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author | Paolo Bonzini <pbonzini@redhat.com> | 2012-10-05 23:00:10 +0200 |
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committer | Richard Henderson <rth@twiddle.net> | 2013-02-18 15:03:57 -0800 |
commit | c365395e9bd2b3bcac48ef562c187ea6ab9820ad (patch) | |
tree | cad75bbb1e297b40f38f469bb657fb27c8603a1c /target-i386 | |
parent | be10b289d697420b6e0d8d1a681aa64555066639 (diff) | |
download | qemu-c365395e9bd2b3bcac48ef562c187ea6ab9820ad.zip qemu-c365395e9bd2b3bcac48ef562c187ea6ab9820ad.tar.gz qemu-c365395e9bd2b3bcac48ef562c187ea6ab9820ad.tar.bz2 |
target-i386: optimize setcc instructions
Reconstruct the arguments for complex conditions involving CC_OP_SUBx (BE,
L, LE). In the others do it via setcond and gen_setcc_slow (which is
not that slow in many cases).
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Richard Henderson <rth@twiddle.net>
Diffstat (limited to 'target-i386')
-rw-r--r-- | target-i386/translate.c | 95 |
1 files changed, 37 insertions, 58 deletions
diff --git a/target-i386/translate.c b/target-i386/translate.c index fea43c7..5c9211f 100644 --- a/target-i386/translate.c +++ b/target-i386/translate.c @@ -1090,55 +1090,55 @@ static void gen_setcc_slow(DisasContext *s, int jcc_op, TCGv reg, bool inv) } } -/* return true if setcc_slow is not needed (WARNING: must be kept in - sync with gen_jcc1) */ -static int is_fast_jcc_case(DisasContext *s, int b) +/* perform a conditional store into register 'reg' according to jump opcode + value 'b'. In the fast case, T0 is guaranted not to be used. */ +static inline void gen_setcc1(DisasContext *s, int b, TCGv reg) { - int jcc_op; + int inv, jcc_op, size, cond; + TCGv t0; + + inv = b & 1; jcc_op = (b >> 1) & 7; - switch(s->cc_op) { - /* we optimize the cmp/jcc case */ + + switch (s->cc_op) { + /* we optimize relational operators for the cmp/jcc case */ case CC_OP_SUBB: case CC_OP_SUBW: case CC_OP_SUBL: case CC_OP_SUBQ: - if (jcc_op == JCC_O || jcc_op == JCC_P) - goto slow_jcc; - break; - - /* some jumps are easy to compute */ - case CC_OP_ADDB: - case CC_OP_ADDW: - case CC_OP_ADDL: - case CC_OP_ADDQ: - - case CC_OP_LOGICB: - case CC_OP_LOGICW: - case CC_OP_LOGICL: - case CC_OP_LOGICQ: - - case CC_OP_INCB: - case CC_OP_INCW: - case CC_OP_INCL: - case CC_OP_INCQ: + size = s->cc_op - CC_OP_SUBB; + switch (jcc_op) { + case JCC_BE: + cond = inv ? TCG_COND_GTU : TCG_COND_LEU; + tcg_gen_add_tl(cpu_tmp4, cpu_cc_dst, cpu_cc_src); + gen_extu(size, cpu_tmp4); + t0 = gen_ext_tl(cpu_tmp0, cpu_cc_src, size, false); + tcg_gen_setcond_tl(cond, reg, cpu_tmp4, t0); + break; - case CC_OP_DECB: - case CC_OP_DECW: - case CC_OP_DECL: - case CC_OP_DECQ: + case JCC_L: + cond = inv ? TCG_COND_GE : TCG_COND_LT; + goto fast_jcc_l; + case JCC_LE: + cond = inv ? TCG_COND_GT : TCG_COND_LE; + fast_jcc_l: + tcg_gen_add_tl(cpu_tmp4, cpu_cc_dst, cpu_cc_src); + gen_exts(size, cpu_tmp4); + t0 = gen_ext_tl(cpu_tmp0, cpu_cc_src, size, true); + tcg_gen_setcond_tl(cond, reg, cpu_tmp4, t0); + break; - case CC_OP_SHLB: - case CC_OP_SHLW: - case CC_OP_SHLL: - case CC_OP_SHLQ: - if (jcc_op != JCC_Z && jcc_op != JCC_S) + default: goto slow_jcc; + } break; + default: slow_jcc: - return 0; + /* gen_setcc_slow actually generates good code for JC, JZ and JS */ + gen_setcc_slow(s, jcc_op, reg, inv); + break; } - return 1; } /* generate a conditional jump to label 'l1' according to jump opcode @@ -2487,28 +2487,7 @@ static inline void gen_jcc(DisasContext *s, int b, static void gen_setcc(DisasContext *s, int b) { - int inv, jcc_op, l1; - TCGv t0; - - if (is_fast_jcc_case(s, b)) { - /* nominal case: we use a jump */ - /* XXX: make it faster by adding new instructions in TCG */ - t0 = tcg_temp_local_new(); - tcg_gen_movi_tl(t0, 0); - l1 = gen_new_label(); - gen_jcc1(s, b ^ 1, l1); - tcg_gen_movi_tl(t0, 1); - gen_set_label(l1); - tcg_gen_mov_tl(cpu_T[0], t0); - tcg_temp_free(t0); - } else { - /* slow case: it is more efficient not to generate a jump, - although it is questionnable whether this optimization is - worth to */ - inv = b & 1; - jcc_op = (b >> 1) & 7; - gen_setcc_slow(s, jcc_op, cpu_T[0], inv); - } + gen_setcc1(s, b, cpu_T[0]); } static inline void gen_op_movl_T0_seg(int seg_reg) |