Add REDUCE_V2 hint (#1420)

* Rename hint REDUCE -> REDUCE_V1 && implement REDUCE_V2

* Add integration test

* Rename hint REDUCE -> REDUCE_V1 in fuzzer

* update CHANGELOG.md

* unit test

* Add unit test for error

CHANGELOG.md

@@ -2,6 +2,10 @@
 
 #### Upcoming Changes
 
+* Add REDUCE_V2 hint [#1420](https://github.com/lambdaclass/cairo-vm/pull/1420):
+    * Implement REDUCE_V2 hint
+    * Rename hint REDUCE -> REDUCE_V1
+
 * BREAKING: Add `disable_trace_padding` to `CairoRunConfig`[#1233](https://github.com/lambdaclass/cairo-rs/pull/1233)
 
 * feat: Implement `CairoRunner.get_cairo_pie`[#1375](https://github.com/lambdaclass/cairo-vm/pull/1375/files)

cairo_programs/reduce.cairo

@@ -83,7 +83,45 @@ func test_reduce_ed25519{range_check_ptr}() {
     return ();
 }
 
+func reduce_v2{range_check_ptr}(x: UnreducedBigInt3) -> (reduced_x: BigInt3) {
+    let orig_x = x;
+    %{ from starkware.cairo.common.cairo_secp.secp256r1_utils import SECP256R1_P as SECP_P %}
+    %{
+        from starkware.cairo.common.cairo_secp.secp_utils import pack
+        value = pack(ids.x, PRIME) % SECP_P
+    %}
+    let (reduced_x: BigInt3) = nondet_bigint3();
+
+    verify_zero(
+        UnreducedBigInt3(
+            d0=orig_x.d0 - reduced_x.d0,
+            d1=orig_x.d1 - reduced_x.d1,
+            d2=orig_x.d2 - reduced_x.d2
+        )
+    );
+    return (reduced_x=reduced_x);
+}
+
 func main{range_check_ptr}() {
     test_reduce_ed25519();
+
+    // reduce_v2 tests
+    let x = UnreducedBigInt3(0, 0, 0);
+    let (reduce_v2_a) = reduce_v2(x);
+    assert reduce_v2_a = BigInt3(
+        0, 0, 0
+    );
+
+    let y = UnreducedBigInt3(12354, 745634534, 81298789312879123);
+    let (reduce_v2_b) = reduce_v2(y);
+    assert reduce_v2_b = BigInt3(
+        12354, 745634534, 81298789312879123
+    );
+
+    let z = UnreducedBigInt3(12354812987893128791212331231233, 7453123123123123312634534, 8129224990312325879);
+    let (reduce_v2_c) = reduce_v2(z);
+    assert reduce_v2_c = BigInt3(
+        16653320122975184709085185, 7453123123123123312794216, 8129224990312325879
+    );
     return ();
 }

fuzzer/src/fuzz_json.rs

@@ -112,7 +112,7 @@ const HINTS_CODE: [&str; 184] = [
     VERIFY_ZERO_V2,
     VERIFY_ZERO_V3,
     VERIFY_ZERO_EXTERNAL_SECP,
-    REDUCE,
+    REDUCE_V1,
     REDUCE_ED25519,
     UNSAFE_KECCAK,
     UNSAFE_KECCAK_FINALIZE,

vm/src/hint_processor/builtin_hint_processor/builtin_hint_processor_definition.rs

@@ -67,8 +67,8 @@ use crate::{
                 },
                 field_utils::{
                     is_zero_assign_scope_variables, is_zero_assign_scope_variables_external_const,
-                    is_zero_nondet, is_zero_pack, is_zero_pack_external_secp, reduce, verify_zero,
-                    verify_zero_with_external_const,
+                    is_zero_nondet, is_zero_pack, is_zero_pack_external_secp, reduce_v1, reduce_v2,
+                    verify_zero, verify_zero_with_external_const,
                 },
                 signature::{
                     div_mod_n_packed_divmod, div_mod_n_packed_external_n, div_mod_n_safe_div,
@@ -329,8 +329,11 @@ impl HintProcessorLogic for BuiltinHintProcessor {
             hint_code::NONDET_BIGINT3_V1 | hint_code::NONDET_BIGINT3_V2 => {
                 nondet_bigint3(vm, exec_scopes, &hint_data.ids_data, &hint_data.ap_tracking)
             }
-            hint_code::REDUCE => {
-                reduce(vm, exec_scopes, &hint_data.ids_data, &hint_data.ap_tracking)
+            hint_code::REDUCE_V1 => {
+                reduce_v1(vm, exec_scopes, &hint_data.ids_data, &hint_data.ap_tracking)
+            }
+            hint_code::REDUCE_V2 => {
+                reduce_v2(vm, exec_scopes, &hint_data.ids_data, &hint_data.ap_tracking)
             }
             hint_code::REDUCE_ED25519 => {
                 ed25519_reduce(vm, exec_scopes, &hint_data.ids_data, &hint_data.ap_tracking)

vm/src/hint_processor/builtin_hint_processor/hint_code.rs

@@ -532,10 +532,13 @@ q, r = divmod(pack(ids.val, PRIME), SECP_P)
 assert r == 0, f"verify_zero: Invalid input {ids.val.d0, ids.val.d1, ids.val.d2}."
 ids.q = q % PRIME"#;
 
-pub const REDUCE: &str = r#"from starkware.cairo.common.cairo_secp.secp_utils import SECP_P, pack
+pub const REDUCE_V1: &str = r#"from starkware.cairo.common.cairo_secp.secp_utils import SECP_P, pack
 
 value = pack(ids.x, PRIME) % SECP_P"#;
 
+pub const REDUCE_V2: &str = r#"from starkware.cairo.common.cairo_secp.secp_utils import pack
+value = pack(ids.x, PRIME) % SECP_P"#;
+
 pub const REDUCE_ED25519: &str = r#"from starkware.cairo.common.cairo_secp.secp_utils import pack
 SECP_P=2**255-19
 

vm/src/hint_processor/builtin_hint_processor/secp/field_utils.rs

@@ -78,7 +78,7 @@ Implements hint:
     value = pack(ids.x, PRIME) % SECP_P
 %}
 */
-pub fn reduce(
+pub fn reduce_v1(
     vm: &mut VirtualMachine,
     exec_scopes: &mut ExecutionScopes,
     ids_data: &HashMap<String, HintReference>,
@@ -90,6 +90,25 @@ pub fn reduce(
     Ok(())
 }
 
+/*
+Implements hint:
+%{
+    from starkware.cairo.common.cairo_secp.secp_utils import pack
+    value = pack(ids.x, PRIME) % SECP_P
+%}
+*/
+pub fn reduce_v2(
+    vm: &mut VirtualMachine,
+    exec_scopes: &mut ExecutionScopes,
+    ids_data: &HashMap<String, HintReference>,
+    ap_tracking: &ApTracking,
+) -> Result<(), HintError> {
+    let secp_p = exec_scopes.get_ref("SECP_P")?;
+    let value = Uint384::from_var_name("x", vm, ids_data, ap_tracking)?.pack86();
+    exec_scopes.insert_value("value", value.mod_floor(secp_p));
+    Ok(())
+}
+
 /*
 Implements hint:
 %{
@@ -191,7 +210,7 @@ pub fn is_zero_assign_scope_variables_external_const(
 #[cfg(test)]
 mod tests {
     use super::*;
-    use crate::hint_processor::builtin_hint_processor::hint_code;
+    use crate::hint_processor::builtin_hint_processor::hint_code::{self, REDUCE_V2};
     use crate::stdlib::string::ToString;
 
     use crate::{
@@ -395,6 +414,61 @@ mod tests {
         );
     }
 
+    #[test]
+    #[cfg_attr(target_arch = "wasm32", wasm_bindgen_test)]
+    fn run_reduce_v2_ok() {
+        let hint_code = REDUCE_V2;
+        let mut vm = vm_with_range_check!();
+        add_segments!(vm, 3);
+
+        //Initialize fp
+        vm.run_context.fp = 25;
+
+        //Create hint data
+        let ids_data = non_continuous_ids_data![("x", -5)];
+
+        vm.segments = segments![
+            ((1, 20), ("132181232131231239112312312313213083892150", 10)),
+            ((1, 21), ("12354812987893128791212331231233", 10)),
+            ((1, 22), ("654867675805132187", 10))
+        ];
+
+        let mut exec_scopes = ExecutionScopes::new();
+        exec_scopes.insert_value("SECP_P", SECP_P.clone());
+        //Execute the hint
+        assert_matches!(run_hint!(vm, ids_data, hint_code, &mut exec_scopes), Ok(()));
+
+        //Check 'value' is defined in the vm scope
+        assert_matches!(
+            exec_scopes.get::<BigInt>("value"),
+            Ok(x) if x == bigint_str!(
+                "3920241379018821570896271640300310233395357371896837069219347149797814"
+            )
+        );
+    }
+
+    #[test]
+    #[cfg_attr(target_arch = "wasm32", wasm_bindgen_test)]
+    fn run_reduce_v2_with_no_secp() {
+        let hint_code = REDUCE_V2;
+        let mut vm = vm_with_range_check!();
+        add_segments!(vm, 3);
+
+        //Initialize fp
+        vm.run_context.fp = 25;
+
+        //Create hint data
+        let ids_data = non_continuous_ids_data![("x", -5)];
+
+        vm.segments = segments![((1, 20), 1), ((1, 21), 1), ((1, 22), 1)];
+
+        let mut exec_scopes = ExecutionScopes::new();
+        // Skip the SECP definition, so the hint fails
+        // exec_scopes.insert_value("SECP_P", SECP_P.clone());
+        //Execute the hint
+        assert_matches!(run_hint!(vm, ids_data, hint_code, &mut exec_scopes), Err(_));
+    }
+
     #[test]
     #[cfg_attr(target_arch = "wasm32", wasm_bindgen_test)]
     fn run_is_zero_pack_ok() {