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b8698a0f | 1 | /* Initialization of uninitialized regs. |
d1e082c2 | 2 | Copyright (C) 2007-2013 Free Software Foundation, Inc. |
6fb5fa3c DB |
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 | |
9dcd6f09 | 8 | Software Foundation; either version 3, or (at your option) any later |
6fb5fa3c DB |
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 | |
9dcd6f09 NC |
17 | along with GCC; see the file COPYING3. If not see |
18 | <http://www.gnu.org/licenses/>. */ | |
6fb5fa3c DB |
19 | |
20 | #include "config.h" | |
21 | #include "system.h" | |
22 | #include "coretypes.h" | |
23 | #include "tm.h" | |
24 | #include "tree.h" | |
25 | #include "rtl.h" | |
26 | #include "regs.h" | |
27 | #include "expr.h" | |
28 | #include "tree-pass.h" | |
29 | #include "basic-block.h" | |
30 | #include "flags.h" | |
31 | #include "df.h" | |
32 | ||
33 | /* Check all of the uses of pseudo variables. If any use that is MUST | |
34 | uninitialized, add a store of 0 immediately before it. For | |
35 | subregs, this makes combine happy. For full word regs, this makes | |
36 | other optimizations, like the register allocator and the reg-stack | |
37 | happy as well as papers over some problems on the arm and other | |
38 | processors where certain isa constraints cannot be handled by gcc. | |
39 | These are of the form where two operands to an insn my not be the | |
40 | same. The ra will only make them the same if they do not | |
41 | interfere, and this can only happen if one is not initialized. | |
42 | ||
43 | There is also the unfortunate consequence that this may mask some | |
44 | buggy programs where people forget to initialize stack variable. | |
45 | Any programmer with half a brain would look at the uninitialized | |
46 | variable warnings. */ | |
47 | ||
48 | static void | |
49 | initialize_uninitialized_regs (void) | |
50 | { | |
51 | basic_block bb; | |
52 | bitmap already_genned = BITMAP_ALLOC (NULL); | |
53 | ||
89a95777 KZ |
54 | if (optimize == 1) |
55 | { | |
56 | df_live_add_problem (); | |
57 | df_live_set_all_dirty (); | |
58 | } | |
59 | ||
6fb5fa3c DB |
60 | df_analyze (); |
61 | ||
62 | FOR_EACH_BB (bb) | |
63 | { | |
64 | rtx insn; | |
65 | bitmap lr = DF_LR_IN (bb); | |
66 | bitmap ur = DF_LIVE_IN (bb); | |
67 | bitmap_clear (already_genned); | |
68 | ||
69 | FOR_BB_INSNS (bb, insn) | |
70 | { | |
71 | unsigned int uid = INSN_UID (insn); | |
57512f53 | 72 | df_ref *use_rec; |
b5b8b0ac | 73 | if (!NONDEBUG_INSN_P (insn)) |
6fb5fa3c DB |
74 | continue; |
75 | ||
76 | for (use_rec = DF_INSN_UID_USES (uid); *use_rec; use_rec++) | |
77 | { | |
57512f53 | 78 | df_ref use = *use_rec; |
6fb5fa3c DB |
79 | unsigned int regno = DF_REF_REGNO (use); |
80 | ||
81 | /* Only do this for the pseudos. */ | |
82 | if (regno < FIRST_PSEUDO_REGISTER) | |
83 | continue; | |
84 | ||
85 | /* Do not generate multiple moves for the same regno. | |
86 | This is common for sequences of subreg operations. | |
87 | They would be deleted during combine but there is no | |
88 | reason to churn the system. */ | |
89 | if (bitmap_bit_p (already_genned, regno)) | |
90 | continue; | |
91 | ||
92 | /* A use is MUST uninitialized if it reaches the top of | |
93 | the block from the inside of the block (the lr test) | |
94 | and no def for it reaches the top of the block from | |
95 | outside of the block (the ur test). */ | |
96 | if (bitmap_bit_p (lr, regno) | |
97 | && (!bitmap_bit_p (ur, regno))) | |
98 | { | |
99 | rtx move_insn; | |
100 | rtx reg = DF_REF_REAL_REG (use); | |
101 | ||
b8698a0f | 102 | bitmap_set_bit (already_genned, regno); |
6fb5fa3c DB |
103 | |
104 | start_sequence (); | |
105 | emit_move_insn (reg, CONST0_RTX (GET_MODE (reg))); | |
106 | move_insn = get_insns (); | |
107 | end_sequence (); | |
e2d3b294 | 108 | emit_insn_before (move_insn, insn); |
6fb5fa3c | 109 | if (dump_file) |
b8698a0f L |
110 | fprintf (dump_file, |
111 | "adding initialization in %s of reg %d at in block %d for insn %d.\n", | |
6fb5fa3c DB |
112 | current_function_name (), regno, bb->index, uid); |
113 | } | |
114 | } | |
115 | } | |
116 | } | |
117 | ||
89a95777 | 118 | if (optimize == 1) |
ba49cb7b | 119 | { |
b8698a0f | 120 | if (dump_file) |
ba49cb7b KZ |
121 | df_dump (dump_file); |
122 | df_remove_problem (df_live); | |
123 | } | |
89a95777 | 124 | |
6fb5fa3c DB |
125 | BITMAP_FREE (already_genned); |
126 | } | |
127 | ||
128 | static bool | |
129 | gate_initialize_regs (void) | |
130 | { | |
131 | return optimize > 0; | |
132 | } | |
133 | ||
134 | static unsigned int | |
135 | rest_of_handle_initialize_regs (void) | |
136 | { | |
6fb5fa3c | 137 | initialize_uninitialized_regs (); |
6fb5fa3c DB |
138 | return 0; |
139 | } | |
140 | ||
8ddbbcae | 141 | struct rtl_opt_pass pass_initialize_regs = |
6fb5fa3c | 142 | { |
8ddbbcae JH |
143 | { |
144 | RTL_PASS, | |
6fb5fa3c | 145 | "init-regs", /* name */ |
2b4e6bf1 | 146 | OPTGROUP_NONE, /* optinfo_flags */ |
6fb5fa3c DB |
147 | gate_initialize_regs, /* gate */ |
148 | rest_of_handle_initialize_regs, /* execute */ | |
149 | NULL, /* sub */ | |
150 | NULL, /* next */ | |
151 | 0, /* static_pass_number */ | |
7072a650 | 152 | TV_NONE, /* tv_id */ |
6fb5fa3c DB |
153 | 0, /* properties_required */ |
154 | 0, /* properties_provided */ | |
155 | 0, /* properties_destroyed */ | |
156 | 0, /* todo_flags_start */ | |
8ddbbcae JH |
157 | TODO_df_finish /* todo_flags_finish */ |
158 | } | |
6fb5fa3c | 159 | }; |