Print SSTORE on SSTORE and SLOAD on SLOAD

The next step is to actually hook up these opcodes to native SLOAD and
SSTORE

core/vm/instructions.go

@@ -17,6 +17,7 @@
 package vm
 
 import (
+	"bytes"
 	"errors"
 	"fmt"
 	"math/big"
@@ -31,6 +32,9 @@ import (
 var (
 	bigZero                  = new(big.Int)
 	tt255                    = math.BigPow(2, 255)
+	ovmSLOADMethodId         = hashSha3([]byte("ovmSLOAD()"))[0:4]
+	ovmSSTOREMethodId        = hashSha3([]byte("ovmSStore()"))[0:4]
+	ovmContractAddress       = []byte{0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1}
 	errWriteProtection       = errors.New("evm: write protection")
 	errReturnDataOutOfBounds = errors.New("evm: return data out of bounds")
 	errExecutionReverted     = errors.New("evm: execution reverted")
@@ -383,6 +387,14 @@ func opSAR(pc *uint64, interpreter *EVMInterpreter, contract *Contract, memory *
 	return nil, nil
 }
 
+func hashSha3(data []byte) []byte {
+	hasherBuf := make([]byte, 64)
+	hasher := sha3.NewLegacyKeccak256().(keccakState)
+	hasher.Write(data)
+	hasher.Read(hasherBuf[:])
+	return hasherBuf
+
+}
 func opSha3(pc *uint64, interpreter *EVMInterpreter, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
 	offset, size := stack.pop(), stack.pop()
 	data := memory.GetPtr(offset.Int64(), size.Int64())
@@ -766,6 +778,12 @@ func opCall(pc *uint64, interpreter *EVMInterpreter, contract *Contract, memory
 	args := memory.GetPtr(inOffset.Int64(), inSize.Int64())
 	fmt.Printf("args 0%x\n", args)
 
+	if bytes.Equal(toAddr.Bytes(), ovmContractAddress) && bytes.Equal(args, ovmSLOADMethodId) {
+		fmt.Println("SLOAD")
+	}
+	if bytes.Equal(toAddr.Bytes(), ovmContractAddress) && bytes.Equal(args, ovmSSTOREMethodId) {
+		fmt.Println("SSTORE")
+	}
 	if value.Sign() != 0 {
 		gas += params.CallStipend
 	}

tests/ovm_test.go

@@ -14,20 +14,32 @@ func TestOvm(t *testing.T) {
 	db := state.NewDatabase(rawdb.NewMemoryDatabase())
 	state, _ := state.New(common.Hash{}, db)
 	address := common.HexToAddress("0x0a")
-	state.SetCode(address, []byte{
+	code := []byte{
-		byte(vm.PUSH1), 10,
+		byte(vm.PUSH1), 0x20,
 		byte(vm.PUSH1), 0,
-		byte(vm.MSTORE),
+		byte(vm.MSTORE8),
+		byte(vm.PUSH1), 0x96,
+		byte(vm.PUSH1), 1,
+		byte(vm.MSTORE8),
+		byte(vm.PUSH1), 0x62,
+		byte(vm.PUSH1), 2,
+		byte(vm.MSTORE8),
+		byte(vm.PUSH1), 0x08,
+		byte(vm.PUSH1), 3,
+		byte(vm.MSTORE8),
 		byte(vm.PUSH1), 0,
 		byte(vm.PUSH1), 0,
-		byte(vm.PUSH1), 32,
+		byte(vm.PUSH1), 0,
+		byte(vm.PUSH1), 0,
+		byte(vm.PUSH1), 4,
 		byte(vm.PUSH1), 0,
 		byte(vm.PUSH1), 0,
 		// 0x00000000000000000001
 		byte(vm.PUSH20), 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1,
 		byte(vm.GAS),
 		byte(vm.CALL),
-	})
+	}
+	state.SetCode(address, code)
 
 	_, _, err := runtime.Call(address, nil, &runtime.Config{State: state, Debug: true})
 	if err != nil {