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LibWasm: Avoid revalidating memory/address for every element in memory.*

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This also "fixes" the "address leak" detected by GCC (which is not
actually leaked to the tailcalled function).
This commit is contained in:
Ali Mohammad Pur 2025-10-06 01:53:22 +02:00 • committed by Ali Mohammad Pur
parent 941cfd8026
commit 9ceb8052c8
Notes: github-actions[bot] 2025-10-06 14:01:13 +00:00
2 changed files with 35 additions and 19 deletions
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51
Libraries/LibWasm/AbstractMachine/BytecodeInterpreter.cpp
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@ -1580,20 +1580,19 @@ HANDLE_INSTRUCTION(memory_fill)
auto address = configuration.frame().module().memories().data()[args.memory_index.value()];
auto instance = configuration.store().get(address);
// bounds checked by verifier.
auto count = configuration.take_source(0, addresses.sources).to<u32>();
u8 value = static_cast<u8>(configuration.take_source(1, addresses.sources).to<u32>());
auto destination_offset = configuration.take_source(2, addresses.sources).to<u32>();
auto const count = configuration.take_source(0, addresses.sources).to<u32>();
auto const value = static_cast<u8>(configuration.take_source(1, addresses.sources).to<u32>());
auto const destination_offset = configuration.take_source(2, addresses.sources).to<u32>();
Checked<u32> checked_end = destination_offset;
Checked<u64> checked_end = destination_offset;
checked_end += count;
TRAP_IN_LOOP_IF_NOT(!checked_end.has_overflow() && static_cast<size_t>(checked_end.value()) <= instance->data().size());
if (count == 0)
TAILCALL return continue_(HANDLER_PARAMS(DECOMPOSE_PARAMS_NAME_ONLY));
Instruction::MemoryArgument memarg { 0, 0, args.memory_index };
for (u32 i = 0; i < count; ++i) {
if (interpreter.store_to_memory(configuration, memarg, { &value, sizeof(value) }, destination_offset + i))
for (u64 i = 0; i < count; ++i) {
if (interpreter.store_to_memory(*instance, destination_offset + i, value))
return Outcome::Return;
}
}
@ -1624,17 +1623,16 @@ HANDLE_INSTRUCTION(memory_copy)
if (count == 0)
TAILCALL return continue_(HANDLER_PARAMS(DECOMPOSE_PARAMS_NAME_ONLY));
Instruction::MemoryArgument memarg { 0, 0, args.dst_index };
if (destination_offset <= source_offset) {
for (auto i = 0; i < count; ++i) {
auto value = source_instance->data()[source_offset + i];
if (interpreter.store_to_memory(configuration, memarg, { &value, sizeof(value) }, destination_offset + i))
if (interpreter.store_to_memory(*destination_instance, destination_offset + i, value))
return Outcome::Return;
}
} else {
for (auto i = count - 1; i >= 0; --i) {
auto value = source_instance->data()[source_offset + i];
if (interpreter.store_to_memory(configuration, memarg, { &value, sizeof(value) }, destination_offset + i))
if (interpreter.store_to_memory(*destination_instance, destination_offset + i, value))
return Outcome::Return;
}
}
@ -1664,10 +1662,9 @@ HANDLE_INSTRUCTION(memory_init)
if (count == 0)
TAILCALL return continue_(HANDLER_PARAMS(DECOMPOSE_PARAMS_NAME_ONLY));
Instruction::MemoryArgument memarg { 0, 0, args.memory_index };
for (size_t i = 0; i < (size_t)count; ++i) {
auto value = data.data()[source_offset + i];
if (interpreter.store_to_memory(configuration, memarg, { &value, sizeof(value) }, destination_offset + i))
if (interpreter.store_to_memory(*memory, destination_offset + i, value))
return Outcome::Return;
}
TAILCALL return continue_(HANDLER_PARAMS(DECOMPOSE_PARAMS_NAME_ONLY));
@ -3984,18 +3981,34 @@ bool BytecodeInterpreter::pop_and_store_lane_n(Configuration& configuration, Ins
bool BytecodeInterpreter::store_to_memory(Configuration& configuration, Instruction::MemoryArgument const& arg, ReadonlyBytes data, u32 base)
{
auto& address = configuration.frame().module().memories().data()[arg.memory_index.value()];
auto const& address = configuration.frame().module().memories().data()[arg.memory_index.value()];
auto memory = configuration.store().get(address);
u64 instance_address = static_cast<u64>(base) + arg.offset;
Checked addition { instance_address };
addition += data.size();
if (addition.has_overflow() || addition.value() > memory->size()) [[unlikely]] {
return store_to_memory(*memory, instance_address, data);
}
template<typename T>
bool BytecodeInterpreter::store_to_memory(MemoryInstance& memory, u64 address, T value)
{
Checked addition { address };
size_t data_size;
if constexpr (IsSame<ReadonlyBytes, T>)
data_size = value.size();
else
data_size = sizeof(T);
addition += data_size;
if (addition.has_overflow() || addition.value() > memory.size()) [[unlikely]] {
m_trap = Trap::from_string("Memory access out of bounds");
dbgln_if(WASM_TRACE_DEBUG, "LibWasm: Memory access out of bounds (expected 0 <= {} and {} <= {})", instance_address, instance_address + data.size(), memory->size());
dbgln_if(WASM_TRACE_DEBUG, "LibWasm: Memory access out of bounds (expected 0 <= {} and {} <= {})", address, address + data_size, memory.size());
return true;
}
dbgln_if(WASM_TRACE_DEBUG, "temporary({}b) -> store({})", data.size(), instance_address);
(void)data.copy_to(memory->data().bytes().slice(instance_address, data.size()));
dbgln_if(WASM_TRACE_DEBUG, "temporary({}b) -> store({})", data_size, address);
if constexpr (IsSame<ReadonlyBytes, T>)
(void)value.copy_to(memory.data().bytes().slice(address, data_size));
else
memcpy(memory.data().bytes().offset_pointer(address), &value, data_size);
return false;
}