bn: Remove the BN_RECURSION cpp define

Just like in previous commit, this define does not represent a toggleable
feature, but is entirely dependent on the OPENSSL_SMALL_FOOTPRINT define.

Reviewed-by: Frederik Wedel-Heinen <fwh.openssl@gmail.com>
Reviewed-by: Tomas Mraz <tomas@openssl.org>
MergeDate: Mon Jan 12 18:44:27 2026
(Merged from https://github.com/openssl/openssl/pull/29204)

diff --git a/crypto/bn/bn_local.h b/crypto/bn/bn_local.h
index 7a4d9e7a088469453445d2f23013dfe734dbd01d..d211ea3433aa6d60cd9b39adaf37ad4f5c120655 100644 (file)
--- a/crypto/bn/bn_local.h
+++ b/crypto/bn/bn_local.h
@@ -52,10 +52,6 @@
 #define BN_SOFT_LIMIT (4096 / BN_BYTES)
 #endif
 
-#ifndef OPENSSL_SMALL_FOOTPRINT
-#define BN_RECURSION
-#endif
-
 /*
  * This next option uses the C libraries (2 word)/(1 word) function. If it is
  * not defined, I use my C version (which is slower). The reason for this

diff --git a/crypto/bn/bn_mul.c b/crypto/bn/bn_mul.c
index 9977479dfcf06e123c2b666d47c449aa5b333466..8e4488b93357ea7a90974dea6c63fafdebc12baa 100644 (file)
--- a/crypto/bn/bn_mul.c
+++ b/crypto/bn/bn_mul.c
@@ -154,7 +154,7 @@ BN_ULONG bn_sub_part_words(BN_ULONG *r,
 }
 #endif
 
-#ifdef BN_RECURSION
+#ifndef OPENSSL_SMALL_FOOTPRINT
 /*
  * Karatsuba recursive multiplication algorithm (cf. Knuth, The Art of
  * Computer Programming, Vol. 2)
@@ -180,7 +180,6 @@ void bn_mul_recursive(BN_ULONG *r, BN_ULONG *a, BN_ULONG *b, int n2,
     unsigned int neg, zero;
     BN_ULONG ln, lo, *p;
 
-#ifndef OPENSSL_SMALL_FOOTPRINT
     /*
      * Only call bn_mul_comba 8 if n2 == 8 and the two arrays are complete
      * [steve]
@@ -189,7 +188,7 @@ void bn_mul_recursive(BN_ULONG *r, BN_ULONG *a, BN_ULONG *b, int n2,
         bn_mul_comba8(r, a, b);
         return;
     }
-#endif /* OPENSSL_SMALL_FOOTPRINT */
+
     /* Else do normal multiply */
     if (n2 < BN_MUL_RECURSIVE_SIZE_NORMAL) {
         bn_mul_normal(r, a, n2 + dna, b, n2 + dnb);
@@ -234,7 +233,6 @@ void bn_mul_recursive(BN_ULONG *r, BN_ULONG *a, BN_ULONG *b, int n2,
         break;
     }
 
-#ifndef OPENSSL_SMALL_FOOTPRINT
     if (n == 4 && dna == 0 && dnb == 0) { /* XXX: bn_mul_comba4 could take
                                            * extra args to do this well */
         if (!zero)
@@ -254,9 +252,7 @@ void bn_mul_recursive(BN_ULONG *r, BN_ULONG *a, BN_ULONG *b, int n2,
 
         bn_mul_comba8(r, a, b);
         bn_mul_comba8(&(r[n2]), &(a[n]), &(b[n]));
-    } else
-#endif /* OPENSSL_SMALL_FOOTPRINT */
-    {
+    } else {
         p = &(t[n2 * 2]);
         if (!zero)
             bn_mul_recursive(&(t[n2]), t, &(t[n]), n, 0, 0, p);
@@ -486,7 +482,7 @@ void bn_mul_low_recursive(BN_ULONG *r, BN_ULONG *a, BN_ULONG *b, int n2,
         bn_add_words(&(r[n]), &(r[n]), &(t[n]), n);
     }
 }
-#endif /* BN_RECURSION */
+#endif /* OPENSSL_SMALL_FOOTPRINT */
 
 int BN_mul(BIGNUM *r, const BIGNUM *a, const BIGNUM *b, BN_CTX *ctx)
 {
@@ -503,10 +499,8 @@ int bn_mul_fixed_top(BIGNUM *r, const BIGNUM *a, const BIGNUM *b, BN_CTX *ctx)
     int ret = 0;
     int top, al, bl;
     BIGNUM *rr;
-#if !defined(OPENSSL_SMALL_FOOTPRINT) || defined(BN_RECURSION)
+#if !defined(OPENSSL_SMALL_FOOTPRINT)
     int i;
-#endif
-#ifdef BN_RECURSION
     BIGNUM *t = NULL;
     int j = 0, k;
 #endif
@@ -531,10 +525,9 @@ int bn_mul_fixed_top(BIGNUM *r, const BIGNUM *a, const BIGNUM *b, BN_CTX *ctx)
     } else
         rr = r;
 
-#if !defined(OPENSSL_SMALL_FOOTPRINT) || defined(BN_RECURSION)
+#if !defined(OPENSSL_SMALL_FOOTPRINT)
     i = al - bl;
-#endif
-#ifndef OPENSSL_SMALL_FOOTPRINT
+
     if (i == 0) {
 #if 0
         if (al == 4) {
@@ -553,8 +546,7 @@ int bn_mul_fixed_top(BIGNUM *r, const BIGNUM *a, const BIGNUM *b, BN_CTX *ctx)
             goto end;
         }
     }
-#endif /* OPENSSL_SMALL_FOOTPRINT */
-#ifdef BN_RECURSION
+
     if ((al >= BN_MULL_SIZE_NORMAL) && (bl >= BN_MULL_SIZE_NORMAL)) {
         if (i >= -1 && i <= 1) {
             /*
@@ -592,13 +584,13 @@ int bn_mul_fixed_top(BIGNUM *r, const BIGNUM *a, const BIGNUM *b, BN_CTX *ctx)
             goto end;
         }
     }
-#endif /* BN_RECURSION */
+#endif /* OPENSSL_SMALL_FOOTPRINT */
     if (bn_wexpand(rr, top) == NULL)
         goto err;
     rr->top = top;
     bn_mul_normal(rr->d, a->d, al, b->d, bl);
 
-#if !defined(OPENSSL_SMALL_FOOTPRINT) || defined(BN_RECURSION)
+#if !defined(OPENSSL_SMALL_FOOTPRINT)
 end:
 #endif
     rr->neg = a->neg ^ b->neg;

diff --git a/crypto/bn/bn_sqr.c b/crypto/bn/bn_sqr.c
index 4d420fa14a10adc0dcd55e43da7bae658b7a9440..98c868f7b7d19140eba42b93263c6d5ab2305fe7 100644 (file)
--- a/crypto/bn/bn_sqr.c
+++ b/crypto/bn/bn_sqr.c
@@ -64,7 +64,11 @@ int bn_sqr_fixed_top(BIGNUM *r, const BIGNUM *a, BN_CTX *ctx)
         bn_sqr_comba8(rr->d, a->d);
 #endif
     } else {
-#if defined(BN_RECURSION)
+#ifdef OPENSSL_SMALL_FOOTPRINT
+        if (bn_wexpand(tmp, max) == NULL)
+            goto err;
+        bn_sqr_normal(rr->d, a->d, al, tmp->d);
+#else
         if (al < BN_SQR_RECURSIVE_SIZE_NORMAL) {
             BN_ULONG t[BN_SQR_RECURSIVE_SIZE_NORMAL * 2];
             bn_sqr_normal(rr->d, a->d, al, t);
@@ -84,10 +88,6 @@ int bn_sqr_fixed_top(BIGNUM *r, const BIGNUM *a, BN_CTX *ctx)
                 bn_sqr_normal(rr->d, a->d, al, tmp->d);
             }
         }
-#else
-        if (bn_wexpand(tmp, max) == NULL)
-            goto err;
-        bn_sqr_normal(rr->d, a->d, al, tmp->d);
 #endif
     }
 
@@ -141,7 +141,7 @@ void bn_sqr_normal(BN_ULONG *r, const BN_ULONG *a, int n, BN_ULONG *tmp)
     bn_add_words(r, r, tmp, max);
 }
 
-#ifdef BN_RECURSION
+#ifndef OPENSSL_SMALL_FOOTPRINT
 /*-
  * r is 2*n words in size,
  * a and b are both n words in size.    (There's not actually a 'b' here ...)
@@ -160,18 +160,10 @@ void bn_sqr_recursive(BN_ULONG *r, const BN_ULONG *a, int n2, BN_ULONG *t)
     BN_ULONG ln, lo, *p;
 
     if (n2 == 4) {
-#ifdef OPENSSL_SMALL_FOOTPRINT
-        bn_sqr_normal(r, a, 4, t);
-#else
         bn_sqr_comba4(r, a);
-#endif
         return;
     } else if (n2 == 8) {
-#ifdef OPENSSL_SMALL_FOOTPRINT
-        bn_sqr_normal(r, a, 8, t);
-#else
         bn_sqr_comba8(r, a);
-#endif
         return;
     }
     if (n2 < BN_SQR_RECURSIVE_SIZE_NORMAL) {