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/*
* Copyright 2020 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.
*/
//
// Lowers a module with loads and stores that access a 64-bit memory with
// one that works as-is on wasm32.
//
// TODO(wvo): make this run in parallel if needed.
#include "ir/bits.h"
#include "ir/import-utils.h"
#include "pass.h"
#include "wasm-builder.h"
#include "wasm.h"
namespace wasm {
static Name MEMORY_BASE("__memory_base");
static Name MEMORY_BASE32("__memory_base32");
struct Memory64Lowering : public WalkerPass<PostWalker<Memory64Lowering>> {
void wrapAddress64(Expression*& ptr, Name memoryName) {
if (ptr->type == Type::unreachable) {
return;
}
auto& module = *getModule();
auto* memory = module.getMemory(memoryName);
if (memory->is64()) {
assert(ptr->type == Type::i64);
ptr = Builder(module).makeUnary(UnaryOp::WrapInt64, ptr);
}
}
void extendAddress64(Expression*& ptr, Name memoryName) {
if (ptr->type == Type::unreachable) {
return;
}
auto& module = *getModule();
auto* memory = module.getMemory(memoryName);
if (memory->is64()) {
assert(ptr->type == Type::i64);
ptr->type = Type::i32;
ptr = Builder(module).makeUnary(UnaryOp::ExtendUInt32, ptr);
}
}
void visitLoad(Load* curr) { wrapAddress64(curr->ptr, curr->memory); }
void visitStore(Store* curr) { wrapAddress64(curr->ptr, curr->memory); }
void visitMemorySize(MemorySize* curr) {
auto& module = *getModule();
auto* memory = module.getMemory(curr->memory);
if (memory->is64()) {
auto* size = static_cast<Expression*>(curr);
extendAddress64(size, curr->memory);
curr->type = Type::i32;
replaceCurrent(size);
}
}
void visitMemoryGrow(MemoryGrow* curr) {
auto& module = *getModule();
auto* memory = module.getMemory(curr->memory);
if (memory->is64()) {
wrapAddress64(curr->delta, curr->memory);
auto* size = static_cast<Expression*>(curr);
// MemoryGrow returns -1 in case of failure. We cannot just use
// extend_32_u in this case so we handle it as follows:
//
// (if (result i64)
// (i32.eq (i32.const -1) (local.tee $tmp (memory.grow X)))
// (then
// (i64.const -1)
// )
// (else
// (i32.extend_32_u (local.get $tmp))
// )
// )
Builder builder(module);
auto tmp = builder.addVar(getFunction(), Type::i32);
Expression* isMinusOne =
builder.makeBinary(EqInt32,
builder.makeConst(int32_t(-1)),
builder.makeLocalTee(tmp, size, Type::i32));
auto* newSize = builder.makeLocalGet(tmp, Type::i32);
builder.makeUnary(UnaryOp::ExtendUInt32, newSize);
Expression* ifExp =
builder.makeIf(isMinusOne,
builder.makeConst(int64_t(-1)),
builder.makeUnary(UnaryOp::ExtendUInt32, newSize));
curr->type = Type::i32;
replaceCurrent(ifExp);
}
}
void visitMemoryInit(MemoryInit* curr) {
wrapAddress64(curr->dest, curr->memory);
}
void visitMemoryFill(MemoryFill* curr) {
wrapAddress64(curr->dest, curr->memory);
wrapAddress64(curr->size, curr->memory);
}
void visitMemoryCopy(MemoryCopy* curr) {
wrapAddress64(curr->dest, curr->destMemory);
wrapAddress64(curr->source, curr->sourceMemory);
wrapAddress64(curr->size, curr->destMemory);
}
void visitAtomicRMW(AtomicRMW* curr) {
wrapAddress64(curr->ptr, curr->memory);
}
void visitAtomicCmpxchg(AtomicCmpxchg* curr) {
wrapAddress64(curr->ptr, curr->memory);
}
void visitAtomicWait(AtomicWait* curr) {
wrapAddress64(curr->ptr, curr->memory);
}
void visitAtomicNotify(AtomicNotify* curr) {
wrapAddress64(curr->ptr, curr->memory);
}
void visitDataSegment(DataSegment* segment) {
auto& module = *getModule();
// passive segments don't have any offset to adjust
if (segment->isPassive || !module.getMemory(segment->memory)->is64()) {
return;
}
if (auto* c = segment->offset->dynCast<Const>()) {
c->value = Literal(static_cast<uint32_t>(c->value.geti64()));
c->type = Type::i32;
} else if (auto* get = segment->offset->dynCast<GlobalGet>()) {
auto* g = module.getGlobal(get->name);
if (g->imported() && g->base == MEMORY_BASE) {
ImportInfo info(module);
auto* memoryBase32 = info.getImportedGlobal(g->module, MEMORY_BASE32);
if (!memoryBase32) {
Builder builder(module);
memoryBase32 = builder
.makeGlobal(MEMORY_BASE32,
Type::i32,
builder.makeConst(int32_t(0)),
Builder::Immutable)
.release();
memoryBase32->module = g->module;
memoryBase32->base = MEMORY_BASE32;
module.addGlobal(memoryBase32);
}
// Use this alternative import when initializing the segment.
assert(memoryBase32);
get->type = Type::i32;
get->name = memoryBase32->name;
}
} else {
WASM_UNREACHABLE("unexpected elem offset");
}
}
void run(Module* module) override {
if (!module->features.has(FeatureSet::Memory64)) {
return;
}
Super::run(module);
// Don't modify the memories themselves until after the traversal since we
// that would require memories to be the last thing that get visited, and
// we don't want to depend on that specific ordering.
for (auto& memory : module->memories) {
if (memory->is64()) {
memory->addressType = Type::i32;
if (memory->hasMax() && memory->max > Memory::kMaxSize32) {
memory->max = Memory::kMaxSize32;
}
}
}
module->features.disable(FeatureSet::Memory64);
}
};
Pass* createMemory64LoweringPass() { return new Memory64Lowering(); }
} // namespace wasm
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