feat(ctb): Proper contract ABI for MIPS.sol

This is necessary so the FaultDisputeGame can easily interact with the
MIPS VM. MIPS.step previously required a non-standard calldata format where the
packed state and proofs did not contain any padding. As such, interacting
with the VM contract in Solidity required careful and expensive construction
of calldata.

cannon/mipsevm/witness.go

@@ -26,13 +26,21 @@ func uint32ToBytes32(v uint32) []byte {
 }
 
 func (wit *StepWitness) EncodeStepInput() []byte {
+	abiStateLen := len(wit.State)
+	if abiStateLen%32 != 0 {
+		abiStateLen += 32 - (abiStateLen % 32)
+	}
+	// pad state to 32 byte multiple per ABI
+	abiState := make([]byte, abiStateLen)
+	copy(abiState, wit.State)
+
 	var input []byte
 	input = append(input, StepBytes4...)
 	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(32*2+32+uint32(len(abiState)))...) // proof data offset in bytes
 
 	input = append(input, uint32ToBytes32(uint32(len(wit.State)))...) // state data length in bytes
-	input = append(input, wit.State[:]...)
+	input = append(input, abiState[:]...)
 	input = append(input, uint32ToBytes32(uint32(len(wit.MemProof)))...) // proof data length in bytes
 	input = append(input, wit.MemProof[:]...)
 	return input

op-chain-ops/srcmap/solutil.go

@@ -220,6 +220,13 @@ func (s *SourceMapTracer) info(codeAddr *common.Address, pc uint64) string {
 }
 
 func (s *SourceMapTracer) CaptureState(pc uint64, op vm.OpCode, gas, cost uint64, scope *vm.ScopeContext, rData []byte, depth int, err error) {
+	if op.IsPush() {
+		start := uint64(op) - uint64(vm.PUSH1) + 1
+		end := pc + 1 + start
+		val := scope.Contract.Code[pc+1 : end]
+		fmt.Fprintf(s.out, "%-40s : pc %x opcode %s (%x)\n", s.info(scope.Contract.CodeAddr, pc), pc, op.String(), val)
+		return
+	}
 	fmt.Fprintf(s.out, "%-40s : pc %x opcode %s\n", s.info(scope.Contract.CodeAddr, pc), pc, op.String())
 }
 

packages/contracts-bedrock/src/cannon/MIPS.sol

@@ -478,8 +478,8 @@ contract MIPS {
     function proofOffset(uint8 _proofIndex) internal pure returns (uint256 offset_) {
         unchecked {
             // 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 == 358
-            offset_ = 358 + (uint256(_proofIndex) * (28 * 32));
+            // And the leaf value itself needs to be encoded as well. And proof.offset == 388
+            offset_ = 388 + (uint256(_proofIndex) * (28 * 32));
             uint256 s = 0;
             assembly { s := calldatasize() }
             require(s >= (offset_ + 28 * 32), "check that there is enough calldata");
@@ -614,7 +614,7 @@ contract MIPS {
                 if iszero(eq(stateData.offset, 100)) { // 32*3+4=100 expected state data offset
                     revert(0,0)
                 }
-                if iszero(eq(proof.offset, 358)) { // 100+32+226=358 expected proof offset
+                if iszero(eq(proof.offset, 388)) { // 100+32+256=388 expected proof offset
                     revert(0,0)
                 }
 

packages/contracts-bedrock/test/MIPS.t.sol

+// SPDX-License-Identifier: MIT
+pragma solidity 0.8.15;
+
+import { Test } from "forge-std/Test.sol";
+import { MIPS } from "src/cannon/MIPS.sol";
+import { PreimageOracle } from "src/cannon/PreimageOracle.sol";
+
+contract MIPS_Test is Test {
+    MIPS internal mips;
+    PreimageOracle internal oracle;
+
+    function setUp() public {
+        oracle = new PreimageOracle();
+        mips = new MIPS();
+        vm.store(address(mips), 0x0, bytes32(abi.encode(address(oracle))));
+        vm.label(address(oracle), "PreimageOracle");
+        vm.label(address(mips), "MIPS");
+    }
+
+    function test_step_abi() external {
+        uint32[32] memory registers;
+        registers[16] = 0xbfff0000;
+        MIPS.State memory state = MIPS.State({
+            memRoot: hex"30be14bdf94d7a93989a6263f1e116943dc052d584730cae844bf330dfddce2f",
+            preimageKey: bytes32(0),
+            preimageOffset: 0,
+            pc: 4,
+            nextPC: 8,
+            lo: 0,
+            hi: 0,
+            heap: 0,
+            exitCode: 0,
+            exited: false,
+            step: 1,
+            registers: registers
+        });
+        bytes memory proof = hex"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";
+
+        bytes32 postState = mips.step(encodeState(state), proof);
+        assertTrue(postState != bytes32(0));
+    }
+
+    function encodeState(MIPS.State memory state) internal pure returns (bytes memory) {
+        bytes memory registers;
+        for (uint i = 0; i < state.registers.length; i++) {
+            registers = bytes.concat(registers, abi.encodePacked(state.registers[i]));
+        }
+        return abi.encodePacked(
+            state.memRoot,
+            state.preimageKey,
+            state.preimageOffset,
+            state.pc,
+            state.nextPC,
+            state.lo,
+            state.hi,
+            state.heap,
+            state.exitCode,
+            state.exited,
+            state.step,
+            registers
+        );
+    }
+}