUInt32:
ret = ValueBuilder::makeBinary(makeSigning(left, JS_UNSIGNED),
DIV,
makeSigning(right, JS_UNSIGNED));
break;
case RemSInt32:
ret = ValueBuilder::makeBinary(makeSigning(left, JS_SIGNED),
MOD,
makeSigning(right, JS_SIGNED));
break;
case RemUInt32:
ret = ValueBuilder::makeBinary(makeSigning(left, JS_UNSIGNED),
MOD,
makeSigning(right, JS_UNSIGNED));
break;
case AndInt32:
ret = ValueBuilder::makeBinary(left, AND, right);
break;
case OrInt32:
ret = ValueBuilder::makeBinary(left, OR, right);
break;
case XorInt32:
ret = ValueBuilder::makeBinary(left, XOR, right);
break;
case ShlInt32:
ret = ValueBuilder::makeBinary(left, LSHIFT, right);
break;
case ShrUInt32:
ret = ValueBuilder::makeBinary(left, TRSHIFT, right);
break;
case ShrSInt32:
ret = ValueBuilder::makeBinary(left, RSHIFT, right);
break;
case EqInt32: {
return ValueBuilder::makeBinary(makeSigning(left, JS_SIGNED),
EQ,
makeSigning(right, JS_SIGNED));
}
case NeInt32: {
return ValueBuilder::makeBinary(makeSigning(left, JS_SIGNED),
NE,
makeSigning(right, JS_SIGNED));
}
case LtSInt32:
return ValueBuilder::makeBinary(makeSigning(left, JS_SIGNED),
LT,
makeSigning(right, JS_SIGNED));
case LtUInt32:
return ValueBuilder::makeBinary(makeSigning(left, JS_UNSIGNED),
LT,
makeSigning(right, JS_UNSIGNED));
case LeSInt32:
return ValueBuilder::makeBinary(makeSigning(left, JS_SIGNED),
LE,
makeSigning(right, JS_SIGNED));
case LeUInt32:
return ValueBuilder::makeBinary(makeSigning(left, JS_UNSIGNED),
LE,
makeSigning(right, JS_UNSIGNED));
case GtSInt32:
return ValueBuilder::makeBinary(makeSigning(left, JS_SIGNED),
GT,
makeSigning(right, JS_SIGNED));
case GtUInt32:
return ValueBuilder::makeBinary(makeSigning(left, JS_UNSIGNED),
GT,
makeSigning(right, JS_UNSIGNED));
case GeSInt32:
return ValueBuilder::makeBinary(makeSigning(left, JS_SIGNED),
GE,
makeSigning(right, JS_SIGNED));
case GeUInt32:
return ValueBuilder::makeBinary(makeSigning(left, JS_UNSIGNED),
GE,
makeSigning(right, JS_UNSIGNED));
case EqFloat32:
case EqFloat64:
return ValueBuilder::makeBinary(left, EQ, right);
case NeFloat32:
case NeFloat64:
return ValueBuilder::makeBinary(left, NE, right);
case GeFloat32:
case GeFloat64:
return ValueBuilder::makeBinary(left, GE, right);
case GtFloat32:
case GtFloat64:
return ValueBuilder::makeBinary(left, GT, right);
case LeFloat32:
case LeFloat64:
return ValueBuilder::makeBinary(left, LE, right);
case LtFloat32:
case LtFloat64:
return ValueBuilder::makeBinary(left, LT, right);
case RotLInt32:
case RotRInt32:
WASM_UNREACHABLE("should be removed already");
default:
WASM_UNREACHABLE("unhandled i32 binary operator");
}
break;
}
case Type::f32:
case Type::f64:
switch (curr->op) {
case AddFloat32:
case AddFloat64:
ret = ValueBuilder::makeBinary(left, PLUS, right);
break;
case SubFloat32:
case SubFloat64:
ret = ValueBuilder::makeBinary(left, MINUS, right);
break;
case MulFloat32:
case MulFloat64:
ret = ValueBuilder::makeBinary(left, MUL, right);
break;
case DivFloat32:
case DivFloat64:
ret = ValueBuilder::makeBinary(left, DIV, right);
break;
case MinFloat32:
case MinFloat64:
ret = ValueBuilder::makeCall(MATH_MIN, left, right);
break;
case MaxFloat32:
case MaxFloat64:
ret = ValueBuilder::makeCall(MATH_MAX, left, right);
break;
case CopySignFloat32:
case CopySignFloat64:
default:
Fatal() << "Unhandled binary float operator: ";
}
if (curr->type == Type::f32) {
return makeJsCoercion(ret, JS_FLOAT);
}
return ret;
default:
Fatal() << "Unhandled type in binary: " << *curr;
}
return makeJsCoercion(ret, wasmToJsType(curr->type));
}
Ref visitSelect(Select* curr) {
// If the condition has effects that interact with the operands, we must
// reorder it to the start. We must also use locals if the values have
// side effects, as a JS conditional does not visit both sides.
bool useLocals = false;
EffectAnalyzer conditionEffects(
parent->options, *module, curr->condition);
EffectAnalyzer ifTrueEffects(parent->options, *module, curr->ifTrue);
EffectAnalyzer ifFalseEffects(parent->options, *module, curr->ifFalse);
if (conditionEffects.invalidates(ifTrueEffects) ||
conditionEffects.invalidates(ifFalseEffects) ||
ifTrueEffects.hasSideEffects() || ifFalseEffects.hasSideEffects()) {
useLocals = true;
}
if (useLocals) {
ScopedTemp tempIfTrue(curr->type, parent, func),
tempIfFalse(curr->type, parent, func),
tempCondition(Type::i32, parent, func);
Ref ifTrue = visit(curr->ifTrue, EXPRESSION_RESULT);
Ref ifFalse = visit(curr->ifFalse, EXPRESSION_RESULT);
Ref condition = visit(curr->condition, EXPRESSION_RESULT);
return ValueBuilder::makeSeq(
ValueBuilder::makeBinary(tempIfTrue.getAstName(), SET, ifTrue),
ValueBuilder::makeSeq(
ValueBuilder::makeBinary(tempIfFalse.getAstName(), SET, ifFalse),
ValueBuilder::makeSeq(
ValueBuilder::makeBinary(
tempCondition.getAstName(), SET, condition),
ValueBuilder::makeConditional(tempCondition.getAstName(),
tempIfTrue.getAstName(),
tempIfFalse.getAstName()))));
} else {
// Simple case without reordering.
return ValueBuilder::makeConditional(
visit(curr->condition, EXPRESSION_RESULT),
visit(curr->ifTrue, EXPRESSION_RESULT),
visit(curr->ifFalse, EXPRESSION_RESULT));
}
}
Ref visitReturn(Return* curr) {
if (!curr->value) {
return ValueBuilder::makeReturn(Ref());
}
Ref val = visit(curr->value, EXPRESSION_RESULT);
bool needCoercion =
parent->options.optimizeLevel == 0 || standaloneFunction ||
parent->functionsCallableFromOutside.count(func->name);
if (needCoercion) {
val = makeJsCoercion(val, wasmToJsType(curr->value->type));
}
return ValueBuilder::makeReturn(val);
}
Ref visitMemorySize(MemorySize* curr) {
return ValueBuilder::makeCall(WASM_MEMORY_SIZE);
}
Ref visitMemoryGrow(MemoryGrow* curr) {
if (!module->memories.empty() &&
module->memories[0]->max > module->memories[0]->initial) {
return ValueBuilder::makeCall(
WASM_MEMORY_GROW,
makeJsCoercion(visit(curr->delta, EXPRESSION_RESULT),
wasmToJsType(curr->delta->type)));
} else {
ABI::wasm2js::ensureHelpers(module, ABI::wasm2js::TRAP);
return ValueBuilder::makeCall(ABI::wasm2js::TRAP);
}
}
Ref visitNop(Nop* curr) { return ValueBuilder::makeToplevel(); }
Ref visitUnreachable(Unreachable* curr) {
ABI::wasm2js::ensureHelpers(module, ABI::wasm2js::TRAP);
return ValueBuilder::makeCall(ABI::wasm2js::TRAP);
}
// Atomics
struct HeapAndPointer {
Ref heap;
Ref ptr;
};
HeapAndPointer
getHeapAndAdjustedPointer(Index bytes, Expression* ptr, Index offset) {
IString heap;
Ref adjustedPtr = makePointer(ptr, offset);
switch (bytes) {
case 1:
heap = HEAP8;
break;
case 2:
heap = HEAP16;
adjustedPtr = ValueBuilder::makePtrShift(adjustedPtr, 1);
break;
case 4:
heap = HEAP32;
adjustedPtr = ValueBuilder::makePtrShift(adjustedPtr, 2);
break;
default: {
WASM_UNREACHABLE("unimp");
}
}
return {ValueBuilder::makeName(heap), adjustedPtr};
}
Ref visitAtomicRMW(AtomicRMW* curr) {
auto hap =
getHeapAndAdjustedPointer(curr->bytes, curr->ptr, curr->offset);
IString target;
switch (curr->op) {
case RMWAdd:
target = IString("add");
break;
case RMWSub:
target = IString("sub");
break;
case RMWAnd:
target = IString("and");
break;
case RMWOr:
target = IString("or");
break;
case RMWXor:
target = IString("xor");
break;
case RMWXchg:
target = IString("exchange");
break;
default:
WASM_UNREACHABLE("unimp");
}
Ref call = ValueBuilder::makeCall(
ValueBuilder::makeDot(ValueBuilder::makeName(ATOMICS), target));
ValueBuilder::appendToCall(call, hap.heap);
ValueBuilder::appendToCall(call, hap.ptr);
ValueBuilder::appendToCall(call, visit(curr->value, EXPRESSION_RESULT));
return call;
}
Ref visitAtomicCmpxchg(AtomicCmpxchg* curr) {
auto hap =
getHeapAndAdjustedPointer(curr->bytes, curr->ptr, curr->offset);
Ref expected = visit(curr->expected, EXPRESSION_RESULT);
Ref replacement = visit(curr->replacement, EXPRESSION_RESULT);
Ref call = ValueBuilder::makeCall(ValueBuilder::makeDot(
ValueBuilder::makeName(ATOMICS), COMPARE_EXCHANGE));
ValueBuilder::appendToCall(call, hap.heap);
ValueBuilder::appendToCall(call, hap.ptr);
ValueBuilder::appendToCall(call, expected);
ValueBuilder::appendToCall(call, replacement);
return makeJsCoercion(call, wasmToJsType(curr->type));
}
Ref visitAtomicWait(AtomicWait* curr) {
unimplemented(curr);
WASM_UNREACHABLE("unimp");
}
Ref visitAtomicNotify(AtomicNotify* curr) {
Ref call = ValueBuilder::makeCall(ValueBuilder::makeDot(
ValueBuilder::makeName(ATOMICS), IString("notify")));
ValueBuilder::appendToCall(call, ValueBuilder::makeName(HEAP32));
ValueBuilder::appendToCall(
call,
ValueBuilder::makePtrShift(makePointer(curr->ptr, curr->offset), 2));
ValueBuilder::appendToCall(
call,
makeSigning(visit(curr->notifyCount, EXPRESSION_RESULT), JS_UNSIGNED));
return call;
}
Ref visitAtomicFence(AtomicFence* curr) {
// Sequentially consistent fences can be lowered to no operation
return ValueBuilder::makeToplevel();
}
// TODOs
Ref visitSIMDExtract(SIMDExtract* curr) {
unimplemented(curr);
WASM_UNREACHABLE("unimp");
}
Ref visitSIMDReplace(SIMDReplace* curr) {
unimplemented(curr);
WASM_UNREACHABLE("unimp");
}
Ref visitSIMDShuffle(SIMDShuffle* curr) {
unimplemented(curr);
WASM_UNREACHABLE("unimp");
}
Ref visitSIMDTernary(SIMDTernary* curr) {
unimplemented(curr);
WASM_UNREACHABLE("unimp");
}
Ref visitSIMDShift(SIMDShift* curr) {
unimplemented(curr);
WASM_UNREACHABLE("unimp");
}
Ref visitSIMDLoad(SIMDLoad* curr) {
unimplemented(curr);
WASM_UNREACHABLE("unimp");
}
Ref visitSIMDLoadStoreLane(SIMDLoadStoreLane* curr) {
unimplemented(curr);
WASM_UNREACHABLE("unimp");
}
Ref visitMemoryInit(MemoryInit* curr) {
ABI::wasm2js::ensureHelpers(module, ABI::wasm2js::MEMORY_INIT);
return ValueBuilder::makeCall(
ABI::wasm2js::MEMORY_INIT,
ValueBuilder::makeNum(parent->getDataIndex(curr->segment)),
visit(curr->dest, EXPRESSION_RESULT),
visit(curr->offset, EXPRESSION_RESULT),
visit(curr->size, EXPRESSION_RESULT));
}
Ref visitDataDrop(DataDrop* curr) {
ABI::wasm2js::ensureHelpers(module, ABI::wasm2js::DATA_DROP);
return ValueBuilder::makeCall(
ABI::wasm2js::DATA_DROP,
ValueBuilder::makeNum(parent->getDataIndex(curr->segment)));
}
Ref visitMemoryCopy(MemoryCopy* curr) {
ABI::wasm2js::ensureHelpers(module, ABI::wasm2js::MEMORY_COPY);
return ValueBuilder::makeCall(ABI::wasm2js::MEMORY_COPY,
visit(curr->dest, EXPRESSION_RESULT),
visit(curr->source, EXPRESSION_RESULT),
visit(curr->size, EXPRESSION_RESULT));
}
Ref visitMemoryFill(MemoryFill* curr) {
ABI::wasm2js::ensureHelpers(module, ABI::wasm2js::MEMORY_FILL);
return ValueBuilder::makeCall(ABI::wasm2js::MEMORY_FILL,
visit(curr->dest, EXPRESSION_RESULT),
visit(curr->value, EXPRESSION_RESULT),
visit(curr->size, EXPRESSION_RESULT));
}
Ref visitRefNull(RefNull* curr) { return ValueBuilder::makeName(NULL_); }
Ref visitRefIsNull(RefIsNull* curr) {
return ValueBuilder::makeBinary(visit(curr->value, EXPRESSION_RESULT),
EQ,
ValueBuilder::makeName(NULL_));
}
Ref visitRefFunc(RefFunc* curr) {
return ValueBuilder::makeName(fromName(curr->func, NameScope::Top));
}
Ref visitRefEq(RefEq* curr) {
return ValueBuilder::makeBinary(visit(curr->left, EXPRESSION_RESULT),
EQ,
visit(curr->right, EXPRESSION_RESULT));
}
Ref visitTableGet(TableGet* curr) {
return ValueBuilder::makeSub(ValueBuilder::makeName(FUNCTION_TABLE),
visit(curr->index, EXPRESSION_RESULT));
}
Ref visitTableSet(TableSet* curr) {
auto sub = ValueBuilder::makeSub(ValueBuilder::makeName(FUNCTION_TABLE),
visit(curr->index, EXPRESSION_RESULT));
auto value = visit(curr->value, EXPRESSION_RESULT);
return ValueBuilder::makeBinary(sub, SET, value);
}
Ref visitTableSize(TableSize* curr) {
return ValueBuilder::makeDot(ValueBuilder::makeName(FUNCTION_TABLE),
ValueBuilder::makeName(LENGTH));
}
Ref visitTableGrow(TableGrow* curr) {
ABI::wasm2js::ensureHelpers(module, ABI::wasm2js::TABLE_GROW);
// Also ensure fill, as grow calls fill internally.
ABI::wasm2js::ensureHelpers(module, ABI::wasm2js::TABLE_FILL);
return ValueBuilder::makeCall(ABI::wasm2js::TABLE_GROW,
visit(curr->value, EXPRESSION_RESULT),
visit(curr->delta, EXPRESSION_RESULT));
}
Ref visitTableFill(TableFill* curr) {
ABI::wasm2js::ensureHelpers(module, ABI::wasm2js::TABLE_FILL);
return ValueBuilder::makeCall(ABI::wasm2js::TABLE_FILL,
visit(curr->dest, EXPRESSION_RESULT),
visit(curr->value, EXPRESSION_RESULT),
visit(curr->size, EXPRESSION_RESULT));
}
Ref visitTableCopy(TableCopy* curr) {
ABI::wasm2js::ensureHelpers(module, ABI::wasm2js::TABLE_COPY);
return ValueBuilder::makeCall(ABI::wasm2js::TABLE_COPY,
visit(curr->dest, EXPRESSION_RESULT),
visit(curr->source, EXPRESSION_RESULT),
visit(curr->size, EXPRESSION_RESULT));
}
Ref visitTableInit(TableInit* curr) {
unimplemented(curr);
WASM_UNREACHABLE("unimp");
}
Ref visitTry(Try* curr) {
unimplemented(curr);
WASM_UNREACHABLE("unimp");
}
Ref visitTryTable(TryTable* curr) {
unimplemented(curr);
WASM_UNREACHABLE("unimp");
}
Ref visitThrow(Throw* curr) {
unimplemented(curr);
WASM_UNREACHABLE("unimp");
}
Ref visitRethrow(Rethrow* curr) {
unimplemented(curr);
WASM_UNREACHABLE("unimp");
}
Ref visitThrowRef(ThrowRef* curr) {
unimplemented(curr);
WASM_UNREACHABLE("unimp");
}
Ref visitPop(Pop* curr) {
unimplemented(curr);
WASM_UNREACHABLE("unimp");
}
Ref visitTupleMake(TupleMake* curr) {
unimplemented(curr);
WASM_UNREACHABLE("unimp");
}
Ref visitTupleExtract(TupleExtract* curr) {
unimplemented(curr);
WASM_UNREACHABLE("unimp");
}
Ref visitRefI31(RefI31* curr) {
unimplemented(curr);
WASM_UNREACHABLE("unimp");
}
Ref visitI31Get(I31Get* curr) {
unimplemented(curr);
WASM_UNREACHABLE("unimp");
}
Ref visitCallRef(CallRef* curr) {
unimplemented(curr);
WASM_UNREACHABLE("unimp");
}
Ref visitRefTest(RefTest* curr) {
unimplemented(curr);
WASM_UNREACHABLE("unimp");
}
Ref visitRefCast(RefCast* curr) {
unimplemented(curr);
WASM_UNREACHABLE("unimp");
}
Ref visitBrOn(BrOn* curr) {
unimplemented(curr);
WASM_UNREACHABLE("unimp");
}
Ref visitStructNew(StructNew* curr) {
unimplemented(curr);
WASM_UNREACHABLE("unimp");
}
Ref visitStructGet(StructGet* curr) {
unimplemented(curr);
WASM_UNREACHABLE("unimp");
}
Ref visitStructSet(StructSet* curr) {
unimplemented(curr);
WASM_UNREACHABLE("unimp");
}
Ref visitArrayNew(ArrayNew* curr) {
unimplemented(curr);
WASM_UNREACHABLE("unimp");
}
Ref visitArrayNewData(ArrayNewData* curr) {
unimplemented(curr);
WASM_UNREACHABLE("unimp");
}
Ref visitArrayNewElem(ArrayNewElem* curr) {
unimplemented(curr);
WASM_UNREACHABLE("unimp");
}
Ref visitArrayNewFixed(ArrayNewFixed* curr) {
unimplemented(curr);
WASM_UNREACHABLE("unimp");
}
Ref visitArrayGet(ArrayGet* curr) {
unimplemented(curr);
WASM_UNREACHABLE("unimp");
}
Ref visitArraySet(ArraySet* curr) {
unimplemented(curr);
WASM_UNREACHABLE("unimp");
}
Ref visitArrayLen(ArrayLen* curr) {
unimplemented(curr);
WASM_UNREACHABLE("unimp");
}
Ref visitArrayCopy(ArrayCopy* curr) {
unimplemented(curr);
WASM_UNREACHABLE("unimp");
}
Ref visitArrayFill(ArrayFill* curr) {
unimplemented(curr);
WASM_UNREACHABLE("unimp");
}
Ref visitArrayInitData(ArrayInitData* curr) {
unimplemented(curr);
WASM_UNREACHABLE("unimp");
}
Ref visitArrayInitElem(ArrayInitElem* curr) {
unimplemented(curr);
WASM_UNREACHABLE("unimp");
}
Ref visitStringNew(StringNew* curr) {
unimplemented(curr);
WASM_UNREACHABLE("unimp");
}
Ref visitStringConst(StringConst* curr) {
unimplemented(curr);
WASM_UNREACHABLE("unimp");
}
Ref visitStringMeasure(StringMeasure* curr) {
unimplemented(curr);
WASM_UNREACHABLE("unimp");
}
Ref visitStringEncode(StringEncode* curr) {
unimplemented(curr);
WASM_UNREACHABLE("unimp");
}
Ref visitStringConcat(StringConcat* curr) {
unimplemented(curr);
WASM_UNREACHABLE("unimp");
}
Ref visitStringEq(StringEq* curr) {
unimplemented(curr);
WASM_UNREACHABLE("unimp");
}
Ref visitStringWTF16Get(StringWTF16Get* curr) {
unimplemented(curr);
WASM_UNREACHABLE("unimp");
}
Ref visitStringSliceWTF(StringSliceWTF* curr) {
unimplemented(curr);
WASM_UNREACHABLE("unimp");
}
Ref visitRefAs(RefAs* curr) {
// TODO: support others
assert(curr->op == RefAsNonNull);
// value || trap()
ABI::wasm2js::ensureHelpers(module, ABI::wasm2js::TRAP);
return ValueBuilder::makeBinary(
visit(curr->value, EXPRESSION_RESULT),
IString("||"),
ValueBuilder::makeCall(ABI::wasm2js::TRAP));
}
Ref visitContBind(ContBind* curr) {
unimplemented(curr);
WASM_UNREACHABLE("unimp");
}
Ref visitContNew(ContNew* curr) {
unimplemented(curr);
WASM_UNREACHABLE("unimp");
}
Ref visitResume(Resume* curr) {
unimplemented(curr);
WASM_UNREACHABLE("unimp");
}
Ref visitSuspend(Suspend* curr) {
unimplemented(curr);
WASM_UNREACHABLE("unimp");
}
private:
Ref makePointer(Expression* ptr, Address offset) {
auto ret = visit(ptr, EXPRESSION_RESULT);
if (offset) {
ret = makeJsCoercion(
ValueBuilder::makeBinary(ret, PLUS, ValueBuilder::makeNum(offset)),
JS_INT);
}
return ret;
}
void unimplemented(Expression* curr) {
Fatal() << "wasm2js cannot convert " << *curr;
}
};
return ExpressionProcessor(this, m, func, standaloneFunction).process(curr);
}
void Wasm2JSBuilder::addMemoryFuncs(Ref ast, Module* wasm) {
Ref memorySizeFunc = ValueBuilder::makeFunction(WASM_MEMORY_SIZE);
memorySizeFunc[3]->push_back(ValueBuilder::makeReturn(
makeJsCoercion(ValueBuilder::makeBinary(
ValueBuilder::makeDot(ValueBuilder::makeName(BUFFER),
IString("byteLength")),
DIV,
ValueBuilder::makeInt(Memory::kPageSize)),
JsType::JS_INT)));
ast->push_back(memorySizeFunc);
if (!wasm->memories.empty() &&
wasm->memories[0]->max > wasm->memories[0]->initial) {
addMemoryGrowFunc(ast, wasm);
}
}
void Wasm2JSBuilder::addMemoryGrowFunc(Ref ast, Module* wasm) {
Ref memoryGrowFunc = ValueBuilder::makeFunction(WASM_MEMORY_GROW);
ValueBuilder::appendArgumentToFunction(memoryGrowFunc, IString("pagesToAdd"));
memoryGrowFunc[3]->push_back(
ValueBuilder::makeStatement(ValueBuilder::makeBinary(
ValueBuilder::makeName(IString("pagesToAdd")),
SET,
makeJsCoercion(ValueBuilder::makeName(IString("pagesToAdd")),
JsType::JS_INT))));
Ref oldPages = ValueBuilder::makeVar();
memoryGrowFunc[3]->push_back(oldPages);
ValueBuilder::appendToVar(
oldPages,
IString("oldPages"),
makeJsCoercion(ValueBuilder::makeCall(WASM_MEMORY_SIZE), JsType::JS_INT));
Ref newPages = ValueBuilder::makeVar();
memoryGrowFunc[3]->push_back(newPages);
ValueBuilder::appendToVar(
newPages,
IString("newPages"),
makeJsCoercion(
ValueBuilder::makeBinary(ValueBuilder::makeName(IString("oldPages")),
PLUS,
ValueBuilder::makeName(IString("pagesToAdd"))),
JsType::JS_INT));
Ref block = ValueBuilder::makeBlock();
memoryGrowFunc[3]->push_back(ValueBuilder::makeIf(
ValueBuilder::makeBinary(
ValueBuilder::makeBinary(ValueBuilder::makeName(IString("oldPages")),
LT,
ValueBuilder::makeName(IString("newPages"))),
IString("&&"),
ValueBuilder::makeBinary(ValueBuilder::makeName(IString("newPages")),
LT,
ValueBuilder::makeInt(Memory::kMaxSize32))),
block,
NULL));
Ref newBuffer = ValueBuilder::makeVar();
ValueBuilder::appendToBlock(block, newBuffer);
ValueBuilder::appendToVar(
newBuffer,
IString("newBuffer"),
ValueBuilder::makeNew(ValueBuilder::makeCall(
ARRAY_BUFFER,
ValueBuilder::makeCall(MATH_IMUL,
ValueBuilder::makeName(IString("newPages")),
ValueBuilder::makeInt(Memory::kPageSize)))));
Ref newHEAP8 = ValueBuilder::makeVar();
ValueBuilder::appendToBlock(block, newHEAP8);
ValueBuilder::appendToVar(newHEAP8,
IString("newHEAP8"),
ValueBuilder::makeNew(ValueBuilder::makeCall(
ValueBuilder::makeName(INT8ARRAY),
ValueBuilder::makeName(IString("newBuffer")))));
ValueBuilder::appendToBlock(
block,
ValueBuilder::makeCall(
ValueBuilder::makeDot(ValueBuilder::makeName(IString("newHEAP8")),
IString("set")),
ValueBuilder::makeName(HEAP8)));
auto setHeap = [&](IString name, IString view) {
ValueBuilder::appendToBlock(
block,
ValueBuilder::makeBinary(
ValueBuilder::makeName(name),
SET,
ValueBuilder::makeNew(ValueBuilder::makeCall(
ValueBuilder::makeName(view),
ValueBuilder::makeName(IString("newBuffer"))))));
};
setHeap(HEAP8, INT8ARRAY);
setHeap(HEAP16, INT16ARRAY);
setHeap(HEAP32, INT32ARRAY);
setHeap(HEAPU8, UINT8ARRAY);
setHeap(HEAPU16, UINT16ARRAY);
setHeap(HEAPU32, UINT32ARRAY);
setHeap(HEAPF32, FLOAT32ARRAY);
setHeap(HEAPF64, FLOAT64ARRAY);
ValueBuilder::appendToBlock(
block,
ValueBuilder::makeBinary(ValueBuilder::makeName(BUFFER),
SET,
ValueBuilder::makeName(IString("newBuffer"))));
// apply the changes to the memory import
if (!wasm->memories.empty() && wasm->memories[0]->imported()) {
ValueBuilder::appendToBlock(
block,
ValueBuilder::makeBinary(
ValueBuilder::makeDot(ValueBuilder::makeName("memory"),
ValueBuilder::makeName(BUFFER)),
SET,
ValueBuilder::makeName(BUFFER)));
}
if (needsBufferView(*wasm)) {
ValueBuilder::appendToBlock(
block,
ValueBuilder::makeBinary(ValueBuilder::makeName("bufferView"),
SET,
ValueBuilder::makeName(HEAPU8)));
}
memoryGrowFunc[3]->push_back(
ValueBuilder::makeReturn(ValueBuilder::makeName(IString("oldPages"))));
ast->push_back(memoryGrowFunc);
}
// Wasm2JSBuilder emits the core of the module - the functions etc. that would
// be the asm.js function in an asm.js world. This class emits the rest of the
// "glue" around that.
class Wasm2JSGlue {
public:
Wasm2JSGlue(Module& wasm,
Output& out,
Wasm2JSBuilder::Flags flags,
Name moduleName)
: wasm(wasm), out(out), flags(flags), moduleName(moduleName) {}
void emitPre();
void emitPost();
private:
Module& wasm;
Output& out;
Wasm2JSBuilder::Flags flags;
Name moduleName;
void emitPreEmscripten();
void emitPreES6();
void emitPostEmscripten();
void emitPostES6();
void emitMemory();
void emitSpecialSupport();
};
void Wasm2JSGlue::emitPre() {
if (flags.emscripten) {
emitPreEmscripten();
} else {
emitPreES6();
}
if (isTableExported(wasm)) {
out << "function Table(ret) {\n";
if (wasm.tables[0]->initial == wasm.tables[0]->max) {
out << " // grow method not included; table is not growable\n";
} else {
out << " ret.grow = function(by) {\n"
<< " var old = this.length;\n"
<< " this.length = this.length + by;\n"
<< " return old;\n"
<< " };\n";
}
out << " ret.set = function(i, func) {\n"
<< " this[i] = func;\n"
<< " };\n"
<< " ret.get = function(i) {\n"
<< " return this[i];\n"
<< " };\n"
<< " return ret;\n"
<< "}\n\n";
}
emitMemory();
emitSpecialSupport();
}
void Wasm2JSGlue::emitPreEmscripten() {
out << "function instantiate(info) {\n";
}
void Wasm2JSGlue::emitPreES6() {
std::unordered_map<Name, Name> baseModuleMap;
std::unordered_set<Name> seenModules;
auto noteImport = [&](Name module, Name base) {
// Right now codegen requires a flat namespace going into the module,
// meaning we don't support importing the same name from multiple namespaces
// yet.
if (baseModuleMap.count(base) && baseModuleMap[base] != module) {
Fatal() << "the name " << base << " cannot be imported from "
<< "two different modules yet";
}
baseModuleMap[base] = module;
if (seenModules.count(module) == 0) {
out << "import * as " << asmangle(module.toString()) << " from '"
<< module << "';\n";
seenModules.insert(module);
}
};
ImportInfo imports(wasm);
ModuleUtils::iterImportedGlobals(
wasm, [&](Global* import) { noteImport(import->module, import->base); });
ModuleUtils::iterImportedTables(
wasm, [&](Table* import) { noteImport(import->module, import->base); });
ModuleUtils::iterImportedFunctions(wasm, [&](Function* import) {
// The special helpers are emitted in the glue, see code and comments
// below.
if (ABI::wasm2js::isHelper(import->base)) {
return;
}
noteImport(import->module, import->base);
});
out << '\n';
}
void Wasm2JSGlue::emitPost() {
if (flags.emscripten) {
emitPostEmscripten();
} else {
emitPostES6();
}
}
void Wasm2JSGlue::emitPostEmscripten() {
out << " return asmFunc(info);\n}\n";
}
void Wasm2JSGlue::emitPostES6() {
// Create an initial `ArrayBuffer` and populate it with static data.
// Currently we use base64 encoding to encode static data and we decode it at
// instantiation time.
//
// Note that the translation here expects that the lower values of this memory
// can be used for conversions, so make sure there's at least one page.
if (!wasm.memories.empty() && wasm.memories[0]->imported()) {
out << "var mem" << moduleName.str << " = new ArrayBuffer("
<< wasm.memories[0]->initial.addr * Memory::kPageSize << ");\n";
}
// Actually invoke the `asmFunc` generated function, passing in all global
// values followed by all imports
out << "var ret" << moduleName.str << " = " << moduleName.str << "({\n";
std::unordered_set<Name> seenModules;
ModuleUtils::iterImportedFunctions(wasm, [&](Function* import) {
// The special helpers are emitted in the glue, see code and comments
// below.
if (ABI::wasm2js::isHelper(import->base)) {
return;
}
if (seenModules.count(import->module) > 0) {
return;
}
out << " \"" << import->module
<< "\": " << asmangle(import->module.toString()) << ",\n";
seenModules.insert(import->module);
});
ModuleUtils::iterImportedMemories(wasm, [&](Memory* import) {
// The special helpers are emitted in the glue, see code and comments
// below.
if (ABI::wasm2js::isHelper(import->base)) {
return;
}
out << " \"" << import->module << "\": {\n";
out << " " << asmangle(import->base.toString()) << ": { buffer : mem"
<< moduleName.str << " }\n";
out << " },\n";
});
ModuleUtils::iterImportedTables(wasm, [&](Table* import) {
// The special helpers are emitted in the glue, see code and comments
// below.
if (ABI::wasm2js::isHelper(import->base)) {
return;
}
if (seenModules.count(import->module) > 0) {
return;
}
out << " \"" << import->module
<< "\": " << asmangle(import->module.toString()) << ",\n";
seenModules.insert(import->module);
});
out << "});\n";
if (flags.allowAsserts) {
return;
}
// And now that we have our returned instance, export all our functions
// that are hanging off it.
for (auto& exp : wasm.exports) {
switch (exp->kind) {
case ExternalKind::Function:
case ExternalKind::Global:
case ExternalKind::Memory:
break;
// Exported globals and function tables aren't supported yet
default:
continue;
}
std::ostringstream export_name;
for (char c : exp->name.str) {
if (c == '-') {
export_name << '_';
} else {
export_name << c;
}
}
out << "export var " << asmangle(exp->name.toString()) << " = ret"
<< moduleName << "." << asmangle(exp->name.toString()) << ";\n";
}
}
void Wasm2JSGlue::emitMemory() {
if (needsBufferView(wasm)) {
// Create a helper bufferView to access the buffer if we need one. We use it
// for creating memory segments if we have any (we may not if the segments
// are shipped in a side .mem file, for example), and also in bulk memory
// operations.
// This will get assigned during `asmFunc` (and potentially re-assigned
// during __wasm_memory_grow).
// TODO: We should probably just share a single HEAPU8 var.
out << " var bufferView;\n";
}
// If there are no memory segments, we don't need to emit any support code for
// segment creation.
if (wasm.dataSegments.empty()) {
return;
}
// If we have passive memory segments, we need to store those.
for (auto& seg : wasm.dataSegments) {
if (seg->isPassive) {
out << " var memorySegments = {};\n";
break;
}
}
out <<
R"( var base64ReverseLookup = new Uint8Array(123/*'z'+1*/);
for (var i = 25; i >= 0; --i) {
base64ReverseLookup[48+i] = 52+i; // '0-9'
base64ReverseLookup[65+i] = i; // 'A-Z'
base64ReverseLookup[97+i] = 26+i; // 'a-z'
}
base64ReverseLookup[43] = 62; // '+'
base64ReverseLookup[47] = 63; // '/'
/** @noinline Inlining this function would mean expanding the base64 string 4x times in the source code, which Closure seems to be happy to do. */
function base64DecodeToExistingUint8Array(uint8Array, offset, b64) {
var b1, b2, i = 0, j = offset, bLength = b64.length, end = offset + (bLength*3>>2) - (b64[bLength-2] == '=') - (b64[bLength-1] == '=');
for (; i < bLength; i += 4) {
b1 = base64ReverseLookup[b64.charCodeAt(i+1)];
b2 = base64ReverseLookup[b64.charCodeAt(i+2)];
uint8Array[j++] = base64ReverseLookup[b64.charCodeAt(i)] << 2 | b1 >> 4;
if (j < end) uint8Array[j++] = b1 << 4 | b2 >> 2;
if (j < end) uint8Array[j++] = b2 << 6 | base64ReverseLookup[b64.charCodeAt(i+3)];
})";
if (wasm.features.hasBulkMemory()) {
// Passive segments in bulk memory are initialized into new arrays that are
// passed into here, and we need to return them.
out << R"(
return uint8Array;)";
}
out << R"(
}
)";
for (Index i = 0; i < wasm.dataSegments.size(); i++) {
auto& seg = wasm.dataSegments[i];
if (seg->isPassive) {
// Fancy passive segments are decoded into typed arrays on the side, for
// later copying.
out << "memorySegments[" << i
<< "] = base64DecodeToExistingUint8Array(new Uint8Array("
<< seg->data.size() << ")"
<< ", 0, \"" << base64Encode(seg->data) << "\");\n";
}
}
if (hasActiveSegments(wasm)) {
auto globalOffset = [&](const DataSegment& segment) {
if (auto* c = segment.offset->dynCast<Const>()) {
return std::to_string(c->value.getInteger());
}
if (auto* get = segment.offset->dynCast<GlobalGet>()) {
auto internalName = get->name;
auto importedGlobal = wasm.getGlobal(internalName);
return std::string("imports['") + importedGlobal->module.toString() +
"']['" + importedGlobal->base.toString() + "']";
}
Fatal() << "non-constant offsets aren't supported yet\n";
};
out << "function initActiveSegments(imports) {\n";
for (Index i = 0; i < wasm.dataSegments.size(); i++) {
auto& seg = wasm.dataSegments[i];
if (!seg->isPassive) {
// Plain active segments are decoded directly into the main memory.
out << " base64DecodeToExistingUint8Array(bufferView, "
<< globalOffset(*seg) << ", \"" << base64Encode(seg->data)
<< "\");\n";
}
}
out << "}\n";
}
}
void Wasm2JSGlue::emitSpecialSupport() {
// The special support functions are emitted as part of the JS glue, if we
// need them.
bool need = false;
bool needScratch = false;
ModuleUtils::iterImportedFunctions(wasm, [&](Function* import) {
if (ABI::wasm2js::isHelper(import->base)) {
need = true;
}
if (import->base == ABI::wasm2js::SCRATCH_STORE_I32 ||
import->base == ABI::wasm2js::SCRATCH_LOAD_I32 ||
import->base == ABI::wasm2js::SCRATCH_STORE_F32 ||
import->base == ABI::wasm2js::SCRATCH_LOAD_F32 ||
import->base == ABI::wasm2js::SCRATCH_STORE_F64 ||
import->base == ABI::wasm2js::SCRATCH_LOAD_F64) {
needScratch = true;
}
});
if (!need) {
return;
}
// Scratch memory uses 3 indexes, each referring to 4 bytes. Indexes 0, 1 are
// used for 64-bit operations, while 2 is for 32-bit. These operations need
// separate indexes because we need to handle the case where the optimizer
// reorders a 32-bit reinterpret in between a 64-bit's split-out parts.
// That situation can occur because the 64-bit reinterpret was split up into
// pieces early, in the 64-bit lowering pass, while the 32-bit reinterprets
// are lowered only at the very end, and until then the optimizer sees wasm
// reinterprets which have no side effects (but they will have the side effect
// of altering scratch memory). That is, conceptual code like this:
//
// a = reinterpret_64(b)
// x = reinterpret_32(y)
//
// turns into
//
// scratch_write(b)
// a_low = scratch_read(0)
// a_high = scratch_read(1)
// x = reinterpret_32(y)
//
// (Note how the single wasm instruction for a 64-bit reinterpret turns into
// multiple operations. We have to do such splitting, because in JS we will
// have to have separate operations to receive each 32-bit chunk anyhow. A
// *32*-bit reinterpret *could* be a single function, but given we have the
// separate functions anyhow for the 64-bit case, it's more compact to reuse
// those.)
// At this point, the scratch_* functions look like they have side effects to
// the optimizer (which is true, as they modify scratch memory), but the
// reinterpret_32 is still a normal wasm instruction without side effects, so
// the optimizer might do this:
//
// scratch_write(b)
// a_low = scratch_read(0)
// x = reinterpret_32(y) ;; this moved one line up
// a_high = scratch_read(1)
//
// When we do lower the reinterpret_32 into JS, we get:
//
// scratch_write(b)
// a_low = scratch_read(0)
// scratch_write(y)
// x = scratch_read()
// a_high = scratch_read(1)
//
// The second write occurs before the first's values have been read, so they
// interfere.
//
// There isn't a problem with reordering 32-bit reinterprets with each other
// as each is lowered into a pair of write+read in JS (after the wasm
// optimizer runs), so they are guaranteed to be adjacent (and a JS optimizer
// that runs later will handle that ok since they are calls, which can always
// have side effects).
if (needScratch) {
out << R"(
var scratchBuffer = new ArrayBuffer(16);
var i32ScratchView = new Int32Array(scratchBuffer);
var f32ScratchView = new Float32Array(scratchBuffer);
var f64ScratchView = new Float64Array(scratchBuffer);
)";
}
ModuleUtils::iterImportedFunctions(wasm, [&](Function* import) {
if (!ABI::wasm2js::isHelper(import->base)) {
return;
}
if (import->base == ABI::wasm2js::SCRATCH_STORE_I32) {
out << R"(
function wasm2js_scratch_store_i32(index, value) {
i32ScratchView[index] = value;
}
)";
} else if (import->base == ABI::wasm2js::SCRATCH_LOAD_I32) {
out << R"(
function wasm2js_scratch_load_i32(index) {
return i32ScratchView[index];
}
)";
} else if (import->base == ABI::wasm2js::SCRATCH_STORE_F32) {
out << R"(
function wasm2js_scratch_store_f32(value) {
f32ScratchView[2] = value;
}
)";
} else if (import->base == ABI::wasm2js::SCRATCH_LOAD_F32) {
out << R"(
function wasm2js_scratch_load_f32() {
return f32ScratchView[2];
}
)";
} else if (import->base == ABI::wasm2js::SCRATCH_STORE_F64) {
out << R"(
function wasm2js_scratch_store_f64(value) {
f64ScratchView[0] = value;
}
)";
} else if (import->base == ABI::wasm2js::SCRATCH_LOAD_F64) {
out << R"(
function wasm2js_scratch_load_f64() {
return f64ScratchView[0];
}
)";
} else if (import->base == ABI::wasm2js::MEMORY_INIT) {
out << R"(
function wasm2js_memory_init(segment, dest, offset, size) {
// TODO: traps on invalid things
bufferView.set(memorySegments[segment].subarray(offset, offset + size), dest);
}
)";
} else if (import->base == ABI::wasm2js::MEMORY_FILL) {
out << R"(
function wasm2js_memory_fill(dest, value, size) {
dest = dest >>> 0;
size = size >>> 0;
if (dest + size > bufferView.length) throw "trap: invalid memory.fill";
bufferView.fill(value, dest, dest + size);
}
)";
} else if (import->base == ABI::wasm2js::MEMORY_COPY) {
out << R"(
function wasm2js_memory_copy(dest, source, size) {
// TODO: traps on invalid things
bufferView.copyWithin(dest, source, source + size);
}
)";
} else if (import->base == ABI::wasm2js::TABLE_GROW) {
out << R"(
function wasm2js_table_grow(value, delta) {
// TODO: traps on invalid things
var oldSize = FUNCTION_TABLE.length;
FUNCTION_TABLE.length = oldSize + delta;
if (newSize > oldSize) {
__wasm_table_fill(oldSize, value, delta)
}
return oldSize;
}
)";
} else if (import->base == ABI::wasm2js::TABLE_FILL) {
out << R"(
function __wasm_table_fill(dest, value, size) {
// TODO: traps on invalid things
for (var i = 0; i < size; i++) {
FUNCTION_TABLE[dest + i] = value;
}
}
)";
} else if (import->base == ABI::wasm2js::TABLE_COPY) {
out << R"(
function __wasm_table_copy(dest, source, size) {
// TODO: traps on invalid things
for (var i = 0; i < size; i++) {
FUNCTION_TABLE[dest + i] = FUNCTION_TABLE[source + i];
}
}
)";
} else if (import->base == ABI::wasm2js::DATA_DROP) {
out << R"(
function wasm2js_data_drop(segment) {
// TODO: traps on invalid things
memorySegments[segment] = new Uint8Array(0);
}
)";
} else if (import->base == ABI::wasm2js::ATOMIC_WAIT_I32) {
out << R"(
function wasm2js_atomic_wait_i32(offset, ptr, expected, timeoutLow, timeoutHigh) {
ptr = (ptr + offset) >> 2;
var timeout = Infinity;
if (timeoutHigh >= 0) {
// Convert from nanoseconds to milliseconds
// Taken from convertI32PairToI53 in emscripten's library_int53.js
timeout = ((timeoutLow >>> 0) / 1e6) + timeoutHigh * (4294967296 / 1e6);
}
var view = new Int32Array(bufferView.buffer); // TODO cache
var result = Atomics.wait(view, ptr, expected, timeout);
if (result == 'ok') return 0;
if (result == 'not-equal') return 1;
if (result == 'timed-out') return 2;
throw 'bad result ' + result;
}
)";
} else if (import->base == ABI::wasm2js::ATOMIC_RMW_I64) {
out << R"(
function wasm2js_atomic_rmw_i64(op, bytes, offset, ptr, valueLow, valueHigh) {
// TODO: support bytes=1, 2, 4 as well as 8.
var view = new BigInt64Array(bufferView.buffer); // TODO cache
ptr = (ptr + offset) >> 3;
var value = BigInt(valueLow >>> 0) | (BigInt(valueHigh >>> 0) << BigInt(32));
var result;
switch (op) {
case 0: { // Add
result = Atomics.add(view, ptr, value);
break;
}
case 1: { // Sub
result = Atomics.sub(view, ptr, value);
break;
}
case 2: { // And
result = Atomics.and(view, ptr, value);
break;
}
case 3: { // Or
result = Atomics.or(view, ptr, value);
break;
}
case 4: { // Xor
result = Atomics.xor(view, ptr, value);
break;
}
case 5: { // Xchg
result = Atomics.exchange(view, ptr, value);
break;
}
default: throw 'bad op';
}
var low = Number(result & BigInt(0xffffffff)) | 0;
var high = Number((result >> BigInt(32)) & BigInt(0xffffffff)) | 0;
stashedBits = high;
return low;
}
)";
} else if (import->base == ABI::wasm2js::GET_STASHED_BITS) {
out << R"(
var stashedBits = 0;
function wasm2js_get_stashed_bits() {
return stashedBits;
}
)";
} else if (import->base == ABI::wasm2js::TRAP) {
out << "function wasm2js_trap() { throw new Error('abort'); }\n";
} else {
WASM_UNREACHABLE("bad helper function");
}
});
out << '\n';
}
} // namespace wasm
#endif // wasm_wasm2js_h