Add GM for base asset ID (#700)

* Refactor fn metadata

* Add GM_BASE_ASSET_ID

* Add changelog entry

* Clippy

* Fix typo bsae->base

* Refactor fn metadata to use correct panics

* Add a test case

CHANGELOG.md

@@ -281,6 +281,8 @@ and this project adheres to [Semantic Versioning](http://semver.org/).
   affected types.
 - [#588](https://github.com/FuelLabs/fuel-vm/pull/588): Re-worked the size calculation of the canonical
   serialization/deserialization.
+- [#700](https://github.com/FuelLabs/fuel-vm/pull/700): Add `BASE_ASSET_ID` to `GM` instruction.
+
 
 #### Removed
 

fuel-asm/src/args.rs

@@ -30,6 +30,9 @@ crate::enum_try_from! {
 
         /// Get memory address where the transaction is located
         TxStart = 0x05,
+
+        /// Get memory address of base asset ID
+        BaseAssetId = 0x06,
     },
     Immediate18
 }
@@ -268,6 +271,8 @@ fn encode_gm_args() {
         GMArgs::GetCaller,
         GMArgs::GetVerifyingPredicate,
         GMArgs::GetChainId,
+        GMArgs::TxStart,
+        GMArgs::BaseAssetId,
     ];
 
     args.into_iter().for_each(|a| {

fuel-asm/src/panic_reason.rs

@@ -129,6 +129,9 @@ enum_from! {
         /// Attempt to use sequential memory instructions with too large slot count,
         /// typically because it cannot fit into usize
         TooManySlots = 0x2d,
+        /// Caller of this internal context is also expected to be internal,
+        /// i.e. $fp->$fp must be non-zero.
+        ExpectedNestedCaller = 0x2e,
     }
 }
 

fuel-tx/src/transaction/consensus_parameters.rs

@@ -389,9 +389,10 @@ impl TxParameters {
     /// Transaction memory offset in VM runtime
     pub const fn tx_offset(&self) -> usize {
         Bytes32::LEN // Tx ID
-            + WORD_SIZE // Tx size
-            // Asset ID/Balance coin input pairs
-            + self.max_inputs as usize * (AssetId::LEN + WORD_SIZE)
+        + AssetId::LEN // Base asset ID
+        // Asset ID/Balance coin input pairs
+        + self.max_inputs as usize * (AssetId::LEN + WORD_SIZE)
+        + WORD_SIZE // Tx size
     }
 
     /// Replace the max inputs with the given argument

fuel-vm/src/consts.rs

@@ -1,6 +1,7 @@
 //! VM parameters
 
 use fuel_types::{
+    AssetId,
     Bytes32,
     Word,
 };
@@ -41,7 +42,11 @@ static_assertions::const_assert!(VM_MAX_RAM < usize::MAX as u64);
 // no limits to heap for now.
 
 /// Offset for the assets balances in VM memory
-pub const VM_MEMORY_BALANCES_OFFSET: usize = Bytes32::LEN;
+pub const VM_MEMORY_BASE_ASSET_ID_OFFSET: usize = Bytes32::LEN;
+
+/// Offset for the assets balances in VM memory
+pub const VM_MEMORY_BALANCES_OFFSET: usize =
+    VM_MEMORY_BASE_ASSET_ID_OFFSET + AssetId::LEN;
 
 /// Encoded len of a register id in an instruction (unused)
 pub const VM_REGISTER_WIDTH: u8 = 6;

fuel-vm/src/interpreter/initialization.rs

@@ -53,6 +53,9 @@ where
 
         self.push_stack(self.transaction().id(&self.chain_id()).as_ref())?;
 
+        let base_asset_id = self.interpreter_params.base_asset_id;
+        self.push_stack(&*base_asset_id)?;
+
         runtime_balances.to_vm(self);
 
         let tx_size = self.transaction().size() as Word;

fuel-vm/src/interpreter/metadata.rs

@@ -108,54 +108,29 @@ pub(crate) fn metadata(
     chain_id: ChainId,
     tx_offset: Word,
 ) -> SimpleResult<()> {
-    let external = context.is_external();
-    let args = GMArgs::try_from(imm)?;
+    let parent = context
+        .is_internal()
+        .then(|| frames.last().map(|f| f.registers()[RegId::FP]))
+        .flatten();
 
-    if external {
-        match args {
-            GMArgs::GetVerifyingPredicate => {
-                *result = context
-                    .predicate()
-                    .map(|p| p.idx() as Word)
-                    .ok_or(PanicReason::TransactionValidity)?;
-            }
-
-            GMArgs::GetChainId => {
-                *result = chain_id.into();
-            }
-
-            GMArgs::TxStart => {
-                *result = tx_offset;
-            }
-
-            _ => return Err(PanicReason::ExpectedInternalContext.into()),
-        }
-    } else {
-        let parent = frames
-            .last()
-            .map(|f| f.registers()[RegId::FP])
-            .expect("External context will always have a frame");
-
-        match args {
-            GMArgs::IsCallerExternal => {
-                *result = (parent == 0) as Word;
-            }
-
-            GMArgs::GetCaller if parent != 0 => {
-                *result = parent;
-            }
-
-            GMArgs::GetChainId => {
-                *result = chain_id.into();
-            }
-
-            GMArgs::TxStart => {
-                *result = tx_offset;
-            }
-
-            _ => return Err(PanicReason::ExpectedInternalContext.into()),
-        }
-    }
+    *result = match GMArgs::try_from(imm)? {
+        GMArgs::GetVerifyingPredicate => context
+            .predicate()
+            .map(|p| p.idx() as Word)
+            .ok_or(PanicReason::TransactionValidity)?,
+        GMArgs::GetChainId => chain_id.into(),
+        GMArgs::BaseAssetId => VM_MEMORY_BASE_ASSET_ID_OFFSET as Word,
+        GMArgs::TxStart => tx_offset,
+        GMArgs::GetCaller => match parent {
+            Some(0) => return Err(PanicReason::ExpectedNestedCaller.into()),
+            Some(parent) => parent,
+            None => return Err(PanicReason::ExpectedInternalContext.into()),
+        },
+        GMArgs::IsCallerExternal => match parent {
+            Some(p) => (p == 0) as Word,
+            None => return Err(PanicReason::ExpectedInternalContext.into()),
+        },
+    };
 
     inc_pc(pc)?;
     Ok(())

fuel-vm/src/tests/metadata.rs

@@ -268,6 +268,51 @@ fn get_metadata_chain_id() {
     }
 }
 
+#[test]
+fn get_metadata_base_asset_id() {
+    let gas_limit = 1_000_000;
+    let height = BlockHeight::default();
+    let mut storage = MemoryStorage::default();
+
+    let mut params = ConsensusParameters::standard();
+    params.set_base_asset_id(AssetId::from([5; 32]));
+
+    let script = TransactionBuilder::script(
+        vec![
+            op::gm_args(0x20, GMArgs::BaseAssetId),
+            op::movi(0x21, AssetId::LEN.try_into().unwrap()),
+            op::logd(RegId::ZERO, RegId::ZERO, 0x20, 0x21),
+            op::ret(RegId::ONE),
+        ]
+        .into_iter()
+        .collect(),
+        vec![],
+    )
+    .script_gas_limit(gas_limit)
+    .add_random_fee_input()
+    .finalize()
+    .into_checked(height, &params)
+    .unwrap();
+
+    let receipts = Transactor::<_, _>::new(
+        &mut storage,
+        InterpreterParams {
+            base_asset_id: *params.base_asset_id(),
+            ..Default::default()
+        },
+    )
+    .transact(script)
+    .receipts()
+    .expect("Failed to transact")
+    .to_owned();
+
+    if let Receipt::LogData { data, .. } = receipts[0].clone() {
+        assert_eq!(data.unwrap(), params.base_asset_id().to_bytes());
+    } else {
+        panic!("expected LogData receipt, instead of {:?}", receipts[0]);
+    }
+}
+
 #[test]
 fn get_metadata_tx_start() {
     let gas_limit = 1_000_000;

fuel-vm/src/tests/validation.rs

@@ -23,8 +23,6 @@ use rand::{
 #[cfg(feature = "alloc")]
 use alloc::vec;
 
-use crate::consts::WORD_SIZE;
-
 #[test]
 fn transaction_can_be_executed_after_maturity() {
     const MATURITY: BlockHeight = BlockHeight::new(1);
@@ -62,9 +60,8 @@ fn malleable_fields_do_not_affect_validity() {
 
     let params = ConsensusParameters::default();
 
-    let tx_size_ptr =
-        32 + (params.tx_params().max_inputs as usize * (AssetId::LEN + WORD_SIZE));
-    let tx_start_ptr = tx_size_ptr + 8;
+    let tx_start_ptr = params.tx_params().tx_offset();
+    let tx_size_ptr = tx_start_ptr - 8;
 
     let tx = TransactionBuilder::script(
         vec![