accel/tcg/translator.c

   1 /*
   2  * Generic intermediate code generation.
   3  *
   4  * Copyright (C) 2016-2017 Lluís Vilanova <vilanova@ac.upc.edu>
   5  *
   6  * This work is licensed under the terms of the GNU GPL, version 2 or later.
   7  * See the COPYING file in the top-level directory.
   8  */
   9
  10 #include "qemu/osdep.h"
  11 #include "qemu/error-report.h"
  12 #include "cpu.h"
  13 #include "tcg/tcg.h"
  14 #include "tcg/tcg-op.h"
  15 #include "exec/exec-all.h"
  16 #include "exec/gen-icount.h"
  17 #include "exec/log.h"
  18 #include "exec/translator.h"
  19
  20 /* Pairs with tcg_clear_temp_count.
  21    To be called by #TranslatorOps.{translate_insn,tb_stop} if
  22    (1) the target is sufficiently clean to support reporting,
  23    (2) as and when all temporaries are known to be consumed.
  24    For most targets, (2) is at the end of translate_insn.  */
  25 void translator_loop_temp_check(DisasContextBase *db)
  26 {
  27     if (tcg_check_temp_count()) {
  28         qemu_log("warning: TCG temporary leaks before "
  29                  TARGET_FMT_lx "\n", db->pc_next);
  30     }
  31 }
  32
  33 void translator_loop(const TranslatorOps *ops, DisasContextBase *db,
  34                      CPUState *cpu, TranslationBlock *tb, int max_insns)
  35 {
  36     int bp_insn = 0;
  37
  38     /* Initialize DisasContext */
  39     db->tb = tb;
  40     db->pc_first = tb->pc;
  41     db->pc_next = db->pc_first;
  42     db->is_jmp = DISAS_NEXT;
  43     db->num_insns = 0;
  44     db->max_insns = max_insns;
  45     db->singlestep_enabled = cpu->singlestep_enabled;
  46
  47     ops->init_disas_context(db, cpu);
  48     tcg_debug_assert(db->is_jmp == DISAS_NEXT);  /* no early exit */
  49
  50     /* Reset the temp count so that we can identify leaks */
  51     tcg_clear_temp_count();
  52
  53     /* Start translating.  */
  54     gen_tb_start(db->tb);
  55     ops->tb_start(db, cpu);
  56     tcg_debug_assert(db->is_jmp == DISAS_NEXT);  /* no early exit */
  57
  58     while (true) {
  59         db->num_insns++;
  60         ops->insn_start(db, cpu);
  61         tcg_debug_assert(db->is_jmp == DISAS_NEXT);  /* no early exit */
  62
  63         /* Pass breakpoint hits to target for further processing */
  64         if (!db->singlestep_enabled
  65             && unlikely(!QTAILQ_EMPTY(&cpu->breakpoints))) {
  66             CPUBreakpoint *bp;
  67             QTAILQ_FOREACH(bp, &cpu->breakpoints, entry) {
  68                 if (bp->pc == db->pc_next) {
  69                     if (ops->breakpoint_check(db, cpu, bp)) {
  70                         bp_insn = 1;
  71                         break;
  72                     }
  73                 }
  74             }
  75             /* The breakpoint_check hook may use DISAS_TOO_MANY to indicate
  76                that only one more instruction is to be executed.  Otherwise
  77                it should use DISAS_NORETURN when generating an exception,
  78                but may use a DISAS_TARGET_* value for Something Else.  */
  79             if (db->is_jmp > DISAS_TOO_MANY) {
  80                 break;
  81             }
  82         }
  83
  84         /* Disassemble one instruction.  The translate_insn hook should
  85            update db->pc_next and db->is_jmp to indicate what should be
  86            done next -- either exiting this loop or locate the start of
  87            the next instruction.  */
  88         if (db->num_insns == db->max_insns
  89             && (tb_cflags(db->tb) & CF_LAST_IO)) {
  90             /* Accept I/O on the last instruction.  */
  91             gen_io_start();
  92             ops->translate_insn(db, cpu);
  93             gen_io_end();
  94         } else {
  95             ops->translate_insn(db, cpu);
  96         }
  97
  98         /* Stop translation if translate_insn so indicated.  */
  99         if (db->is_jmp != DISAS_NEXT) {
 100             break;
 101         }
 102
 103         /* Stop translation if the output buffer is full,
 104            or we have executed all of the allowed instructions.  */
 105         if (tcg_op_buf_full() || db->num_insns >= db->max_insns) {
 106             db->is_jmp = DISAS_TOO_MANY;
 107             break;
 108         }
 109     }
 110
 111     /* Emit code to exit the TB, as indicated by db->is_jmp.  */
 112     ops->tb_stop(db, cpu);
 113     gen_tb_end(db->tb, db->num_insns - bp_insn);
 114
 115     /* The disas_log hook may use these values rather than recompute.  */
 116     db->tb->size = db->pc_next - db->pc_first;
 117     db->tb->icount = db->num_insns;
 118
 119 #ifdef DEBUG_DISAS
 120     if (qemu_loglevel_mask(CPU_LOG_TB_IN_ASM)
 121         && qemu_log_in_addr_range(db->pc_first)) {
 122         qemu_log_lock();
 123         qemu_log("----------------\n");
 124         ops->disas_log(db, cpu);
 125         qemu_log("\n");
 126         qemu_log_unlock();
 127     }
 128 #endif
 129 }