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1 | /* Manipulation of formal and actual parameters of functions and function |
2 | calls. | |
99dee823 | 3 | Copyright (C) 2017-2021 Free Software Foundation, Inc. |
4d99a848 MJ |
4 | |
5 | This file is part of GCC. | |
6 | ||
7 | GCC is free software; you can redistribute it and/or modify it under | |
8 | the terms of the GNU General Public License as published by the Free | |
9 | Software Foundation; either version 3, or (at your option) any later | |
10 | version. | |
11 | ||
12 | GCC is distributed in the hope that it will be useful, but WITHOUT ANY | |
13 | WARRANTY; without even the implied warranty of MERCHANTABILITY or | |
14 | FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License | |
15 | for more details. | |
16 | ||
17 | You should have received a copy of the GNU General Public License | |
18 | along with GCC; see the file COPYING3. If not see | |
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19 | <http://www.gnu.org/licenses/>. |
20 | ||
21 | ||
22 | ||
23 | This file defines classes and other data structures that are used to manipulate | |
24 | the prototype of a function, especially to create, remove or split its formal | |
25 | parameters, but also to remove its return value, and also its call statements | |
26 | correspondingly. | |
27 | ||
28 | The most basic one is a vector of structures ipa_adjusted_param. It is simply | |
29 | a description how the new parameters should look like after the transformation | |
30 | in what way they relate to the previous ones (if in any). Such relation to an | |
31 | old parameter can be an outright copy or an IPA-SRA replacement. If an old | |
32 | parameter is not listed or otherwise mentioned, it is removed as unused or at | |
33 | least unnecessary. Note that this most basic structure does not work for | |
34 | modifying calls of functions with variable number of arguments. | |
35 | ||
36 | Class ipa_param_adjustments is only a little more than a thin encapsulation of | |
37 | a vector of ipa_param_adjustments. Along with this vector it contains an index | |
38 | of the first potential vararg argument and a boolean flag whether the return | |
39 | value should be removed or not. Moreover, the class contains method | |
40 | modify_call which can transform a call statement so that it correctly calls a | |
41 | modified function. These two data structures were designed to have a small | |
42 | memory footprint because they are allocated for each clone of a call graph node | |
43 | that has its prototype changed and live until the end of IPA clone | |
44 | materialization and call redirection phase. | |
45 | ||
46 | On the other hand, class ipa_param_body_adjustments can afford to allocate more | |
47 | data because its life span is much smaller, it is allocated and destroyed in | |
48 | the course of materialization of each single clone that needs it or only when a | |
49 | particular pass needs to change a function it is operating on. This class has | |
50 | various methods required to change function declaration and the body of the | |
51 | function according to instructions given either by class ipa_param_adjustments | |
52 | or only a vector of ipa_adjusted_params. | |
53 | ||
54 | When these classes are used in the context of call graph clone materialization | |
55 | and subsequent call statement redirection - which is the point at which we | |
56 | modify arguments in call statements - they need to cooperate with each other in | |
87467f45 | 57 | order to handle what we refer to as pass-through (IPA-SRA) splits. These are |
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58 | situations when a formal parameter of one function is split into several |
59 | smaller ones and some of them are then passed on in a call to another function | |
60 | because the formal parameter of this callee has also been split. | |
61 | ||
62 | Consider a simple example: | |
63 | ||
64 | struct S {int a, b, c;}; | |
65 | struct Z {int x; S s;}; | |
66 | ||
67 | foo (S s) | |
68 | { | |
69 | use (s.b); | |
70 | } | |
71 | ||
72 | bar (Z z) | |
73 | { | |
74 | use (z.s.a); | |
75 | foo (z.s); | |
76 | } | |
77 | ||
78 | baz () | |
79 | { | |
80 | bar (*global); | |
81 | } | |
82 | ||
83 | Both bar and foo would have their parameter split. Foo would receive one | |
84 | replacement representing s.b. Function bar would see its parameter split into | |
85 | one replacement representing z.s.a and another representing z.s.b which would | |
87467f45 | 86 | be passed on to foo. It would be a so called pass-through split IPA-SRA |
ff6686d2 MJ |
87 | replacement, one which is passed in a call as an actual argument to another |
88 | IPA-SRA replacement in another function. | |
89 | ||
90 | Note that the call chain the example can be arbitrarily long and recursive and | |
91 | that any function in it can be cloned by another IPA pass and any number of | |
92 | adjacent functions in the call chain can be inlined into each other. Call | |
93 | redirection takes place only after bodies of the function have been modified by | |
94 | all of the above. | |
95 | ||
96 | Call redirection has to be able to find the right decl or SSA_NAME that | |
97 | corresponds to the transitive split in the caller. The SSA names are assigned | |
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98 | right after clone materialization/ modification and cannot be "added" to call |
99 | arguments at any later point. Moreover, if the caller has been inlined the | |
100 | SSA_NAMEs in question no longer belong to PARM_DECLs but to VAR_DECLs, | |
101 | indistinguishable from any others. | |
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102 | |
103 | Therefore, when clone materialization finds a call statement which it knows is | |
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104 | a part of a transitive split, it will simply add as arguments all new "split" |
105 | replacements (that have grater or equal offset than the original call | |
106 | argument): | |
ff6686d2 | 107 | |
87467f45 | 108 | foo (repl_for_a, repl_for_b, <rest of original arguments>); |
ff6686d2 | 109 | |
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110 | It will also store into ipa_edge_modification_info (which is internal to |
111 | ipa-param-modification.c) information about which replacement is which and | |
112 | where original arguments are. Call redirection will then invoke | |
113 | ipa_param_adjustments::modify_call which will access this information and | |
114 | eliminate all replacements which the callee does not expect (repl_for_a in our | |
115 | example above). In between these two steps, however, a call statement might | |
116 | have extraneous arguments. */ | |
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117 | |
118 | #ifndef IPA_PARAM_MANIPULATION_H | |
119 | #define IPA_PARAM_MANIPULATION_H | |
120 | ||
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121 | /* Indices into ipa_param_prefixes to identify a human-readable prefix for newly |
122 | synthesized parameters. Keep in sync with the array. */ | |
123 | enum ipa_param_name_prefix_indices | |
124 | { | |
125 | IPA_PARAM_PREFIX_SYNTH, | |
126 | IPA_PARAM_PREFIX_ISRA, | |
127 | IPA_PARAM_PREFIX_SIMD, | |
128 | IPA_PARAM_PREFIX_MASK, | |
129 | IPA_PARAM_PREFIX_COUNT | |
130 | }; | |
131 | ||
132 | /* We do not support manipulating functions with more than | |
133 | 1<<IPA_PARAM_MAX_INDEX_BITS parameters. */ | |
134 | #define IPA_PARAM_MAX_INDEX_BITS 16 | |
135 | ||
4d99a848 MJ |
136 | /* Operation to be performed for the parameter in ipa_parm_adjustment |
137 | below. */ | |
4d99a848 | 138 | |
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139 | enum ipa_parm_op |
140 | { | |
141 | /* Do not use or you will trigger an assert. */ | |
142 | IPA_PARAM_OP_UNDEFINED, | |
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143 | |
144 | /* This new parameter is an unmodified parameter at index base_index. */ | |
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145 | IPA_PARAM_OP_COPY, |
146 | ||
147 | /* This describes a brand new parameter. If it somehow relates to any | |
148 | original parameters, the user needs to manage the transition itself. */ | |
149 | IPA_PARAM_OP_NEW, | |
4d99a848 | 150 | |
ff6686d2 MJ |
151 | /* Split parameter as indicated by fields base_index, offset and type. */ |
152 | IPA_PARAM_OP_SPLIT | |
4d99a848 MJ |
153 | }; |
154 | ||
ff6686d2 MJ |
155 | /* Structure that describes one parameter of a function after transformation. |
156 | Omitted parameters will be removed. */ | |
4d99a848 | 157 | |
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158 | struct GTY(()) ipa_adjusted_param |
159 | { | |
160 | /* Type of the new parameter. Required for all operations except | |
161 | IPA_PARM_OP_COPY when the original type will be preserved. */ | |
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162 | tree type; |
163 | ||
ff6686d2 MJ |
164 | /* Alias reference type to be used in MEM_REFs when adjusting caller |
165 | arguments. Required for IPA_PARM_OP_SPLIT operation. */ | |
4d99a848 MJ |
166 | tree alias_ptr_type; |
167 | ||
ff6686d2 MJ |
168 | /* Offset into the original parameter (for the cases when the new parameter |
169 | is a component of an original one). Required for IPA_PARM_OP_SPLIT | |
170 | operation. */ | |
171 | unsigned unit_offset; | |
4d99a848 | 172 | |
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173 | /* Zero based index of the original parameter this one is based on. Required |
174 | for IPA_PARAM_OP_COPY and IPA_PARAM_OP_SPLIT, users of IPA_PARAM_OP_NEW | |
175 | only need to specify it if they use replacement lookup provided by | |
176 | ipa_param_body_adjustments. */ | |
177 | unsigned base_index : IPA_PARAM_MAX_INDEX_BITS; | |
4d99a848 | 178 | |
ff6686d2 MJ |
179 | /* Zero based index of the parameter this one is based on in the previous |
180 | clone. If there is no previous clone, it must be equal to base_index. */ | |
181 | unsigned prev_clone_index : IPA_PARAM_MAX_INDEX_BITS; | |
4d99a848 | 182 | |
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183 | /* Specify the operation, if any, to be performed on the parameter. */ |
184 | enum ipa_parm_op op : 2; | |
4d99a848 | 185 | |
ff6686d2 MJ |
186 | /* If set, this structure describes a parameter copied over from a previous |
187 | IPA clone, any transformations are thus not to be re-done. */ | |
188 | unsigned prev_clone_adjustment : 1; | |
4d99a848 | 189 | |
ff6686d2 MJ |
190 | /* Index into ipa_param_prefixes specifying a prefix to be used with |
191 | DECL_NAMEs of newly synthesized parameters. */ | |
192 | unsigned param_prefix_index : 2; | |
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193 | |
194 | /* Storage order of the original parameter (for the cases when the new | |
195 | parameter is a component of an original one). */ | |
196 | unsigned reverse : 1; | |
197 | ||
ff6686d2 MJ |
198 | /* A bit free for the user. */ |
199 | unsigned user_flag : 1; | |
200 | }; | |
201 | ||
202 | void ipa_dump_adjusted_parameters (FILE *f, | |
203 | vec<ipa_adjusted_param, va_gc> *adj_params); | |
204 | ||
ff6686d2 MJ |
205 | /* Class used to record planned modifications to parameters of a function and |
206 | also to perform necessary modifications at the caller side at the gimple | |
207 | level. Used to describe all cgraph node clones that have their parameters | |
208 | changed, therefore the class should only have a small memory footprint. */ | |
209 | ||
210 | class GTY(()) ipa_param_adjustments | |
211 | { | |
212 | public: | |
213 | /* Constructor from NEW_PARAMS showing how new parameters should look like | |
214 | plus copying any pre-existing actual arguments starting from argument | |
215 | with index ALWAYS_COPY_START (if non-negative, negative means do not copy | |
216 | anything beyond what is described in NEW_PARAMS), and SKIP_RETURN, which | |
217 | indicates that the function should return void after transformation. */ | |
218 | ||
219 | ipa_param_adjustments (vec<ipa_adjusted_param, va_gc> *new_params, | |
220 | int always_copy_start, bool skip_return) | |
221 | : m_adj_params (new_params), m_always_copy_start (always_copy_start), | |
222 | m_skip_return (skip_return) | |
223 | {} | |
224 | ||
225 | /* Modify a call statement arguments (and possibly remove the return value) | |
226 | as described in the data fields of this class. */ | |
87467f45 | 227 | gcall *modify_call (cgraph_edge *cs, bool update_references); |
ff6686d2 MJ |
228 | /* Return if the first parameter is left intact. */ |
229 | bool first_param_intact_p (); | |
230 | /* Build a function type corresponding to the modified call. */ | |
231 | tree build_new_function_type (tree old_type, bool type_is_original_p); | |
232 | /* Build a declaration corresponding to the target of the modified call. */ | |
233 | tree adjust_decl (tree orig_decl); | |
234 | /* Fill a vector marking which parameters are intact by the described | |
235 | modifications. */ | |
236 | void get_surviving_params (vec<bool> *surviving_params); | |
237 | /* Fill a vector with new indices of surviving original parameters. */ | |
238 | void get_updated_indices (vec<int> *new_indices); | |
c7ac9a0c JH |
239 | /* Return the original index for the given new parameter index. Return a |
240 | negative number if not available. */ | |
241 | int get_original_index (int newidx); | |
ff6686d2 MJ |
242 | |
243 | void dump (FILE *f); | |
244 | void debug (); | |
245 | ||
246 | /* How the known part of arguments should look like. */ | |
247 | vec<ipa_adjusted_param, va_gc> *m_adj_params; | |
248 | ||
249 | /* If non-negative, copy any arguments starting at this offset without any | |
250 | modifications so that functions with variable number of arguments can be | |
251 | modified. This number should be equal to the number of original forma | |
252 | parameters. */ | |
253 | int m_always_copy_start; | |
254 | /* If true, make the function not return any value. */ | |
255 | bool m_skip_return; | |
256 | ||
257 | private: | |
258 | ipa_param_adjustments () {} | |
259 | ||
260 | void init (vec<tree> *cur_params); | |
261 | int get_max_base_index (); | |
262 | bool method2func_p (tree orig_type); | |
263 | }; | |
264 | ||
265 | /* Structure used to map expressions accessing split or replaced parameters to | |
266 | new PARM_DECLs. */ | |
267 | ||
268 | struct ipa_param_body_replacement | |
269 | { | |
270 | /* The old decl of the original parameter. */ | |
271 | tree base; | |
272 | /* The new decl it should be replaced with. */ | |
273 | tree repl; | |
87467f45 MJ |
274 | /* Users of ipa_param_body_adjustments that modify standalone functions |
275 | outside of IPA clone materialization can use the following field for their | |
276 | internal purposes. */ | |
ff6686d2 MJ |
277 | tree dummy; |
278 | /* The offset within BASE that REPL represents. */ | |
279 | unsigned unit_offset; | |
280 | }; | |
281 | ||
282 | struct ipa_replace_map; | |
283 | ||
284 | /* Class used when actually performing adjustments to formal parameters of a | |
285 | function to map accesses that need to be replaced to replacements. The | |
286 | class attempts to work in two very different sets of circumstances: as a | |
287 | part of tree-inine.c's tree_function_versioning machinery to clone functions | |
288 | (when M_ID is not NULL) and in s standalone fashion, modifying an existing | |
289 | function in place (when M_ID is NULL). While a lot of stuff handled in a | |
290 | unified way in both modes, there are many aspects of the processs that | |
291 | requires distinct paths. */ | |
292 | ||
293 | class ipa_param_body_adjustments | |
294 | { | |
295 | public: | |
296 | /* Constructor to use from within tree-inline. */ | |
297 | ipa_param_body_adjustments (ipa_param_adjustments *adjustments, | |
298 | tree fndecl, tree old_fndecl, | |
299 | struct copy_body_data *id, tree *vars, | |
300 | vec<ipa_replace_map *, va_gc> *tree_map); | |
301 | /* Constructor to use for modifying a function outside of tree-inline from an | |
302 | instance of ipa_param_adjustments. */ | |
303 | ipa_param_body_adjustments (ipa_param_adjustments *adjustments, | |
304 | tree fndecl); | |
305 | /* Constructor to use for modifying a function outside of tree-inline from a | |
306 | simple vector of desired parameter modification. */ | |
307 | ipa_param_body_adjustments (vec<ipa_adjusted_param, va_gc> *adj_params, | |
308 | tree fndecl); | |
309 | ||
310 | /* The do-it-all function for modifying a function outside of | |
311 | tree-inline. */ | |
312 | bool perform_cfun_body_modifications (); | |
313 | ||
314 | /* Change the PARM_DECLs. */ | |
315 | void modify_formal_parameters (); | |
316 | /* Register a replacement decl for the transformation done in APM. */ | |
87467f45 | 317 | void register_replacement (ipa_adjusted_param *apm, tree replacement); |
ff6686d2 MJ |
318 | /* Lookup a replacement for a given offset within a given parameter. */ |
319 | tree lookup_replacement (tree base, unsigned unit_offset); | |
320 | /* Lookup a replacement for an expression, if there is one. */ | |
321 | ipa_param_body_replacement *get_expr_replacement (tree expr, | |
322 | bool ignore_default_def); | |
323 | /* Lookup the new base for surviving names previously belonging to a | |
324 | parameter. */ | |
325 | tree get_replacement_ssa_base (tree old_decl); | |
326 | /* Modify a statement. */ | |
87467f45 MJ |
327 | bool modify_gimple_stmt (gimple **stmt, gimple_seq *extra_stmts, |
328 | gimple *orig_stmt); | |
ff6686d2 MJ |
329 | /* Return the new chain of parameters. */ |
330 | tree get_new_param_chain (); | |
331 | ||
332 | /* Pointers to data structures defining how the function should be | |
333 | modified. */ | |
334 | vec<ipa_adjusted_param, va_gc> *m_adj_params; | |
335 | ipa_param_adjustments *m_adjustments; | |
336 | ||
337 | /* Vector of old parameter declarations that must have their debug bind | |
338 | statements re-mapped and debug decls created. */ | |
339 | ||
340 | auto_vec<tree, 16> m_reset_debug_decls; | |
341 | ||
342 | /* Set to true if there are any IPA_PARAM_OP_SPLIT adjustments among stored | |
343 | adjustments. */ | |
344 | bool m_split_modifications_p; | |
2902991a MJ |
345 | |
346 | /* Sets of statements and SSA_NAMEs that only manipulate data from parameters | |
347 | removed because they are not necessary. */ | |
348 | hash_set<gimple *> m_dead_stmts; | |
349 | hash_set<tree> m_dead_ssas; | |
350 | ||
ff6686d2 MJ |
351 | private: |
352 | void common_initialization (tree old_fndecl, tree *vars, | |
353 | vec<ipa_replace_map *, va_gc> *tree_map); | |
231f7546 | 354 | tree carry_over_param (tree t); |
ff6686d2 MJ |
355 | unsigned get_base_index (ipa_adjusted_param *apm); |
356 | ipa_param_body_replacement *lookup_replacement_1 (tree base, | |
357 | unsigned unit_offset); | |
358 | tree replace_removed_params_ssa_names (tree old_name, gimple *stmt); | |
359 | bool modify_expression (tree *expr_p, bool convert); | |
360 | bool modify_assignment (gimple *stmt, gimple_seq *extra_stmts); | |
87467f45 | 361 | bool modify_call_stmt (gcall **stmt_p, gimple *orig_stmt); |
ff6686d2 MJ |
362 | bool modify_cfun_body (); |
363 | void reset_debug_stmts (); | |
87467f45 | 364 | void mark_dead_statements (tree dead_param); |
ff6686d2 MJ |
365 | |
366 | /* Declaration of the function that is being transformed. */ | |
367 | ||
368 | tree m_fndecl; | |
369 | ||
370 | /* If non-NULL, the tree-inline master data structure guiding materialization | |
371 | of the current clone. */ | |
372 | struct copy_body_data *m_id; | |
373 | ||
374 | /* Vector of old parameter declarations (before changing them). */ | |
375 | ||
376 | auto_vec<tree, 16> m_oparms; | |
377 | ||
378 | /* Vector of parameter declarations the function will have after | |
379 | transformation. */ | |
380 | ||
381 | auto_vec<tree, 16> m_new_decls; | |
382 | ||
383 | /* If the function type has non-NULL TYPE_ARG_TYPES, this is the vector of | |
384 | these types after transformation, otherwise an empty one. */ | |
385 | ||
386 | auto_vec<tree, 16> m_new_types; | |
387 | ||
700d4cb0 | 388 | /* Vector of structures telling how to replace old parameters in the |
ff6686d2 MJ |
389 | function body. TODO: Even though there usually be only few, but should we |
390 | use a hash? */ | |
391 | ||
392 | auto_vec<ipa_param_body_replacement, 16> m_replacements; | |
393 | ||
394 | /* Vector for remapping SSA_BASES from old parameter declarations that are | |
395 | being removed as a part of the transformation. Before a new VAR_DECL is | |
396 | created, it holds the old PARM_DECL, once the variable is built it is | |
397 | stored here. */ | |
398 | ||
399 | auto_vec<tree> m_removed_decls; | |
400 | ||
401 | /* Hash to quickly lookup the item in m_removed_decls given the old decl. */ | |
402 | ||
403 | hash_map<tree, unsigned> m_removed_map; | |
404 | ||
405 | /* True iff the transformed function is a class method that is about to loose | |
406 | its this pointer and must be converted to a normal function. */ | |
407 | ||
408 | bool m_method2func; | |
4d99a848 MJ |
409 | }; |
410 | ||
ff6686d2 MJ |
411 | void push_function_arg_decls (vec<tree> *args, tree fndecl); |
412 | void push_function_arg_types (vec<tree> *types, tree fntype); | |
87467f45 MJ |
413 | void ipa_verify_edge_has_no_modifications (cgraph_edge *cs); |
414 | void ipa_edge_modifications_finalize (); | |
415 | ||
4d99a848 MJ |
416 | |
417 | #endif /* IPA_PARAM_MANIPULATION_H */ |