rvgo: Embed witness and stateHash to state

rvgo/cmd/load_elf.go

@@ -32,6 +32,10 @@ func LoadELF(ctx *cli.Context) error {
 	if err != nil {
 		return fmt.Errorf("failed to compute program metadata: %w", err)
 	}
+	// Must set witness and stateHash after initial state is prepared
+	if err := state.SetWitnessAndStateHash(); err != nil {
+		return fmt.Errorf("failed to set witness and stateHash: %w", err)
+	}
 	if err := jsonutil.WriteJSON[*Metadata](ctx.Path(cannon.LoadELFMetaFlag.Name), meta, OutFilePerm); err != nil {
 		return fmt.Errorf("failed to output metadata: %w", err)
 	}

rvgo/cmd/run.go

@@ -223,6 +223,10 @@ func Run(ctx *cli.Context) error {
 		}
 	}
 
+	if err := state.SetWitnessAndStateHash(); err != nil {
+		return fmt.Errorf("failed to set witness and stateHash: %w", err)
+	}
+
 	if err := jsonutil.WriteJSON(ctx.Path(cannon.RunOutputFlag.Name), state, OutFilePerm); err != nil {
 		return fmt.Errorf("failed to write state output: %w", err)
 	}

rvgo/fast/state.go

@@ -50,6 +50,11 @@ type VMState struct {
 	// Warning: the hint MAY NOT BE COMPLETE. I.e. this is buffered,
 	// and should only be read when len(LastHint) > 4 && uint32(LastHint[:4]) >= len(LastHint[4:])
 	LastHint hexutil.Bytes `json:"lastHint,omitempty"`
+
+	// VMState must hold these values because if not, we must ask FPVM again to
+	// compute these values.
+	Witness   []byte   `json:"witness,omitempty"`
+	StateHash [32]byte `json:"stateHash,omitempty"`
 }
 
 func NewVMState() *VMState {
@@ -59,6 +64,17 @@ func NewVMState() *VMState {
 	}
 }
 
+func (state *VMState) SetWitnessAndStateHash() error {
+	witness := state.EncodeWitness()
+	state.Witness = witness
+	stateHash, err := witness.StateHash()
+	if err != nil {
+		return fmt.Errorf("failed to compute stateHash: %w", err)
+	}
+	state.StateHash = stateHash
+	return nil
+}
+
 func (state *VMState) GetStep() uint64 { return state.Step }
 
 func (state *VMState) EncodeWitness() StateWitness {