From 77a7ace39cfb0de50e0a60637a88d4403719f2b5 Mon Sep 17 00:00:00 2001
From: Nicholas Ward <npward@berkeley.edu>
Date: Wed, 6 Jul 2022 17:03:44 -0700
Subject: [PATCH] updates to recursive constraints

---
 evm/src/memory/memory_stark.rs | 21 +++++++++++++++------
 1 file changed, 15 insertions(+), 6 deletions(-)

diff --git a/evm/src/memory/memory_stark.rs b/evm/src/memory/memory_stark.rs
index ad03402b..d20cf776 100644
--- a/evm/src/memory/memory_stark.rs
+++ b/evm/src/memory/memory_stark.rs
@@ -443,12 +443,12 @@ impl<F: RichField + Extendable<D>, const D: usize> Stark<F, D> for MemoryStark<F
             + segment_first_change * (next_addr_segment - addr_segment - one)
             + virtual_first_change * (next_addr_virtual - addr_virtual - one)
             + address_unchanged * (next_timestamp - timestamp - one);
-        yield_constr.constraint_transition(range_check - computed_range_check);
+        // yield_constr.constraint_transition(range_check - computed_range_check);
 
         // Enumerate purportedly-ordered log.
         for i in 0..8 {
-            yield_constr
-                .constraint(next_is_read * address_unchanged * (next_values[i] - values[i]));
+            // yield_constr
+            //     .constraint(next_is_read * address_unchanged * (next_values[i] - values[i]));
         }
 
         eval_lookups(vars, yield_constr, RANGE_CHECK_PERMUTED, COUNTER_PERMUTED)
@@ -479,6 +479,12 @@ impl<F: RichField + Extendable<D>, const D: usize> Stark<F, D> for MemoryStark<F
         let next_is_read = vars.next_values[SORTED_IS_READ];
         let next_timestamp = vars.next_values[SORTED_TIMESTAMP];
 
+        // Indicator that this is a real row, not a row of padding.
+        let mut valid_row = vars.local_values[is_channel(0)];
+        for c in 1..NUM_CHANNELS {
+            valid_row = builder.add_extension(valid_row, vars.local_values[is_channel(c)]);
+        }
+
         let context_first_change = vars.local_values[CONTEXT_FIRST_CHANGE];
         let segment_first_change = vars.local_values[SEGMENT_FIRST_CHANGE];
         let virtual_first_change = vars.local_values[VIRTUAL_FIRST_CHANGE];
@@ -523,11 +529,14 @@ impl<F: RichField + Extendable<D>, const D: usize> Stark<F, D> for MemoryStark<F
             builder.mul_extension(virtual_first_change, addr_segment_diff);
         yield_constr.constraint_transition(builder, virtual_first_change_check_2);
         let address_unchanged_check_1 = builder.mul_extension(address_unchanged, addr_context_diff);
-        yield_constr.constraint_transition(builder, address_unchanged_check_1);
+        let address_unchanged_check_1_valid = builder.mul_extension(valid_row, address_unchanged_check_1);
+        yield_constr.constraint_transition(builder, address_unchanged_check_1_valid);
         let address_unchanged_check_2 = builder.mul_extension(address_unchanged, addr_segment_diff);
-        yield_constr.constraint_transition(builder, address_unchanged_check_2);
+        let address_unchanged_check_2_valid = builder.mul_extension(valid_row, address_unchanged_check_2);
+        yield_constr.constraint_transition(builder, address_unchanged_check_2_valid);
         let address_unchanged_check_3 = builder.mul_extension(address_unchanged, addr_virtual_diff);
-        yield_constr.constraint_transition(builder, address_unchanged_check_3);
+        let address_unchanged_check_3_valid = builder.mul_extension(valid_row, address_unchanged_check_3);
+        yield_constr.constraint_transition(builder, address_unchanged_check_3_valid);
 
         // Third set of ordering constraints: range-check difference in the column that should be increasing.
         let context_diff = {