diff options
| author | Paolo Bonzini <pbonzini@redhat.com> | 2024-06-20 10:34:28 +0200 |
|---|---|---|
| committer | Paolo Bonzini <pbonzini@redhat.com> | 2024-10-31 18:28:33 +0100 |
| commit | ae14b33de8d329d5497db5446bdc0b0cb6ba756b (patch) | |
| tree | ee8f830177d04ee80dbbe80b2598669ff501887c /target | |
| parent | 1f7f72bdc4faece6af875503a3abe992e87e776b (diff) | |
target/i386: optimize computation of ZF from CC_OP_DYNAMIC
Most uses of CC_OP_DYNAMIC are for CMP/JB/JE or similar sequences.
We can optimize many of them to avoid computation of the flags.
This eliminates both TCG ops to set up the new cc_op, and helper
instructions because evaluating just ZF is much cheaper.
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'target')
| -rw-r--r-- | target/i386/helper.h | 1 | ||||
| -rw-r--r-- | target/i386/tcg/cc_helper.c | 13 | ||||
| -rw-r--r-- | target/i386/tcg/translate.c | 10 |
3 files changed, 21 insertions, 3 deletions
diff --git a/target/i386/helper.h b/target/i386/helper.h index eeb8df56ea..3f67098f11 100644 --- a/target/i386/helper.h +++ b/target/i386/helper.h @@ -1,5 +1,6 @@ DEF_HELPER_FLAGS_4(cc_compute_all, TCG_CALL_NO_RWG_SE, tl, tl, tl, tl, int) DEF_HELPER_FLAGS_4(cc_compute_c, TCG_CALL_NO_RWG_SE, tl, tl, tl, tl, int) +DEF_HELPER_FLAGS_3(cc_compute_nz, TCG_CALL_NO_RWG_SE, tl, tl, tl, int) DEF_HELPER_3(write_eflags, void, env, tl, i32) DEF_HELPER_1(read_eflags, tl, env) diff --git a/target/i386/tcg/cc_helper.c b/target/i386/tcg/cc_helper.c index 40583c04cf..1b83775a91 100644 --- a/target/i386/tcg/cc_helper.c +++ b/target/i386/tcg/cc_helper.c @@ -95,6 +95,19 @@ static target_ulong compute_all_adcox(target_ulong dst, target_ulong src1, return (src1 & ~(CC_C | CC_O)) | (dst * CC_C) | (src2 * CC_O); } +target_ulong helper_cc_compute_nz(target_ulong dst, target_ulong src1, + int op) +{ + if (CC_OP_HAS_EFLAGS(op)) { + return ~src1 & CC_Z; + } else { + MemOp size = cc_op_size(op); + target_ulong mask = MAKE_64BIT_MASK(0, 8 << size); + + return dst & mask; + } +} + target_ulong helper_cc_compute_all(target_ulong dst, target_ulong src1, target_ulong src2, int op) { diff --git a/target/i386/tcg/translate.c b/target/i386/tcg/translate.c index 1a9a2fe709..5e326ab1af 100644 --- a/target/i386/tcg/translate.c +++ b/target/i386/tcg/translate.c @@ -1008,15 +1008,19 @@ static CCPrepare gen_prepare_eflags_o(DisasContext *s, TCGv reg) static CCPrepare gen_prepare_eflags_z(DisasContext *s, TCGv reg) { switch (s->cc_op) { - case CC_OP_DYNAMIC: - gen_compute_eflags(s); - /* FALLTHRU */ case CC_OP_EFLAGS: case CC_OP_ADCX: case CC_OP_ADOX: case CC_OP_ADCOX: return (CCPrepare) { .cond = TCG_COND_TSTNE, .reg = cpu_cc_src, .imm = CC_Z }; + case CC_OP_DYNAMIC: + gen_update_cc_op(s); + if (!reg) { + reg = tcg_temp_new(); + } + gen_helper_cc_compute_nz(reg, cpu_cc_dst, cpu_cc_src, cpu_cc_op); + return (CCPrepare) { .cond = TCG_COND_EQ, .reg = reg, .imm = 0 }; default: { MemOp size = cc_op_size(s->cc_op); |