Add GTF getters for tx bytes size and address (#692)

* Add GTF getters for tx bytes size and address

* fmt

* Add changelog entry

* Move TxStart to GM

* Reassign TxLength

* fmt

CHANGELOG.md

@@ -7,6 +7,12 @@ and this project adheres to [Semantic Versioning](http://semver.org/).
 
 ## [Unreleased]
 
+### Changed
+
+#### Breaking
+
+- [#692](https://github.com/FuelLabs/fuel-vm/pull/692): Add GTF getters for tx size and address.
+
 ## [Version 0.47.1]
 
 ### Added

fuel-asm/src/args.rs

@@ -27,6 +27,9 @@ crate::enum_try_from! {
 
         /// Get the Chain ID this VM is operating within
         GetChainId = 0x04,
+
+        /// Get memory address where the transaction is located
+        TxStart = 0x05,
     },
     Immediate18
 }
@@ -86,6 +89,9 @@ crate::enum_try_from! {
         /// Set `$rA` to `Memory address of tx.witnesses[$rB]`
         ScriptWitnessAtIndex = 0x00D,
 
+        /// Set `$rA` to size of the transaction in memory, in bytes
+        TxLength = 0x00E,
+
         /// Set `$rA` to `tx.bytecodeLength`
         CreateBytecodeLength = 0x100,
 

fuel-vm/src/interpreter/metadata.rs

@@ -10,6 +10,7 @@ use crate::{
     context::Context,
     convert,
     error::SimpleResult,
+    interpreter::memory::read_bytes,
 };
 
 use fuel_asm::{
@@ -55,10 +56,19 @@ where
         ra: RegisterId,
         imm: Immediate18,
     ) -> SimpleResult<()> {
+        let tx_offset = self.tx_offset() as Word;
         let chain_id = self.chain_id();
         let (SystemRegisters { pc, .. }, mut w) = split_registers(&mut self.registers);
         let result = &mut w[WriteRegKey::try_from(ra)?];
-        metadata(&self.context, &self.frames, pc, result, imm, chain_id)
+        metadata(
+            &self.context,
+            &self.frames,
+            pc,
+            result,
+            imm,
+            chain_id,
+            tx_offset,
+        )
     }
 
     pub(crate) fn get_transaction_field(
@@ -68,11 +78,21 @@ where
         imm: Immediate12,
     ) -> SimpleResult<()> {
         let tx_offset = self.tx_offset();
+        let tx_size = Word::from_be_bytes(
+            read_bytes(
+                &self.memory,
+                (tx_offset - 8) // Tx size is stored just below the tx bytes
+                    .try_into()
+                    .expect("tx offset impossibly large"),
+            )
+            .expect("Tx length not in memory"),
+        );
         let (SystemRegisters { pc, .. }, mut w) = split_registers(&mut self.registers);
         let result = &mut w[WriteRegKey::try_from(ra)?];
         let input = GTFInput {
             tx: &self.tx,
             tx_offset,
+            tx_size,
             pc,
         };
         input.get_transaction_field(result, b, imm)
@@ -86,6 +106,7 @@ pub(crate) fn metadata(
     result: &mut Word,
     imm: Immediate18,
     chain_id: ChainId,
+    tx_offset: Word,
 ) -> SimpleResult<()> {
     let external = context.is_external();
     let args = GMArgs::try_from(imm)?;
@@ -103,6 +124,10 @@ pub(crate) fn metadata(
                 *result = chain_id.into();
             }
 
+            GMArgs::TxStart => {
+                *result = tx_offset;
+            }
+
             _ => return Err(PanicReason::ExpectedInternalContext.into()),
         }
     } else {
@@ -123,6 +148,11 @@ pub(crate) fn metadata(
             GMArgs::GetChainId => {
                 *result = chain_id.into();
             }
+
+            GMArgs::TxStart => {
+                *result = tx_offset;
+            }
+
             _ => return Err(PanicReason::ExpectedInternalContext.into()),
         }
     }
@@ -134,6 +164,7 @@ pub(crate) fn metadata(
 struct GTFInput<'vm, Tx> {
     tx: &'vm Tx,
     tx_offset: usize,
+    tx_size: Word,
     pc: RegMut<'vm, PC>,
 }
 
@@ -198,6 +229,7 @@ impl<Tx> GTFInput<'_, Tx> {
                     .witnesses_offset_at(b)
                     .ok_or(PanicReason::WitnessNotFound)?) as Word
             }
+            GTFArgs::TxLength => self.tx_size,
 
             // Input
             GTFArgs::InputType => {

fuel-vm/src/interpreter/metadata/tests.rs

@@ -1,6 +1,9 @@
 use alloc::vec;
 
-use fuel_tx::Script;
+use fuel_tx::{
+    Script,
+    TxParameters,
+};
 use fuel_types::BlockHeight;
 use test_case::test_case;
 
@@ -22,6 +25,7 @@ fn test_metadata() {
         &mut result,
         imm,
         ChainId::default(),
+        TxParameters::default().tx_offset() as Word,
     )
     .unwrap();
     assert_eq!(pc, 8);
@@ -35,6 +39,7 @@ fn test_get_transaction_field() {
     let input = GTFInput {
         tx: &tx,
         tx_offset: 0,
+        tx_size: fuel_tx::TxParameters::DEFAULT.tx_offset() as Word,
         pc: RegMut::new(&mut pc),
     };
     let mut result = 1;
@@ -66,6 +71,7 @@ fn get_chain_id(context: Context, chain_id: u64) {
         &mut result,
         imm,
         chain_id.into(),
+        TxParameters::default().tx_offset() as Word,
     )
     .unwrap();
 

fuel-vm/src/tests/metadata.rs

@@ -268,6 +268,37 @@ fn get_metadata_chain_id() {
     }
 }
 
+#[test]
+fn get_metadata_tx_start() {
+    let gas_limit = 1_000_000;
+    let height = BlockHeight::default();
+    let mut storage = MemoryStorage::default();
+
+    let script = TransactionBuilder::script(
+        vec![op::gm_args(0x20, GMArgs::TxStart), op::ret(0x20)]
+            .into_iter()
+            .collect(),
+        vec![],
+    )
+    .script_gas_limit(gas_limit)
+    .add_random_fee_input()
+    .finalize()
+    .into_checked(height, &ConsensusParameters::default())
+    .unwrap();
+
+    let receipts = Transactor::<_, _>::new(&mut storage, InterpreterParams::default())
+        .transact(script)
+        .receipts()
+        .expect("Failed to transact")
+        .to_owned();
+
+    if let Receipt::Return { val, .. } = receipts[0].clone() {
+        assert_eq!(val, TxParameters::DEFAULT.tx_offset() as Word);
+    } else {
+        panic!("expected return receipt, instead of {:?}", receipts[0])
+    }
+}
+
 #[test]
 fn get_transaction_fields() {
     let rng = &mut StdRng::seed_from_u64(2322u64);
@@ -484,6 +515,14 @@ fn get_transaction_fields() {
         op::eq(0x10, 0x10, 0x11),
         op::and(0x20, 0x20, 0x10),
 
+        op::gtf_args(0x10, RegId::ZERO, GTFArgs::TxLength),
+        op::movi(0x11, 100), // Tx lenght is too complicated to backpatch
+        op::gt(0x10, 0x10, 0x11), // so just make sure it's over some arbitrary number
+        op::and(0x20, 0x20, 0x10),
+        op::movi(0x11, 10_000), // and
+        op::lt(0x10, 0x10, 0x11), // below some arbitrary number
+        op::and(0x20, 0x20, 0x10),
+
         op::movi(0x11, tip as Immediate18),
         op::movi(0x19, 0x00),
         op::gtf_args(0x10, 0x19, GTFArgs::PolicyTip),