target/arm: optimize indirect branches
Speed up indirect branches by jumping to the target if it is valid. Softmmu measurements (see later commit for user-mode results): Note: baseline (i.e. speedup == 1x) is QEMU v2.9.0. - Impact on Boot time | setup | ARM debian jessie boot+shutdown time | stddev | |--------+--------------------------------------+--------| | v2.9.0 | 8.84 | 0.07 | | +cross | 8.85 | 0.03 | | +jr | 8.83 | 0.06 | - NBench, arm-softmmu (debian jessie guest). Host: Intel i7-4790K @ 4.00GHz 1.3x +-+-------------------------------------------------------------------------------------------------------------+-+ | | | cross #### | 1.25x +cross+jr..........................................................#++#.........................................+-+ | #### # # | | +++# # # # | | +++ **** # # # | 1.2x +-+...................................####............*..*..#......#..#.........................................+-+ | **** # * * # # # #### | | * * # * * # # # # # | 1.15x +-+................................*..*..#............*..*..#......#..#.....#..#................................+-+ | * * # * * # # # # # | | * * # #### * * # # # # # | | * * # # # * * # # # # # #### | 1.1x +-+................................*..*..#......#..#..*..*..#......#..#.....#..#.........................#..#...+-+ | * * # # # * * # # # # # # # | | * * # # # * * # # # # # # # | 1.05x +-+..........................####..*..*..#......#..#..*..*..#......#..#.....#..#......+++............*****..#...+-+ | ***** # * * # # # * * # ***** # # # +++ | ****### * * # | | *+++* # * * # # # * * # *+++* # **** # *****### * * # * * # | | *****### +++#### * * # * * # ***** # * * # * * # * * # * | *++# * * # * * # | 1x +-++-+*+++*-+#++****++#++*+-+*++#+-*++*++#-+*+++*-+#++*++*++#++*+-+*++#+-*++*++#-+*+++*-+#++*++*++#++*+-+*++#+-++-+ | * * # * * # * * # * * # * * # * * # * * # * * # * * # * * # * * # | | * * # * * # * * # * * # * * # * * # * * # * * # * * # * * # * * # | 0.95x +-+---*****###--****###--*****###--****###--*****###--****###--*****###--****###--*****###--****###--*****###---+-+ ASSIGNMENT BITFIELD FOURFP EMULATION HUFFMAN LU DECOMPOSITIONEURAL NNUMERIC SOSTRING SORT hmean png: http://imgur.com/eOLmZNR NB. 'cross' represents the previous commit. Signed-off-by: Emilio G. Cota <cota@braap.org> Message-Id: <1493263764-18657-8-git-send-email-cota@braap.org> [rth: Replace gen_jr global variable with DISAS_EXIT state.] Signed-off-by: Richard Henderson <rth@twiddle.net>
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@ -1182,7 +1182,7 @@ static void gen_exception_internal_insn(DisasContext *s, int offset, int excp)
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gen_set_condexec(s);
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gen_set_pc_im(s, s->pc - offset);
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gen_exception_internal(excp);
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s->is_jmp = DISAS_JUMP;
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s->is_jmp = DISAS_EXC;
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}
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static void gen_exception_insn(DisasContext *s, int offset, int excp,
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@ -1191,14 +1191,14 @@ static void gen_exception_insn(DisasContext *s, int offset, int excp,
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gen_set_condexec(s);
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gen_set_pc_im(s, s->pc - offset);
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gen_exception(excp, syn, target_el);
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s->is_jmp = DISAS_JUMP;
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s->is_jmp = DISAS_EXC;
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}
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/* Force a TB lookup after an instruction that changes the CPU state. */
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static inline void gen_lookup_tb(DisasContext *s)
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{
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tcg_gen_movi_i32(cpu_R[15], s->pc & ~1);
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s->is_jmp = DISAS_JUMP;
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s->is_jmp = DISAS_EXIT;
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}
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static inline void gen_hlt(DisasContext *s, int imm)
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@ -4150,19 +4150,23 @@ static inline bool use_goto_tb(DisasContext *s, target_ulong dest)
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#endif
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}
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static inline void gen_goto_tb(DisasContext *s, int n, target_ulong dest)
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static void gen_goto_ptr(void)
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{
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TCGv addr = tcg_temp_new();
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tcg_gen_extu_i32_tl(addr, cpu_R[15]);
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tcg_gen_lookup_and_goto_ptr(addr);
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tcg_temp_free(addr);
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}
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static void gen_goto_tb(DisasContext *s, int n, target_ulong dest)
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{
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if (use_goto_tb(s, dest)) {
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tcg_gen_goto_tb(n);
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gen_set_pc_im(s, dest);
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tcg_gen_exit_tb((uintptr_t)s->tb + n);
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} else {
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TCGv addr = tcg_temp_new();
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gen_set_pc_im(s, dest);
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tcg_gen_extu_i32_tl(addr, cpu_R[15]);
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tcg_gen_lookup_and_goto_ptr(addr);
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tcg_temp_free(addr);
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gen_goto_ptr();
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}
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}
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@ -12095,11 +12099,14 @@ void gen_intermediate_code(CPUARMState *env, TranslationBlock *tb)
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gen_set_pc_im(dc, dc->pc);
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/* fall through */
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case DISAS_JUMP:
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gen_goto_ptr();
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break;
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default:
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/* indicate that the hash table must be used to find the next TB */
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tcg_gen_exit_tb(0);
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break;
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case DISAS_TB_JUMP:
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case DISAS_EXC:
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/* nothing more to generate */
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break;
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case DISAS_WFI:
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@ -139,6 +139,10 @@ static void disas_set_insn_syndrome(DisasContext *s, uint32_t syn)
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* custom end-of-TB code)
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*/
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#define DISAS_BX_EXCRET 11
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/* For instructions which want an immediate exit to the main loop,
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* as opposed to attempting to use lookup_and_goto_ptr.
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*/
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#define DISAS_EXIT 12
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#ifdef TARGET_AARCH64
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void a64_translate_init(void);
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