TVM upgrade Feb 2025

tip

This upgrade is active on the Mainnet since February 13, 2025. See details here.

This update is enabled with Config8 version >= 9.

c7 tuple extension

The c7 tuple parameter number 13 (previous blocks info tuple) now has a third element, containing IDs of the last 16 masterchain blocks with seqno divisible by 100.

Example: if the last masterchain block seqno is 19071, the list contains block IDs with seqnos 19000, 18900, ..., 17500.

New TVM instructions - cryptographic and continuation operations

Fift syntax	Stack	Description
SECP256K1_XONLY_PUBKEY_TWEAK_ADD	key tweak - 0 or f x y -1	Performs secp256k1_xonly_pubkey_tweak_add. Inputs are two 256-bit unsigned integers (key, tweak). Returns a 65-byte public key as uint8 f, uint256 x, uint256 y (similar to ECRECOVER). Gas cost: 1276.
mask SETCONTCTRMANY	cont - cont'	For each bit set in mask (range 0..255), applies c[i] PUSHCTR SWAP c[i] SETCONTCNR to the continuation. Efficiently updates multiple continuations.
SETCONTCTRMANYX	cont mask - cont'	Same as SETCONTCTRMANY, but reads mask from the stack.
PREVMCBLOCKS_100	- list	Returns the new third element in c7[13]: a list of 16 recent masterchain block IDs (where seqno is divisible by 100).

Execution and gas logic improvements

• When the RAWRESERVE action uses flag 4, the original balance is calculated as balance - msg_balance_remaining. Previously, this calculation did not work correctly if the storage fee exceeded the original balance.
• The gas cost for continuation jumps deeper than 8 levels is increased by one additional gas unit per extra level.
• Jumps to continuations with non-null control data now execute without error.
• The RESERVE action in mode +2 supports reserving extra currencies in addition to TON.
• Executing contract code from a library cell does not consume additional gas.
• Accounts with previously locked highload-v2 wallets are assigned higher gas limits to enable unlocking and improved operation.

Error handling improvements

If these instructions encounter multiple error conditions, the TVM prioritizes stk_und (stack underflow) over other errors.

Fift syntax	Stack	Description
GETGASFEE	gas_used is_mc - price	Calculates the computation cost in nanotons for a transaction that consumes gas_used gas.
GETSTORAGEFEE	cells bits seconds is_mc - price	Calculates the storage fees in nanotons for the contract based on current storage prices. cells and bits represent the size of the AccountState with deduplication, including the root cell.
GETFORWARDFEE	cells bits is_mc - price	Calculates forward fees in nanotons for an outgoing message. is_mc is true if the source or the destination is in the MasterChain and false if both are in the basechain.
GETORIGINALFWDFEE	fwd_fee is_mc - orig_fwd_fee	Calculates fwd_fee * 2^16 / first_frac. Used to derive the original forwarding fee.
GETGASFEESIMPLE	gas_used is_mc - price	Computes simplified gas cost using (gas_used * price) / 2^16.
GETFORWARDFEESIMPLE	cells bits is_mc - price	Computes simplified forwarding fee using (bits * bit_price + cells * cell_price) / 2^16.
HASHEXT	cell i - hash	Computes an extended hash of a cell at the given index.
PFXDICTSET	x k D n – D0 −1 or D 0	Sets a value in a prefix code dictionary. Fails if prefix constraints are violated.
PFXDICTREPLACE	x k D n – D0 −1 or D 0	Replaces a value in a prefix code dictionary if constraints are satisfied.
PFXDICTADD	x k D n – D0 −1 or D 0	Adds an entry to a prefix code dictionary. Fails if entry already exists.
PFXDICTDEL	k D n – D0 −1 or D 0	Deletes an entry from a prefix code dictionary.

Emulator and validator improvements

Validator nodes now perform more reliable IP discovery by retrying DHT queries, making it easier to locate updated peers during upgrades or restarts. The validator console also displays dashed names and shard formats in a more readable format, helping operators better monitor network activity.

In the emulator, handling of library cells and extra currency operations has been improved to provide more accurate behavior during local testing. Support for extra currencies has been refined across both rungetmethod and reserve modes, ensuring compatibility for contracts that rely on multi-currency interactions.

TL-B schema fixes

• Corrected CRC computations ensuring accurate validation of TL-B schema data.
• Fixed incorrect tags in Merkle proofs, improving proof reliability.
• Improved handling of advance_ext for better spec alignment.
• Fixed NatWidth print function to properly display natural width representations.

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