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This patch set mainly aims at improving the S/390 disassembler's 

readability and also fixes some minor issues.

  S/390: Split disassembler routine into smaller functions
  S/390: Fix disassembler's treatment of signed/unsigned operands
  S/390: Fix off-by-one error in disassembler initialization
  S/390: Simplify opcode search loop in disassembler
  S/390: Drop function pointer dereferences in disassembler
  S/390: Various minor simplifications in disassembler
binutils-2_25-branch
Andreas Arnez 12 years ago
committed by Nick Clifton
parent
cb417230fb
commit
9ace48f3d7
2 changed files with 184 additions and 134 deletions
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  1. 27
      opcodes/ChangeLog
  2. 291
      opcodes/s390-dis.c

27
opcodes/ChangeLog
View File

@ -1,3 +1,30 @@
2014-08-19 Andreas Arnez <arnez@linux.vnet.ibm.com>
* s390-dis.c (s390_insn_length, s390_insn_matches_opcode)
(s390_print_insn_with_opcode, opcode_mask_more_specific): New
static functions, code was moved from...
(print_insn_s390): ...here.
(s390_extract_operand): Adjust comment. Change type of first
parameter from 'unsigned char *' to 'const bfd_byte *'.
(union operand_value): New.
(s390_extract_operand): Change return type to union operand_value.
Also avoid integer overflow in sign-extension.
(s390_print_insn_with_opcode): Adjust to changed return value from
s390_extract_operand(). Change "%i" printf format to "%u" for
unsigned values.
(init_disasm): Simplify initialization of opc_index[]. This also
fixes an access after the last element of s390_opcodes[].
(print_insn_s390): Simplify the opcode search loop.
Check architecture mask against all searched opcodes, not just the
first matching one.
(s390_print_insn_with_opcode): Drop function pointer dereferences
without effect.
(print_insn_s390): Likewise.
(s390_insn_length): Simplify formula for return value.
(s390_print_insn_with_opcode): Avoid special handling for the
separator before the first operand. Use new local variable
'flags' in place of 'operand->flags'.
2014-08-14 Mike Frysinger <vapier@gentoo.org>
* bfin-dis.c (struct private): Change int's to bfd_boolean's.

291
opcodes/s390-dis.c
View File

@ -35,19 +35,15 @@ static int current_arch_mask = 0;
static void
init_disasm (struct disassemble_info *info)
{
const struct s390_opcode *opcode;
const struct s390_opcode *opcode_end;
int i;
const char *p;
memset (opc_index, 0, sizeof (opc_index));
opcode_end = s390_opcodes + s390_num_opcodes;
for (opcode = s390_opcodes; opcode < opcode_end; opcode++)
{
opc_index[(int) opcode->opcode[0]] = opcode - s390_opcodes;
while ((opcode < opcode_end) &&
(opcode[1].opcode[0] == opcode->opcode[0]))
opcode++;
}
/* Reverse order, such that each opc_index ends up pointing to the
first matching entry instead of the last. */
for (i = s390_num_opcodes; i--; )
opc_index[s390_opcodes[i].opcode[0]] = i;
for (p = info->disassembler_options; p != NULL; )
{
@ -69,15 +65,46 @@ init_disasm (struct disassemble_info *info)
init_flag = 1;
}
/* Derive the length of an instruction from its first byte. */
static inline int
s390_insn_length (const bfd_byte *buffer)
{
/* 00xxxxxx -> 2, 01xxxxxx/10xxxxxx -> 4, 11xxxxxx -> 6. */
return ((buffer[0] >> 6) + 3) & ~1U;
}
/* Match the instruction in BUFFER against the given OPCODE, excluding
the first byte. */
static inline int
s390_insn_matches_opcode (const bfd_byte *buffer,
const struct s390_opcode *opcode)
{
return (buffer[1] & opcode->mask[1]) == opcode->opcode[1]
&& (buffer[2] & opcode->mask[2]) == opcode->opcode[2]
&& (buffer[3] & opcode->mask[3]) == opcode->opcode[3]
&& (buffer[4] & opcode->mask[4]) == opcode->opcode[4]
&& (buffer[5] & opcode->mask[5]) == opcode->opcode[5];
}
union operand_value
{
int i;
unsigned int u;
};
/* Extracts an operand value from an instruction. */
/* We do not perform the shift operation for larl-type address
operands here since that would lead to an overflow of the 32 bit
integer value. Instead the shift operation is done when printing
the operand in print_insn_s390. */
the operand. */
static inline unsigned int
s390_extract_operand (unsigned char *insn, const struct s390_operand *operand)
static inline union operand_value
s390_extract_operand (const bfd_byte *insn,
const struct s390_operand *operand)
{
union operand_value ret;
unsigned int val;
int bits;
@ -99,15 +126,97 @@ s390_extract_operand (unsigned char *insn, const struct s390_operand *operand)
if (operand->bits == 20 && operand->shift == 20)
val = (val & 0xff) << 12 | (val & 0xfff00) >> 8;
/* Sign extend value if the operand is signed or pc relative. */
if ((operand->flags & (S390_OPERAND_SIGNED | S390_OPERAND_PCREL))
&& (val & (1U << (operand->bits - 1))))
val |= (-1U << (operand->bits - 1)) << 1;
/* Sign extend value if the operand is signed or pc relative. Avoid
integer overflows. */
if (operand->flags & (S390_OPERAND_SIGNED | S390_OPERAND_PCREL))
{
unsigned int m = 1U << (operand->bits - 1);
if (val >= m)
ret.i = (int) (val - m) - 1 - (int) (m - 1U);
else
ret.i = (int) val;
}
else if (operand->flags & S390_OPERAND_LENGTH)
/* Length x in an instruction has real length x + 1. */
ret.u = val + 1;
else
ret.u = val;
return ret;
}
/* Print the S390 instruction in BUFFER, assuming that it matches the
given OPCODE. */
static void
s390_print_insn_with_opcode (bfd_vma memaddr,
struct disassemble_info *info,
const bfd_byte *buffer,
const struct s390_opcode *opcode)
{
const unsigned char *opindex;
char separator;
/* Mnemonic. */
info->fprintf_func (info->stream, "%s", opcode->name);
/* Operands. */
separator = '\t';
for (opindex = opcode->operands; *opindex != 0; opindex++)
{
const struct s390_operand *operand = s390_operands + *opindex;
union operand_value val = s390_extract_operand (buffer, operand);
unsigned long flags = operand->flags;
if ((flags & S390_OPERAND_INDEX) && val.u == 0)
continue;
if ((flags & S390_OPERAND_BASE) &&
val.u == 0 && separator == '(')
{
separator = ',';
continue;
}
info->fprintf_func (info->stream, "%c", separator);
if (flags & S390_OPERAND_GPR)
info->fprintf_func (info->stream, "%%r%u", val.u);
else if (flags & S390_OPERAND_FPR)
info->fprintf_func (info->stream, "%%f%u", val.u);
else if (flags & S390_OPERAND_AR)
info->fprintf_func (info->stream, "%%a%u", val.u);
else if (flags & S390_OPERAND_CR)
info->fprintf_func (info->stream, "%%c%u", val.u);
else if (flags & S390_OPERAND_PCREL)
info->print_address_func (memaddr + val.i + val.i, info);
else if (flags & S390_OPERAND_SIGNED)
info->fprintf_func (info->stream, "%i", val.i);
else
info->fprintf_func (info->stream, "%u", val.u);
if (flags & S390_OPERAND_DISP)
separator = '(';
else if (flags & S390_OPERAND_BASE)
{
info->fprintf_func (info->stream, ")");
separator = ',';
}
else
separator = ',';
}
}
/* Check whether opcode A's mask is more specific than that of B. */
/* Length x in an instructions has real length x + 1. */
if (operand->flags & S390_OPERAND_LENGTH)
val++;
return val;
static int
opcode_mask_more_specific (const struct s390_opcode *a,
const struct s390_opcode *b)
{
return (((int) a->mask[0] + a->mask[1] + a->mask[2]
+ a->mask[3] + a->mask[4] + a->mask[5])
> ((int) b->mask[0] + b->mask[1] + b->mask[2]
+ b->mask[3] + b->mask[4] + b->mask[5]));
}
/* Print a S390 instruction. */
@ -116,11 +225,9 @@ int
print_insn_s390 (bfd_vma memaddr, struct disassemble_info *info)
{
bfd_byte buffer[6];
const struct s390_opcode *opcode;
const struct s390_opcode *opcode_end;
const struct s390_opcode *opcode = NULL;
unsigned int value;
int status, opsize, bufsize;
char separator;
if (init_flag == 0)
init_disasm (info);
@ -130,156 +237,72 @@ print_insn_s390 (bfd_vma memaddr, struct disassemble_info *info)
/* Every S390 instruction is max 6 bytes long. */
memset (buffer, 0, 6);
status = (*info->read_memory_func) (memaddr, buffer, 6, info);
status = info->read_memory_func (memaddr, buffer, 6, info);
if (status != 0)
{
for (bufsize = 0; bufsize < 6; bufsize++)
if ((*info->read_memory_func) (memaddr, buffer, bufsize + 1, info) != 0)
if (info->read_memory_func (memaddr, buffer, bufsize + 1, info) != 0)
break;
if (bufsize <= 0)
{
(*info->memory_error_func) (status, memaddr, info);
info->memory_error_func (status, memaddr, info);
return -1;
}
/* Opsize calculation looks strange but it works
00xxxxxx -> 2 bytes, 01xxxxxx/10xxxxxx -> 4 bytes,
11xxxxxx -> 6 bytes. */
opsize = ((((buffer[0] >> 6) + 1) >> 1) + 1) << 1;
opsize = s390_insn_length (buffer);
status = opsize > bufsize;
}
else
{
bufsize = 6;
opsize = ((((buffer[0] >> 6) + 1) >> 1) + 1) << 1;
opsize = s390_insn_length (buffer);
}
if (status == 0)
{
const struct s390_opcode *op;
/* Find the first match in the opcode table. */
opcode_end = s390_opcodes + s390_num_opcodes;
for (opcode = s390_opcodes + opc_index[(int) buffer[0]];
(opcode < opcode_end) && (buffer[0] == opcode->opcode[0]);
opcode++)
/* Find the "best match" in the opcode table. */
for (op = s390_opcodes + opc_index[buffer[0]];
op != s390_opcodes + s390_num_opcodes
&& op->opcode[0] == buffer[0];
op++)
{
const struct s390_operand *operand;
const unsigned char *opindex;
/* Check architecture. */
if (!(opcode->modes & current_arch_mask))
continue;
/* Check signature of the opcode. */
if ((buffer[1] & opcode->mask[1]) != opcode->opcode[1]
|| (buffer[2] & opcode->mask[2]) != opcode->opcode[2]
|| (buffer[3] & opcode->mask[3]) != opcode->opcode[3]
|| (buffer[4] & opcode->mask[4]) != opcode->opcode[4]
|| (buffer[5] & opcode->mask[5]) != opcode->opcode[5])
continue;
/* Advance to an opcode with a more specific mask. */
for (op = opcode + 1; op < opcode_end; op++)
{
if ((buffer[0] & op->mask[0]) != op->opcode[0])
break;
if ((buffer[1] & op->mask[1]) != op->opcode[1]
|| (buffer[2] & op->mask[2]) != op->opcode[2]
|| (buffer[3] & op->mask[3]) != op->opcode[3]
|| (buffer[4] & op->mask[4]) != op->opcode[4]
|| (buffer[5] & op->mask[5]) != op->opcode[5])
continue;
if (((int)opcode->mask[0] + opcode->mask[1] +
opcode->mask[2] + opcode->mask[3] +
opcode->mask[4] + opcode->mask[5]) <
((int)op->mask[0] + op->mask[1] +
op->mask[2] + op->mask[3] +
op->mask[4] + op->mask[5]))
opcode = op;
}
/* The instruction is valid. */
if (opcode->operands[0] != 0)
(*info->fprintf_func) (info->stream, "%s\t", opcode->name);
else
(*info->fprintf_func) (info->stream, "%s", opcode->name);
/* Extract the operands. */
separator = 0;
for (opindex = opcode->operands; *opindex != 0; opindex++)
{
operand = s390_operands + *opindex;
value = s390_extract_operand (buffer, operand);
if ((operand->flags & S390_OPERAND_INDEX) && value == 0)
continue;
if ((operand->flags & S390_OPERAND_BASE) &&
value == 0 && separator == '(')
{
separator = ',';
continue;
}
if (separator)
(*info->fprintf_func) (info->stream, "%c", separator);
if (operand->flags & S390_OPERAND_GPR)
(*info->fprintf_func) (info->stream, "%%r%i", value);
else if (operand->flags & S390_OPERAND_FPR)
(*info->fprintf_func) (info->stream, "%%f%i", value);
else if (operand->flags & S390_OPERAND_AR)
(*info->fprintf_func) (info->stream, "%%a%i", value);
else if (operand->flags & S390_OPERAND_CR)
(*info->fprintf_func) (info->stream, "%%c%i", value);
else if (operand->flags & S390_OPERAND_PCREL)
(*info->print_address_func) (memaddr + (int)value + (int)value,
info);
else if (operand->flags & S390_OPERAND_SIGNED)
(*info->fprintf_func) (info->stream, "%i", (int) value);
else
(*info->fprintf_func) (info->stream, "%u", value);
if (operand->flags & S390_OPERAND_DISP)
{
separator = '(';
}
else if (operand->flags & S390_OPERAND_BASE)
{
(*info->fprintf_func) (info->stream, ")");
separator = ',';
}
else
separator = ',';
}
/* Found instruction, printed it, return its size. */
return opsize;
if ((op->modes & current_arch_mask)
&& s390_insn_matches_opcode (buffer, op)
&& (opcode == NULL
|| opcode_mask_more_specific (op, opcode)))
opcode = op;
}
/* No matching instruction found, fall through to hex print. */
}
if (opcode != NULL)
{
/* The instruction is valid. Print it and return its size. */
s390_print_insn_with_opcode (memaddr, info, buffer, opcode);
return opsize;
}
/* Fall back to hex print. */
if (bufsize >= 4)
{
value = (unsigned int) buffer[0];
value = (value << 8) + (unsigned int) buffer[1];
value = (value << 8) + (unsigned int) buffer[2];
value = (value << 8) + (unsigned int) buffer[3];
(*info->fprintf_func) (info->stream, ".long\t0x%08x", value);
info->fprintf_func (info->stream, ".long\t0x%08x", value);
return 4;
}
else if (bufsize >= 2)
{
value = (unsigned int) buffer[0];
value = (value << 8) + (unsigned int) buffer[1];
(*info->fprintf_func) (info->stream, ".short\t0x%04x", value);
info->fprintf_func (info->stream, ".short\t0x%04x", value);
return 2;
}
else
{
value = (unsigned int) buffer[0];
(*info->fprintf_func) (info->stream, ".byte\t0x%02x", value);
info->fprintf_func (info->stream, ".byte\t0x%02x", value);
return 1;
}
}

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