feat: EIP-8024 — DUPN, SWAPN, EXCHANGE opcodes (Amsterdam)#11
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garyschulte merged 4 commits intoConsensys:mainfrom Apr 1, 2026
Merged
feat: EIP-8024 — DUPN, SWAPN, EXCHANGE opcodes (Amsterdam)#11garyschulte merged 4 commits intoConsensys:mainfrom
garyschulte merged 4 commits intoConsensys:mainfrom
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Adds three generalized stack manipulation opcodes, each with a 1-byte immediate operand. Gas: G_VERYLOW (3) for all three. - DUPN (0xE6): duplicates stack item at depth (imm+145)%256 - SWAPN (0xE7): swaps top with item at depth (imm+145)%256 - EXCHANGE (0xE8): swaps two non-top items decoded via decode_pair; immediates 82..=127 are invalid (exceptional halt) Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
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garyschulte
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Mar 20, 2026
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LGTM, but cursor bot feedback needs to be fixed
Signed-off-by: garyschulte <garyschulte@gmail.com>
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Summary
Implements EIP-8024 for the Amsterdam hardfork.
Adds three generalized stack manipulation opcodes that take a 1-byte immediate operand, lifting the DUP/SWAP limit beyond 16 items:
DUPN0xE6 nn+1th stack item (1-indexed)SWAPN0xE7 nn+2th itemEXCHANGE0xE8 nimm[7:4]+1th andimm[3:0]+2th itemsG_VERYLOW(3) eachChanges
src/bytecode/main.zig— opcode constants + info entriessrc/interpreter/opcodes/stack.zig—opDupN,opSwapN,opExchangeimplementationssrc/interpreter/opcodes/main.zig— re-exportssrc/interpreter/protocol_schedule.zig—applyAmsterdamChangesactivating the 3 opcodesPart of Amsterdam hardfork
Related PRs: EIP-7843 (SLOTNUM), EIP-7954 (max code size), EIP-7708 (transfer logs), EIP-8037 (state gas reservoir)
Note
Medium Risk
Touches core interpreter execution (new opcodes + dispatch) and modifies gas/memory arithmetic; incorrect edge-case handling could change consensus-critical behavior or gas accounting.
Overview
Implements Amsterdam’s EIP-8024 by adding new opcodes
DUPN(0xE6),SWAPN(0xE7), andEXCHANGE(0xE8), wiring them into opcode metadata and the Amsterdam dispatch table atG_VERYLOW.Adds opcode handlers in
opcodes/stack.zigthat decode 1-byte immediates, enforce EIP-specified invalid immediate ranges (halting withinvalid_opcode), and perform the corresponding stack operations; includes extensive new unit tests covering valid cases and failure modes.Separately hardens memory expansion and
KECCAK256word-cost calculations by switching to overflow-safestd.math.divCeil/mul/addand early bounds checks, returning max costs or halting on overflow instead of wrapping.Written by Cursor Bugbot for commit 528163e. This will update automatically on new commits. Configure here.