From cdf0a7450d4e55d24d9f02b3c55745afcb173295 Mon Sep 17 00:00:00 2001
From: vezenovm <mvezenov@gmail.com>
Date: Tue, 29 Aug 2023 18:10:59 +0000
Subject: [PATCH] remove padding from constant to_radix

---
 .../to_bytes_consistent/Nargo.toml                 |  7 +++++++
 .../to_bytes_consistent/Prover.toml                |  1 +
 .../to_bytes_consistent/src/main.nr                | 14 ++++++++++++++
 .../noirc_evaluator/src/ssa/ir/instruction/call.rs |  9 ---------
 crates/noirc_evaluator/src/ssa/ssa_builder/mod.rs  |  4 ++--
 5 files changed, 24 insertions(+), 11 deletions(-)
 create mode 100644 crates/nargo_cli/tests/execution_success/to_bytes_consistent/Nargo.toml
 create mode 100644 crates/nargo_cli/tests/execution_success/to_bytes_consistent/Prover.toml
 create mode 100644 crates/nargo_cli/tests/execution_success/to_bytes_consistent/src/main.nr

diff --git a/crates/nargo_cli/tests/execution_success/to_bytes_consistent/Nargo.toml b/crates/nargo_cli/tests/execution_success/to_bytes_consistent/Nargo.toml
new file mode 100644
index 00000000000..65f95d159c8
--- /dev/null
+++ b/crates/nargo_cli/tests/execution_success/to_bytes_consistent/Nargo.toml
@@ -0,0 +1,7 @@
+[package]
+name = "to_bytes_consistent"
+type = "bin"
+authors = [""]
+compiler_version = "0.10.3"
+
+[dependencies]
\ No newline at end of file
diff --git a/crates/nargo_cli/tests/execution_success/to_bytes_consistent/Prover.toml b/crates/nargo_cli/tests/execution_success/to_bytes_consistent/Prover.toml
new file mode 100644
index 00000000000..07fe857ac7c
--- /dev/null
+++ b/crates/nargo_cli/tests/execution_success/to_bytes_consistent/Prover.toml
@@ -0,0 +1 @@
+x = "2040124"
diff --git a/crates/nargo_cli/tests/execution_success/to_bytes_consistent/src/main.nr b/crates/nargo_cli/tests/execution_success/to_bytes_consistent/src/main.nr
new file mode 100644
index 00000000000..270491e132d
--- /dev/null
+++ b/crates/nargo_cli/tests/execution_success/to_bytes_consistent/src/main.nr
@@ -0,0 +1,14 @@
+// This test aims to check that we have consistent behavior 
+// between a `to_be_bytes` call (which is radix decomposition under the hood) 
+// with constant inputs or with witness inputs.
+
+// x = 2040124
+fn main(x : Field) {
+    let byte_array = x.to_be_bytes(31);
+    let x_as_constant = 2040124;
+    let constant_byte_array = x_as_constant.to_be_bytes(31);
+    assert(constant_byte_array.len() == byte_array.len());
+    for i in 0..constant_byte_array.len() {
+        assert(constant_byte_array[i] == byte_array[i]);
+    }
+}
diff --git a/crates/noirc_evaluator/src/ssa/ir/instruction/call.rs b/crates/noirc_evaluator/src/ssa/ir/instruction/call.rs
index 713bc8b0997..34ec8a90092 100644
--- a/crates/noirc_evaluator/src/ssa/ir/instruction/call.rs
+++ b/crates/noirc_evaluator/src/ssa/ir/instruction/call.rs
@@ -334,15 +334,6 @@ fn constant_to_radix(
         limbs.reverse();
     }
 
-    // For legacy reasons (see #617) the to_radix interface supports 256 bits even though
-    // FieldElement::max_num_bits() is only 254 bits. Any limbs beyond the specified count
-    // become zero padding.
-    let max_decomposable_bits: u32 = 256;
-    let limb_count_with_padding = max_decomposable_bits / bit_size;
-    while limbs.len() < limb_count_with_padding as usize {
-        limbs.push(FieldElement::zero());
-    }
-
     make_constant_array(dfg, limbs, Type::unsigned(bit_size))
 }
 
diff --git a/crates/noirc_evaluator/src/ssa/ssa_builder/mod.rs b/crates/noirc_evaluator/src/ssa/ssa_builder/mod.rs
index 06218dd6899..fab94b43689 100644
--- a/crates/noirc_evaluator/src/ssa/ssa_builder/mod.rs
+++ b/crates/noirc_evaluator/src/ssa/ssa_builder/mod.rs
@@ -385,7 +385,7 @@ mod tests {
 
     #[test]
     fn insert_constant_call() {
-        // `bits` should be an array of constants [1, 1, 1, 0...]:
+        // `bits` should be an array of constants [1, 1, 1, 0...] of length 8:
         // let x = 7;
         // let bits = x.to_le_bits(8);
         let func_id = Id::test_new(0);
@@ -404,7 +404,7 @@ mod tests {
             Value::NumericConstant { constant, .. } => *constant,
             _ => panic!(),
         };
-        assert_eq!(slice_len, FieldElement::from(256u128));
+        assert_eq!(slice_len, FieldElement::from(8_u128));
 
         let slice = match &builder.current_function.dfg[call_results[1]] {
             Value::Array { array, .. } => array,