chore: rename PUBLIC_VALUES_AIR_ID to MEMORY_AIRS_START_IDX (#2482)

## Summary

- Renames the constant `PUBLIC_VALUES_AIR_ID` to `MEMORY_AIRS_START_IDX`
across 8 files
- Removes old unused `BOUNDARY_AIR_ID`
- Updates the doc comment to reflect the constant's current purpose as
the boundary AIR index
- The `PublicValuesChip` was removed in #2480, making the old name
misleading

Follows up on review comment in #2480.

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---------

Co-authored-by: claude[bot] <41898282+claude[bot]@users.noreply.github.com>
Co-authored-by: Jonathan Wang <jonathanpwang@users.noreply.github.com>
Co-authored-by: Jonathan Wang <31040440+jonathanpwang@users.noreply.github.com>
Co-authored-by: Ayush Shukla <shuklaayush@users.noreply.github.com>
Co-authored-by: Ayush Shukla <ayush@axiom.xyz>

Author: 4 people

crates/sdk/src/keygen/dummy.rs

@@ -8,7 +8,7 @@ use openvm_circuit::{
         },
         ContinuationVmProof, Executor, MatrixRecordArena, MeteredExecutor,
         PreflightExecutionOutput, PreflightExecutor, SingleSegmentVmProver, SystemConfig,
-        VirtualMachine, VirtualMachineError, VmBuilder, VmExecutionConfig, PUBLIC_VALUES_AIR_ID,
+        VirtualMachine, VirtualMachineError, VmBuilder, VmExecutionConfig,
     },
     system::program::trace::VmCommittedExe,
     utils::next_power_of_two_or_zero,
@@ -65,7 +65,6 @@ pub(super) fn compute_root_proof_heights(
     // The following is the same as impl SingleSegmentVmProver for VmLocalProver except we stop
     // after tracegen:
     let mut trace_heights = NATIVE_MAX_TRACE_HEIGHTS.to_vec();
-    trace_heights[PUBLIC_VALUES_AIR_ID] = num_public_values as u32;
     let state = root_vm.create_initial_state(&root_committed_exe.exe, root_input.write());
     let cached_program_trace = root_vm.transport_committed_exe_to_device(root_committed_exe);
     root_vm.load_program(cached_program_trace);

crates/sdk/src/keygen/perm.rs

@@ -21,7 +21,7 @@ impl AirIdPermutation {
     }
     #[cfg(feature = "evm-prove")]
     pub fn get_special_air_ids(&self) -> SpecialAirIds {
-        use openvm_circuit::arch::{CONNECTOR_AIR_ID, PROGRAM_AIR_ID, PUBLIC_VALUES_AIR_ID};
+        use openvm_circuit::arch::{BOUNDARY_AIR_ID, CONNECTOR_AIR_ID, PROGRAM_AIR_ID};
 
         let perm_len = self.perm.len();
         let mut ret = SpecialAirIds {
@@ -34,7 +34,7 @@ impl AirIdPermutation {
                 ret.program_air_id = i;
             } else if air_id == CONNECTOR_AIR_ID {
                 ret.connector_air_id = i;
-            } else if air_id == PUBLIC_VALUES_AIR_ID {
+            } else if air_id == BOUNDARY_AIR_ID {
                 ret.public_values_air_id = i;
             }
         }

crates/sdk/src/lib.rs

@@ -23,8 +23,8 @@ use openvm_circuit::{
         hasher::{poseidon2::vm_poseidon2_hasher, Hasher},
         instructions::exe::VmExe,
         Executor, InitFileGenerator, MeteredExecutor, PreflightExecutor, VirtualMachineError,
-        VmBuilder, VmExecutionConfig, VmExecutor, VmVerificationError, CONNECTOR_AIR_ID,
-        PROGRAM_AIR_ID, PROGRAM_CACHED_TRACE_INDEX, PUBLIC_VALUES_AIR_ID,
+        VmBuilder, VmExecutionConfig, VmExecutor, VmVerificationError, BOUNDARY_AIR_ID,
+        CONNECTOR_AIR_ID, PROGRAM_AIR_ID, PROGRAM_CACHED_TRACE_INDEX,
     },
     system::{
         memory::{
@@ -705,9 +705,9 @@ where
                 air_id: CONNECTOR_AIR_ID,
             }
             .into());
-        } else if proof.inner.per_air[2].air_id != PUBLIC_VALUES_AIR_ID {
+        } else if proof.inner.per_air[2].air_id != BOUNDARY_AIR_ID {
             return Err(VmVerificationError::SystemAirMissing {
-                air_id: PUBLIC_VALUES_AIR_ID,
+                air_id: BOUNDARY_AIR_ID,
             }
             .into());
         }

crates/vm/src/arch/config.rs

@@ -16,7 +16,7 @@ use openvm_stark_backend::{
 };
 use serde::{de::DeserializeOwned, Deserialize, Serialize};
 
-use super::{AnyEnum, VmChipComplex, CONNECTOR_AIR_ID, PROGRAM_AIR_ID, PUBLIC_VALUES_AIR_ID};
+use super::{AnyEnum, VmChipComplex, BOUNDARY_AIR_ID, CONNECTOR_AIR_ID, PROGRAM_AIR_ID};
 use crate::{
     arch::{
         execution_mode::metered::segment_ctx::SegmentationConfig, AirInventory, AirInventoryError,
@@ -342,7 +342,7 @@ impl SystemConfig {
 
     /// Returns the AIR ID of the memory boundary AIR. Panic if the boundary AIR is not enabled.
     pub fn memory_boundary_air_id(&self) -> usize {
-        PUBLIC_VALUES_AIR_ID
+        BOUNDARY_AIR_ID
     }
 
     /// Returns the AIR ID of the memory merkle AIR. Returns None if continuations are not enabled.

crates/vm/src/arch/extensions.rs

@@ -44,14 +44,13 @@ pub const PROGRAM_AIR_ID: usize = 0;
 /// ProgramAir is the first AIR so its cached trace should be the first main trace.
 pub const PROGRAM_CACHED_TRACE_INDEX: usize = 0;
 pub const CONNECTOR_AIR_ID: usize = 1;
-/// If PublicValuesAir is **enabled**, its AIR ID is 2. PublicValuesAir is always disabled when
-/// continuations is enabled.
-pub const PUBLIC_VALUES_AIR_ID: usize = 2;
-/// AIR ID of the Memory Boundary AIR.
-pub const BOUNDARY_AIR_ID: usize = PUBLIC_VALUES_AIR_ID + 1 + BOUNDARY_AIR_OFFSET;
+/// Starting AIR index of memory AIRs in the VM circuit.
+pub const MEMORY_AIRS_START_IDX: usize = 2;
+/// AIR index of the boundary AIR in the VM circuit.
+pub const BOUNDARY_AIR_ID: usize = MEMORY_AIRS_START_IDX + BOUNDARY_AIR_OFFSET;
 /// If VM has continuations enabled, all AIRs of MemoryController are added after ConnectorChip.
 /// Merkle AIR commits start/final memory states.
-pub const MERKLE_AIR_ID: usize = CONNECTOR_AIR_ID + 1 + MERKLE_AIR_OFFSET;
+pub const MERKLE_AIR_ID: usize = MEMORY_AIRS_START_IDX + MERKLE_AIR_OFFSET;
 
 pub type ExecutorId = u32;
 

crates/vm/src/arch/vm.rs

@@ -54,7 +54,7 @@ use super::{
     ExecutorInventory, ExecutorInventoryError, MemoryConfig, MeteredExecutor, PreflightExecutor,
     StaticProgramError, SystemConfig, VmBuilder, VmChipComplex, VmCircuitConfig, VmExecState,
     VmExecutionConfig, VmState, CONNECTOR_AIR_ID, MERKLE_AIR_ID, PROGRAM_AIR_ID,
-    PROGRAM_CACHED_TRACE_INDEX, PUBLIC_VALUES_AIR_ID,
+    PROGRAM_CACHED_TRACE_INDEX,
 };
 use crate::{
     arch::{deferral::DeferralState, DEFAULT_RNG_SEED},
@@ -1232,8 +1232,7 @@ where
         let vm = &mut self.vm;
         let exe = &self.exe;
         assert!(!vm.config().as_ref().continuation_enabled);
-        let mut trace_heights = trace_heights.to_vec();
-        trace_heights[PUBLIC_VALUES_AIR_ID] = vm.config().as_ref().num_public_values as u32;
+        let trace_heights = trace_heights.to_vec();
         let state = self.state.take().expect("State should always be present");
         let num_custom_pvs = state.custom_pvs.len();
         let (proof, final_memory) = vm.prove(&mut self.interpreter, state, None, &trace_heights)?;

crates/vm/src/system/cuda/mod.rs

@@ -130,9 +130,9 @@ impl SystemChipComplex<DenseRecordArena, GpuBackend> for SystemChipInventoryGPU
 
     #[cfg(feature = "metrics")]
     fn finalize_trace_heights(&self, heights: &mut [usize]) {
-        use crate::system::{cuda::boundary::BoundaryFields, PUBLIC_VALUES_AIR_ID};
+        use crate::{arch::BOUNDARY_AIR_ID, system::cuda::boundary::BoundaryFields};
 
-        let boundary_idx = PUBLIC_VALUES_AIR_ID;
+        let boundary_idx = BOUNDARY_AIR_ID;
         let mut access_adapter_offset = boundary_idx + 1;
         match self.memory_inventory.boundary.fields {
             BoundaryFields::Volatile(_) => {

crates/vm/src/system/mod.rs

@@ -27,7 +27,7 @@ use crate::{
         ChipInventoryError, DenseRecordArena, ExecutionBridge, ExecutionBus, ExecutionState,
         ExecutorInventory, ExecutorInventoryError, MatrixRecordArena, PhantomSubExecutor,
         RowMajorMatrixArena, SystemConfig, VmBuilder, VmChipComplex, VmCircuitConfig,
-        VmExecutionConfig, VmField, CONNECTOR_AIR_ID, PROGRAM_AIR_ID, PUBLIC_VALUES_AIR_ID,
+        VmExecutionConfig, VmField, CONNECTOR_AIR_ID, MEMORY_AIRS_START_IDX, PROGRAM_AIR_ID,
     },
     system::{
         connector::VmConnectorChip,
@@ -431,9 +431,9 @@ where
 
     #[cfg(feature = "metrics")]
     fn finalize_trace_heights(&self, heights: &mut [usize]) {
-        use crate::system::memory::interface::MemoryInterface;
+        use crate::{arch::BOUNDARY_AIR_ID, system::memory::interface::MemoryInterface};
 
-        let boundary_idx = PUBLIC_VALUES_AIR_ID;
+        let boundary_idx = BOUNDARY_AIR_ID;
         let mut access_adapter_offset = boundary_idx + 1;
         match &self.memory_controller.interface_chip {
             MemoryInterface::Volatile { boundary_chip } => {
@@ -541,6 +541,6 @@ where
         );
         assert_eq!(heights[CONNECTOR_AIR_ID], 2);
         self.memory_controller
-            .set_override_trace_heights(&heights[PUBLIC_VALUES_AIR_ID..]);
+            .set_override_trace_heights(&heights[MEMORY_AIRS_START_IDX..]);
     }
 }