1 | /* Information about fuunction binary interfaces. |
2 | Copyright (C) 2019-2023 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 "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 |
53 | targetm.hard_regno_call_part_clobbered (m_id, R, M) is true. |
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 |
69 | && targetm.hard_regno_call_part_clobbered (m_id, regno, mode)) |
70 | SET_HARD_REG_BIT (set&: m_full_and_partial_reg_clobbers, bit: 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 (regs: m_full_reg_clobbers, mode, regno) |
92 | && !targetm.hard_regno_call_part_clobbered (m_id, regno, mode)) |
93 | remove_from_hard_reg_set (regs: &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 (regs: m_full_reg_clobbers, mode, regno) |
107 | && targetm.hard_regno_call_part_clobbered (m_id, regno, mode)) |
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 (set&: m_full_reg_clobbers, bit: regno); |
124 | SET_HARD_REG_BIT (set&: m_full_and_partial_reg_clobbers, bit: regno); |
125 | for (unsigned int i = 0; i < NUM_MACHINE_MODES; ++i) |
126 | SET_HARD_REG_BIT (set&: m_mode_clobbers[i], bit: regno); |
127 | } |
128 | |
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 (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 (x: 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 ; |
150 | CLEAR_HARD_REG_SET (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 | |
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 (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 | |
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)); |
196 | if (targetm.calls.fntype_abi) |
197 | return targetm.calls.fntype_abi (type); |
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); |
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; |
231 | } |
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 | |
252 | gcc_assert (POINTER_TYPE_P (type)); |
253 | return fntype_abi (TREE_TYPE (type)); |
254 | } |
255 | |