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x86: avoid i386_dis_printf()'s staging area for a fair part of output

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While PR binutils/29483 has now been addressed differently, this
originally proposed change still has its merits: Avoiding vsnprintf()
for typically far more than half of the overall output results in a 2-3%
performance gain in my testing (with debug builds of objdump, libbfd,
and libopcodes).

With that part of output no longer using staging_area[], the array also
doesn't need to be quite as large anymore (the largest presently used
size is 27, from "64-bit address is disabled").

While limiting the scope of "res" it became apparent that
- no caller cares about the function's return value,
- the comment about the return value was wrong,
- a particular positive return value would have been meaningless to the
  caller.
Therefore convert the function to return "void" at the same time.
This commit is contained in:
Jan Beulich 2022-09-12 08:19:55 +02:00
parent ecb915b4de
commit ac3fe48fd6
1 changed files with 24 additions and 20 deletions
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44
opcodes/i386-dis.c
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@ -9267,31 +9267,40 @@ oappend_register (instr_info *ins, const char *s)
STYLE is the default style to use in the fprintf_styled_func calls,
however, FMT might include embedded style markers (see oappend_style),
these embedded markers are not printed, but instead change the style
used in the next fprintf_styled_func call.
used in the next fprintf_styled_func call. */
Return non-zero to indicate the print call was a success. */
static int ATTRIBUTE_PRINTF_3
static void ATTRIBUTE_PRINTF_3
i386_dis_printf (instr_info *ins, enum disassembler_style style,
const char *fmt, ...)
{
va_list ap;
enum disassembler_style curr_style = style;
char *start, *curr;
char staging_area[MAX_OPERAND_BUFFER_SIZE];
int res;
const char *start, *curr;
char staging_area[40];
va_start (ap, fmt);
res = vsnprintf (staging_area, sizeof (staging_area), fmt, ap);
va_end (ap);
/* In particular print_insn()'s processing of op_txt[] can hand rather long
strings here. Bypass vsnprintf() in such cases to avoid capacity issues
with the staging area. */
if (strcmp (fmt, "%s"))
{
int res = vsnprintf (staging_area, sizeof (staging_area), fmt, ap);
if (res < 0)
return res;
va_end (ap);
if ((size_t) res >= sizeof (staging_area))
abort ();
if (res < 0)
return;
start = curr = staging_area;
if ((size_t) res >= sizeof (staging_area))
abort ();
start = curr = staging_area;
}
else
{
start = curr = va_arg (ap, const char *);
va_end (ap);
}
do
{
@ -9306,10 +9315,7 @@ i386_dis_printf (instr_info *ins, enum disassembler_style style,
curr_style,
"%.*s", len, start);
if (n < 0)
{
res = n;
break;
}
break;
if (*curr == '\0')
break;
@ -9343,8 +9349,6 @@ i386_dis_printf (instr_info *ins, enum disassembler_style style,
++curr;
}
while (true);
return res;
}
static int