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Split args and locals #345

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chfast wants to merge 2 commits into from
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Split args and locals #345

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b887102
Add get_local() helper
chfast May 26, 2020
e78731e
Split args and locals by handling args "in place"
chfast May 26, 2020
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24 changes: 13 additions & 11 deletions lib/fizzy/execute.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -489,6 +489,15 @@ std::optional<uint32_t> find_export(const Module& module, ExternalKind kind, std
return (it != module.exportsec.end() ? std::make_optional(it->index) : std::nullopt);
}

inline uint64_t& get_local(
std::vector<uint64_t>& args, std::vector<uint64_t>& locals, uint32_t idx) noexcept
{
if (idx < args.size())
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@axic axic May 27, 2020

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Without making any further optimisations, isn't this making it slower? Previously we copied arguments once.

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@chfast chfast May 27, 2020

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Much slower. See description.

return args[idx];
assert((idx - args.size()) <= locals.size());
return locals[idx - args.size()];
}

} // namespace

std::unique_ptr<Instance> instantiate(Module module,
Expand Down Expand Up @@ -641,8 +650,7 @@ execution_result execute(
const auto& code = instance.module.codesec[code_idx];
auto* const memory = instance.memory.get();

std::vector<uint64_t> locals = std::move(args);
locals.resize(locals.size() + code.local_count);
std::vector<uint64_t> locals(code.local_count, 0);

OperandStack stack(static_cast<size_t>(code.max_stack_height));

Expand Down Expand Up @@ -842,23 +850,17 @@ execution_result execute(
}
case Instr::local_get:
{
const auto idx = read<uint32_t>(immediates);
assert(idx <= locals.size());
stack.push(locals[idx]);
stack.push(get_local(args, locals, read<uint32_t>(immediates)));
break;
}
case Instr::local_set:
{
const auto idx = read<uint32_t>(immediates);
assert(idx <= locals.size());
locals[idx] = stack.pop();
get_local(args, locals, read<uint32_t>(immediates)) = stack.pop();
break;
}
case Instr::local_tee:
{
const auto idx = read<uint32_t>(immediates);
assert(idx <= locals.size());
locals[idx] = stack.top();
get_local(args, locals, read<uint32_t>(immediates)) = stack.top();
break;
}
case Instr::global_get:
Expand Down