Ledger LandISSUE #28 of 90

evm · opcodes · stack · memory · storage

BlockyVSDouble-Spend Dan

Blocky saysThe EVM works with opcodes over a stack, volatile memory, and persistent storage.

EVM bytecode is a sequence of opcodes (ADD, SSTORE, CALL…) operating on a stack. Three data areas matter: the stack (cheap, transient), memory (cheap, cleared each call), and storage (persistent on-chain, expensive — every SSTORE costs significant gas). Knowing storage is the costly one is why gas optimization centers on minimizing writes.

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Opcodes operate on a stack
memory: transient, cheap
storage: persistent, expensive (SSTORE)
Gas optimization = minimize storage writes

Double-Spend Dan attacks — common mistakes

Writing to storage when memory would do
Ignoring that each SSTORE is costly
Confusing transient memory with persistent storage

Boss battleRank stack, memory, and storage by gas cost and explain why.

Example code

<!doctype html><html><head><meta charset="utf-8"></head>
<body style="background:#06040d;color:#e6e0ff;font-family:monospace;padding:20px"><pre>stack   → cheapest, transient
memory  → cheap, cleared per call
storage → persistent, EXPENSIVE (SSTORE)
→ optimize by writing storage less</pre></body></html>

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