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[MIPS, committed] Tidy handling of MIPS16 extended instructions
- From: Richard Sandiford <rdsandiford at googlemail dot com>
- To: binutils at sourceware dot org
- Date: Sun, 23 Sep 2012 10:24:27 +0100
- Subject: [MIPS, committed] Tidy handling of MIPS16 extended instructions
We store 32-bit microMIPS instructions and 32-bit MIPS16 branches as
a single unsigned long opcode, but split extended MIPS16 instructions
into two. Things seem simpler without that distinction.
The patch also replaces the three mips16_immed boolean parameters with
a single forced_insn_length-style one.
The ugly bfd_byte casts go away in the next patch.
Tested on the usual round of MIPS targets and applied.
Richard
gas/
* config/tc-mips.c (mips_cl_insn): Remove use_extend and extend.
(MIPS16_EXTEND): New macro.
(mips16_opcode_length): New function.
(insn_length): Use it.
(create_insn): Update after mips_cl_insn change.
(write_compressed_insn): New function.
(install_insn): Use it.
(append_insn): Use insn_length to check for unextended MIPS16
instructions.
(mips16_macro_build): Update call to mips16_immed.
(mips16_ip): Likewise. Use MIPS16_EXTEND to force an extended
instruction.
(mips16_immed): Remove use_extend and extend; install EXTEND
opcodes in the upper 16 bits of *INSN instead. Keep the
instruction extended if it already is. Replace warn, small
and ext with a forced_insn_length-like parameter.
(md_convert_frag): Update call mips16_immed.
Use write_compressed_insn.
Index: gas/config/tc-mips.c
===================================================================
--- gas/config/tc-mips.c 2012-09-23 10:14:43.188305263 +0100
+++ gas/config/tc-mips.c 2012-09-23 10:14:47.447305141 +0100
@@ -145,15 +145,10 @@ struct mips_cl_insn
/* The opcode's entry in mips_opcodes or mips16_opcodes. */
const struct mips_opcode *insn_mo;
- /* True if this is a mips16 instruction and if we want the extended
- form of INSN_MO. */
- bfd_boolean use_extend;
-
- /* The 16-bit extension instruction to use when USE_EXTEND is true. */
- unsigned short extend;
-
/* The 16-bit or 32-bit bitstring of the instruction itself. This is
- a copy of INSN_MO->match with the operands filled in. */
+ a copy of INSN_MO->match with the operands filled in. If we have
+ decided to use an extended MIPS16 instruction, this includes the
+ extension. */
unsigned long insn_opcode;
/* The frag that contains the instruction. */
@@ -1240,6 +1235,9 @@ #define MIPS16_EXTRACT_OPERAND(FIELD, IN
EXTRACT_BITS ((INSN).insn_opcode, \
MIPS16OP_MASK_##FIELD, \
MIPS16OP_SH_##FIELD)
+
+/* The MIPS16 EXTEND opcode, shifted left 16 places. */
+#define MIPS16_EXTEND (0xf000U << 16)
/* Whether or not we are emitting a branch-likely macro. */
static bfd_boolean emit_branch_likely_macro = FALSE;
@@ -1323,8 +1321,7 @@ static void mips16_macro (struct mips_cl
static void mips_ip (char *str, struct mips_cl_insn * ip);
static void mips16_ip (char *str, struct mips_cl_insn * ip);
static void mips16_immed
- (char *, unsigned int, int, offsetT, bfd_boolean, bfd_boolean, bfd_boolean,
- unsigned long *, bfd_boolean *, unsigned short *);
+ (char *, unsigned int, int, offsetT, unsigned int, unsigned long *);
static size_t my_getSmallExpression
(expressionS *, bfd_reloc_code_real_type *, char *);
static void my_getExpression (expressionS *, char *);
@@ -1635,6 +1632,14 @@ micromips_insn_length (const struct mips
return (mo->mask >> 16) == 0 ? 2 : 4;
}
+/* Return the length of MIPS16 instruction OPCODE. */
+
+static inline unsigned int
+mips16_opcode_length (unsigned long opcode)
+{
+ return (opcode >> 16) == 0 ? 2 : 4;
+}
+
/* Return the length of instruction INSN. */
static inline unsigned int
@@ -1643,7 +1648,7 @@ insn_length (const struct mips_cl_insn *
if (mips_opts.micromips)
return micromips_insn_length (insn->insn_mo);
else if (mips_opts.mips16)
- return insn->mips16_absolute_jump_p || insn->use_extend ? 4 : 2;
+ return mips16_opcode_length (insn->insn_opcode);
else
return 4;
}
@@ -1656,8 +1661,6 @@ create_insn (struct mips_cl_insn *insn,
size_t i;
insn->insn_mo = mo;
- insn->use_extend = FALSE;
- insn->extend = 0;
insn->insn_opcode = mo->match;
insn->frag = NULL;
insn->where = 0;
@@ -1683,42 +1686,29 @@ mips_record_compressed_mode (void)
si->tc_segment_info_data.micromips = mips_opts.micromips;
}
+/* Write microMIPS or MIPS16 instruction INSN to BUF, given that the
+ instruction is LENGTH bytes long. Return a pointer to the next byte. */
+
+static char *
+write_compressed_insn (char *buf, unsigned int insn, unsigned int length)
+{
+ unsigned int i;
+
+ for (i = 0; i < length; i += 2)
+ md_number_to_chars (buf + i, insn >> ((length - i - 2) * 8), 2);
+ return buf + length;
+}
+
/* Install INSN at the location specified by its "frag" and "where" fields. */
static void
install_insn (const struct mips_cl_insn *insn)
{
char *f = insn->frag->fr_literal + insn->where;
- if (!HAVE_CODE_COMPRESSION)
- md_number_to_chars (f, insn->insn_opcode, 4);
- else if (mips_opts.micromips)
- {
- unsigned int length = insn_length (insn);
- if (length == 2)
- md_number_to_chars (f, insn->insn_opcode, 2);
- else if (length == 4)
- {
- md_number_to_chars (f, insn->insn_opcode >> 16, 2);
- f += 2;
- md_number_to_chars (f, insn->insn_opcode & 0xffff, 2);
- }
- else
- as_bad (_("48-bit microMIPS instructions are not supported"));
- }
- else if (insn->mips16_absolute_jump_p)
- {
- md_number_to_chars (f, insn->insn_opcode >> 16, 2);
- md_number_to_chars (f + 2, insn->insn_opcode & 0xffff, 2);
- }
+ if (HAVE_CODE_COMPRESSION)
+ write_compressed_insn (f, insn->insn_opcode, insn_length (insn));
else
- {
- if (insn->use_extend)
- {
- md_number_to_chars (f, 0xf000 | insn->extend, 2);
- f += 2;
- }
- md_number_to_chars (f, insn->insn_opcode, 2);
- }
+ md_number_to_chars (f, insn->insn_opcode, 4);
mips_record_compressed_mode ();
}
@@ -4274,9 +4264,7 @@ append_insn (struct mips_cl_insn *ip, ex
history[0].mips16_absolute_jump_p),
make_expr_symbol (address_expr), 0);
}
- else if (mips_opts.mips16
- && ! ip->use_extend
- && *reloc_type != BFD_RELOC_MIPS16_JMP)
+ else if (mips_opts.mips16 && insn_length (ip) == 2)
{
if (!delayed_branch_p (ip))
/* Make sure there is enough room to swap this instruction with
@@ -5191,9 +5179,8 @@ mips16_macro_build (expressionS *ep, con
*r = (int) BFD_RELOC_UNUSED + c;
else
{
- mips16_immed (NULL, 0, c, ep->X_add_number, FALSE, FALSE,
- FALSE, &insn.insn_opcode, &insn.use_extend,
- &insn.extend);
+ mips16_immed (NULL, 0, c, ep->X_add_number,
+ 0, &insn.insn_opcode);
ep = NULL;
*r = BFD_RELOC_UNUSED;
}
@@ -13370,9 +13357,7 @@ mips16_ip (char *str, struct mips_cl_ins
*offset_reloc = BFD_RELOC_UNUSED;
mips16_immed (NULL, 0, *imm_reloc - BFD_RELOC_UNUSED,
- tmp, TRUE, forced_insn_length == 2,
- forced_insn_length == 4, &ip->insn_opcode,
- &ip->use_extend, &ip->extend);
+ tmp, forced_insn_length, &ip->insn_opcode);
imm_expr.X_op = O_absent;
*imm_reloc = BFD_RELOC_UNUSED;
}
@@ -13552,8 +13537,7 @@ mips16_ip (char *str, struct mips_cl_ins
if (imm_expr.X_op != O_constant)
{
forced_insn_length = 4;
- ip->use_extend = TRUE;
- ip->extend = 0;
+ ip->insn_opcode |= MIPS16_EXTEND;
}
else
{
@@ -13707,7 +13691,7 @@ mips16_ip (char *str, struct mips_cl_ins
case 'm': /* Register list for save insn. */
case 'M': /* Register list for restore insn. */
{
- int opcode = 0;
+ int opcode = ip->insn_opcode;
int framesz = 0, seen_framesz = 0;
int nargs = 0, statics = 0, sregs = 0;
@@ -13861,11 +13845,8 @@ mips16_ip (char *str, struct mips_cl_ins
/* Finally build the instruction. */
if ((opcode >> 16) != 0 || framesz == 0)
- {
- ip->use_extend = TRUE;
- ip->extend = opcode >> 16;
- }
- ip->insn_opcode |= opcode & 0x7f;
+ opcode |= MIPS16_EXTEND;
+ ip->insn_opcode = opcode;
}
continue;
@@ -13960,23 +13941,19 @@ static const struct mips16_immed_operand
#define MIPS16_NUM_IMMED \
(sizeof mips16_immed_operands / sizeof mips16_immed_operands[0])
-/* Handle a mips16 instruction with an immediate value. This or's the
- small immediate value into *INSN. It sets *USE_EXTEND to indicate
- whether an extended value is needed; if one is needed, it sets
- *EXTEND to the value. The argument type is TYPE. The value is VAL.
- If SMALL is true, an unextended opcode was explicitly requested.
- If EXT is true, an extended opcode was explicitly requested. If
- WARN is true, warn if EXT does not match reality. */
+/* Install immediate value VAL into MIPS16 instruction *INSN,
+ extending it if necessary. The instruction in *INSN may
+ already be extended.
+
+ TYPE is the type of the immediate field. USER_INSN_LENGTH is the
+ length that the user requested, or 0 if none. */
static void
mips16_immed (char *file, unsigned int line, int type, offsetT val,
- bfd_boolean warn, bfd_boolean small, bfd_boolean ext,
- unsigned long *insn, bfd_boolean *use_extend,
- unsigned short *extend)
+ unsigned int user_insn_length, unsigned long *insn)
{
const struct mips16_immed_operand *op;
int mintiny, maxtiny;
- bfd_boolean needext;
op = mips16_immed_operands;
while (op->type != type)
@@ -14011,21 +13988,26 @@ mips16_immed (char *file, unsigned int l
if ((val & ((1 << op->shift) - 1)) != 0
|| val < (mintiny << op->shift)
|| val > (maxtiny << op->shift))
- needext = TRUE;
- else
- needext = FALSE;
-
- if (warn && ext && ! needext)
- as_warn_where (file, line,
- _("extended operand requested but not required"));
- if (small && needext)
- as_bad_where (file, line, _("invalid unextended operand value"));
+ {
+ /* We need an extended instruction. */
+ if (user_insn_length == 2)
+ as_bad_where (file, line, _("invalid unextended operand value"));
+ else
+ *insn |= MIPS16_EXTEND;
+ }
+ else if (user_insn_length == 4)
+ {
+ /* The operand doesn't force an unextended instruction to be extended.
+ Warn if the user wanted an extended instruction anyway. */
+ *insn |= MIPS16_EXTEND;
+ as_warn_where (file, line,
+ _("extended operand requested but not required"));
+ }
- if (small || (! ext && ! needext))
+ if (mips16_opcode_length (*insn) == 2)
{
int insnval;
- *use_extend = FALSE;
insnval = ((val >> op->shift) & ((1 << op->nbits) - 1));
insnval <<= op->op_shift;
*insn |= insnval;
@@ -14049,7 +14031,6 @@ mips16_immed (char *file, unsigned int l
as_bad_where (file, line,
_("operand value out of range for instruction"));
- *use_extend = TRUE;
if (op->extbits == 16)
{
extval = ((val >> 11) & 0x1f) | (val & 0x7e0);
@@ -14066,8 +14047,7 @@ mips16_immed (char *file, unsigned int l
val = 0;
}
- *extend = (unsigned short) extval;
- *insn |= val;
+ *insn |= (extval << 16) | val;
}
}
@@ -18250,29 +18230,18 @@ md_convert_frag (bfd *abfd ATTRIBUTE_UNU
{
int type;
const struct mips16_immed_operand *op;
- bfd_boolean small, ext;
offsetT val;
- bfd_byte *buf;
+ char *buf;
+ unsigned int user_length, length;
unsigned long insn;
- bfd_boolean use_extend;
- unsigned short extend;
+ bfd_boolean ext;
type = RELAX_MIPS16_TYPE (fragp->fr_subtype);
op = mips16_immed_operands;
while (op->type != type)
++op;
- if (RELAX_MIPS16_EXTENDED (fragp->fr_subtype))
- {
- small = FALSE;
- ext = TRUE;
- }
- else
- {
- small = TRUE;
- ext = FALSE;
- }
-
+ ext = RELAX_MIPS16_EXTENDED (fragp->fr_subtype);
val = resolve_symbol_value (fragp->fr_symbol);
if (op->pcrel)
{
@@ -18312,27 +18281,30 @@ md_convert_frag (bfd *abfd ATTRIBUTE_UNU
as_warn_where (fragp->fr_file, fragp->fr_line,
_("extended instruction in delay slot"));
- buf = (bfd_byte *) (fragp->fr_literal + fragp->fr_fix);
+ buf = fragp->fr_literal + fragp->fr_fix;
if (target_big_endian)
- insn = bfd_getb16 (buf);
+ insn = bfd_getb16 ((bfd_byte *) buf);
else
- insn = bfd_getl16 (buf);
+ insn = bfd_getl16 ((bfd_byte *) buf);
- mips16_immed (fragp->fr_file, fragp->fr_line, type, val,
- RELAX_MIPS16_USER_EXT (fragp->fr_subtype),
- small, ext, &insn, &use_extend, &extend);
+ if (ext)
+ insn |= MIPS16_EXTEND;
- if (use_extend)
- {
- md_number_to_chars ((char *) buf, 0xf000 | extend, 2);
- fragp->fr_fix += 2;
- buf += 2;
- }
+ if (RELAX_MIPS16_USER_EXT (fragp->fr_subtype))
+ user_length = 4;
+ else if (RELAX_MIPS16_USER_SMALL (fragp->fr_subtype))
+ user_length = 2;
+ else
+ user_length = 0;
+
+ mips16_immed (fragp->fr_file, fragp->fr_line, type, val,
+ user_length, &insn);
- md_number_to_chars ((char *) buf, insn, 2);
- fragp->fr_fix += 2;
- buf += 2;
+ length = (ext ? 4 : 2);
+ gas_assert (mips16_opcode_length (insn) == length);
+ write_compressed_insn (buf, insn, length);
+ fragp->fr_fix += length;
}
else
{