mipsevm,contracts: reduce step arguments

contracts/src/MIPS.sol

@@ -310,8 +310,8 @@ contract MIPS {
 
   function proofOffset(uint8 proofIndex) internal pure returns (uint256 offset) {
     // A proof of 32 bit memory, with 32-byte leaf values, is (32-5)=27 bytes32 entries.
-    // And the leaf value itself needs to be encoded as well. And proof.offset == 390
-    offset = 390 + (uint256(proofIndex) * (28*32));
+    // And the leaf value itself needs to be encoded as well. And proof.offset == 358
+    offset = 358 + (uint256(proofIndex) * (28*32));
     uint256 s = 0;
     assembly { s := calldatasize() }
     require(s >= (offset + 28*32), "check that there is enough calldata");
@@ -379,7 +379,7 @@ contract MIPS {
   }
 
   // will revert if any required input state is missing
-  function Step(bytes32 stateHash, bytes calldata stateData, bytes calldata proof) public returns (bytes32) {
+  function Step(bytes calldata stateData, bytes calldata proof) public returns (bytes32) {
     State memory state;
     // packed data is ~6 times smaller
     assembly {
@@ -389,10 +389,10 @@ contract MIPS {
       if iszero(eq(mload(0x40), mul(32, 48))) { // expected memory check
         revert(0,0)
       }
-      if iszero(eq(stateData.offset, 132)) { // 32*4+4=132 expected state data offset
+      if iszero(eq(stateData.offset, 100)) { // 32*3+4=100 expected state data offset
         revert(0,0)
       }
-      if iszero(eq(proof.offset, 390)) { // 132+32+226=390 expected proof offset
+      if iszero(eq(proof.offset, 358)) { // 100+32+226=358 expected proof offset
         revert(0,0)
       }
       function putField(callOffset, memOffset, size) -> callOffsetOut, memOffsetOut {
@@ -420,7 +420,7 @@ contract MIPS {
       for { let i := 0 } lt(i, 32) { i := add(i, 1) } { c, m := putField(c, m, 4) } // registers
     }
     if(state.exited) { // don't change state once exited
-      return stateHash;
+      return outputState();
     }
     state.step += 1;
 

mipsevm/evm.go

@@ -21,7 +21,7 @@ import (
 )
 
 var (
-	StepBytes4                      = crypto.Keccak256([]byte("Step(bytes32,bytes,bytes)"))[:4]
+	StepBytes4                      = crypto.Keccak256([]byte("Step(bytes,bytes)"))[:4]
 	CheatBytes4                     = crypto.Keccak256([]byte("cheat(uint256,bytes32,bytes32,uint256)"))[:4]
 	LoadKeccak256PreimagePartBytes4 = crypto.Keccak256([]byte("loadKeccak256PreimagePart(uint256,bytes)"))[:4]
 )

mipsevm/witness.go

@@ -5,8 +5,6 @@ import (
 	"errors"
 	"fmt"
 
-	"github.com/ethereum/go-ethereum/crypto"
-
 	"github.com/ethereum-optimism/cannon/preimage"
 )
 
@@ -28,12 +26,10 @@ func uint32ToBytes32(v uint32) []byte {
 }
 
 func (wit *StepWitness) EncodeStepInput() []byte {
-	stateHash := crypto.Keccak256Hash(wit.State)
 	var input []byte
 	input = append(input, StepBytes4...)
-	input = append(input, stateHash[:]...)
-	input = append(input, uint32ToBytes32(32*3)...)                           // state data offset in bytes
-	input = append(input, uint32ToBytes32(32*3+32+uint32(len(wit.State)))...) // proof data offset in bytes
+	input = append(input, uint32ToBytes32(32*2)...)                           // state data offset in bytes
+	input = append(input, uint32ToBytes32(32*2+32+uint32(len(wit.State)))...) // proof data offset in bytes
 
 	input = append(input, uint32ToBytes32(uint32(len(wit.State)))...) // state data length in bytes
 	input = append(input, wit.State[:]...)