gas/arc: Handle multiple arc_opcode chains for same mnemonic

This commit completes support for having multiple instructions with the
same mnemonic in non-contiguous blocks within the arc_opcodes table.

The commit adds an iterator mechanism for the arc_opcode_hash_entry
structure, which is then used in find_opcode_match to consider all
arc_opcode entries with the same mnemonic, even when these instructions
are stored in non-contiguous blocks.

I extend the comment on the arc_opcodes table to discuss how entries
within the table are organised, and to mention how instructions can be
split into multiple groups if needed, but that the table is still
searched in table order.

There should be no user visible changes after this commit.

gas/ChangeLog:

	* config/tc-arc.c (struct arc_opcode_hash_entry_iterator): New
	structure.
	(arc_opcode_hash_entry_iterator_init): New function.
	(arc_opcode_hash_entry_iterator_next): New function.
	(find_opcode_match): Iterate over all arc_opcode entries
	referenced by the arc_opcode_hash_entry passed in as a parameter.

opcodes/ChangeLog:

	* arc-opc.c (arc_opcodes): Extend comment to discus table layout.

1 files changed, 60 insertions, 12 deletions

diff --git a/gas/config/tc-arc.c b/gas/config/tc-arc.c
index 4c5af3f..1b70e03 100644
--- a/gas/config/tc-arc.c
+++ b/gas/config/tc-arc.c
@@ -318,6 +318,17 @@ struct arc_opcode_hash_entry
   const struct arc_opcode **opcode;
 };
 
+/* Structure used for iterating through an arc_opcode_hash_entry.  */
+struct arc_opcode_hash_entry_iterator
+{
+  /* Index into the OPCODE element of the arc_opcode_hash_entry.  */
+  size_t index;
+
+  /* The specific ARC_OPCODE from the ARC_OPCODES table that was last
+     returned by this iterator.  */
+  const struct arc_opcode *opcode;
+};
+
 /* Forward declaration.  */
 static void assemble_insn
   (const struct arc_opcode *, const expressionS *, int,
@@ -577,6 +588,47 @@ arc_find_opcode (const char *name)
   return entry;
 }
 
+/* Initialise the iterator ITER.  */
+
+static void
+arc_opcode_hash_entry_iterator_init (struct arc_opcode_hash_entry_iterator *iter)
+{
+  iter->index = 0;
+  iter->opcode = NULL;
+}
+
+/* Return the next ARC_OPCODE from ENTRY, using ITER to hold state between
+   calls to this function.  Return NULL when all ARC_OPCODE entries have
+   been returned.  */
+
+static const struct arc_opcode *
+arc_opcode_hash_entry_iterator_next (const struct arc_opcode_hash_entry *entry,
+				     struct arc_opcode_hash_entry_iterator *iter)
+{
+  if (iter->opcode == NULL && iter->index == 0)
+    {
+      gas_assert (entry->count > 0);
+      iter->opcode = entry->opcode[iter->index];
+    }
+  else if (iter->opcode != NULL)
+    {
+      const char *old_name = iter->opcode->name;
+
+      iter->opcode++;
+      if ((iter->opcode - arc_opcodes >= (int) arc_num_opcodes)
+	  || (strcmp (old_name, iter->opcode->name) != 0))
+	{
+	  iter->index++;
+	  if (iter->index == entry->count)
+	    iter->opcode = NULL;
+	  else
+	    iter->opcode = entry->opcode[iter->index];
+	}
+    }
+
+  return iter->opcode;
+}
+
 /* Like md_number_to_chars but used for limms.  The 4-byte limm value,
    is encoded as 'middle-endian' for a little-endian target.  FIXME!
    this function is used for regular 4 byte instructions as well.  */
@@ -1406,23 +1458,22 @@ find_opcode_match (const struct arc_opcode_hash_entry *entry,
 		   int nflgs,
 		   int *pcpumatch)
 {
-  const struct arc_opcode *first_opcode = entry->opcode[0];
-  const struct arc_opcode *opcode = first_opcode;
+  const struct arc_opcode *opcode;
+  struct arc_opcode_hash_entry_iterator iter;
   int ntok = *pntok;
   int got_cpu_match = 0;
   expressionS bktok[MAX_INSN_ARGS];
   int bkntok;
   expressionS emptyE;
 
-  gas_assert (entry->count > 0);
-  if (entry->count > 1)
-    as_fatal (_("unable to lookup `%s', too many opcode chains"),
-	      first_opcode->name);
+  arc_opcode_hash_entry_iterator_init (&iter);
   memset (&emptyE, 0, sizeof (emptyE));
   memcpy (bktok, tok, MAX_INSN_ARGS * sizeof (*tok));
   bkntok = ntok;
 
-  do
+  for (opcode = arc_opcode_hash_entry_iterator_next (entry, &iter);
+       opcode != NULL;
+       opcode = arc_opcode_hash_entry_iterator_next (entry, &iter))
     {
       const unsigned char *opidx;
       const unsigned char *flgidx;
@@ -1743,8 +1794,6 @@ find_opcode_match (const struct arc_opcode_hash_entry *entry,
       memcpy (tok, bktok, MAX_INSN_ARGS * sizeof (*tok));
       ntok = bkntok;
     }
-  while (++opcode - arc_opcodes < (int) arc_num_opcodes
-	 && !strcmp (opcode->name, first_opcode->name));
 
   if (*pcpumatch)
     *pcpumatch = got_cpu_match;
@@ -2054,9 +2103,8 @@ assemble_tokens (const char *opname,
     {
       const struct arc_opcode *opcode;
 
-      pr_debug ("%s:%d: assemble_tokens: %s trying opcode 0x%08X\n",
-		frag_now->fr_file, frag_now->fr_line, opcode->name,
-		opcode->opcode);
+      pr_debug ("%s:%d: assemble_tokens: %s\n",
+		frag_now->fr_file, frag_now->fr_line, opname);
       found_something = TRUE;
       opcode = find_opcode_match (entry, tok, &ntok, pflags,
 				  nflgs, &cpumatch);