On 04/20/2016 02:55 AM, Alex Bennée wrote:
+static void tcg_out_nopn(TCGContext *s, int n)
+{
+ static const uint8_t nop1[] = { 0x90 };
+ static const uint8_t nop2[] = { 0x66, 0x90 };
+ static const uint8_t nop3[] = { 0x8d, 0x76, 0x00 };
+ static const uint8_t *const nopn[] = { nop1, nop2, nop3 };
+ int i;
+ assert(n <= ARRAY_SIZE(nopn));
+ for (i = 0; i < n; ++i) {
+ tcg_out8(s, nopn[n - 1][i]);
+ }
+}
*shudder* I recall x86 instruction encoding is weird. Maybe a comment
for the function to describe the 3 forms of NOP we have here?
I think I'd prefer to drop the tables and do
/* Emit 1 or 2 operand size prefixes for the standard one byte nop,
xchg %eax,%eax, forming xchg %ax,%ax. All cores accept the
duplicate prefix, and all of the interesting recent cores can
decode and discard the duplicates in a single cycle. */
for (i = 1; i < n; ++i) {
tcg_out8(s, 0x66);
}
tcg_out8(s, 0x90);
r~
