diff options
Diffstat (limited to 'target/i386/translate.c')
| -rw-r--r-- | target/i386/translate.c | 31 |
1 files changed, 14 insertions, 17 deletions
diff --git a/target/i386/translate.c b/target/i386/translate.c index 816d0b192c..ce9ccb8951 100644 --- a/target/i386/translate.c +++ b/target/i386/translate.c @@ -6807,21 +6807,18 @@ static target_ulong disas_insn(CPUX86State *env, DisasContext *s, ? s->cpuid_ext3_features & CPUID_EXT3_ABM : s->cpuid_7_0_ebx_features & CPUID_7_0_EBX_BMI1)) { int size = 8 << ot; + /* For lzcnt/tzcnt, C bit is defined related to the input. */ tcg_gen_mov_tl(cpu_cc_src, cpu_T0); if (b & 1) { /* For lzcnt, reduce the target_ulong result by the number of zeros that we expect to find at the top. */ - gen_helper_clz(cpu_T0, cpu_T0); + tcg_gen_clzi_tl(cpu_T0, cpu_T0, TARGET_LONG_BITS); tcg_gen_subi_tl(cpu_T0, cpu_T0, TARGET_LONG_BITS - size); } else { - /* For tzcnt, a zero input must return the operand size: - force all bits outside the operand size to 1. */ - target_ulong mask = (target_ulong)-2 << (size - 1); - tcg_gen_ori_tl(cpu_T0, cpu_T0, mask); - gen_helper_ctz(cpu_T0, cpu_T0); - } - /* For lzcnt/tzcnt, C and Z bits are defined and are - related to the result. */ + /* For tzcnt, a zero input must return the operand size. */ + tcg_gen_ctzi_tl(cpu_T0, cpu_T0, size); + } + /* For lzcnt/tzcnt, Z bit is defined related to the result. */ gen_op_update1_cc(); set_cc_op(s, CC_OP_BMILGB + ot); } else { @@ -6829,20 +6826,20 @@ static target_ulong disas_insn(CPUX86State *env, DisasContext *s, to the input and not the result. */ tcg_gen_mov_tl(cpu_cc_dst, cpu_T0); set_cc_op(s, CC_OP_LOGICB + ot); + + /* ??? The manual says that the output is undefined when the + input is zero, but real hardware leaves it unchanged, and + real programs appear to depend on that. Accomplish this + by passing the output as the value to return upon zero. */ if (b & 1) { /* For bsr, return the bit index of the first 1 bit, not the count of leading zeros. */ - gen_helper_clz(cpu_T0, cpu_T0); + tcg_gen_xori_tl(cpu_T1, cpu_regs[reg], TARGET_LONG_BITS - 1); + tcg_gen_clz_tl(cpu_T0, cpu_T0, cpu_T1); tcg_gen_xori_tl(cpu_T0, cpu_T0, TARGET_LONG_BITS - 1); } else { - gen_helper_ctz(cpu_T0, cpu_T0); + tcg_gen_ctz_tl(cpu_T0, cpu_T0, cpu_regs[reg]); } - /* ??? The manual says that the output is undefined when the - input is zero, but real hardware leaves it unchanged, and - real programs appear to depend on that. */ - tcg_gen_movi_tl(cpu_tmp0, 0); - tcg_gen_movcond_tl(TCG_COND_EQ, cpu_T0, cpu_cc_dst, cpu_tmp0, - cpu_regs[reg], cpu_T0); } gen_op_mov_reg_v(ot, reg, cpu_T0); break; |