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tcg/i386: Always use TZCNT when available

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I think this is cleaner than sometimes using BSF.

Signed-off-by: Richard Henderson <rth@twiddle.net>
This commit is contained in:
Richard Henderson 2017-01-17 12:02:08 -08:00
parent 9bf38308f6
commit 39f099ec9d
1 changed files with 7 additions and 3 deletions
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10
tcg/i386/tcg-target.inc.c
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@ -1143,10 +1143,14 @@ static void tcg_out_movcond64(TCGContext *s, TCGCond cond, TCGReg dest,
static void tcg_out_ctz(TCGContext *s, int rexw, TCGReg dest, TCGReg arg1,
TCGArg arg2, bool const_a2)
{
if (const_a2) {
tcg_debug_assert(have_bmi1);
tcg_debug_assert(arg2 == (rexw ? 64 : 32));
if (have_bmi1) {
tcg_out_modrm(s, OPC_TZCNT + rexw, dest, arg1);
if (const_a2) {
tcg_debug_assert(arg2 == (rexw ? 64 : 32));
} else {
tcg_debug_assert(dest != arg2);
tcg_out_cmov(s, TCG_COND_LTU, rexw, dest, arg2);
}
} else {
tcg_debug_assert(dest != arg2);
tcg_out_modrm(s, OPC_BSF + rexw, dest, arg1);