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refactor(spec-specs): credit CREATE refund before child incorporation #3099

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refactor(spec-specs): credit CREATE refund before child incorporation #3099

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5 changes: 4 additions & 1 deletion src/ethereum/forks/amsterdam/vm/instructions/system.py
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Original file line number Diff line number Diff line change
Expand Up @@ -162,9 +162,12 @@ def generic_create(
evm.return_data = child_evm.output
push(evm.stack, U256(0))
else:
incorporate_child_on_success(evm, child_evm)
if target_alive:
# Target already existed: no new account, refund the state gas.
# Credit before incorporating the child so the refund reverses
# the parent's own spill only (as the error path does).

@gurukamath gurukamath Jul 13, 2026 •
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If the parent's StateGasCosts.NEW_ACCOUNT charge is covered by the state_gas_reservoir but the child's initcode spills state charges into gas_left and then successfully deploys onto an already-alive address, the two orderings route the refund differently:

  1. The old code credits the child's spill back into gas_left while refunding StateGasCosts.NEW_ACCOUNT
  2. The new code credits everything in StateGasCosts.NEW_ACCOUNT to the reservoir.

Since the GAS opcode excludes the reservoir, this is observable behaviour. Probably needs a test case.

credit_state_gas_refund(evm, StateGasCosts.NEW_ACCOUNT)
incorporate_child_on_success(evm, child_evm)
evm.return_data = b""
push(evm.stack, U256.from_be_bytes(child_evm.message.current_target))

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