Automatically merged updates to draft EIP(s) 1985 (#2179)

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EIPS/eip-1985.md

@@ -50,14 +50,15 @@ They restrict the results (i.e. values pushed to the stack) of the instructions
    - `CREATE` (`0xf0`),
    - `CREATE2` (`0xf5`).
 
-4. *buffer size*
+4. *buffer size*, *code size*, *memory size*
    is a range between `0` and `0xffffffff` (`2**32 - 1`, `4294967295`).
    It affects the following instructions:
    - `CALLDATASIZE` (`0x36`),
    - `CODESIZE` (`0x38`),
    - `EXTCODESIZE` (`0x3b`),
    - `RETURNDATASIZE` (`0x3d`),
-   - `MSIZE` (`0x59`).
+   - `MSIZE` (`0x59`),
+   - `PC` (`0x58`).
 
 
 ## Rationale
@@ -85,10 +86,24 @@ IEEE Std 1003.1-2001 (POSIX.1) leaves that definition implementation defined.
 The size of addresses is specified in the [Yellow Paper] as 20 bytes.
 E.g. the `COINBASE` instruction is specified to return *H*<sub>c</sub> ∈ 𝔹<sub>20</sub> which has 20 bytes.
 
+### Memory size
+
+Memory expansion cost is not linear and is determined by the following formula:
+        cost = cost_per_word * number_of_words + (number_of_words ^ 2 / 512)
+
+Expanding to over `2^32 - 1` bytes would cost `35184774742016` gas. This number fits into the gas limit imposed above (`2 ^ 63 - 1`) and would cost around 35184 Ether in a transaction to exhaust, with a 1 GWei gas cost, which can be attained on mainnet.
+
+However, setting the limit `2^32 - 1` is beneficial from a VM design perspective and we believe limiting memory should be done via carefully selecting the block gas limit.
+
+### Code size
+
+[EIP-170](http://eips.ethereum.org/EIPS/eip-170) has implemented a code size limit of 0x6000, however even before that, it was practically impossible to deploy a code blob exceeding `2**32 - 1` bytes in size.
+
 ### Comparing current implementations
 
 - Timestamp is implemented as a 64-bit value in [Aleth], [geth] and [Parity]
 - Block gas limit is implemented as a 64-bit in [Aleth] and [geth]
+- Memory, buffer and code sizes are implemented as 64-bit values in [geth]
 
 ## Backwards Compatibility
 
@@ -104,7 +119,8 @@ TBA
 
 ## References
 
-[EIP-106](https://github.com/ethereum/EIPs/issues/106) proposed the block gas limit to be limited at `2**63 - 1`.
+- [EIP-92](https://github.com/ethereum/EIPs/issues/92) proposed the transaction gas limit to be limited at `2**63 - 1` and had a lengthy discussion about other limits.
+- [EIP-106](https://github.com/ethereum/EIPs/issues/106) proposed the block gas limit to be limited at `2**63 - 1`.
 
 ## TODO