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bd785b44 | 1 | /* Information about fuunction binary interfaces. |
7adcbafe | 2 | Copyright (C) 2019-2022 Free Software Foundation, Inc. |
bd785b44 RS |
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 "target.h" | |
25 | #include "rtl.h" | |
26 | #include "tree.h" | |
27 | #include "regs.h" | |
28 | #include "function-abi.h" | |
29 | #include "varasm.h" | |
30 | #include "cgraph.h" | |
31 | ||
32 | target_function_abi_info default_target_function_abi_info; | |
33 | #if SWITCHABLE_TARGET | |
34 | target_function_abi_info *this_target_function_abi_info | |
35 | = &default_target_function_abi_info; | |
36 | #endif | |
37 | ||
38 | /* Initialize a predefined function ABI with the given values of | |
39 | ID and FULL_REG_CLOBBERS. */ | |
40 | ||
41 | void | |
42 | predefined_function_abi::initialize (unsigned int id, | |
43 | const_hard_reg_set full_reg_clobbers) | |
44 | { | |
45 | m_id = id; | |
46 | m_initialized = true; | |
47 | m_full_reg_clobbers = full_reg_clobbers; | |
48 | ||
49 | /* Set up the value of m_full_and_partial_reg_clobbers. | |
50 | ||
51 | If the ABI specifies that part of a hard register R is call-clobbered, | |
52 | we should be able to find a single-register mode M for which | |
6ee2cc70 | 53 | targetm.hard_regno_call_part_clobbered (m_id, R, M) is true. |
bd785b44 RS |
54 | In other words, it shouldn't be the case that R can hold all |
55 | single-register modes across a call, but can't hold part of | |
56 | a multi-register mode. | |
57 | ||
58 | If that assumption doesn't hold for a future target, we would need | |
59 | to change the interface of TARGET_HARD_REGNO_CALL_PART_CLOBBERED so | |
60 | that it tells us which registers in a multi-register value are | |
61 | actually clobbered. */ | |
62 | m_full_and_partial_reg_clobbers = full_reg_clobbers; | |
63 | for (unsigned int i = 0; i < NUM_MACHINE_MODES; ++i) | |
64 | { | |
65 | machine_mode mode = (machine_mode) i; | |
66 | for (unsigned int regno = 0; regno < FIRST_PSEUDO_REGISTER; ++regno) | |
67 | if (targetm.hard_regno_mode_ok (regno, mode) | |
68 | && hard_regno_nregs (regno, mode) == 1 | |
6ee2cc70 | 69 | && targetm.hard_regno_call_part_clobbered (m_id, regno, mode)) |
bd785b44 RS |
70 | SET_HARD_REG_BIT (m_full_and_partial_reg_clobbers, regno); |
71 | } | |
72 | ||
73 | /* For each mode MODE, work out which registers are unable to hold | |
74 | any part of a MODE value across a call, i.e. those for which no | |
75 | overlapping call-preserved (reg:MODE REGNO) exists. | |
76 | ||
77 | We assume that this can be flipped around to say that a call | |
78 | preserves (reg:MODE REGNO) unless the register overlaps this set. | |
79 | The usual reason for this being true is that if (reg:MODE REGNO) | |
80 | contains a part-clobbered register, that register would be | |
81 | part-clobbered regardless of which part of MODE it holds. | |
82 | For example, if (reg:M 2) occupies two registers and if the | |
83 | register 3 portion of it is part-clobbered, (reg:M 3) is usually | |
84 | either invalid or also part-clobbered. */ | |
85 | for (unsigned int i = 0; i < NUM_MACHINE_MODES; ++i) | |
86 | { | |
87 | machine_mode mode = (machine_mode) i; | |
88 | m_mode_clobbers[i] = m_full_and_partial_reg_clobbers; | |
89 | for (unsigned int regno = 0; regno < FIRST_PSEUDO_REGISTER; ++regno) | |
90 | if (targetm.hard_regno_mode_ok (regno, mode) | |
91 | && !overlaps_hard_reg_set_p (m_full_reg_clobbers, mode, regno) | |
6ee2cc70 | 92 | && !targetm.hard_regno_call_part_clobbered (m_id, regno, mode)) |
bd785b44 RS |
93 | remove_from_hard_reg_set (&m_mode_clobbers[i], mode, regno); |
94 | } | |
95 | ||
96 | /* Check that the assumptions above actually hold, i.e. that testing | |
97 | for single-register modes makes sense, and that overlap tests for | |
98 | mode_clobbers work as expected. */ | |
99 | if (flag_checking) | |
100 | for (unsigned int i = 0; i < NUM_MACHINE_MODES; ++i) | |
101 | { | |
102 | machine_mode mode = (machine_mode) i; | |
103 | const_hard_reg_set all_clobbers = m_full_and_partial_reg_clobbers; | |
104 | for (unsigned int regno = 0; regno < FIRST_PSEUDO_REGISTER; ++regno) | |
105 | if (targetm.hard_regno_mode_ok (regno, mode) | |
106 | && !overlaps_hard_reg_set_p (m_full_reg_clobbers, mode, regno) | |
6ee2cc70 | 107 | && targetm.hard_regno_call_part_clobbered (m_id, regno, mode)) |
bd785b44 RS |
108 | gcc_assert (overlaps_hard_reg_set_p (all_clobbers, mode, regno) |
109 | && overlaps_hard_reg_set_p (m_mode_clobbers[i], | |
110 | mode, regno)); | |
111 | } | |
112 | } | |
113 | ||
114 | /* If the ABI has been initialized, add REGNO to the set of registers | |
115 | that can be completely altered by a call. */ | |
116 | ||
117 | void | |
118 | predefined_function_abi::add_full_reg_clobber (unsigned int regno) | |
119 | { | |
120 | if (!m_initialized) | |
121 | return; | |
122 | ||
123 | SET_HARD_REG_BIT (m_full_reg_clobbers, regno); | |
124 | SET_HARD_REG_BIT (m_full_and_partial_reg_clobbers, regno); | |
125 | for (unsigned int i = 0; i < NUM_MACHINE_MODES; ++i) | |
126 | SET_HARD_REG_BIT (m_mode_clobbers[i], regno); | |
127 | } | |
128 | ||
6d1e98df RS |
129 | /* Return the set of registers that the caller of the recorded functions must |
130 | save in order to honor the requirements of CALLER_ABI. */ | |
131 | ||
132 | HARD_REG_SET | |
133 | function_abi_aggregator:: | |
134 | caller_save_regs (const function_abi &caller_abi) const | |
135 | { | |
136 | HARD_REG_SET result; | |
137 | CLEAR_HARD_REG_SET (result); | |
138 | for (unsigned int abi_id = 0; abi_id < NUM_ABI_IDS; ++abi_id) | |
139 | { | |
140 | const predefined_function_abi &callee_abi = function_abis[abi_id]; | |
141 | ||
142 | /* Skip cases that clearly aren't problematic. */ | |
143 | if (abi_id == caller_abi.id () | |
144 | || hard_reg_set_empty_p (m_abi_clobbers[abi_id])) | |
145 | continue; | |
146 | ||
147 | /* Collect the set of registers that can be "more clobbered" by | |
148 | CALLEE_ABI than by CALLER_ABI. */ | |
149 | HARD_REG_SET extra_clobbers; | |
150 | CLEAR_HARD_REG_SET (extra_clobbers); | |
151 | for (unsigned int i = 0; i < NUM_MACHINE_MODES; ++i) | |
152 | { | |
153 | machine_mode mode = (machine_mode) i; | |
154 | extra_clobbers |= (callee_abi.mode_clobbers (mode) | |
155 | & ~caller_abi.mode_clobbers (mode)); | |
156 | } | |
157 | ||
158 | /* Restrict it to the set of registers that we actually saw | |
159 | clobbers for (e.g. taking -fipa-ra into account). */ | |
160 | result |= (extra_clobbers & m_abi_clobbers[abi_id]); | |
161 | } | |
162 | return result; | |
163 | } | |
164 | ||
6c476222 RS |
165 | /* Return the set of registers that cannot be used to hold a value of |
166 | mode MODE across the calls in a region described by ABIS and MASK, where: | |
167 | ||
168 | * Bit ID of ABIS is set if the region contains a call with | |
169 | function_abi identifier ID. | |
170 | ||
171 | * MASK contains all the registers that are fully or partially | |
172 | clobbered by calls in the region. | |
173 | ||
174 | This is not quite as accurate as testing each individual call, | |
175 | but it's a close and conservatively-correct approximation. | |
176 | It's much better for some targets than just using MASK. */ | |
177 | ||
178 | HARD_REG_SET | |
179 | call_clobbers_in_region (unsigned int abis, const_hard_reg_set mask, | |
180 | machine_mode mode) | |
181 | { | |
182 | HARD_REG_SET result; | |
183 | CLEAR_HARD_REG_SET (result); | |
184 | for (unsigned int id = 0; abis; abis >>= 1, ++id) | |
185 | if (abis & 1) | |
186 | result |= function_abis[id].mode_clobbers (mode); | |
187 | return result & mask; | |
188 | } | |
189 | ||
bd785b44 RS |
190 | /* Return the predefined ABI used by functions with type TYPE. */ |
191 | ||
192 | const predefined_function_abi & | |
193 | fntype_abi (const_tree type) | |
194 | { | |
195 | gcc_assert (FUNC_OR_METHOD_TYPE_P (type)); | |
002ffd3c RS |
196 | if (targetm.calls.fntype_abi) |
197 | return targetm.calls.fntype_abi (type); | |
bd785b44 RS |
198 | return default_function_abi; |
199 | } | |
200 | ||
201 | /* Return the ABI of function decl FNDECL. */ | |
202 | ||
203 | function_abi | |
204 | fndecl_abi (const_tree fndecl) | |
205 | { | |
206 | gcc_assert (TREE_CODE (fndecl) == FUNCTION_DECL); | |
5a5a3bc5 RS |
207 | const predefined_function_abi &base_abi = fntype_abi (TREE_TYPE (fndecl)); |
208 | ||
209 | if (flag_ipa_ra && decl_binds_to_current_def_p (fndecl)) | |
210 | if (cgraph_rtl_info *info = cgraph_node::rtl_info (fndecl)) | |
211 | return function_abi (base_abi, info->function_used_regs); | |
212 | ||
213 | return base_abi; | |
214 | } | |
215 | ||
216 | /* Return the ABI of the function called by INSN. */ | |
217 | ||
218 | function_abi | |
219 | insn_callee_abi (const rtx_insn *insn) | |
220 | { | |
221 | gcc_assert (insn && CALL_P (insn)); | |
222 | ||
223 | if (flag_ipa_ra) | |
224 | if (tree fndecl = get_call_fndecl (insn)) | |
225 | return fndecl_abi (fndecl); | |
226 | ||
227 | if (targetm.calls.insn_callee_abi) | |
228 | return targetm.calls.insn_callee_abi (insn); | |
229 | ||
230 | return default_function_abi; | |
bd785b44 | 231 | } |
63d25773 RS |
232 | |
233 | /* Return the ABI of the function called by CALL_EXPR EXP. Return the | |
234 | default ABI for erroneous calls. */ | |
235 | ||
236 | function_abi | |
237 | expr_callee_abi (const_tree exp) | |
238 | { | |
239 | gcc_assert (TREE_CODE (exp) == CALL_EXPR); | |
240 | ||
241 | if (tree fndecl = get_callee_fndecl (exp)) | |
242 | return fndecl_abi (fndecl); | |
243 | ||
244 | tree callee = CALL_EXPR_FN (exp); | |
245 | if (callee == error_mark_node) | |
246 | return default_function_abi; | |
247 | ||
248 | tree type = TREE_TYPE (callee); | |
249 | if (type == error_mark_node) | |
250 | return default_function_abi; | |
251 | ||
50425706 RS |
252 | gcc_assert (POINTER_TYPE_P (type)); |
253 | return fntype_abi (TREE_TYPE (type)); | |
63d25773 | 254 | } |