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tcg/i386 fixes

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Merge remote-tracking branch 'remotes/rth/tags/pull-tcg-20170117' into staging

tcg/i386 fixes

# gpg: Signature made Tue 17 Jan 2017 22:58:04 GMT
# gpg:                using RSA key 0xAD1270CC4DD0279B
# gpg: Good signature from "Richard Henderson <rth7680@gmail.com>"
# gpg:                 aka "Richard Henderson <rth@redhat.com>"
# gpg:                 aka "Richard Henderson <rth@twiddle.net>"
# Primary key fingerprint: 9CB1 8DDA F8E8 49AD 2AFC  16A4 AD12 70CC 4DD0 279B

* remotes/rth/tags/pull-tcg-20170117:
  tcg/i386: Always use TZCNT when available
  Revert "tcg/i386: Rely on undefined/undocumented behaviour of BSF/BSR"

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
This commit is contained in:
Peter Maydell 2017-01-19 13:36:21 +00:00
commit 5e59fb10ce
1 changed files with 20 additions and 25 deletions
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45
tcg/i386/tcg-target.inc.c
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@ -1143,17 +1143,18 @@ 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 {
/* ??? The manual says that the output is undefined when the
input is zero, but real hardware leaves it unchanged. As
noted in target-i386/translate.c, real programs depend on
this -- now we are one more of those. */
tcg_debug_assert(dest == arg2);
tcg_debug_assert(dest != arg2);
tcg_out_modrm(s, OPC_BSF + rexw, dest, arg1);
tcg_out_cmov(s, TCG_COND_EQ, rexw, dest, arg2);
}
}
@ -1166,26 +1167,20 @@ static void tcg_out_clz(TCGContext *s, int rexw, TCGReg dest, TCGReg arg1,
tcg_debug_assert(arg2 == (rexw ? 64 : 32));
} else {
tcg_debug_assert(dest != arg2);
/* LZCNT sets C if the input was zero. */
tcg_out_cmov(s, TCG_COND_LTU, rexw, dest, arg2);
}
} else {
TCGType type = rexw ? TCG_TYPE_I64: TCG_TYPE_I32;
TCGArg rev = rexw ? 63 : 31;
tcg_debug_assert(!const_a2);
tcg_debug_assert(dest != arg1);
tcg_debug_assert(dest != arg2);
/* Recall that the output of BSR is the index not the count.
Therefore we must adjust the result by ^ (SIZE-1). In some
cases below, we prefer an extra XOR to a JMP. */
/* ??? See the comment in tcg_out_ctz re BSF. */
if (const_a2) {
tcg_debug_assert(dest != arg1);
tcg_out_movi(s, type, dest, arg2 ^ rev);
} else {
tcg_debug_assert(dest == arg2);
tgen_arithi(s, ARITH_XOR + rexw, dest, rev, 0);
}
/* Recall that the output of BSR is the index not the count. */
tcg_out_modrm(s, OPC_BSR + rexw, dest, arg1);
tgen_arithi(s, ARITH_XOR + rexw, dest, rev, 0);
tgen_arithi(s, ARITH_XOR + rexw, dest, rexw ? 63 : 31, 0);
/* Since we have destroyed the flags from BSR, we have to re-test. */
tcg_out_cmp(s, arg1, 0, 1, rexw);
tcg_out_cmov(s, TCG_COND_EQ, rexw, dest, arg2);
}
}
@ -2459,7 +2454,7 @@ static const TCGTargetOpDef *tcg_target_op_def(TCGOpcode op)
case INDEX_op_ctz_i64:
{
static const TCGTargetOpDef ctz[2] = {
{ .args_ct_str = { "r", "r", "0" } },
{ .args_ct_str = { "&r", "r", "r" } },
{ .args_ct_str = { "&r", "r", "rW" } },
};
return &ctz[have_bmi1];
@ -2468,7 +2463,7 @@ static const TCGTargetOpDef *tcg_target_op_def(TCGOpcode op)
case INDEX_op_clz_i64:
{
static const TCGTargetOpDef clz[2] = {
{ .args_ct_str = { "&r", "r", "0i" } },
{ .args_ct_str = { "&r", "r", "r" } },
{ .args_ct_str = { "&r", "r", "rW" } },
};
return &clz[have_lzcnt];