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perf: right-size register tuple allocations #153

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Merged
davydog187 merged 1 commit into from
Feb 27, 2026
Merged

perf: right-size register tuple allocations #153

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7 changes: 4 additions & 3 deletions lib/lua/vm.ex
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Original file line number Diff line number Diff line change
Expand Up @@ -16,9 +16,10 @@ defmodule Lua.VM do
"""
@spec execute(Prototype.t(), State.t()) :: {:ok, list(), State.t()}
def execute(%Prototype{} = proto, state \\ State.new()) do
# Create register file - tuple of nils
# For now, just allocate 256 registers (we'll optimize this later)
registers = Tuple.duplicate(nil, 256)
# Create register file sized to the prototype's needs.
# The +16 buffer covers multi-return expansion slots that the codegen doesn't
# always track in max_registers (call results can land beyond the stated max).
registers = Tuple.duplicate(nil, proto.max_registers + 16)

# Execute the prototype instructions
{results, _final_regs, final_state} =
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6 changes: 3 additions & 3 deletions lib/lua/vm/executor.ex
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Original file line number Diff line number Diff line change
Expand Up @@ -32,7 +32,7 @@ defmodule Lua.VM.Executor do
@spec call_function(term(), list(), State.t()) :: {list(), State.t()}
def call_function({:lua_closure, callee_proto, callee_upvalues}, args, state) do
callee_regs =
Tuple.duplicate(nil, max(callee_proto.max_registers, callee_proto.param_count) + 64)
Tuple.duplicate(nil, max(callee_proto.max_registers, callee_proto.param_count) + 16)

callee_regs =
args
Expand Down Expand Up @@ -499,7 +499,7 @@ defmodule Lua.VM.Executor do

# Create new register file for the callee
callee_regs =
Tuple.duplicate(nil, max(callee_proto.max_registers, callee_proto.param_count) + 64)
Tuple.duplicate(nil, max(callee_proto.max_registers, callee_proto.param_count) + 16)

# Copy arguments into callee registers (params are R[0..N-1])
callee_regs =
Expand Down Expand Up @@ -1104,7 +1104,7 @@ defmodule Lua.VM.Executor do
# Helper: call a function value inline (used by generic_for)
defp call_value({:lua_closure, callee_proto, callee_upvalues}, args, _proto, state) do
callee_regs =
Tuple.duplicate(nil, max(callee_proto.max_registers, callee_proto.param_count) + 64)
Tuple.duplicate(nil, max(callee_proto.max_registers, callee_proto.param_count) + 16)

callee_regs =
args
Expand Down