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1 | /* Information about fuunction binary interfaces. |
2 | Copyright (C) 2019 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 (NULL, 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 (NULL, regno, mode)) | |
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) | |
92 | && !targetm.hard_regno_call_part_clobbered (NULL, regno, mode)) | |
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) | |
107 | && targetm.hard_regno_call_part_clobbered (NULL, 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 (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 | ||
129 | /* Return the predefined ABI used by functions with type TYPE. */ | |
130 | ||
131 | const predefined_function_abi & | |
132 | fntype_abi (const_tree type) | |
133 | { | |
134 | gcc_assert (FUNC_OR_METHOD_TYPE_P (type)); | |
002ffd3c RS |
135 | if (targetm.calls.fntype_abi) |
136 | return targetm.calls.fntype_abi (type); | |
bd785b44 RS |
137 | return default_function_abi; |
138 | } | |
139 | ||
140 | /* Return the ABI of function decl FNDECL. */ | |
141 | ||
142 | function_abi | |
143 | fndecl_abi (const_tree fndecl) | |
144 | { | |
145 | gcc_assert (TREE_CODE (fndecl) == FUNCTION_DECL); | |
5a5a3bc5 RS |
146 | const predefined_function_abi &base_abi = fntype_abi (TREE_TYPE (fndecl)); |
147 | ||
148 | if (flag_ipa_ra && decl_binds_to_current_def_p (fndecl)) | |
149 | if (cgraph_rtl_info *info = cgraph_node::rtl_info (fndecl)) | |
150 | return function_abi (base_abi, info->function_used_regs); | |
151 | ||
152 | return base_abi; | |
153 | } | |
154 | ||
155 | /* Return the ABI of the function called by INSN. */ | |
156 | ||
157 | function_abi | |
158 | insn_callee_abi (const rtx_insn *insn) | |
159 | { | |
160 | gcc_assert (insn && CALL_P (insn)); | |
161 | ||
162 | if (flag_ipa_ra) | |
163 | if (tree fndecl = get_call_fndecl (insn)) | |
164 | return fndecl_abi (fndecl); | |
165 | ||
166 | if (targetm.calls.insn_callee_abi) | |
167 | return targetm.calls.insn_callee_abi (insn); | |
168 | ||
169 | return default_function_abi; | |
bd785b44 | 170 | } |