Avoid unnecessary memset (#14180)

Avoid unnecessary memset from `_bc_do_sub`

Author: SakiTakamachi

ext/bcmath/libbcmath/src/add.c

@@ -52,7 +52,7 @@ bc_num bc_add(bc_num n1, bc_num n2, size_t scale_min)
 		switch (_bc_do_compare(n1, n2, false)) {
 			case -1:
 				/* n1 is less than n2, subtract n1 from n2. */
-				sum = _bc_do_sub(n2, n1, scale_min);
+				sum = _bc_do_sub(n2, n1);
 				sum->n_sign = n2->n_sign;
 				break;
 			case 0:
@@ -61,7 +61,7 @@ bc_num bc_add(bc_num n1, bc_num n2, size_t scale_min)
 				break;
 			case 1:
 				/* n2 is less than n1, subtract n2 from n1. */
-				sum = _bc_do_sub(n1, n2, scale_min);
+				sum = _bc_do_sub(n1, n2);
 				sum->n_sign = n1->n_sign;
 		}
 	}

ext/bcmath/libbcmath/src/doaddsub.c

@@ -169,7 +169,7 @@ bc_num _bc_do_add(bc_num n1, bc_num n2, size_t scale_min)
    returned.  The signs of N1 and N2 are ignored.  Also, N1 is
    assumed to be larger than N2.  SCALE_MIN is the minimum scale
    of the result. */
-bc_num _bc_do_sub(bc_num n1, bc_num n2, size_t scale_min)
+bc_num _bc_do_sub(bc_num n1, bc_num n2)
 {
 	bc_num diff;
 	/* The caller is guaranteed that n1 is always large. */
@@ -185,7 +185,7 @@ bc_num _bc_do_sub(bc_num n1, bc_num n2, size_t scale_min)
 	char *n1ptr, *n2ptr, *diffptr;
 
 	/* Allocate temporary storage. */
-	diff = bc_new_num (diff_len, MAX(diff_scale, scale_min));
+	diff = bc_new_num_nonzeroed(diff_len, diff_scale);
 
 	/* Initialize the subtract. */
 	n1ptr = (char *) (n1->n_value + n1->n_len + n1->n_scale - 1);

ext/bcmath/libbcmath/src/private.h

@@ -99,5 +99,5 @@ static inline uint64_t BC_BSWAP64(uint64_t u)
 /* routines */
 int _bc_do_compare (bc_num n1, bc_num n2, bool use_sign);
 bc_num _bc_do_add (bc_num n1, bc_num n2, size_t scale_min);
-bc_num _bc_do_sub (bc_num n1, bc_num n2, size_t scale_min);
+bc_num _bc_do_sub (bc_num n1, bc_num n2);
 void _bc_rm_leading_zeros (bc_num num);

ext/bcmath/libbcmath/src/sub.c

@@ -52,7 +52,7 @@ bc_num bc_sub(bc_num n1, bc_num n2, size_t scale_min)
 		switch (_bc_do_compare(n1, n2, false)) {
 			case -1:
 				/* n1 is less than n2, subtract n1 from n2. */
-				diff = _bc_do_sub(n2, n1, scale_min);
+				diff = _bc_do_sub(n2, n1);
 				diff->n_sign = (n2->n_sign == PLUS ? MINUS : PLUS);
 				break;
 			case 0: {
@@ -63,7 +63,7 @@ bc_num bc_sub(bc_num n1, bc_num n2, size_t scale_min)
 			}
 			case 1:
 				/* n2 is less than n1, subtract n2 from n1. */
-				diff = _bc_do_sub(n1, n2, scale_min);
+				diff = _bc_do_sub(n1, n2);
 				diff->n_sign = n1->n_sign;
 				break;
 		}