src/ecmult_impl.h

@@ -417,12 +417,11 @@ static int secp256k1_ecmult_wnaf(int *wnaf, int len, const secp256k1_scalar *a,
 
         bit += now;
     }
-#ifdef VERIFY
-    CHECK(carry == 0);
+    VERIFY_CHECK(carry == 0);
     while (bit < 256) {
-        CHECK(secp256k1_scalar_get_bits(&s, bit++, 1) == 0);
+        VERIFY_CHECK(secp256k1_scalar_get_bits(&s, bit, 1) == 0);
+        bit++;
     }
-#endif
     return last_set_bit + 1;
 }
 

src/util.h

@@ -47,7 +47,17 @@ static SECP256K1_INLINE void secp256k1_callback_call(const secp256k1_callback *
 #define EXPECT(x,c) (x)
 #endif
 
-#ifdef DETERMINISTIC
+/* CHECK() is like assert(). We use it only in the tests. */
+#if defined(COVERAGE)
+/* Don't abort in coverage mode.
+   This avoids branches which are not expected to be taken.
+   We still use cond as usual to avoid unused variable warnings. */
+#define CHECK(cond) do { \
+    if (EXPECT(!(cond), 0)) { \
+        ; \
+    } \
+} while (0)
+#elif defined(DETERMINISTIC)
 #define CHECK(cond) do { \
     if (EXPECT(!(cond), 0)) { \
         TEST_FAILURE("test condition failed"); \
@@ -62,7 +72,14 @@ static SECP256K1_INLINE void secp256k1_callback_call(const secp256k1_callback *
 #endif
 
 /* Like assert(), but when VERIFY is defined, and side-effect safe. */
-#if defined(VERIFY)
+#if defined(COVERAGE)
+/* Do nothing in coverage mode but try to stay syntactically correct.
+   This suppresses a lot of implicit branches introduced by shortcutting
+   operators at the cost of not being side-effect safe in coverage mode.
+   We rely on the compiler to eliminate the if (0) statement entirely. */
+#define VERIFY_CHECK(cond) do { if (0) (void)(cond); } while(0)
+#define VERIFY_SETUP(stmt)
+#elif defined(VERIFY)
 #define VERIFY_CHECK CHECK
 #define VERIFY_SETUP(stmt) do { stmt; } while(0)
 #else