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 #include "exec/plugin-gen.h"
  20
  21 /* Pairs with tcg_clear_temp_count.
  22    To be called by #TranslatorOps.{translate_insn,tb_stop} if
  23    (1) the target is sufficiently clean to support reporting,
  24    (2) as and when all temporaries are known to be consumed.
  25    For most targets, (2) is at the end of translate_insn.  */
  26 void translator_loop_temp_check(DisasContextBase *db)
  27 {
  28     if (tcg_check_temp_count()) {
  29         qemu_log("warning: TCG temporary leaks before "
  30                  TARGET_FMT_lx "\n", db->pc_next);
  31     }
  32 }
  33
  34 void translator_loop(const TranslatorOps *ops, DisasContextBase *db,
  35                      CPUState *cpu, TranslationBlock *tb, int max_insns)
  36 {
  37     int bp_insn = 0;
  38     bool plugin_enabled;
  39
  40     /* Initialize DisasContext */
  41     db->tb = tb;
  42     db->pc_first = tb->pc;
  43     db->pc_next = db->pc_first;
  44     db->is_jmp = DISAS_NEXT;
  45     db->num_insns = 0;
  46     db->max_insns = max_insns;
  47     db->singlestep_enabled = cpu->singlestep_enabled;
  48
  49     ops->init_disas_context(db, cpu);
  50     tcg_debug_assert(db->is_jmp == DISAS_NEXT);  /* no early exit */
  51
  52     /* Reset the temp count so that we can identify leaks */
  53     tcg_clear_temp_count();
  54
  55     /* Start translating.  */
  56     gen_tb_start(db->tb);
  57     ops->tb_start(db, cpu);
  58     tcg_debug_assert(db->is_jmp == DISAS_NEXT);  /* no early exit */
  59
  60     plugin_enabled = plugin_gen_tb_start(cpu, tb);
  61
  62     while (true) {
  63         db->num_insns++;
  64         ops->insn_start(db, cpu);
  65         tcg_debug_assert(db->is_jmp == DISAS_NEXT);  /* no early exit */
  66
  67         if (plugin_enabled) {
  68             plugin_gen_insn_start(cpu, db);
  69         }
  70
  71         /* Pass breakpoint hits to target for further processing */
  72         if (!db->singlestep_enabled
  73             && unlikely(!QTAILQ_EMPTY(&cpu->breakpoints))) {
  74             CPUBreakpoint *bp;
  75             QTAILQ_FOREACH(bp, &cpu->breakpoints, entry) {
  76                 if (bp->pc == db->pc_next) {
  77                     if (ops->breakpoint_check(db, cpu, bp)) {
  78                         bp_insn = 1;
  79                         break;
  80                     }
  81                 }
  82             }
  83             /* The breakpoint_check hook may use DISAS_TOO_MANY to indicate
  84                that only one more instruction is to be executed.  Otherwise
  85                it should use DISAS_NORETURN when generating an exception,
  86                but may use a DISAS_TARGET_* value for Something Else.  */
  87             if (db->is_jmp > DISAS_TOO_MANY) {
  88                 break;
  89             }
  90         }
  91
  92         /* Disassemble one instruction.  The translate_insn hook should
  93            update db->pc_next and db->is_jmp to indicate what should be
  94            done next -- either exiting this loop or locate the start of
  95            the next instruction.  */
  96         if (db->num_insns == db->max_insns
  97             && (tb_cflags(db->tb) & CF_LAST_IO)) {
  98             /* Accept I/O on the last instruction.  */
  99             gen_io_start();
 100             ops->translate_insn(db, cpu);
 101         } else {
 102             ops->translate_insn(db, cpu);
 103         }
 104
 105         /* Stop translation if translate_insn so indicated.  */
 106         if (db->is_jmp != DISAS_NEXT) {
 107             break;
 108         }
 109
 110         /*
 111          * We can't instrument after instructions that change control
 112          * flow although this only really affects post-load operations.
 113          */
 114         if (plugin_enabled) {
 115             plugin_gen_insn_end();
 116         }
 117
 118         /* Stop translation if the output buffer is full,
 119            or we have executed all of the allowed instructions.  */
 120         if (tcg_op_buf_full() || db->num_insns >= db->max_insns) {
 121             db->is_jmp = DISAS_TOO_MANY;
 122             break;
 123         }
 124     }
 125
 126     /* Emit code to exit the TB, as indicated by db->is_jmp.  */
 127     ops->tb_stop(db, cpu);
 128     gen_tb_end(db->tb, db->num_insns - bp_insn);
 129
 130     if (plugin_enabled) {
 131         plugin_gen_tb_end(cpu);
 132     }
 133
 134     /* The disas_log hook may use these values rather than recompute.  */
 135     db->tb->size = db->pc_next - db->pc_first;
 136     db->tb->icount = db->num_insns;
 137
 138 #ifdef DEBUG_DISAS
 139     if (qemu_loglevel_mask(CPU_LOG_TB_IN_ASM)
 140         && qemu_log_in_addr_range(db->pc_first)) {
 141         FILE *logfile = qemu_log_lock();
 142         qemu_log("----------------\n");
 143         ops->disas_log(db, cpu);
 144         qemu_log("\n");
 145         qemu_log_unlock(logfile);
 146     }
 147 #endif
 148 }