Optimizations to field and curve arithmetic

bls12_381/src/fields/fq2.rs

@@ -21,7 +21,22 @@ impl Fp2Config for Fq2Config {
     ];
 
     #[inline(always)]
-    fn mul_fp_by_nonresidue(fp: &Self::Fp) -> Self::Fp {
-        -(*fp)
+    fn mul_fp_by_nonresidue_in_place(fp: &mut Self::Fp) -> &mut Self::Fp {
+        fp.neg_in_place()
+    }
+
+    #[inline(always)]
+    fn sub_and_mul_fp_by_nonresidue(y: &mut Self::Fp, x: &Self::Fp) {
+        *y += x;
+    }
+
+    #[inline(always)]
+    fn add_and_mul_fp_by_nonresidue_plus_one(y: &mut Self::Fp, x: &Self::Fp) {
+        *y = *x;
+    }
+
+    fn add_and_mul_fp_by_nonresidue_in_place(y: &mut Self::Fp, x: &Self::Fp) {
+        y.neg_in_place();
+        *y += x;
     }
 }