1/* Register note definitions.
2 Copyright (C) 2004-2025 Free Software Foundation, Inc.
3
4This file is part of GCC.
5
6GCC is free software; you can redistribute it and/or modify it under
7the terms of the GNU General Public License as published by the Free
8Software Foundation; either version 3, or (at your option) any later
9version.
10
11GCC is distributed in the hope that it will be useful, but WITHOUT ANY
12WARRANTY; without even the implied warranty of MERCHANTABILITY or
13FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14for more details.
15
16You should have received a copy of the GNU General Public License
17along with GCC; see the file COPYING3. If not see
18<http://www.gnu.org/licenses/>. */
19
20/* This file defines all the codes that may appear on individual
21 EXPR_LIST, INSN_LIST and INT_LIST rtxes in the REG_NOTES chain of an insn.
22 The codes are stored in the mode field of the rtx. Source files
23 define DEF_REG_NOTE appropriately before including this file.
24
25 CFA related notes meant for RTX_FRAME_RELATED_P instructions
26 should be declared with REG_CFA_NOTE macro instead of REG_NOTE. */
27
28/* Shorthand. */
29#define REG_NOTE(NAME) DEF_REG_NOTE (REG_##NAME)
30#ifndef REG_CFA_NOTE
31# define REG_CFA_NOTE(NAME) REG_NOTE (NAME)
32#endif
33
34/* REG_DEP_TRUE is used in scheduler dependencies lists to represent a
35 read-after-write dependency (i.e. a true data dependency). This is
36 here, not grouped with REG_DEP_ANTI and REG_DEP_OUTPUT, because some
37 passes use a literal 0 for it. */
38REG_NOTE (DEP_TRUE)
39
40/* The value in REG dies in this insn (i.e., it is not needed past
41 this insn). If REG is set in this insn, the REG_DEAD note may,
42 but need not, be omitted. */
43REG_NOTE (DEAD)
44
45/* The REG is autoincremented or autodecremented in this insn. */
46REG_NOTE (INC)
47
48/* Describes the insn as a whole; it says that the insn sets a
49 register to a constant value or to be equivalent to a memory
50 address. If the register is spilled to the stack then the constant
51 value should be substituted for it. The contents of the REG_EQUIV
52 is the constant value or memory address, which may be different
53 from the source of the SET although it has the same value. A
54 REG_EQUIV note may also appear on an insn which copies a register
55 parameter to a pseudo-register, if there is a memory address which
56 could be used to hold that pseudo-register throughout the function. */
57REG_NOTE (EQUIV)
58
59/* Like REG_EQUIV except that the destination is only momentarily
60 equal to the specified rtx. Therefore, it cannot be used for
61 substitution; but it can be used for cse. */
62REG_NOTE (EQUAL)
63
64/* The register is always nonnegative during the containing loop.
65 This is used in branches so that decrement and branch instructions
66 terminating on zero can be matched. There must be an insn pattern
67 in the md file named `decrement_and_branch_until_zero' or else this
68 will never be added to any instructions. */
69REG_NOTE (NONNEG)
70
71/* Identifies a register set in this insn and never used. */
72REG_NOTE (UNUSED)
73
74/* Points to a CODE_LABEL. Used by JUMP_INSNs to say that the CODE_LABEL
75 contained in the REG_LABEL_TARGET note is a possible jump target of
76 this insn. This note is an INSN_LIST. */
77REG_NOTE (LABEL_TARGET)
78
79/* Points to a CODE_LABEL. Used by any insn to say that the CODE_LABEL
80 contained in the REG_LABEL_OPERAND note is used by the insn, but as an
81 operand, not as a jump target (though it may indirectly be a jump
82 target for a later jump insn). This note is an INSN_LIST. */
83REG_NOTE (LABEL_OPERAND)
84
85/* REG_DEP_OUTPUT and REG_DEP_ANTI are used in scheduler dependencies lists
86 to represent write-after-write and write-after-read dependencies
87 respectively. */
88REG_NOTE (DEP_OUTPUT)
89REG_NOTE (DEP_ANTI)
90REG_NOTE (DEP_CONTROL)
91
92/* REG_BR_PROB is attached to JUMP_INSNs. It has an
93 integer value (in an INT_LIST). For jumps, it is the probability
94 that this is a taken branch. The integer represents a value of
95 profile_probability type. Use to_reg_br_prob_note and from_reg_br_prob_note
96 to extract the actual value. */
97REG_NOTE (BR_PROB)
98
99/* Attached to a move insn which receives the result of a call; indicates that
100 the call is malloc-like and that the pointer returned cannot alias anything
101 else. */
102REG_NOTE (NOALIAS)
103
104/* REG_BR_PRED is attached to JUMP_INSNs. It contains
105 CONCAT of two integer value. First specifies the branch predictor
106 that added the note, second specifies the predicted hitrate of
107 branch in a fixed point arithmetic based on REG_BR_PROB_BASE. */
108REG_NOTE (BR_PRED)
109
110/* Attached to insns that are RTX_FRAME_RELATED_P, but are too complex
111 for DWARF to interpret what they imply. The attached rtx is used
112 instead of intuition. */
113REG_CFA_NOTE (FRAME_RELATED_EXPR)
114
115/* Attached to insns that are RTX_FRAME_RELATED_P, but are too complex
116 for FRAME_RELATED_EXPR intuition. The insn's first pattern must be
117 a SET, and the destination must be the CFA register. The attached
118 rtx is an expression that defines the CFA. In the simplest case, the
119 rtx could be just the stack_pointer_rtx; more common would be a PLUS
120 with a base register and a constant offset. In the most complicated
121 cases, this will result in a DW_CFA_def_cfa_expression with the rtx
122 expression rendered in a dwarf location expression. */
123REG_CFA_NOTE (CFA_DEF_CFA)
124
125/* Attached to insns that are RTX_FRAME_RELATED_P, but are too complex
126 for FRAME_RELATED_EXPR intuition. This note adjusts the expression
127 from which the CFA is computed. The attached rtx defines a new CFA
128 expression, relative to the old CFA expression. This rtx must be of
129 the form (SET new-cfa-reg (PLUS old-cfa-reg const_int)). If the note
130 rtx is NULL, we use the first SET of the insn. */
131REG_CFA_NOTE (CFA_ADJUST_CFA)
132
133/* Similar to FRAME_RELATED_EXPR, with the additional information that
134 this is a save to memory, i.e. will result in DW_CFA_offset or the
135 like. The pattern or the insn should be a simple store relative to
136 the CFA. */
137REG_CFA_NOTE (CFA_OFFSET)
138
139/* Similar to FRAME_RELATED_EXPR, with the additional information that this
140 is a save to a register, i.e. will result in DW_CFA_register. The insn
141 or the pattern should be simple reg-reg move. */
142REG_CFA_NOTE (CFA_REGISTER)
143
144/* Attached to insns that are RTX_FRAME_RELATED_P, but are too complex
145 for FRAME_RELATED_EXPR intuition. This is a save to memory, i.e. will
146 result in a DW_CFA_expression. The pattern or the insn should be a
147 store of a register to an arbitrary (non-validated) memory address. */
148REG_CFA_NOTE (CFA_EXPRESSION)
149
150/* Attached to insns that are RTX_FRAME_RELATED_P, but are too complex
151 for FRAME_RELATED_EXPR intuition. The DWARF expression computes the value of
152 the given register. */
153REG_CFA_NOTE (CFA_VAL_EXPRESSION)
154
155/* Attached to insns that are RTX_FRAME_RELATED_P, with the information
156 that this is a restore operation, i.e. will result in DW_CFA_restore
157 or the like. Either the attached rtx, or the destination of the insn's
158 first pattern is the register to be restored. */
159REG_CFA_NOTE (CFA_RESTORE)
160
161/* Like CFA_RESTORE but without actually emitting CFI. This can be
162 used to tell the verification infrastructure that a register is
163 saved without intending to restore it. */
164REG_CFA_NOTE (CFA_NO_RESTORE)
165
166/* Attached to insns that are RTX_FRAME_RELATED_P, marks insn that sets
167 vDRAP from DRAP. If vDRAP is a register, vdrap_reg is initalized
168 to the argument, if it is a MEM, it is ignored. */
169REG_CFA_NOTE (CFA_SET_VDRAP)
170
171/* Attached to insns that are RTX_FRAME_RELATED_P, indicating a window
172 save operation, i.e. will result in a DW_CFA_GNU_window_save.
173 The argument is ignored. */
174REG_CFA_NOTE (CFA_WINDOW_SAVE)
175
176/* Attached to insns that are RTX_FRAME_RELATED_P, marks the insn as
177 requiring that all queued information should be flushed *before* insn,
178 regardless of what is visible in the rtl. The argument is ignored.
179 This is normally used for a call instruction which is not exposed to
180 the rest of the compiler as a CALL_INSN. */
181REG_CFA_NOTE (CFA_FLUSH_QUEUE)
182
183/* Attached to insns that are RTX_FRAME_RELATED_P, indicating an authentication
184 of the return address. Currently it's only used by AArch64.
185 The argument is ignored. */
186REG_CFA_NOTE (CFA_NEGATE_RA_STATE)
187
188/* Indicates what exception region an INSN belongs in. This is used
189 to indicate what region to which a call may throw. REGION 0
190 indicates that a call cannot throw at all. REGION -1 indicates
191 that it cannot throw, nor will it execute a non-local goto. */
192REG_NOTE (EH_REGION)
193
194/* Used by haifa-sched to save NOTE_INSN notes across scheduling. */
195REG_NOTE (SAVE_NOTE)
196
197/* Indicates that a call does not return. */
198REG_NOTE (NORETURN)
199
200/* Indicates that an indirect jump is a non-local goto instead of a
201 computed goto. */
202REG_NOTE (NON_LOCAL_GOTO)
203
204/* This kind of note is generated at each to `setjmp', and similar
205 functions that can return twice. */
206REG_NOTE (SETJMP)
207
208/* This kind of note is generated at each transactional memory
209 builtin, to indicate we need to generate transaction restart
210 edges for this insn. */
211REG_NOTE (TM)
212
213/* Indicates the cumulative offset of the stack pointer accounting
214 for pushed arguments. This will only be generated when
215 ACCUMULATE_OUTGOING_ARGS is false. */
216REG_NOTE (ARGS_SIZE)
217
218/* Used for communication between IRA and caller-save.cc, indicates
219 that the return value of a call can be used to reinitialize a
220 pseudo reg. */
221REG_NOTE (RETURNED)
222
223/* Indicates the instruction is a stack check probe that should not
224 be combined with other stack adjustments. */
225REG_NOTE (STACK_CHECK)
226
227/* Used to mark a call with the function decl called by the call.
228 The decl might not be available in the call due to splitting of the call
229 insn. This note is a SYMBOL_REF. */
230REG_NOTE (CALL_DECL)
231
232/* Indicates that the call is an untyped_call. These calls are special
233 in that they set all of the target ABI's return value registers to a
234 defined value without explicitly saying so. For example, a typical
235 untyped_call sequence has the form:
236
237 (call (mem (symbol_ref "foo")))
238 (set (reg pseudo1) (reg result1))
239 ...
240 (set (reg pseudon) (reg resultn))
241
242 The ABI specifies that result1..resultn are clobbered by the call,
243 but the RTL does not indicate that result1..resultn are the results
244 of the call. */
245REG_NOTE (UNTYPED_CALL)
246
247/* Indicate that a call should not be verified for control-flow consistency.
248 The target address of the call is assumed as a valid address and no check
249 to validate a branch to the target address is needed. The call is marked
250 when a called function has a 'notrack' attribute. This note is used by the
251 compiler when the option -fcf-protection=branch is specified. */
252REG_NOTE (CALL_NOCF_CHECK)
253
254/* The values passed to callee, for debuginfo purposes. */
255REG_NOTE (CALL_ARG_LOCATION)
256

source code of gcc/reg-notes.def