Remove the non-storage cmov

src/field.h

@@ -117,7 +117,6 @@ static void secp256k1_fe_to_storage(secp256k1_fe_storage_t *r, const secp256k1_f
 static void secp256k1_fe_from_storage(secp256k1_fe_t *r, const secp256k1_fe_storage_t*);
 
 /** If flag is true, set *r equal to *a; otherwise leave it. Constant-time. */
-static void secp256k1_fe_cmov(secp256k1_fe_t *r, const secp256k1_fe_t *a, int flag);
 static void secp256k1_fe_storage_cmov(secp256k1_fe_storage_t *r, const secp256k1_fe_storage_t *a, int flag);
 
 #endif

src/field_10x26_impl.h

@@ -1063,26 +1063,6 @@ static void secp256k1_fe_sqr(secp256k1_fe_t *r, const secp256k1_fe_t *a) {
 #endif
 }
 
-static void secp256k1_fe_cmov(secp256k1_fe_t *r, const secp256k1_fe_t *a, int flag) {
-    uint32_t mask0 = flag + ~((uint32_t)0), mask1 = ~mask0;
-    r->n[0] = (r->n[0] & mask0) | (a->n[0] & mask1);
-    r->n[1] = (r->n[1] & mask0) | (a->n[1] & mask1);
-    r->n[2] = (r->n[2] & mask0) | (a->n[2] & mask1);
-    r->n[3] = (r->n[3] & mask0) | (a->n[3] & mask1);
-    r->n[4] = (r->n[4] & mask0) | (a->n[4] & mask1);
-    r->n[5] = (r->n[5] & mask0) | (a->n[5] & mask1);
-    r->n[6] = (r->n[6] & mask0) | (a->n[6] & mask1);
-    r->n[7] = (r->n[7] & mask0) | (a->n[7] & mask1);
-    r->n[8] = (r->n[8] & mask0) | (a->n[8] & mask1);
-    r->n[9] = (r->n[9] & mask0) | (a->n[9] & mask1);
-#ifdef VERIFY
-    if (flag) {
-        r->magnitude = a->magnitude;
-        r->normalized = a->normalized;
-    }
-#endif
-}
-
 static inline void secp256k1_fe_storage_cmov(secp256k1_fe_storage_t *r, const secp256k1_fe_storage_t *a, int flag) {
     uint32_t mask0 = flag + ~((uint32_t)0), mask1 = ~mask0;
     r->n[0] = (r->n[0] & mask0) | (a->n[0] & mask1);

src/field_5x52_impl.h

@@ -398,21 +398,6 @@ static void secp256k1_fe_sqr(secp256k1_fe_t *r, const secp256k1_fe_t *a) {
 #endif
 }
 
-static void secp256k1_fe_cmov(secp256k1_fe_t *r, const secp256k1_fe_t *a, int flag) {
-    uint64_t mask0 = flag + ~((uint64_t)0), mask1 = ~mask0;
-    r->n[0] = (r->n[0] & mask0) | (a->n[0] & mask1);
-    r->n[1] = (r->n[1] & mask0) | (a->n[1] & mask1);
-    r->n[2] = (r->n[2] & mask0) | (a->n[2] & mask1);
-    r->n[3] = (r->n[3] & mask0) | (a->n[3] & mask1);
-    r->n[4] = (r->n[4] & mask0) | (a->n[4] & mask1);
-#ifdef VERIFY
-    if (flag) {
-        r->magnitude = a->magnitude;
-        r->normalized = a->normalized;
-    }
-#endif
-}
-
 static inline void secp256k1_fe_storage_cmov(secp256k1_fe_storage_t *r, const secp256k1_fe_storage_t *a, int flag) {
     uint64_t mask0 = flag + ~((uint64_t)0), mask1 = ~mask0;
     r->n[0] = (r->n[0] & mask0) | (a->n[0] & mask1);

src/tests.c

@@ -685,12 +685,18 @@ void run_field_misc(void) {
         z = x;
         secp256k1_fe_add(&z,&y);
         secp256k1_fe_normalize(&z);
-        /* Test the conditional move. */
+        /* Test storage conversion and conditional moves. */
-        secp256k1_fe_cmov(&z, &x, 0);
+        secp256k1_fe_storage_t xs, ys, zs;
-        CHECK(secp256k1_fe_equal_var(&x, &z) == 0);
+        secp256k1_fe_to_storage(&xs, &x);
-        CHECK(secp256k1_fe_cmp_var(&x, &z) != 0);
+        secp256k1_fe_to_storage(&ys, &y);
-        secp256k1_fe_cmov(&y, &x, 1);
+        secp256k1_fe_to_storage(&zs, &z);
-        CHECK(secp256k1_fe_equal_var(&x, &y));
+        secp256k1_fe_storage_cmov(&zs, &xs, 0);
+        CHECK(memcmp(&xs, &zs, sizeof(xs)) != 0);
+        secp256k1_fe_storage_cmov(&ys, &xs, 1);
+        CHECK(memcmp(&xs, &ys, sizeof(xs)) == 0);
+        secp256k1_fe_from_storage(&x, &xs);
+        secp256k1_fe_from_storage(&y, &ys);
+        secp256k1_fe_from_storage(&z, &zs);
         /* Test that mul_int, mul, and add agree. */
         secp256k1_fe_add(&y, &x);
         secp256k1_fe_add(&y, &x);