2001-11-14 Dave Brolley <brolley@redhat.com>

	* cgen-dis.c (count_decodable_bits): New function.
	(add_insn_to_hash_chain): New function.
	(hash_insn_array): Call add_insn_to_hash_chain.
	(hash_insn_list): Call add_insn_to_hash_chain.

2 files changed, 58 insertions, 7 deletions

diff --git a/opcodes/ChangeLog b/opcodes/ChangeLog
index b041d52..e4117bc 100644
--- a/opcodes/ChangeLog
+++ b/opcodes/ChangeLog
@@ -1,5 +1,9 @@
 2001-11-14  Dave Brolley  <brolley@redhat.com>
 
+	* cgen-dis.c (count_decodable_bits): New function.
+	(add_insn_to_hash_chain): New function.
+	(hash_insn_array): Call add_insn_to_hash_chain.
+	(hash_insn_list): Call add_insn_to_hash_chain.
 	* m32r-dis.c: Regenerated.
 	* fr30-dis.c: Regenerated.
 
diff --git a/opcodes/cgen-dis.c b/opcodes/cgen-dis.c
index 8e9fe56..4622c8c 100644
--- a/opcodes/cgen-dis.c
+++ b/opcodes/cgen-dis.c
@@ -30,7 +30,58 @@
 static CGEN_INSN_LIST *  hash_insn_array      PARAMS ((CGEN_CPU_DESC, const CGEN_INSN *, int, int, CGEN_INSN_LIST **, CGEN_INSN_LIST *));
 static CGEN_INSN_LIST *  hash_insn_list       PARAMS ((CGEN_CPU_DESC, const CGEN_INSN_LIST *, CGEN_INSN_LIST **, CGEN_INSN_LIST *));
 static void              build_dis_hash_table PARAMS ((CGEN_CPU_DESC));
-     
+
+/* Return the number of decodable bits in this insn.  */
+static int
+count_decodable_bits (insn)
+  const CGEN_INSN *insn;
+{
+  unsigned mask = CGEN_INSN_BASE_MASK (insn);
+  int bits = 0;
+  int m;
+  for (m = 1; m != 0; m <<= 1)
+    {
+      if (mask & m)
+	++bits;
+    }
+  return bits;
+}
+
+/* Add an instruction to the hash chain.  */     
+static void
+add_insn_to_hash_chain (hentbuf, insn, htable, hash)
+     CGEN_INSN_LIST *hentbuf;
+     const CGEN_INSN *insn;
+     CGEN_INSN_LIST **htable;
+     unsigned int hash;
+{
+  CGEN_INSN_LIST *current_buf;
+  CGEN_INSN_LIST *previous_buf;
+  int insn_decodable_bits;
+
+  /* Add insns sorted by the number of decodable bits, in decreasing order.
+     This ensures that any insn which is a special case of another will be
+     checked first.  */
+  insn_decodable_bits = count_decodable_bits (insn);
+  previous_buf = NULL;
+  for (current_buf = htable[hash]; current_buf != NULL;
+       current_buf = current_buf->next)
+    {
+      int current_decodable_bits = count_decodable_bits (current_buf->insn);
+      if (insn_decodable_bits >= current_decodable_bits)
+	break;
+      previous_buf = current_buf;
+    }
+
+  /* Now insert the new insn.  */
+  hentbuf->insn = insn;
+  hentbuf->next = current_buf;
+  if (previous_buf == NULL)
+    htable[hash] = hentbuf;
+  else
+    previous_buf->next = hentbuf;
+}
+
 /* Subroutine of build_dis_hash_table to add INSNS to the hash table.
 
    COUNT is the number of elements in INSNS.
@@ -74,9 +125,7 @@ hash_insn_array (cd, insns, count, entsize, htable, hentbuf)
 		    CGEN_INSN_MASK_BITSIZE (insn),
 		    big_p);
       hash = (* cd->dis_hash) (buf, value);
-      hentbuf->next = htable[hash];
-      hentbuf->insn = insn;
-      htable[hash] = hentbuf;
+      add_insn_to_hash_chain (hentbuf, insn, htable, hash);
     }
 
   return hentbuf;
@@ -114,9 +163,7 @@ hash_insn_list (cd, insns, htable, hentbuf)
 		   CGEN_INSN_MASK_BITSIZE (ilist->insn),
 		   big_p);
       hash = (* cd->dis_hash) (buf, value);
-      hentbuf->next = htable [hash];
-      hentbuf->insn = ilist->insn;
-      htable [hash] = hentbuf;
+      add_insn_to_hash_chain (hentbuf, ilist->insn, htable, hash);
     }
 
   return hentbuf;