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d41c8b4c SE |
1 | /* Analyze functions to determine if callers need to allocate a frame header |
2 | on the stack. The frame header is used by callees to save their arguments. | |
3 | This optimization is specific to TARGET_OLDABI targets. For TARGET_NEWABI | |
4 | targets, if a frame header is required, it is allocated by the callee. | |
5 | ||
6 | ||
a5544970 | 7 | Copyright (C) 2015-2019 Free Software Foundation, Inc. |
d41c8b4c SE |
8 | |
9 | This file is part of GCC. | |
10 | ||
11 | GCC is free software; you can redistribute it and/or modify it | |
12 | under the terms of the GNU General Public License as published by the | |
13 | Free Software Foundation; either version 3, or (at your option) any | |
14 | later version. | |
15 | ||
16 | GCC is distributed in the hope that it will be useful, but WITHOUT | |
17 | ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or | |
18 | FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License | |
19 | for more details. | |
20 | ||
21 | You should have received a copy of the GNU General Public License | |
22 | along with GCC; see the file COPYING3. If not see | |
23 | <http://www.gnu.org/licenses/>. */ | |
24 | ||
25 | ||
8fcc61f8 RS |
26 | #define IN_TARGET_CODE 1 |
27 | ||
d41c8b4c SE |
28 | #include "config.h" |
29 | #include "system.h" | |
30 | #include "context.h" | |
31 | #include "coretypes.h" | |
507c82f6 | 32 | #include "backend.h" |
d41c8b4c SE |
33 | #include "tree.h" |
34 | #include "tree-core.h" | |
35 | #include "tree-pass.h" | |
36 | #include "target.h" | |
37 | #include "target-globals.h" | |
e09f2fb0 | 38 | #include "profile-count.h" |
d41c8b4c SE |
39 | #include "cgraph.h" |
40 | #include "function.h" | |
41 | #include "basic-block.h" | |
42 | #include "gimple.h" | |
43 | #include "gimple-iterator.h" | |
44 | #include "gimple-walk.h" | |
45 | ||
46 | static unsigned int frame_header_opt (void); | |
47 | ||
48 | namespace { | |
49 | ||
50 | const pass_data pass_data_ipa_frame_header_opt = | |
51 | { | |
52 | IPA_PASS, /* type */ | |
53 | "frame-header-opt", /* name */ | |
54 | OPTGROUP_NONE, /* optinfo_flags */ | |
55 | TV_CGRAPHOPT, /* tv_id */ | |
56 | 0, /* properties_required */ | |
57 | 0, /* properties_provided */ | |
58 | 0, /* properties_destroyed */ | |
59 | 0, /* todo_flags_start */ | |
60 | 0, /* todo_flags_finish */ | |
61 | }; | |
62 | ||
63 | class pass_ipa_frame_header_opt : public ipa_opt_pass_d | |
64 | { | |
65 | public: | |
66 | pass_ipa_frame_header_opt (gcc::context *ctxt) | |
67 | : ipa_opt_pass_d (pass_data_ipa_frame_header_opt, ctxt, | |
68 | NULL, /* generate_summary */ | |
69 | NULL, /* write_summary */ | |
70 | NULL, /* read_summary */ | |
71 | NULL, /* write_optimization_summary */ | |
72 | NULL, /* read_optimization_summary */ | |
73 | NULL, /* stmt_fixup */ | |
74 | 0, /* function_transform_todo_flags_start */ | |
75 | NULL, /* function_transform */ | |
76 | NULL) /* variable_transform */ | |
77 | {} | |
78 | ||
79 | /* opt_pass methods: */ | |
80 | virtual bool gate (function *) | |
81 | { | |
82 | /* This optimization has no affect if TARGET_NEWABI. If optimize | |
83 | is not at least 1 then the data needed for the optimization is | |
84 | not available and nothing will be done anyway. */ | |
0bfbc166 | 85 | return TARGET_OLDABI && flag_frame_header_optimization && optimize > 0; |
d41c8b4c SE |
86 | } |
87 | ||
88 | virtual unsigned int execute (function *) { return frame_header_opt (); } | |
89 | ||
90 | }; // class pass_ipa_frame_header_opt | |
91 | ||
92 | } // anon namespace | |
93 | ||
94 | static ipa_opt_pass_d * | |
95 | make_pass_ipa_frame_header_opt (gcc::context *ctxt) | |
96 | { | |
97 | return new pass_ipa_frame_header_opt (ctxt); | |
98 | } | |
99 | ||
100 | void | |
101 | mips_register_frame_header_opt (void) | |
102 | { | |
103 | opt_pass *p = make_pass_ipa_frame_header_opt (g); | |
06988296 | 104 | struct register_pass_info f = { p, "comdats", 1, PASS_POS_INSERT_AFTER }; |
d41c8b4c SE |
105 | register_pass (&f); |
106 | } | |
107 | ||
108 | ||
109 | /* Return true if it is certain that this is a leaf function. False if it is | |
110 | not a leaf function or if it is impossible to tell. */ | |
111 | ||
112 | static bool | |
113 | is_leaf_function (function *fn) | |
114 | { | |
115 | basic_block bb; | |
116 | gimple_stmt_iterator gsi; | |
117 | ||
118 | /* If we do not have a cfg for this function be conservative and assume | |
119 | it is not a leaf function. */ | |
120 | if (fn->cfg == NULL) | |
121 | return false; | |
122 | ||
123 | FOR_EACH_BB_FN (bb, fn) | |
124 | for (gsi = gsi_start_bb (bb); !gsi_end_p (gsi); gsi_next (&gsi)) | |
125 | if (is_gimple_call (gsi_stmt (gsi))) | |
126 | return false; | |
127 | return true; | |
128 | } | |
129 | ||
0bfbc166 SE |
130 | /* Return true if this function has inline assembly code or if we cannot |
131 | be certain that it does not. False if we know that there is no inline | |
132 | assembly. */ | |
133 | ||
134 | static bool | |
135 | has_inlined_assembly (function *fn) | |
136 | { | |
137 | basic_block bb; | |
138 | gimple_stmt_iterator gsi; | |
139 | ||
140 | /* If we do not have a cfg for this function be conservative and assume | |
141 | it is may have inline assembly. */ | |
142 | if (fn->cfg == NULL) | |
143 | return true; | |
144 | ||
145 | FOR_EACH_BB_FN (bb, fn) | |
146 | for (gsi = gsi_start_bb (bb); !gsi_end_p (gsi); gsi_next (&gsi)) | |
147 | if (gimple_code (gsi_stmt (gsi)) == GIMPLE_ASM) | |
148 | return true; | |
149 | ||
150 | return false; | |
151 | } | |
152 | ||
d41c8b4c SE |
153 | /* Return true if this function will use the stack space allocated by its |
154 | caller or if we cannot determine for certain that it does not. */ | |
155 | ||
156 | static bool | |
157 | needs_frame_header_p (function *fn) | |
158 | { | |
159 | tree t; | |
160 | ||
161 | if (fn->decl == NULL) | |
162 | return true; | |
163 | ||
0bfbc166 | 164 | if (fn->stdarg) |
d41c8b4c SE |
165 | return true; |
166 | ||
167 | for (t = DECL_ARGUMENTS (fn->decl); t; t = TREE_CHAIN (t)) | |
168 | { | |
169 | if (!use_register_for_decl (t)) | |
0bfbc166 SE |
170 | return true; |
171 | ||
172 | /* Some 64-bit types may get copied to general registers using the frame | |
173 | header, see mips_output_64bit_xfer. Checking for SImode only may be | |
174 | overly restrictive but it is guaranteed to be safe. */ | |
175 | if (DECL_MODE (t) != SImode) | |
176 | return true; | |
d41c8b4c SE |
177 | } |
178 | ||
179 | return false; | |
180 | } | |
181 | ||
0bfbc166 SE |
182 | /* Return true if the argument stack space allocated by function FN is used. |
183 | Return false if the space is needed or if the need for the space cannot | |
d41c8b4c SE |
184 | be determined. */ |
185 | ||
186 | static bool | |
187 | callees_functions_use_frame_header (function *fn) | |
188 | { | |
189 | basic_block bb; | |
190 | gimple_stmt_iterator gsi; | |
191 | gimple *stmt; | |
192 | tree called_fn_tree; | |
193 | function *called_fn; | |
194 | ||
195 | if (fn->cfg == NULL) | |
196 | return true; | |
197 | ||
198 | FOR_EACH_BB_FN (bb, fn) | |
199 | { | |
200 | for (gsi = gsi_start_bb (bb); !gsi_end_p (gsi); gsi_next (&gsi)) | |
201 | { | |
202 | stmt = gsi_stmt (gsi); | |
203 | if (is_gimple_call (stmt)) | |
204 | { | |
205 | called_fn_tree = gimple_call_fndecl (stmt); | |
206 | if (called_fn_tree != NULL) | |
207 | { | |
208 | called_fn = DECL_STRUCT_FUNCTION (called_fn_tree); | |
209 | if (called_fn == NULL | |
210 | || DECL_WEAK (called_fn_tree) | |
0bfbc166 SE |
211 | || has_inlined_assembly (called_fn) |
212 | || !is_leaf_function (called_fn) | |
d41c8b4c SE |
213 | || !called_fn->machine->does_not_use_frame_header) |
214 | return true; | |
215 | } | |
216 | else | |
217 | return true; | |
218 | } | |
219 | } | |
220 | } | |
221 | return false; | |
222 | } | |
223 | ||
0bfbc166 SE |
224 | /* Set the callers_may_not_allocate_frame flag for any function which |
225 | function FN calls because FN may not allocate a frame header. */ | |
226 | ||
227 | static void | |
228 | set_callers_may_not_allocate_frame (function *fn) | |
229 | { | |
230 | basic_block bb; | |
231 | gimple_stmt_iterator gsi; | |
232 | gimple *stmt; | |
233 | tree called_fn_tree; | |
234 | function *called_fn; | |
235 | ||
236 | if (fn->cfg == NULL) | |
237 | return; | |
238 | ||
239 | FOR_EACH_BB_FN (bb, fn) | |
240 | { | |
241 | for (gsi = gsi_start_bb (bb); !gsi_end_p (gsi); gsi_next (&gsi)) | |
242 | { | |
243 | stmt = gsi_stmt (gsi); | |
244 | if (is_gimple_call (stmt)) | |
245 | { | |
246 | called_fn_tree = gimple_call_fndecl (stmt); | |
247 | if (called_fn_tree != NULL) | |
248 | { | |
249 | called_fn = DECL_STRUCT_FUNCTION (called_fn_tree); | |
250 | if (called_fn != NULL) | |
251 | called_fn->machine->callers_may_not_allocate_frame = true; | |
252 | } | |
253 | } | |
254 | } | |
255 | } | |
256 | return; | |
257 | } | |
258 | ||
d41c8b4c SE |
259 | /* Scan each function to determine those that need its frame headers. Perform |
260 | a second scan to determine if the allocation can be skipped because none of | |
261 | their callees require the frame header. */ | |
262 | ||
263 | static unsigned int | |
264 | frame_header_opt () | |
265 | { | |
266 | struct cgraph_node *node; | |
267 | function *fn; | |
268 | ||
269 | FOR_EACH_DEFINED_FUNCTION (node) | |
270 | { | |
271 | fn = node->get_fun (); | |
272 | if (fn != NULL) | |
273 | fn->machine->does_not_use_frame_header = !needs_frame_header_p (fn); | |
274 | } | |
275 | ||
276 | FOR_EACH_DEFINED_FUNCTION (node) | |
277 | { | |
278 | fn = node->get_fun (); | |
279 | if (fn != NULL) | |
0bfbc166 SE |
280 | fn->machine->optimize_call_stack |
281 | = !callees_functions_use_frame_header (fn) && !is_leaf_function (fn); | |
d41c8b4c | 282 | } |
0bfbc166 SE |
283 | |
284 | FOR_EACH_DEFINED_FUNCTION (node) | |
285 | { | |
286 | fn = node->get_fun (); | |
287 | if (fn != NULL && fn->machine->optimize_call_stack) | |
288 | set_callers_may_not_allocate_frame (fn); | |
289 | } | |
290 | ||
d41c8b4c SE |
291 | return 0; |
292 | } |