Merge pull request #1027 from 0xPolygonMiden/grjte-rc-logup

feat(air): migrate range checker bus to LogUp

CHANGELOG.md

@@ -9,6 +9,8 @@
 
 #### VM Internals
 - Simplified range checker and removed 1 main and 1 auxiliary trace column (#949).
+- Migrated range checker lookups to use LogUp and reduced the number of trace columns to 2 main and 
+  1 auxiliary (#1027).
 - Added `get_mapped_values()` and `get_store_subset()` methods to the `AdviceProvider` trait (#987).
 - [BREAKING] Added options to specify maximum number of cycles and expected number of cycles for a program (#998).
 - Improved handling of invalid/incomplete parameters in `StackOutputs` constructors (#1010).

air/src/constraints/chiplets/memory/mod.rs

@@ -355,32 +355,3 @@ impl<E: FieldElement> EvaluationFrameExt<E> for &EvaluationFrame<E> {
         self.selector_next(1)
     }
 }
-
-// EXTERNAL ACCESSORS
-// ================================================================================================
-/// Trait to allow other processors to easily access the memory column values they need for
-/// constraint calculations.
-pub trait MemoryFrameExt<E: FieldElement> {
-    // --- Column accessors -----------------------------------------------------------------------
-
-    /// The value of the lower 16-bits of the delta value being tracked between two consecutive
-    /// context IDs, addresses, or clock cycles in the current row.
-    fn memory_d0(&self) -> E;
-    /// The value of the upper 16-bits of the delta value being tracked between two consecutive
-    /// context IDs, addresses, or clock cycles in the current row.
-    fn memory_d1(&self) -> E;
-}
-
-impl<E: FieldElement> MemoryFrameExt<E> for &EvaluationFrame<E> {
-    // --- Column accessors -----------------------------------------------------------------------
-
-    #[inline(always)]
-    fn memory_d0(&self) -> E {
-        self.current()[MEMORY_D0_COL_IDX]
-    }
-
-    #[inline(always)]
-    fn memory_d1(&self) -> E {
-        self.current()[MEMORY_D1_COL_IDX]
-    }
-}

air/src/constraints/chiplets/mod.rs

@@ -6,7 +6,6 @@ use crate::utils::{are_equal, binary_not, is_binary};
 mod bitwise;
 mod hasher;
 mod memory;
-pub use memory::MemoryFrameExt;
 
 // CONSTANTS
 // ================================================================================================

air/src/constraints/mod.rs

@@ -1,3 +1,106 @@
+use super::{EvaluationFrame, ExtensionOf, Felt, FieldElement};
+use crate::trace::{
+    chiplets::{MEMORY_D0_COL_IDX, MEMORY_D1_COL_IDX},
+    decoder::{DECODER_OP_BITS_OFFSET, DECODER_USER_OP_HELPERS_OFFSET},
+};
+use crate::utils::binary_not;
+
 pub mod chiplets;
 pub mod range;
 pub mod stack;
+
+// ACCESSORS
+// ================================================================================================
+/// Trait to allow other processors to easily access the column values they need for constraint
+/// calculations.
+pub trait MainFrameExt<F, E>
+where
+    F: FieldElement<BaseField = Felt>,
+    E: FieldElement<BaseField = Felt> + ExtensionOf<F>,
+{
+    /// Returns true when a u32 stack operation that requires range checks is being performed.
+    fn u32_rc_op(&self) -> F;
+
+    // --- Range check lookup accessors -----------------------------------------------------------------------
+
+    /// The value required for the first memory lookup when the memory chiplet requests range
+    /// checks. The value returned is the denominator used for including the value into the LogUp
+    /// lookup: (alpha - d0). The value d0 which is being range-checked is the lower 16-bits of the
+    /// delta value being tracked between two consecutive context IDs, addresses, or clock cycles in
+    /// the current row.
+    fn lookup_mv0(&self, alpha: E) -> E;
+    /// The value required for the second memory lookup when the memory chiplet requests range
+    /// checks. The value returned is the denominator used for including the value into the LogUp
+    /// lookup: (alpha - d1). The value d1 which is being range-checked is the upper 16-bits of the
+    /// delta value being tracked between two consecutive context IDs, addresses, or clock cycles in
+    /// the current row.
+    fn lookup_mv1(&self, alpha: E) -> E;
+    /// The value required for the first stack lookup when the stack requests range checks. The
+    /// value returned is the denominator used for including the value into the LogUp lookup:
+    /// (alpha - h0). The value h0 which is being range checked by the stack operation is stored in
+    /// the helper columns of the decoder section of the trace.
+    fn lookup_sv0(&self, alpha: E) -> E;
+    /// The value required for the second stack lookup when the stack requests range checks. The
+    /// value returned is the denominator used for including the value into the LogUp lookup:
+    /// (alpha - h1). The value h1 which is being range checked by the stack operation is stored in
+    /// the helper columns of the decoder section of the trace.
+    fn lookup_sv1(&self, alpha: E) -> E;
+    /// The value required for the third stack lookup when the stack requests range checks. The
+    /// value returned is the denominator used for including the value into the LogUp lookup:
+    /// (alpha - h2). The value h2 which is being range checked by the stack operation is stored in
+    /// the helper columns of the decoder section of the trace.
+    fn lookup_sv2(&self, alpha: E) -> E;
+    /// The value required for the fourth stack lookup when the stack requests range checks. The
+    /// value returned is the denominator used for including the value into the LogUp lookup:
+    /// (alpha - h3). The value h3 which is being range checked by the stack operation is stored in
+    /// the helper columns of the decoder section of the trace.
+    fn lookup_sv3(&self, alpha: E) -> E;
+}
+
+impl<F, E> MainFrameExt<F, E> for EvaluationFrame<F>
+where
+    F: FieldElement<BaseField = Felt>,
+    E: FieldElement<BaseField = Felt> + ExtensionOf<F>,
+{
+    /// Returns true when the stack operation is a u32 operation that requires range checks.
+    /// TODO: this is also defined in the op flags. It's redefined here to avoid computing all of
+    /// the op flags when this is the only one needed, but ideally this should only be defined once.
+    #[inline(always)]
+    fn u32_rc_op(&self) -> F {
+        let not_4 = binary_not(self.current()[DECODER_OP_BITS_OFFSET + 4]);
+        let not_5 = binary_not(self.current()[DECODER_OP_BITS_OFFSET + 5]);
+        self.current()[DECODER_OP_BITS_OFFSET + 6].mul(not_5).mul(not_4)
+    }
+
+    // --- Intermediate values for LogUp lookups --------------------------------------------------
+
+    #[inline(always)]
+    fn lookup_mv0(&self, alpha: E) -> E {
+        alpha - self.current()[MEMORY_D0_COL_IDX].into()
+    }
+
+    #[inline(always)]
+    fn lookup_mv1(&self, alpha: E) -> E {
+        alpha - self.current()[MEMORY_D1_COL_IDX].into()
+    }
+
+    #[inline(always)]
+    fn lookup_sv0(&self, alpha: E) -> E {
+        alpha - self.current()[DECODER_USER_OP_HELPERS_OFFSET].into()
+    }
+
+    #[inline(always)]
+    fn lookup_sv1(&self, alpha: E) -> E {
+        alpha - self.current()[DECODER_USER_OP_HELPERS_OFFSET + 1].into()
+    }
+
+    #[inline(always)]
+    fn lookup_sv2(&self, alpha: E) -> E {
+        alpha - self.current()[DECODER_USER_OP_HELPERS_OFFSET + 2].into()
+    }
+
+    #[inline(always)]
+    fn lookup_sv3(&self, alpha: E) -> E {
+        alpha - self.current()[DECODER_USER_OP_HELPERS_OFFSET + 3].into()
+    }
+}