diff options
Diffstat (limited to 'tcg/i386')
| -rw-r--r-- | tcg/i386/tcg-target.inc.c | 35 |
1 files changed, 22 insertions, 13 deletions
diff --git a/tcg/i386/tcg-target.inc.c b/tcg/i386/tcg-target.inc.c index 3ed8cd1bf7..3650340fd9 100644 --- a/tcg/i386/tcg-target.inc.c +++ b/tcg/i386/tcg-target.inc.c @@ -1146,9 +1146,12 @@ static void tcg_out_ctz(TCGContext *s, int rexw, TCGReg dest, TCGReg arg1, tcg_debug_assert(arg2 == (rexw ? 64 : 32)); tcg_out_modrm(s, OPC_TZCNT + rexw, dest, arg1); } else { - tcg_debug_assert(dest != arg2); + /* ??? 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_out_modrm(s, OPC_BSF + rexw, dest, arg1); - tcg_out_cmov(s, TCG_COND_EQ, rexw, dest, arg2); } } @@ -1161,20 +1164,26 @@ 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 { - tcg_debug_assert(!const_a2); - tcg_debug_assert(dest != arg1); - tcg_debug_assert(dest != arg2); + TCGType type = rexw ? TCG_TYPE_I64: TCG_TYPE_I32; + TCGArg rev = rexw ? 63 : 31; - /* Recall that the output of BSR is the index not the count. */ + /* 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); + } tcg_out_modrm(s, OPC_BSR + rexw, dest, arg1); - 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); + tgen_arithi(s, ARITH_XOR + rexw, dest, rev, 0); } } @@ -2443,7 +2452,7 @@ static const TCGTargetOpDef *tcg_target_op_def(TCGOpcode op) case INDEX_op_ctz_i64: { static const TCGTargetOpDef ctz[2] = { - { .args_ct_str = { "&r", "r", "r" } }, + { .args_ct_str = { "r", "r", "0" } }, { .args_ct_str = { "&r", "r", "rW" } }, }; return &ctz[have_bmi1]; @@ -2452,7 +2461,7 @@ static const TCGTargetOpDef *tcg_target_op_def(TCGOpcode op) case INDEX_op_clz_i64: { static const TCGTargetOpDef clz[2] = { - { .args_ct_str = { "&r", "r", "r" } }, + { .args_ct_str = { "&r", "r", "0i" } }, { .args_ct_str = { "&r", "r", "rW" } }, }; return &clz[have_lzcnt]; |