LXR qemu/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
   9static TCGOp *icount_start_insn;
  10
  11static 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
  20static 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
  77static 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
  95