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commit 9ace48f3d7d80ce09c5df60cccb433470410b11b
Author: Andreas Arnez <arnez@linux.vnet.ibm.com>
Date: Tue Aug 19 15:42:13 2014 +0100
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
### a/opcodes/ChangeLog
### b/opcodes/ChangeLog
## -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.
--- a/opcodes/s390-dis.c
+++ b/opcodes/s390-dis.c
@@ -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;
}
}