Add opcode relaxation for rl78-elf

This patch adds initial in-gas opcode relaxation for the rl78
backend.  Specifically, it checks for conditional branches that
are too far and replaces them with inverted branches around longer
fixed branches.
This commit is contained in:
DJ Delorie 2014-03-20 17:50:49 -04:00
parent deba7593bb
commit 0c315784bf
5 changed files with 511 additions and 23 deletions

View File

@ -1,3 +1,19 @@
2014-03-20 DJ Delorie <dj@redhat.com>
* config/rl78-defs.h (RL78_RELAX_NONE, RL78_RELAX_BRANCH): Add.
* config/rl78-parse.y (BC, BNC, BZ, BNZ, BH, BHZ, bt_bf): Call
rl78_relax().
* config/tc-rl78.h (md_relax_frag): Define.
(rl78_relax_frag): Declare.
* config/tc-rl78.c (rl78_relax): Add.
(md_assemble): Set up the variable frags also when relaxing.
(op_type_T): New.
(rl78_opcode_type): New.
(rl78_frag_fix_value): New.
(md_estimate_size_before_relax): New-ish.
(rl78_relax_frag): New.
(md_convert_frag): New-ish.
2014-03-20 Richard Sandiford <rdsandiford@googlemail.com>
* config/tc-mips.h (DIFF_EXPR_OK, CFI_DIFF_EXPR_OK): Define.

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@ -25,6 +25,9 @@
#define RL78REL_DATA 0
#define RL78REL_PCREL 1
#define RL78_RELAX_NONE 0
#define RL78_RELAX_BRANCH 1
extern int rl78_error (const char *);
extern void rl78_lex_init (char *, char *);
extern void rl78_prefix (int);

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@ -290,22 +290,22 @@ statement :
/* ---------------------------------------------------------------------- */
| BC '$' EXPR
{ B1 (0xdc); PC1 ($3); }
{ B1 (0xdc); PC1 ($3); rl78_relax (RL78_RELAX_BRANCH, 0); }
| BNC '$' EXPR
{ B1 (0xde); PC1 ($3); }
{ B1 (0xde); PC1 ($3); rl78_relax (RL78_RELAX_BRANCH, 0); }
| BZ '$' EXPR
{ B1 (0xdd); PC1 ($3); }
{ B1 (0xdd); PC1 ($3); rl78_relax (RL78_RELAX_BRANCH, 0); }
| BNZ '$' EXPR
{ B1 (0xdf); PC1 ($3); }
{ B1 (0xdf); PC1 ($3); rl78_relax (RL78_RELAX_BRANCH, 0); }
| BH '$' EXPR
{ B2 (0x61, 0xc3); PC1 ($3); }
{ B2 (0x61, 0xc3); PC1 ($3); rl78_relax (RL78_RELAX_BRANCH, 0); }
| BNH '$' EXPR
{ B2 (0x61, 0xd3); PC1 ($3); }
{ B2 (0x61, 0xd3); PC1 ($3); rl78_relax (RL78_RELAX_BRANCH, 0); }
/* ---------------------------------------------------------------------- */
@ -1153,12 +1153,12 @@ addsubw : ADDW { $$ = 0x00; }
;
andor1 : AND1 { $$ = 0x05; rl78_bit_insn = 1; }
| OR1 { $$ = 0x06; rl78_bit_insn = 1;}
| OR1 { $$ = 0x06; rl78_bit_insn = 1; }
| XOR1 { $$ = 0x07; rl78_bit_insn = 1; }
;
bt_bf : BT { $$ = 0x02; rl78_bit_insn = 1;}
| BF { $$ = 0x04; rl78_bit_insn = 1; }
bt_bf : BT { $$ = 0x02; rl78_bit_insn = 1; rl78_relax (RL78_RELAX_BRANCH, 0); }
| BF { $$ = 0x04; rl78_bit_insn = 1; rl78_relax (RL78_RELAX_BRANCH, 0); }
| BTCLR { $$ = 0x00; rl78_bit_insn = 1; }
;

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@ -85,6 +85,15 @@ typedef struct rl78_bytesT
static rl78_bytesT rl78_bytes;
void
rl78_relax (int type, int pos)
{
rl78_bytes.relax[rl78_bytes.n_relax].type = type;
rl78_bytes.relax[rl78_bytes.n_relax].field_pos = pos;
rl78_bytes.relax[rl78_bytes.n_relax].val_ofs = rl78_bytes.n_base + rl78_bytes.n_ops;
rl78_bytes.n_relax ++;
}
void
rl78_linkrelax_addr16 (void)
{
@ -486,12 +495,13 @@ md_assemble (char * str)
rl78_parse ();
/* This simplifies the relaxation code. */
if (rl78_bytes.link_relax)
if (rl78_bytes.n_relax || rl78_bytes.link_relax)
{
int olen = rl78_bytes.n_prefix + rl78_bytes.n_base + rl78_bytes.n_ops;
/* We do it this way because we want the frag to have the
rl78_bytes in it, which we initialize above. */
bytes = frag_more (olen);
rl78_bytes in it, which we initialize above. The extra bytes
are for relaxing. */
bytes = frag_more (olen + 3);
frag_then = frag_now;
frag_variant (rs_machine_dependent,
olen /* max_chars */,
@ -638,13 +648,478 @@ rl78_cons_fix_new (fragS * frag,
}
}
/* No relaxation just yet */
/*----------------------------------------------------------------------*/
/* To recap: we estimate everything based on md_estimate_size, then
adjust based on rl78_relax_frag. When it all settles, we call
md_convert frag to update the bytes. The relaxation types and
relocations are in fragP->tc_frag_data, which is a copy of that
rl78_bytes.
Our scheme is as follows: fr_fix has the size of the smallest
opcode (like BRA.S). We store the number of total bytes we need in
fr_subtype. When we're done relaxing, we use fr_subtype and the
existing opcode bytes to figure out what actual opcode we need to
put in there. If the fixup isn't resolvable now, we use the
maximal size. */
#define TRACE_RELAX 0
#define tprintf if (TRACE_RELAX) printf
typedef enum
{
OT_other,
OT_bt,
OT_bt_sfr,
OT_bt_es,
OT_bc,
OT_bh
} op_type_T;
/* We're looking for these types of relaxations:
BT 00110001 sbit0cc1 addr---- (cc is 10 (BF) or 01 (BT))
B~T 00110001 sbit0cc1 00000011 11101110 pcrel16- -------- (BR $!pcrel20)
BT sfr 00110001 sbit0cc0 sfr----- addr----
BT ES: 00010001 00101110 sbit0cc1 addr----
BC 110111cc addr----
B~C 110111cc 00000011 11101110 pcrel16- -------- (BR $!pcrel20)
BH 01100001 110c0011 00000011 11101110 pcrel16- -------- (BR $!pcrel20)
B~H 01100001 110c0011 00000011 11101110 pcrel16- -------- (BR $!pcrel20)
*/
/* Given the opcode bytes at OP, figure out which opcode it is and
return the type of opcode. We use this to re-encode the opcode as
a different size later. */
static op_type_T
rl78_opcode_type (char * op)
{
if (op[0] == 0x31
&& ((op[1] & 0x0f) == 0x05
|| (op[1] & 0x0f) == 0x03))
return OT_bt;
if (op[0] == 0x31
&& ((op[1] & 0x0f) == 0x04
|| (op[1] & 0x0f) == 0x02))
return OT_bt_sfr;
if (op[0] == 0x11
&& op[1] == 0x31
&& ((op[2] & 0x0f) == 0x05
|| (op[2] & 0x0f) == 0x03))
return OT_bt_es;
if ((op[0] & 0xfc) == 0xdc)
return OT_bc;
if (op[0] == 0x61
&& (op[1] & 0xef) == 0xc3)
return OT_bh;
return OT_other;
}
/* Returns zero if *addrP has the target address. Else returns nonzero
if we cannot compute the target address yet. */
static int
rl78_frag_fix_value (fragS * fragP,
segT segment,
int which,
addressT * addrP,
int need_diff,
addressT * sym_addr)
{
addressT addr = 0;
rl78_bytesT * b = fragP->tc_frag_data;
expressionS * exp = & b->fixups[which].exp;
if (need_diff && exp->X_op != O_subtract)
return 1;
if (exp->X_add_symbol)
{
if (S_FORCE_RELOC (exp->X_add_symbol, 1))
return 1;
if (S_GET_SEGMENT (exp->X_add_symbol) != segment)
return 1;
addr += S_GET_VALUE (exp->X_add_symbol);
}
if (exp->X_op_symbol)
{
if (exp->X_op != O_subtract)
return 1;
if (S_FORCE_RELOC (exp->X_op_symbol, 1))
return 1;
if (S_GET_SEGMENT (exp->X_op_symbol) != segment)
return 1;
addr -= S_GET_VALUE (exp->X_op_symbol);
}
if (sym_addr)
* sym_addr = addr;
addr += exp->X_add_number;
* addrP = addr;
return 0;
}
/* Estimate how big the opcode is after this relax pass. The return
value is the difference between fr_fix and the actual size. We
compute the total size in rl78_relax_frag and store it in fr_subtype,
sowe only need to subtract fx_fix and return it. */
int
md_estimate_size_before_relax (fragS * fragP ATTRIBUTE_UNUSED, segT segment ATTRIBUTE_UNUSED)
{
return 0;
int opfixsize;
int delta;
/* This is the size of the opcode that's accounted for in fr_fix. */
opfixsize = fragP->fr_fix - (fragP->fr_opcode - fragP->fr_literal);
/* This is the size of the opcode that isn't. */
delta = (fragP->fr_subtype - opfixsize);
tprintf (" -> opfixsize %d delta %d\n", opfixsize, delta);
return delta;
}
/* Given the new addresses for this relax pass, figure out how big
each opcode must be. We store the total number of bytes needed in
fr_subtype. The return value is the difference between the size
after the last pass and the size after this pass, so we use the old
fr_subtype to calculate the difference. */
int
rl78_relax_frag (segT segment ATTRIBUTE_UNUSED, fragS * fragP, long stretch)
{
addressT addr0, sym_addr;
addressT mypc;
int disp;
int oldsize = fragP->fr_subtype;
int newsize = oldsize;
op_type_T optype;
int ri;
mypc = fragP->fr_address + (fragP->fr_opcode - fragP->fr_literal);
/* If we ever get more than one reloc per opcode, this is the one
we're relaxing. */
ri = 0;
optype = rl78_opcode_type (fragP->fr_opcode);
/* Try to get the target address. */
if (rl78_frag_fix_value (fragP, segment, ri, & addr0,
fragP->tc_frag_data->relax[ri].type != RL78_RELAX_BRANCH,
& sym_addr))
{
/* If we don't, we must use the maximum size for the linker. */
switch (fragP->tc_frag_data->relax[ri].type)
{
case RL78_RELAX_BRANCH:
switch (optype)
{
case OT_bt:
newsize = 6;
break;
case OT_bt_sfr:
case OT_bt_es:
newsize = 7;
break;
case OT_bc:
newsize = 5;
break;
case OT_bh:
newsize = 6;
break;
case OT_other:
newsize = oldsize;
break;
}
break;
}
fragP->fr_subtype = newsize;
tprintf (" -> new %d old %d delta %d (external)\n", newsize, oldsize, newsize-oldsize);
return newsize - oldsize;
}
if (sym_addr > mypc)
addr0 += stretch;
switch (fragP->tc_frag_data->relax[ri].type)
{
case RL78_RELAX_BRANCH:
disp = (int) addr0 - (int) mypc;
switch (optype)
{
case OT_bt:
if (disp >= -128 && (disp - (oldsize-2)) <= 127)
newsize = 3;
else
newsize = 6;
break;
case OT_bt_sfr:
case OT_bt_es:
if (disp >= -128 && (disp - (oldsize-3)) <= 127)
newsize = 4;
else
newsize = 7;
break;
case OT_bc:
if (disp >= -128 && (disp - (oldsize-1)) <= 127)
newsize = 2;
else
newsize = 5;
break;
case OT_bh:
if (disp >= -128 && (disp - (oldsize-2)) <= 127)
newsize = 3;
else
newsize = 6;
break;
case OT_other:
newsize = oldsize;
break;
}
break;
}
/* This prevents infinite loops in align-heavy sources. */
if (newsize < oldsize)
{
if (fragP->tc_frag_data->times_shrank > 10
&& fragP->tc_frag_data->times_grown > 10)
newsize = oldsize;
if (fragP->tc_frag_data->times_shrank < 20)
fragP->tc_frag_data->times_shrank ++;
}
else if (newsize > oldsize)
{
if (fragP->tc_frag_data->times_grown < 20)
fragP->tc_frag_data->times_grown ++;
}
fragP->fr_subtype = newsize;
tprintf (" -> new %d old %d delta %d\n", newsize, oldsize, newsize-oldsize);
return newsize - oldsize;
}
/* This lets us test for the opcode type and the desired size in a
switch statement. */
#define OPCODE(type,size) ((type) * 16 + (size))
/* Given the opcode stored in fr_opcode and the number of bytes we
think we need, encode a new opcode. We stored a pointer to the
fixup for this opcode in the tc_frag_data structure. If we can do
the fixup here, we change the relocation type to "none" (we test
for that in tc_gen_reloc) else we change it to the right type for
the new (biggest) opcode. */
void
md_convert_frag (bfd * abfd ATTRIBUTE_UNUSED,
segT segment ATTRIBUTE_UNUSED,
fragS * fragP ATTRIBUTE_UNUSED)
{
rl78_bytesT * rl78b = fragP->tc_frag_data;
addressT addr0, mypc;
int disp;
int reloc_type, reloc_adjust;
char * op = fragP->fr_opcode;
int keep_reloc = 0;
int ri;
int fi = (rl78b->n_fixups > 1) ? 1 : 0;
fixS * fix = rl78b->fixups[fi].fixP;
/* If we ever get more than one reloc per opcode, this is the one
we're relaxing. */
ri = 0;
/* We used a new frag for this opcode, so the opcode address should
be the frag address. */
mypc = fragP->fr_address + (fragP->fr_opcode - fragP->fr_literal);
tprintf("\033[32mmypc: 0x%x\033[0m\n", (int)mypc);
/* Try to get the target address. If we fail here, we just use the
largest format. */
if (rl78_frag_fix_value (fragP, segment, 0, & addr0,
fragP->tc_frag_data->relax[ri].type != RL78_RELAX_BRANCH, 0))
{
/* We don't know the target address. */
keep_reloc = 1;
addr0 = 0;
disp = 0;
tprintf ("unknown addr ? - %x = ?\n", (int)mypc);
}
else
{
/* We know the target address, and it's in addr0. */
disp = (int) addr0 - (int) mypc;
tprintf ("known addr %x - %x = %d\n", (int)addr0, (int)mypc, disp);
}
if (linkrelax)
keep_reloc = 1;
reloc_type = BFD_RELOC_NONE;
reloc_adjust = 0;
switch (fragP->tc_frag_data->relax[ri].type)
{
case RL78_RELAX_BRANCH:
switch (OPCODE (rl78_opcode_type (fragP->fr_opcode), fragP->fr_subtype))
{
case OPCODE (OT_bt, 3): /* BT A,$ - no change. */
disp -= 3;
op[2] = disp;
break;
case OPCODE (OT_bt, 6): /* BT A,$ - long version. */
disp -= 3;
op[1] ^= 0x06; /* toggle conditional. */
op[2] = 3; /* displacement over long branch. */
disp -= 3;
op[3] = 0xEE; /* BR $!addr20 */
op[4] = disp & 0xff;
op[5] = disp >> 8;
reloc_type = keep_reloc ? BFD_RELOC_16_PCREL : BFD_RELOC_NONE;
reloc_adjust = 2;
break;
case OPCODE (OT_bt_sfr, 4): /* BT PSW,$ - no change. */
disp -= 4;
op[3] = disp;
break;
case OPCODE (OT_bt_sfr, 7): /* BT PSW,$ - long version. */
disp -= 4;
op[1] ^= 0x06; /* toggle conditional. */
op[3] = 3; /* displacement over long branch. */
disp -= 3;
op[4] = 0xEE; /* BR $!addr20 */
op[5] = disp & 0xff;
op[6] = disp >> 8;
reloc_type = keep_reloc ? BFD_RELOC_16_PCREL : BFD_RELOC_NONE;
reloc_adjust = 2;
break;
case OPCODE (OT_bt_es, 4): /* BT ES:[HL],$ - no change. */
disp -= 4;
op[3] = disp;
break;
case OPCODE (OT_bt_es, 7): /* BT PSW,$ - long version. */
disp -= 4;
op[2] ^= 0x06; /* toggle conditional. */
op[3] = 3; /* displacement over long branch. */
disp -= 3;
op[4] = 0xEE; /* BR $!addr20 */
op[5] = disp & 0xff;
op[6] = disp >> 8;
reloc_type = keep_reloc ? BFD_RELOC_16_PCREL : BFD_RELOC_NONE;
reloc_adjust = 2;
break;
case OPCODE (OT_bc, 2): /* BC $ - no change. */
disp -= 2;
op[1] = disp;
break;
case OPCODE (OT_bc, 5): /* BC $ - long version. */
disp -= 2;
op[0] ^= 0x02; /* toggle conditional. */
op[1] = 3;
disp -= 3;
op[2] = 0xEE; /* BR $!addr20 */
op[3] = disp & 0xff;
op[4] = disp >> 8;
reloc_type = keep_reloc ? BFD_RELOC_16_PCREL : BFD_RELOC_NONE;
reloc_adjust = 2;
break;
case OPCODE (OT_bh, 3): /* BH $ - no change. */
disp -= 3;
op[2] = disp;
break;
case OPCODE (OT_bh, 6): /* BC $ - long version. */
disp -= 3;
op[1] ^= 0x10; /* toggle conditional. */
op[2] = 3;
disp -= 3;
op[3] = 0xEE; /* BR $!addr20 */
op[4] = disp & 0xff;
op[5] = disp >> 8;
reloc_type = keep_reloc ? BFD_RELOC_16_PCREL : BFD_RELOC_NONE;
reloc_adjust = 2;
break;
default:
fprintf(stderr, "Missed case %d %d at 0x%lx\n",
rl78_opcode_type (fragP->fr_opcode), fragP->fr_subtype, mypc);
abort ();
}
break;
default:
if (rl78b->n_fixups)
{
reloc_type = fix->fx_r_type;
reloc_adjust = 0;
}
break;
}
if (rl78b->n_fixups)
{
fix->fx_r_type = reloc_type;
fix->fx_where += reloc_adjust;
switch (reloc_type)
{
case BFD_RELOC_NONE:
fix->fx_size = 0;
break;
case BFD_RELOC_8:
fix->fx_size = 1;
break;
case BFD_RELOC_16_PCREL:
fix->fx_size = 2;
break;
}
}
fragP->fr_fix = fragP->fr_subtype + (fragP->fr_opcode - fragP->fr_literal);
tprintf ("fragP->fr_fix now %ld (%d + (%p - %p)\n", (long) fragP->fr_fix,
fragP->fr_subtype, fragP->fr_opcode, fragP->fr_literal);
fragP->fr_var = 0;
tprintf ("compare 0x%lx vs 0x%lx - 0x%lx = 0x%lx (%p)\n",
(long)fragP->fr_fix,
(long)fragP->fr_next->fr_address, (long)fragP->fr_address,
(long)(fragP->fr_next->fr_address - fragP->fr_address),
fragP->fr_next);
if (fragP->fr_next != NULL
&& ((offsetT) (fragP->fr_next->fr_address - fragP->fr_address)
!= fragP->fr_fix))
as_bad (_("bad frag at %p : fix %ld addr %ld %ld \n"), fragP,
(long) fragP->fr_fix,
(long) fragP->fr_address, (long) fragP->fr_next->fr_address);
}
/* End of relaxation code.
----------------------------------------------------------------------*/
arelent **
tc_gen_reloc (asection * seg ATTRIBUTE_UNUSED, fixS * fixp)
{
@ -867,12 +1342,3 @@ md_section_align (segT segment, valueT size)
int align = bfd_get_section_alignment (stdoutput, segment);
return ((size + (1 << align) - 1) & (-1 << align));
}
void
md_convert_frag (bfd * abfd ATTRIBUTE_UNUSED,
segT segment ATTRIBUTE_UNUSED,
fragS * fragP ATTRIBUTE_UNUSED)
{
/* No relaxation yet */
fragP->fr_var = 0;
}

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@ -49,6 +49,9 @@ extern int target_little_endian;
#define md_end rl78_md_end
extern void rl78_md_end (void);
#define md_relax_frag rl78_relax_frag
extern int rl78_relax_frag (segT, fragS *, long);
#define TC_FRAG_TYPE struct rl78_bytesT *
#define TC_FRAG_INIT rl78_frag_init
extern void rl78_frag_init (fragS *);