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Merge pull request #123 from zama-ai/docs/update-0.5.0
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Docs/update 0.5.0
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immortal-tofu authored Jun 20, 2024
2 parents 3a576c4 + 4beef31 commit 6f02d11
Showing 1 changed file with 19 additions and 77 deletions.
96 changes: 19 additions & 77 deletions docs/getting_started/Integration.md
Original file line number Diff line number Diff line change
Expand Up @@ -143,18 +143,6 @@ to:
RunPrecompiledContract(p, evm, caller.Address(), addr, input, gas)
```

#### Rewrite `Create` and `Create2` by a call to their fhevm implementation

```go
func (evm *EVM) Create(caller ContractRef, code []byte, gas uint64, value *big.Int) (ret []byte, contractAddr common.Address, leftOverGas uint64, err error) {
return fhevm.Create(evm.FhevmEnvironment(), caller.Address(), code, gas, value)
}

func (evm *EVM) Create2(caller ContractRef, code []byte, gas uint64, endowment *big.Int, salt *uint256.Int) (ret []byte, contractAddr common.Address, leftOverGas uint64, err error) {
return fhevm.Create2(evm.FhevmEnvironment(), caller.Address(), code, gas, endowment, salt)
}
```

#### Implement EVMEnvironment interface

Now implement the `fhevm.EVMEnvironment` interface for `FhevmImplementation`:
Expand Down Expand Up @@ -232,66 +220,14 @@ func (evm *FhevmImplementation) CreateContract2(caller common.Address, code []by

### Step 5: update `core/vm/instructions.go`

#### Update `opSload`, `opSstore` and `opReturn`
#### Update `opSstore`

Rewrite `opSload`, `opSstore` and `opReturn` by a call to their fhevm implementation:
Rewrite `opSstore` by a call to their fhevm implementation:

```go
func opSload(pc *uint64, interpreter *EVMInterpreter, scope *ScopeContext) ([]byte, error) {
return fhevm.OpSload(pc, interpreter.evm.FhevmEnvironment(), scope)
}

func opSstore(pc *uint64, interpreter *EVMInterpreter, scope *ScopeContext) ([]byte, error) {
return fhevm.OpSstore(pc, interpreter.evm.FhevmEnvironment(), scope)
}

func opReturn(pc *uint64, interpreter *EVMInterpreter, scope *ScopeContext) ([]byte, error) {
return fhevm.OpReturn(pc, interpreter.evm.FhevmEnvironment(), scope), errStopToken
}
```

#### Update `opCall`, `opCallCode` and `opStaticCall`

In `opCall`, `opCallCode` and `opStaticCall`, add lines to delegate ciphertexts before the call and to restore at the end of function (using `defer`)

{% hint style="info" %}
There might be other functions that calls other contracts (e.g. `opDelegateCall`), in which case you will also need to do the same modifications as below. Basically, anything that will execute code after incrementing the depth would need this.
{% endhint %}

Add the 2 following lines:

```go
verifiedBefore := fhevm.DelegateCiphertextHandlesInArgs(interpreter.evm.FhevmEnvironment(), args)
defer fhevm.RestoreVerifiedDepths(interpreter.evm.FhevmEnvironment(), verifiedBefore)
```

The call function is named differently in the 3 functions to update:

```go
ret, returnGas, err := interpreter.evm.Call(scope.Contract, toAddr, args, gas, bigVal)
```

#### Update `opSelfdestruct`

In:

```go
func opSelfdestruct(pc *uint64, interpreter *EVMInterpreter, scope *ScopeContext) ([]byte, error)
```

Replace the following lines:

```go
beneficiary := scope.Stack.pop()
balance := interpreter.evm.StateDB.GetBalance(scope.Contract.Address())
interpreter.evm.StateDB.AddBalance(beneficiary.Bytes20(), balance)
interpreter.evm.StateDB.SelfDestruct(scope.Contract.Address())
```

with this call to the fhevm:

```go
beneficiary, balance := fhevm.OpSelfdestruct(pc, interpreter.evm.FhevmEnvironment(), scope)
```

### Step 6: update `core/vm/interpreter.go`
Expand Down Expand Up @@ -327,15 +263,6 @@ In:
func (in *EVMInterpreter) Run(contract *Contract, input []byte, readOnly bool) (ret []byte, err error)
```

- Add the deletion of verified ciphertexts at current depth in the `defer` at the top:

```go
defer func() {
fhevm.RemoveVerifiedCipherextsAtCurrentDepth(in.evm.FhevmEnvironment())
in.evm.depth--
}()
```

### Step 7: update `core/vm/stack.go`

#### Implement the following methods
Expand All @@ -350,7 +277,22 @@ func (st *Stack) Peek() *uint256.Int {
}
```

### Step 8: update `internal/ethapi/api.go`
### Step 8: update `core/vm/operations_acl.go`

#### Implement gas cost for storing a ciphertext

In `func makeGasSStoreFunc(clearingRefund uint64) gasFunc {`

Just before `original := evm.StateDB.GetCommittedState(contract.Address(), x.Bytes32())`, add this block to increase SSTORE gas cost for storing a ciphertext:

```go
ct := fhevm.GetCiphertextFromMemory(evm.FhevmEnvironment(), value)
if ct != nil {
cost += evm.fhevmEnvironment.params.GasCosts.FheStorageSstoreGas[ct.Type()]
}
```

### Step 9: update `internal/ethapi/api.go`

- Add `isGasEstimation, isEthCall bool` arguments to `func doCall` and pass them in `vm.Config` during EVM creation:

Expand All @@ -361,6 +303,6 @@ evm, vmError := b.GetEVM(ctx, msg, state, header, &vm.Config{NoBaseFee: true, Is
- Add `isGasEstimation, isEthCall bool` arguments to `func DoCall` and forward them in the call to `doCall`
- Update usages of `doCall` and `DoCall` by simply setting `IsEthCall` to `true` when it’s a call, and `IsGasEstimation` to `true` when it’s estimating gas

### Step 9: update `graphql/graphql.go`
### Step 10: update `graphql/graphql.go`

Update usages of `doCall` and `DoCall` by simply setting `IsEthCall` to `true` when it’s a call, and `IsGasEstimation` to `true` when it’s estimating gas

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