LCOV - code coverage report
Current view: top level - gcc - init-regs.c (source / functions) Hit Total Coverage
Test: gcc.info Lines: 50 52 96.2 %
Date: 2020-04-04 11:58:09 Functions: 4 4 100.0 %
Legend: Lines: hit not hit | Branches: + taken - not taken # not executed Branches: 0 0 -

           Branch data     Line data    Source code
       1                 :            : /* Initialization of uninitialized regs.
       2                 :            :    Copyright (C) 2007-2020 Free Software Foundation, Inc.
       3                 :            : 
       4                 :            : This file is part of GCC.
       5                 :            : 
       6                 :            : GCC is free software; you can redistribute it and/or modify it under
       7                 :            : the terms of the GNU General Public License as published by the Free
       8                 :            : Software Foundation; either version 3, or (at your option) any later
       9                 :            : version.
      10                 :            : 
      11                 :            : GCC is distributed in the hope that it will be useful, but WITHOUT ANY
      12                 :            : WARRANTY; without even the implied warranty of MERCHANTABILITY or
      13                 :            : FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
      14                 :            : for more details.
      15                 :            : 
      16                 :            : You should have received a copy of the GNU General Public License
      17                 :            : along with GCC; see the file COPYING3.  If not see
      18                 :            : <http://www.gnu.org/licenses/>.  */
      19                 :            : 
      20                 :            : #include "config.h"
      21                 :            : #include "system.h"
      22                 :            : #include "coretypes.h"
      23                 :            : #include "backend.h"
      24                 :            : #include "rtl.h"
      25                 :            : #include "tree.h"
      26                 :            : #include "df.h"
      27                 :            : #include "memmodel.h"
      28                 :            : #include "emit-rtl.h"
      29                 :            : #include "expr.h"
      30                 :            : #include "tree-pass.h"
      31                 :            : 
      32                 :            : /* Check all of the uses of pseudo variables.  If any use that is MUST
      33                 :            :    uninitialized, add a store of 0 immediately before it.  For
      34                 :            :    subregs, this makes combine happy.  For full word regs, this makes
      35                 :            :    other optimizations, like the register allocator and the reg-stack
      36                 :            :    happy as well as papers over some problems on the arm and other
      37                 :            :    processors where certain isa constraints cannot be handled by gcc.
      38                 :            :    These are of the form where two operands to an insn my not be the
      39                 :            :    same.  The ra will only make them the same if they do not
      40                 :            :    interfere, and this can only happen if one is not initialized.
      41                 :            : 
      42                 :            :    There is also the unfortunate consequence that this may mask some
      43                 :            :    buggy programs where people forget to initialize stack variable.
      44                 :            :    Any programmer with half a brain would look at the uninitialized
      45                 :            :    variable warnings.  */
      46                 :            : 
      47                 :            : static void
      48                 :     688541 : initialize_uninitialized_regs (void)
      49                 :            : {
      50                 :     688541 :   basic_block bb;
      51                 :     688541 :   auto_bitmap already_genned;
      52                 :            : 
      53                 :     688541 :   if (optimize == 1)
      54                 :            :     {
      55                 :      43183 :       df_live_add_problem ();
      56                 :      43183 :       df_live_set_all_dirty ();
      57                 :            :     }
      58                 :            : 
      59                 :     688541 :   df_analyze ();
      60                 :            : 
      61                 :    7329650 :   FOR_EACH_BB_FN (bb, cfun)
      62                 :            :     {
      63                 :    6641110 :       rtx_insn *insn;
      64                 :    6641110 :       bitmap lr = DF_LR_IN (bb);
      65                 :    6641110 :       bitmap ur = DF_LIVE_IN (bb);
      66                 :    6641110 :       bitmap_clear (already_genned);
      67                 :            : 
      68                 :  158947000 :       FOR_BB_INSNS (bb, insn)
      69                 :            :         {
      70                 :   76153000 :           df_ref use;
      71                 :   76153000 :           if (!NONDEBUG_INSN_P (insn))
      72                 :   38502800 :             continue;
      73                 :            : 
      74                 :   85549400 :           FOR_EACH_INSN_USE (use, insn)
      75                 :            :             {
      76                 :   47899300 :               unsigned int regno = DF_REF_REGNO (use);
      77                 :            : 
      78                 :            :               /* Only do this for the pseudos.  */
      79                 :   47899300 :               if (regno < FIRST_PSEUDO_REGISTER)
      80                 :   23867500 :                 continue;
      81                 :            : 
      82                 :            :               /* Ignore pseudo PIC register.  */
      83                 :   24281900 :               if (pic_offset_table_rtx
      84                 :   24031800 :                   && regno == REGNO (pic_offset_table_rtx))
      85                 :     250135 :                 continue;
      86                 :            : 
      87                 :            :               /* Do not generate multiple moves for the same regno.
      88                 :            :                  This is common for sequences of subreg operations.
      89                 :            :                  They would be deleted during combine but there is no
      90                 :            :                  reason to churn the system.  */
      91                 :   23781600 :               if (bitmap_bit_p (already_genned, regno))
      92                 :     127417 :                 continue;
      93                 :            : 
      94                 :            :               /* A use is MUST uninitialized if it reaches the top of
      95                 :            :                  the block from the inside of the block (the lr test)
      96                 :            :                  and no def for it reaches the top of the block from
      97                 :            :                  outside of the block (the ur test).  */
      98                 :   23654200 :               if (bitmap_bit_p (lr, regno)
      99                 :   23654200 :                   && (!bitmap_bit_p (ur, regno)))
     100                 :            :                 {
     101                 :      94354 :                   rtx_insn *move_insn;
     102                 :      94354 :                   rtx reg = DF_REF_REAL_REG (use);
     103                 :            : 
     104                 :      94354 :                   bitmap_set_bit (already_genned, regno);
     105                 :            : 
     106                 :      94354 :                   start_sequence ();
     107                 :      94354 :                   emit_clobber (reg);
     108                 :      94354 :                   emit_move_insn (reg, CONST0_RTX (GET_MODE (reg)));
     109                 :      94354 :                   move_insn = get_insns ();
     110                 :      94354 :                   end_sequence ();
     111                 :      94354 :                   emit_insn_before (move_insn, insn);
     112                 :      94354 :                   if (dump_file)
     113                 :          0 :                     fprintf (dump_file,
     114                 :            :                              "adding initialization in %s of reg %d at in block %d for insn %d.\n",
     115                 :            :                              current_function_name (), regno, bb->index,
     116                 :          0 :                              INSN_UID (insn));
     117                 :            :                 }
     118                 :            :             }
     119                 :            :         }
     120                 :            :     }
     121                 :            : 
     122                 :     688541 :   if (optimize == 1)
     123                 :            :     {
     124                 :      43183 :       if (dump_file)
     125                 :          8 :         df_dump (dump_file);
     126                 :      43183 :       df_remove_problem (df_live);
     127                 :            :     }
     128                 :     688541 : }
     129                 :            : 
     130                 :            : namespace {
     131                 :            : 
     132                 :            : const pass_data pass_data_initialize_regs =
     133                 :            : {
     134                 :            :   RTL_PASS, /* type */
     135                 :            :   "init-regs", /* name */
     136                 :            :   OPTGROUP_NONE, /* optinfo_flags */
     137                 :            :   TV_NONE, /* tv_id */
     138                 :            :   0, /* properties_required */
     139                 :            :   0, /* properties_provided */
     140                 :            :   0, /* properties_destroyed */
     141                 :            :   0, /* todo_flags_start */
     142                 :            :   TODO_df_finish, /* todo_flags_finish */
     143                 :            : };
     144                 :            : 
     145                 :            : class pass_initialize_regs : public rtl_opt_pass
     146                 :            : {
     147                 :            : public:
     148                 :     200773 :   pass_initialize_regs (gcc::context *ctxt)
     149                 :     401546 :     : rtl_opt_pass (pass_data_initialize_regs, ctxt)
     150                 :            :   {}
     151                 :            : 
     152                 :            :   /* opt_pass methods: */
     153                 :     944101 :   virtual bool gate (function *) { return optimize > 0; }
     154                 :     688541 :   virtual unsigned int execute (function *)
     155                 :            :     {
     156                 :     688541 :       initialize_uninitialized_regs ();
     157                 :     688541 :       return 0;
     158                 :            :     }
     159                 :            : 
     160                 :            : }; // class pass_initialize_regs
     161                 :            : 
     162                 :            : } // anon namespace
     163                 :            : 
     164                 :            : rtl_opt_pass *
     165                 :     200773 : make_pass_initialize_regs (gcc::context *ctxt)
     166                 :            : {
     167                 :     200773 :   return new pass_initialize_regs (ctxt);
     168                 :            : }

Generated by: LCOV version 1.0

LCOV profile is generated on x86_64 machine using following configure options: configure --disable-bootstrap --enable-coverage=opt --enable-languages=c,c++,fortran,go,jit,lto --enable-host-shared. GCC test suite is run with the built compiler.