Slightly rework bn_mulw_addtw().

Call bn_mulw_addw() rather than doing bn_mulw() follow by bn_addw(). This
simplifies the code slightly, plus on some platforms bn_mulw_addw() can
be optimised (and bn_mulw_addtw() will then benefit from such an
optimisation).

ok tb@

1 files changed, 3 insertions, 5 deletions

diff --git a/src/lib/libcrypto/bn/bn_internal.h b/src/lib/libcrypto/bn/bn_internal.h
index 4f4d1c31f5..8a729b8e44 100644
--- a/src/lib/libcrypto/bn/bn_internal.h
+++ b/src/lib/libcrypto/bn/bn_internal.h
@@ -1,4 +1,4 @@
-/*      $OpenBSD: bn_internal.h,v 1.10 2023/03/07 05:57:01 jsing Exp $ */
+/*      $OpenBSD: bn_internal.h,v 1.11 2023/03/07 09:35:55 jsing Exp $ */
 /*
  * Copyright (c) 2023 Joel Sing <jsing@openbsd.org>
  *
@@ -347,11 +347,9 @@ static inline void
 bn_mulw_addtw(BN_ULONG a, BN_ULONG b, BN_ULONG c2, BN_ULONG c1, BN_ULONG c0,
     BN_ULONG *out_r2, BN_ULONG *out_r1, BN_ULONG *out_r0)
 {
-        BN_ULONG carry, r2, r1, r0, x1, x0;
+        BN_ULONG carry, r2, r1, r0, x1;
 
-        bn_mulw(a, b, &x1, &x0);
-        bn_addw(c0, x0, &carry, &r0);
-        x1 += carry;
+        bn_mulw_addw(a, b, c0, &x1, &r0);
         bn_addw(c1, x1, &carry, &r1);
         r2 = c2 + carry;