hash.c: remove the caml_hash_univ_param function

This function implements the old, pre-4.00 hashing scheme that is
no longer used (as a compatibility backup) in stdlib/hashtbl.ml.
It is therefore dead code.

runtime/hash.c

@@ -25,8 +25,8 @@
 #include "caml/memory.h"
 #include "caml/hash.h"
 
-/* The new implementation, based on MurmurHash 3,
-     http://code.google.com/p/smhasher/  */
+/* The implementation based on MurmurHash 3,
+   https://github.com/aappleby/smhasher/ */
 
 #define ROTL32(x,n) ((x) << n | (x) >> (32-n))
 
@@ -301,146 +301,6 @@ CAMLprim value caml_hash(value count, value limit, value seed, value obj)
   return Val_int(h & 0x3FFFFFFFU);
 }
 
-/* The old implementation */
-
-struct hash_state {
-  uintnat accu;
-  intnat univ_limit, univ_count;
-};
-
-static void hash_aux(struct hash_state*, value obj);
-
-CAMLprim value caml_hash_univ_param(value count, value limit, value obj)
-{
-  struct hash_state h;
-  h.univ_limit = Long_val(limit);
-  h.univ_count = Long_val(count);
-  h.accu = 0;
-  hash_aux(&h, obj);
-  return Val_long(h.accu & 0x3FFFFFFF);
-  /* The & has two purposes: ensure that the return value is positive
-     and give the same result on 32 bit and 64 bit architectures. */
-}
-
-#define Alpha 65599
-#define Beta 19
-#define Combine(new)  (h->accu = h->accu * Alpha + (new))
-#define Combine_small(new) (h->accu = h->accu * Beta + (new))
-
-static void hash_aux(struct hash_state* h, value obj)
-{
-  unsigned char * p;
-  mlsize_t i, j;
-  tag_t tag;
-
-  h->univ_limit--;
-  if (h->univ_count < 0 || h->univ_limit < 0) return;
-
- again:
-  if (Is_long(obj)) {
-    h->univ_count--;
-    Combine(Long_val(obj));
-    return;
-  }
-  if (! Is_in_value_area(obj)) {
-    /* obj is a pointer outside the heap, to an object with
-       a priori unknown structure. Use its physical address as hash key. */
-    Combine((intnat) obj);
-    return;
-  }
-  /* Pointers into the heap are well-structured blocks. So are atoms.
-     We can inspect the block contents. */
-  /* The code needs reindenting later. Leaving as is to facilitate review. */
-    tag = Tag_val(obj);
-    switch (tag) {
-    case String_tag:
-      h->univ_count--;
-      i = caml_string_length(obj);
-      for (p = &Byte_u(obj, 0); i > 0; i--, p++)
-        Combine_small(*p);
-      break;
-    case Double_tag:
-      /* For doubles, we inspect their binary representation, LSB first.
-         The results are consistent among all platforms with IEEE floats. */
-      h->univ_count--;
-#ifdef ARCH_BIG_ENDIAN
-      for (p = &Byte_u(obj, sizeof(double) - 1), i = sizeof(double);
-           i > 0;
-           p--, i--)
-#else
-      for (p = &Byte_u(obj, 0), i = sizeof(double);
-           i > 0;
-           p++, i--)
-#endif
-        Combine_small(*p);
-      break;
-    case Double_array_tag:
-      h->univ_count--;
-      for (j = 0; j < Bosize_val(obj); j += sizeof(double)) {
-#ifdef ARCH_BIG_ENDIAN
-      for (p = &Byte_u(obj, j + sizeof(double) - 1), i = sizeof(double);
-           i > 0;
-           p--, i--)
-#else
-      for (p = &Byte_u(obj, j), i = sizeof(double);
-           i > 0;
-           p++, i--)
-#endif
-        Combine_small(*p);
-      }
-      break;
-    case Abstract_tag:
-      /* We don't know anything about the contents of the block.
-         Better do nothing. */
-      break;
-    case Infix_tag:
-      hash_aux(h, obj - Infix_offset_val(obj));
-      break;
-    case Forward_tag:
-      obj = Forward_val (obj);
-      goto again;
-    case Object_tag:
-      h->univ_count--;
-      Combine(Oid_val(obj));
-      break;
-    case Custom_tag:
-      /* If no hashing function provided, do nothing */
-      if (Custom_ops_val(obj)->hash != NULL) {
-        h->univ_count--;
-        Combine(Custom_ops_val(obj)->hash(obj));
-      }
-      break;
-#ifdef NO_NAKED_POINTERS
-    case Closure_tag:
-      h->univ_count--;
-      Combine_small(tag);
-      /* Recursively hash the environment fields */
-      i = Wosize_val(obj);
-      j = Start_env_closinfo(Closinfo_val(obj));
-      while (i > j) {
-        i--;
-        hash_aux(h, Field(obj, i));
-      }
-      /* Combine the code pointers, closure info fields, and infix headers */
-      while (i > 0) {
-        i--;
-        Combine(Field(obj, i));
-        h->univ_count--;
-      }
-      break;
-#endif
-    default:
-      h->univ_count--;
-      Combine_small(tag);
-      i = Wosize_val(obj);
-      while (i != 0) {
-        i--;
-        hash_aux(h, Field(obj, i));
-      }
-      break;
-    }
-}
-
 /* Hashing variant tags */
 
 CAMLexport value caml_hash_variant(char const * tag)