chore: add reproduction case for bignum test failure (#6464)

test_programs/execution_success/regression_bignum/Nargo.toml

@@ -0,0 +1,7 @@
+[package]
+name = "regression_bignum"
+version = "0.1.0"
+type = "bin"
+authors = [""]
+
+[dependencies]

test_programs/execution_success/regression_bignum/src/main.nr

@@ -0,0 +1,51 @@
+fn main() {
+    let numerator =
+        [790096867046896348, 1063071665130103641, 602707730209562162, 996751591622961462, 28650, 0];
+    unsafe { __udiv_mod(numerator) };
+
+    let denominator = [12, 0, 0, 0, 0, 0];
+    let result = unsafe { __validate_gt_remainder(denominator) };
+    assert(result[4] == 0);
+    assert(result[5] == 0);
+}
+
+unconstrained fn __udiv_mod(remainder_u60: [u64; 6]) {
+    let bit_difference = get_msb(remainder_u60);
+    let accumulator_u60: [u64; 6] = shl(bit_difference);
+}
+
+unconstrained fn __validate_gt_remainder(a_u60: [u64; 6]) -> [u64; 6] {
+    let mut addend_u60: [u64; 6] = [0; 6];
+    let mut result_u60: [u64; 6] = [0; 6];
+
+    for i in 0..6 {
+        result_u60[i] = a_u60[i] + addend_u60[i];
+    }
+
+    result_u60
+}
+
+unconstrained fn get_msb(val: [u64; 6]) -> u32 {
+    let mut count = 0;
+    for i in 0..6 {
+        let v = val[(6 - 1) - i];
+        if (v > 0) {
+            count = 60 * ((6 - 1) - i);
+            break;
+        }
+    }
+    count
+}
+
+unconstrained fn shl(shift: u32) -> [u64; 6] {
+    let num_shifted_limbs = shift / 60;
+    let limb_shift = (shift % 60) as u8;
+
+    let mut result = [0; 6];
+    result[num_shifted_limbs] = (1 << limb_shift);
+
+    for i in 1..(6 - num_shifted_limbs) {
+        result[i + num_shifted_limbs] = 0;
+    }
+    result
+}