include/exec/gen-icount.h

   1 #ifndef GEN_ICOUNT_H
   2 #define GEN_ICOUNT_H
   3
   4 #include "exec/exec-all.h"
   5 #include "qemu/timer.h"
   6
   7 /* Helpers for instruction counting code generation.  */
   8
   9 static TCGOp *icount_start_insn;
  10
  11 static inline void gen_io_start(void)
  12 {
  13     TCGv_i32 tmp = tcg_const_i32(1);
  14     tcg_gen_st_i32(tmp, cpu_env,
  15                    offsetof(ArchCPU, parent_obj.can_do_io) -
  16                    offsetof(ArchCPU, env));
  17     tcg_temp_free_i32(tmp);
  18 }
  19
  20 static inline void gen_tb_start(const TranslationBlock *tb)
  21 {
  22     TCGv_i32 count;
  23
  24     if (tb_cflags(tb) & CF_USE_ICOUNT) {
  25         count = tcg_temp_local_new_i32();
  26     } else {
  27         count = tcg_temp_new_i32();
  28     }
  29
  30     tcg_gen_ld_i32(count, cpu_env,
  31                    offsetof(ArchCPU, neg.icount_decr.u32) -
  32                    offsetof(ArchCPU, env));
  33
  34     if (tb_cflags(tb) & CF_USE_ICOUNT) {
  35         /*
  36          * We emit a sub with a dummy immediate argument. Keep the insn index
  37          * of the sub so that we later (when we know the actual insn count)
  38          * can update the argument with the actual insn count.
  39          */
  40         tcg_gen_sub_i32(count, count, tcg_constant_i32(0));
  41         icount_start_insn = tcg_last_op();
  42     }
  43
  44     /*
  45      * Emit the check against icount_decr.u32 to see if we should exit
  46      * unless we suppress the check with CF_NOIRQ. If we are using
  47      * icount and have suppressed interruption the higher level code
  48      * should have ensured we don't run more instructions than the
  49      * budget.
  50      */
  51     if (tb_cflags(tb) & CF_NOIRQ) {
  52         tcg_ctx->exitreq_label = NULL;
  53     } else {
  54         tcg_ctx->exitreq_label = gen_new_label();
  55         tcg_gen_brcondi_i32(TCG_COND_LT, count, 0, tcg_ctx->exitreq_label);
  56     }
  57
  58     if (tb_cflags(tb) & CF_USE_ICOUNT) {
  59         tcg_gen_st16_i32(count, cpu_env,
  60                          offsetof(ArchCPU, neg.icount_decr.u16.low) -
  61                          offsetof(ArchCPU, env));
  62         /*
  63          * cpu->can_do_io is cleared automatically here at the beginning of
  64          * each translation block.  The cost is minimal and only paid for
  65          * -icount, plus it would be very easy to forget doing it in the
  66          * translator. Doing it here means we don't need a gen_io_end() to
  67          * go with gen_io_start().
  68          */
  69         tcg_gen_st_i32(tcg_constant_i32(0), cpu_env,
  70                        offsetof(ArchCPU, parent_obj.can_do_io) -
  71                        offsetof(ArchCPU, env));
  72     }
  73
  74     tcg_temp_free_i32(count);
  75 }
  76
  77 static inline void gen_tb_end(const TranslationBlock *tb, int num_insns)
  78 {
  79     if (tb_cflags(tb) & CF_USE_ICOUNT) {
  80         /*
  81          * Update the num_insn immediate parameter now that we know
  82          * the actual insn count.
  83          */
  84         tcg_set_insn_param(icount_start_insn, 2,
  85                            tcgv_i32_arg(tcg_constant_i32(num_insns)));
  86     }
  87
  88     if (tcg_ctx->exitreq_label) {
  89         gen_set_label(tcg_ctx->exitreq_label);
  90         tcg_gen_exit_tb(tb, TB_EXIT_REQUESTED);
  91     }
  92 }
  93
  94 #endif