Add RVRT instruction implementation (#27)

`RVRT` halts the execution of the VM and revert the storage changes.

src/interpreter/executors/debug.rs

@@ -17,6 +17,8 @@ where
 
             ProgramState::ReturnData(d) => Ok(ProgramState::ReturnData(d)),
 
+            ProgramState::Revert(w) => Ok(ProgramState::Revert(w)),
+
             ProgramState::RunProgram(_) => self.run_program(),
 
             ProgramState::VerifyPredicate(_) => unimplemented!(),

src/interpreter/executors/instruction.rs

@@ -277,6 +277,10 @@ where
                 result = Ok(ExecuteState::ReturnData(digest));
             }
 
+            Opcode::RVRT(ra) if self.gas_charge(&op).is_ok() && self.revert(self.registers[ra]).is_ok() => {
+                result = Ok(ExecuteState::Revert(self.registers[ra]))
+            }
+
             Opcode::ALOC(ra) if self.gas_charge(&op).is_ok() && self.malloc(self.registers[ra]).is_ok() => {}
 
             Opcode::CFEI(imm)
@@ -467,7 +471,6 @@ where
 
             Opcode::LDC(_ra, _rb, _rc) => result = Err(InterpreterError::OpcodeUnimplemented(op)),
             Opcode::SLDC(_ra, _rb, _rc) => result = Err(InterpreterError::OpcodeUnimplemented(op)),
-            Opcode::RVRT(_ra) => result = Err(InterpreterError::OpcodeUnimplemented(op)),
             Opcode::TR(_ra, _rb, _rc) => result = Err(InterpreterError::OpcodeUnimplemented(op)),
             Opcode::TRO(_ra, _rb, _rc, _rd) => result = Err(InterpreterError::OpcodeUnimplemented(op)),
             Opcode::Undefined => result = Err(InterpreterError::OpcodeFailure(op)),

src/interpreter/executors/main.rs

@@ -137,12 +137,16 @@ where
                     return Ok(ProgramState::ReturnData(d));
                 }
 
+                ExecuteState::Revert(r) => {
+                    return Ok(ProgramState::Revert(r));
+                }
+
+                ExecuteState::Proceed => (),
+
                 #[cfg(feature = "debug")]
                 ExecuteState::DebugEvent(d) => {
                     return Ok(ProgramState::RunProgram(d));
                 }
-
-                _ => (),
             }
         }
     }

src/interpreter/executors/predicate.rs

@@ -38,12 +38,14 @@ where
                 // A predicate is not expected to return data
                 ExecuteState::ReturnData(_) => return Err(InterpreterError::PredicateFailure),
 
+                ExecuteState::Revert(r) => return Ok(ProgramState::Revert(r)),
+
+                ExecuteState::Proceed => (),
+
                 #[cfg(feature = "debug")]
                 ExecuteState::DebugEvent(d) => {
                     return Ok(ProgramState::VerifyPredicate(d));
                 }
-
-                _ => (),
             }
 
             if self.registers[REG_PC] < pc || self.registers[REG_PC] >= end {

src/interpreter/flow.rs

@@ -156,6 +156,7 @@ where
         self.registers[REG_RET] = a;
         self.registers[REG_RETL] = 0;
 
+        // TODO if ret instruction is in memory boundary, inc_pc shouldn't fail
         self.return_from_context(receipt)
     }
 
@@ -181,4 +182,26 @@ where
 
         self.return_from_context(receipt)
     }
+
+    pub(crate) fn revert(&mut self, a: Word) -> Result<(), InterpreterError> {
+        let receipt = Receipt::revert(
+            self.internal_contract_or_default(),
+            a,
+            self.registers[REG_PC],
+            self.registers[REG_IS],
+        );
+
+        self.receipts.push(receipt);
+
+        // TODO
+        // All OutputContract outputs will have the same amount and stateRoot as on
+        // initialization.
+        //
+        // All OutputVariable outputs will have to and amount of zero.
+        //
+        // All OutputContractConditional outputs will have contractID, amount, and
+        // stateRoot of zero.
+
+        Ok(())
+    }
 }

src/state.rs

@@ -21,6 +21,7 @@ pub enum ExecuteState {
     Proceed,
     Return(Word),
     ReturnData(Bytes32),
+    Revert(Word),
 
     #[cfg(feature = "debug")]
     DebugEvent(DebugEval),
@@ -44,6 +45,7 @@ impl From<DebugEval> for ExecuteState {
 pub enum ProgramState {
     Return(Word),
     ReturnData(Bytes32),
+    Revert(Word),
 
     #[cfg(feature = "debug")]
     RunProgram(DebugEval),

tests/flow.rs

@@ -1,3 +1,5 @@
+use fuel_tx::crypto::Hasher;
+use fuel_types::bytes;
 use fuel_vm::consts::*;
 use fuel_vm::prelude::*;
 use rand::rngs::StdRng;
@@ -285,3 +287,186 @@ fn call_frame_code_offset() {
     assert_eq!(ssp, fp + stack);
     assert_eq!(ssp, sp_p);
 }
+
+#[test]
+fn revert() {
+    let rng = &mut StdRng::seed_from_u64(2322u64);
+
+    let mut client = MemoryClient::default();
+
+    let gas_price = 0;
+    let gas_limit = 1_000_000;
+    let maturity = 0;
+
+    let salt: Salt = rng.gen();
+
+    #[rustfmt::skip]
+    let call_arguments_parser: Vec<Opcode> = vec![
+        Opcode::ADDI(0x10, REG_FP, CallFrame::a_offset() as Immediate12),
+        Opcode::LW(0x10, 0x10, 0),
+        Opcode::ADDI(0x11, REG_FP, CallFrame::b_offset() as Immediate12),
+        Opcode::LW(0x11, 0x11, 0),
+    ];
+
+    #[rustfmt::skip]
+    let routine_add_word_to_state: Vec<Opcode> = vec![
+        Opcode::JNEI(0x10, 0x30, 13),       // (0, b) Add word to state
+        Opcode::LW(0x20, 0x11, 4),          // r[0x20]      := m[b+32, 8]
+        Opcode::SRW(0x21, 0x11),            // r[0x21]      := s[m[b, 32], 8]
+        Opcode::ADD(0x20, 0x20, 0x21),      // r[0x20]      += r[0x21]
+        Opcode::SWW(0x11, 0x20),            // s[m[b,32]]   := r[0x20]
+        Opcode::LOG(0x20, 0x21, 0x00, 0x00),
+        Opcode::RET(REG_ONE),
+    ];
+
+    let program: Witness = call_arguments_parser
+        .into_iter()
+        .chain(routine_add_word_to_state.into_iter())
+        .collect::<Vec<u8>>()
+        .into();
+
+    let contract = Contract::from(program.as_ref());
+    let contract_root = contract.root();
+    let contract = contract.id(&salt, &contract_root);
+
+    let output = Output::contract_created(contract);
+
+    let bytecode_witness = 0;
+    let tx = Transaction::create(
+        gas_price,
+        gas_limit,
+        maturity,
+        bytecode_witness,
+        salt,
+        vec![],
+        vec![],
+        vec![output],
+        vec![program],
+    );
+
+    // Deploy the contract into the blockchain
+    client.transition(vec![tx]).expect("Failed to transact");
+
+    let input = Input::contract(rng.gen(), rng.gen(), rng.gen(), contract);
+    let output = Output::contract(0, rng.gen(), rng.gen());
+
+    // The script needs to locate the data offset at runtime. Hence, we need to know
+    // upfront the serialized size of the script so we can set the registers
+    // accordingly.
+    //
+    // This variable is created to assert we have correct script size in the
+    // instructions.
+    let script_len = 16;
+
+    // Based on the defined script length, we set the appropriate data offset
+    let script_data_offset = VM_TX_MEMORY + Transaction::script_offset() + script_len;
+    let script_data_offset = script_data_offset as Immediate12;
+
+    let script = vec![
+        Opcode::ADDI(0x10, REG_ZERO, script_data_offset),
+        Opcode::ADDI(0x11, REG_ZERO, gas_limit as Immediate12),
+        Opcode::CALL(0x10, REG_ZERO, 0x10, 0x11),
+        Opcode::RET(REG_ONE),
+    ]
+    .iter()
+    .copied()
+    .collect::<Vec<u8>>();
+
+    // Assert the offsets are set correctnly
+    let offset = VM_TX_MEMORY + Transaction::script_offset() + bytes::padded_len(script.as_slice());
+    assert_eq!(script_data_offset, offset as Immediate12);
+
+    let mut script_data = vec![];
+
+    // Routine to be called: Add word to state
+    let routine: Word = 0;
+
+    // Offset of the script data relative to the call data
+    let call_data_offset = script_data_offset as usize + ContractId::LEN + 2 * WORD_SIZE;
+    let call_data_offset = call_data_offset as Word;
+
+    // Key and value to be added
+    let key = Hasher::hash(b"some key");
+    let val: Word = 150;
+
+    // Script data containing the call arguments (contract, a, b) and (key, value)
+    script_data.extend(contract.as_ref());
+    script_data.extend(&routine.to_be_bytes());
+    script_data.extend(&call_data_offset.to_be_bytes());
+    script_data.extend(key.as_ref());
+    script_data.extend(&val.to_be_bytes());
+
+    let tx = Transaction::script(
+        gas_price,
+        gas_limit,
+        maturity,
+        script.clone(),
+        script_data,
+        vec![input.clone()],
+        vec![output],
+        vec![],
+    );
+
+    // Assert the initial state of `key` is empty
+    let state = client.as_ref().contract_state(&contract, &key);
+    assert_eq!(Bytes32::default(), state.into_owned());
+
+    let receipts = client.transition(vec![tx]).expect("Failed to transact");
+    let state = client.as_ref().contract_state(&contract, &key);
+
+    // Assert the state of `key` is mutated to `val`
+    assert_eq!(&val.to_be_bytes()[..], &state.as_ref()[..WORD_SIZE]);
+
+    // Expect the correct receipt
+    assert_eq!(receipts[1].ra().expect("Register value expected"), val);
+    assert_eq!(receipts[1].rb().expect("Register value expected"), 0);
+
+    // Create a script with revert instruction
+    let script = vec![
+        Opcode::ADDI(0x10, REG_ZERO, script_data_offset),
+        Opcode::ADDI(0x11, REG_ZERO, gas_limit as Immediate12),
+        Opcode::CALL(0x10, REG_ZERO, 0x10, 0x11),
+        Opcode::RVRT(REG_ONE),
+    ]
+    .iter()
+    .copied()
+    .collect::<Vec<u8>>();
+
+    let mut script_data = vec![];
+
+    // Value to be added
+    let rev: Word = 250;
+
+    // Script data containing the call arguments (contract, a, b) and (key, value)
+    script_data.extend(contract.as_ref());
+    script_data.extend(&routine.to_be_bytes());
+    script_data.extend(&call_data_offset.to_be_bytes());
+    script_data.extend(key.as_ref());
+    script_data.extend(&rev.to_be_bytes());
+
+    let tx = Transaction::script(
+        gas_price,
+        gas_limit,
+        maturity,
+        script.clone(),
+        script_data,
+        vec![input.clone()],
+        vec![output],
+        vec![],
+    );
+
+    let receipts = client.transition(vec![tx]).expect("Failed to transact");
+    let state = client.as_ref().contract_state(&contract, &key);
+
+    // Assert the state of `key` is reverted to `val`
+    assert_eq!(&val.to_be_bytes()[..], &state.as_ref()[..WORD_SIZE]);
+
+    // Expect the correct receipt
+    assert_eq!(receipts[1].ra().expect("Register value expected"), val + rev);
+    assert_eq!(receipts[1].rb().expect("Register value expected"), val);
+
+    match receipts[3] {
+        Receipt::Revert { ra, .. } if ra == 1 => (),
+        _ => panic!("Expected revert receipt: {:?}", receipts[3]),
+    }
+}