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,
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. */
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;
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;
{
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);
The format of the opcode table is:
- NAME OPCODE MASK CPU CLASS SUBCLASS { OPERANDS } { FLAGS }. */
+ NAME OPCODE MASK CPU CLASS SUBCLASS { OPERANDS } { FLAGS }.
+
+ The table is organised such that, where possible, all instructions with
+ the same mnemonic are together in a block. When the assembler searches
+ for a suitable instruction the entries are checked in table order, so
+ more specific, or specialised cases should appear earlier in the table.
+
+ As an example, consider two instructions 'add a,b,u6' and 'add
+ a,b,limm'. The first takes a 6-bit immediate that is encoded within the
+ 32-bit instruction, while the second takes a 32-bit immediate that is
+ encoded in a follow-on 32-bit, making the total instruction length
+ 64-bits. In this case the u6 variant must appear first in the table, as
+ all u6 immediates could also be encoded using the 'limm' extension,
+ however, we want to use the shorter instruction wherever possible.
+
+ It is possible though to split instructions with the same mnemonic into
+ multiple groups. However, the instructions are still checked in table
+ order, even across groups. The only time that instructions with the
+ same mnemonic should be split into different groups is when different
+ variants of the instruction appear in different architectures, in which
+ case, grouping all instructions from a particular architecture together
+ might be preferable to merging the instruction into the main instruction
+ table.
+
+ An example of this split instruction groups can be found with the 'sync'
+ instruction. The core arc architecture provides a 'sync' instruction,
+ while the nps instruction set extension provides 'sync.rd' and
+ 'sync.wr'. The rd/wr flags are instruction flags, not part of the
+ mnemonic, so we end up with two groups for the sync instruction, the
+ first within the core arc instruction table, and the second within the
+ nps extension instructions. */
const struct arc_opcode arc_opcodes[] =
{
#include "arc-tbl.h"
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