Fix UB in bf_set_ui()

Ref: bellard/quickjs#131

Author: bellard

libbf.c

@@ -164,6 +164,21 @@ static inline slimb_t sat_add(slimb_t a, slimb_t b)
     return r;
 }
 
+static inline __maybe_unused limb_t shrd(limb_t low, limb_t high, long shift)
+{
+    if (shift != 0)
+        low = (low >> shift) | (high << (LIMB_BITS - shift));
+    return low;
+}
+
+static inline __maybe_unused limb_t shld(limb_t a1, limb_t a0, long shift)
+{
+    if (shift != 0)
+        return (a1 << shift) | (a0 >> (LIMB_BITS - shift));
+    else
+        return a1;
+}
+
 #define malloc(s) malloc_is_forbidden(s)
 #define free(p) free_is_forbidden(p)
 #define realloc(p, s) realloc_is_forbidden(p, s)
@@ -236,7 +251,7 @@ int bf_set_ui(bf_t *r, uint64_t a)
         a1 = a >> 32;
         shift = clz(a1);
         r->tab[0] = a0 << shift;
-        r->tab[1] = (a1 << shift) | (a0 >> (LIMB_BITS - shift));
+        r->tab[1] = shld(a1, a0, shift);
         r->expn = 2 * LIMB_BITS - shift;
     }
 #endif
@@ -5388,21 +5403,6 @@ int bf_acos(bf_t *r, const bf_t *a, limb_t prec, bf_flags_t flags)
 
 #endif /* LIMB_BITS != 64 */
 
-static inline __maybe_unused limb_t shrd(limb_t low, limb_t high, long shift)
-{
-    if (shift != 0)
-        low = (low >> shift) | (high << (LIMB_BITS - shift));
-    return low;
-}
-
-static inline __maybe_unused limb_t shld(limb_t a1, limb_t a0, long shift)
-{
-    if (shift != 0)
-        return (a1 << shift) | (a0 >> (LIMB_BITS - shift));
-    else
-        return a1;
-}
-
 #if LIMB_DIGITS == 19
 
 /* WARNING: hardcoded for b = 1e19. It is assumed that: