feat(example): caller as local variable (#270)

* feat(example): introduce example for caller

* feat(zint): introduce caller for address

* chore(example): apply no_mangle for internal functions in ERC20

* chore(example) preview tests for caller in memory

codegen/src/codegen/function.rs

@@ -98,8 +98,6 @@ impl Function {
         // Record the offset for validation.
         while let Ok((count, val)) = locals.read() {
             for _ in 0..count {
-                // TODO: the below here is outdated, sp is not required anymore after #245
-
                 // Define locals.
                 self.locals
                     .push(LocalSlot::new(val, LocalSlotType::Variable, sp));

codegen/src/local.rs

@@ -87,7 +87,6 @@ impl Locals {
         let offset = if local.ty() == &LocalSlotType::Parameter {
             self.inner[..index].iter().fold(0, |acc, x| acc + x.align())
         } else {
-            // panic!("This should never be reached");
             self.inner[..index]
                 .iter()
                 .filter(|x| x.ty() == &LocalSlotType::Variable)

codegen/src/visitor/local.rs

@@ -56,7 +56,7 @@ impl Function {
 
     /// Local get for variables.
     fn _local_get_var(&mut self, local_index: usize) -> Result<()> {
-        tracing::trace!("Local get variable: {local_index}");
+        tracing::debug!("Local get variable: {local_index}");
         if local_index + 1 > self.locals.len() {
             // The local we want is not from function arguments
             return Err(Error::InvalidLocalIndex(local_index));

codegen/src/wasm/mod.rs

@@ -154,7 +154,7 @@ impl Env {
     /// Allocate memory slots from local index
     pub fn alloc(&self, index: u32) -> SmallVec<[u8; 4]> {
         let slots = index + self.reserved();
-        tracing::trace!(
+        tracing::debug!(
             "allocating memory for local {index} of function {:?}, slot: {slots}",
             self.index
         );

examples/approval.rs

@@ -0,0 +1,105 @@
+#![cfg_attr(target_arch = "wasm32", no_std)]
+#![cfg_attr(target_arch = "wasm32", no_main)]
+
+extern crate zink;
+
+use zink::{
+    primitives::{Address, U256},
+    DoubleKeyMapping,
+};
+
+#[zink::storage(Address, Address, U256)]
+pub struct Allowance;
+
+#[zink::external]
+pub fn approve(spender: Address, value: U256) -> bool {
+    let owner = Address::caller();
+    _approve(owner, spender, value);
+    true
+}
+
+#[zink::external]
+pub fn spend_allowance(spender: Address, value: U256) -> bool {
+    let owner = Address::caller();
+    let current_allowance = Allowance::get(owner, spender);
+    if current_allowance.lt(U256::max()) {
+        if current_allowance.lt(value) {
+            zink::revert!("ERC20 Insufficient allowance");
+        }
+
+        _approve(owner, spender, current_allowance.sub(value))
+    }
+    true
+}
+
+// NOTE: issue #272
+//
+// #[no_mangle] here is required otherwise the inner functions could
+// not get the passing variables correctly.
+#[no_mangle]
+fn _approve(owner: Address, spender: Address, value: U256) {
+    if owner.eq(Address::empty()) {
+        zink::revert!("ERC20 Invalid approval");
+    }
+
+    if spender.eq(Address::empty()) {
+        zink::revert!("ERC20 Invalid spender");
+    }
+
+    Allowance::set(owner, spender, value);
+}
+
+#[cfg(not(target_arch = "wasm32"))]
+fn main() {}
+
+#[test]
+fn test_approval() -> anyhow::Result<()> {
+    use zint::{Bytes32, Contract, EVM};
+
+    let mut evm = EVM::default().commit(true).caller([1; 20]);
+    let contract = Contract::search("approval")?.compile()?;
+    let info = evm.deploy(&contract.bytecode()?)?;
+    let address = info.address;
+
+    let value = 42;
+
+    let spender = [42; 20];
+    let info = evm
+        .calldata(&contract.encode(&[
+            b"approve(address,uint256)".to_vec(),
+            spender.to_bytes32().to_vec(),
+            value.to_bytes32().to_vec(),
+        ])?)
+        .call(address)?;
+    assert_eq!(info.ret, true.to_bytes32());
+
+    let allowance = evm.storage(
+        address,
+        Allowance::storage_key(Address(evm.caller), Address(spender)),
+    )?;
+    assert_eq!(value.to_bytes32(), allowance);
+
+    // TODO: #273
+    //
+    // error: invalid jump while there are to composed functions
+    //
+    // This could be caused by the `caller()` on stack is not consumed correctly
+    //
+    // // spend allowance
+    // let half_value = 21;
+    // let info = evm
+    //     .calldata(&contract.encode(&[
+    //         b"spend_allowance(address,uint256)".to_vec(),
+    //         spender.to_bytes32().to_vec(),
+    //         half_value.to_bytes32().to_vec(),
+    //     ])?)
+    //     .call(address)?;
+    // println!("{info:?}");
+    // assert_eq!(info.ret, true.to_bytes32());
+    // let allowance = evm.storage(
+    //     address,
+    //     Allowance::storage_key(Address(evm.caller), Address(spender)),
+    // )?;
+    // assert_eq!(half_value.to_bytes32(), allowance);
+    Ok(())
+}

examples/erc20.rs

@@ -60,6 +60,7 @@ pub fn transfer_from(from: Address, to: Address, value: U256) -> bool {
     true
 }
 
+#[no_mangle]
 fn _transfer(from: Address, to: Address, value: U256) {
     if from.eq(Address::empty()) {
         zink::revert!("Empty from address");
@@ -72,6 +73,7 @@ fn _transfer(from: Address, to: Address, value: U256) {
     _update(from, to, value)
 }
 
+#[no_mangle]
 fn _update(from: Address, to: Address, value: U256) {
     if from.eq(Address::empty()) {
         TotalSupply::set(TotalSupply::get().add(value));
@@ -91,6 +93,7 @@ fn _update(from: Address, to: Address, value: U256) {
     }
 }
 
+#[no_mangle]
 fn _mint(account: Address, value: U256) {
     if account.eq(Address::empty()) {
         zink::revert!("ERC20 invalid receiver");
@@ -99,6 +102,7 @@ fn _mint(account: Address, value: U256) {
     _update(Address::empty(), account, value)
 }
 
+#[no_mangle]
 fn _burn(account: Address, value: U256) {
     if account.eq(Address::empty()) {
         zink::revert!("ERC20 invalid sender");
@@ -107,6 +111,7 @@ fn _burn(account: Address, value: U256) {
     _update(account, Address::empty(), value)
 }
 
+#[no_mangle]
 fn _approve(owner: Address, spender: Address, value: U256, _emit_event: bool) {
     if owner.eq(Address::empty()) {
         zink::revert!("ERC20 Invalid approval");
@@ -119,6 +124,7 @@ fn _approve(owner: Address, spender: Address, value: U256, _emit_event: bool) {
     Allowance::set(owner, spender, value);
 }
 
+#[no_mangle]
 fn _spend_allowance(owner: Address, spender: Address, value: U256) {
     let current_allowance = Allowance::get(owner, spender);
     if current_allowance.lt(U256::max()) {
@@ -137,14 +143,13 @@ fn main() {}
 //
 // 1. nested function allocations
 // 2. memory slots for local variables
-#[ignore]
 #[test]
+#[ignore]
 fn deploy() -> anyhow::Result<()> {
     use zint::{Bytes32, Contract, EVM};
 
     let mut contract = Contract::search("erc20")?.compile()?;
-
-    let mut evm = EVM::default();
+    let mut evm = EVM::default().commit(true);
     let name = "The Zink Language";
     let symbol = "zink";
 

zink/src/primitives/address.rs

@@ -21,10 +21,16 @@ impl Address {
         Address(0)
     }
 
+    /// Returns empty address
+    pub fn caller() -> Self {
+        unsafe { ffi::evm::caller() }
+    }
+
     /// if self equal to another
     ///
     /// NOTE: not using core::cmp because it uses registers in wasm
     #[allow(clippy::should_implement_trait)]
+    #[inline(always)]
     pub fn eq(self, other: Self) -> bool {
         unsafe { ffi::address_eq(self, other) }
     }

zink/src/storage/dkmapping.rs

@@ -20,6 +20,7 @@ pub trait DoubleKeyMapping {
     }
 
     /// Set key and value
+    #[inline(always)]
     fn set(key1: Self::Key1, key2: Self::Key2, value: Self::Value) {
         value.push();
         load_double_key(key1, key2, Self::STORAGE_SLOT);

zint/src/evm.rs

@@ -23,6 +23,8 @@ pub const CONTRACT: [u8; 20] = [1; 20];
 /// Wrapper of full REVM
 pub struct EVM<'e> {
     inner: Revm<'e, (), InMemoryDB>,
+    /// Caller for the execution
+    pub caller: [u8; 20],
     /// If commit changes
     commit: bool,
 }
@@ -35,6 +37,7 @@ impl<'e> Default for EVM<'e> {
         let evm = Revm::<'e, (), EmptyDB>::builder().with_db(db).build();
         Self {
             inner: evm,
+            caller: [0; 20],
             commit: false,
         }
     }
@@ -63,11 +66,19 @@ impl<'e> EVM<'e> {
         self
     }
 
+    /// Set caller for the execution
+    pub fn caller(mut self, caller: [u8; 20]) -> Self {
+        self.caller = caller;
+        self
+    }
+
     /// Send transaction to the provided address.
     pub fn call(&mut self, to: [u8; 20]) -> Result<Info> {
         let to = TransactTo::Call(to.into());
         self.inner.tx_mut().gas_limit = GAS_LIMIT;
         self.inner.tx_mut().transact_to = to;
+        self.inner.tx_mut().caller = self.caller.into();
+
         if self.commit {
             self.inner.transact_commit()?.try_into()
         } else {