From c07fa00997fe7afcc3dbb2c6593f0dc7230fffa1 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Matthias=20G=C3=B6rgens?= <matthias.goergens@gmail.com>
Date: Thu, 12 Dec 2024 14:52:31 +0800
Subject: [PATCH] Remove unused and untested `u128`/`i128` implementations
 (#737)

Extracted from https://github.com/scroll-tech/ceno/pull/736 for ease of
review.
---
 ceno_zkvm/src/expression.rs | 16 ++++------------
 1 file changed, 4 insertions(+), 12 deletions(-)

diff --git a/ceno_zkvm/src/expression.rs b/ceno_zkvm/src/expression.rs
index d0f557579..611eb25d8 100644
--- a/ceno_zkvm/src/expression.rs
+++ b/ceno_zkvm/src/expression.rs
@@ -601,17 +601,17 @@ macro_rules! mixed_binop_instances {
 mixed_binop_instances!(
     Add,
     add,
-    (u8, u16, u32, u64, usize, i8, i16, i32, i64, i128, isize)
+    (u8, u16, u32, u64, usize, i8, i16, i32, i64, isize)
 );
 mixed_binop_instances!(
     Sub,
     sub,
-    (u8, u16, u32, u64, usize, i8, i16, i32, i64, i128, isize)
+    (u8, u16, u32, u64, usize, i8, i16, i32, i64, isize)
 );
 mixed_binop_instances!(
     Mul,
     mul,
-    (u8, u16, u32, u64, usize, i8, i16, i32, i64, i128, isize)
+    (u8, u16, u32, u64, usize, i8, i16, i32, i64, isize)
 );
 
 impl<E: ExtensionField> Mul for Expression<E> {
@@ -901,14 +901,6 @@ macro_rules! impl_from_unsigned {
 }
 impl_from_unsigned!(u8, u16, u32, u64, usize, RAMType, InsnKind);
 
-// Implement From trait for u128 separately since it requires explicit reduction
-impl<F: SmallField, E: ExtensionField<BaseField = F>> From<u128> for Expression<E> {
-    fn from(value: u128) -> Self {
-        let reduced = value.rem_euclid(F::MODULUS_U64 as u128) as u64;
-        Expression::Constant(F::from(reduced))
-    }
-}
-
 // Implement From trait for signed types
 macro_rules! impl_from_signed {
     ($($t:ty),*) => {
@@ -922,7 +914,7 @@ macro_rules! impl_from_signed {
         )*
     };
 }
-impl_from_signed!(i8, i16, i32, i64, i128, isize);
+impl_from_signed!(i8, i16, i32, i64, isize);
 
 impl<E: ExtensionField> Display for Expression<E> {
     fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {