[gcc.git] / gcc / reg-notes.def

/* Register note definitions.
   Copyright (C) 2004 Free Software Foundation, Inc.

This file is part of GCC.

GCC is free software; you can redistribute it and/or modify it under
the terms of the GNU General Public License as published by the Free
Software Foundation; either version 2, or (at your option) any later
version.

GCC is distributed in the hope that it will be useful, but WITHOUT ANY
WARRANTY; without even the implied warranty of MERCHANTABILITY or
FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
for more details.

You should have received a copy of the GNU General Public License
along with GCC; see the file COPYING.  If not, write to the Free
Software Foundation, 59 Temple Place - Suite 330, Boston, MA
02111-1307, USA.  */

/* This file defines all the codes that may appear on individual
   EXPR_LIST rtxes in the REG_NOTES chain of an insn.  The codes are
   stored in the mode field of the EXPR_LIST.  Source files define
   DEF_REG_NOTE appropriately before including this file.  */

/* Shorthand.  */
#define REG_NOTE(NAME) DEF_REG_NOTE (REG_##NAME)

/* The value in REG dies in this insn (i.e., it is not needed past
   this insn).  If REG is set in this insn, the REG_DEAD note may,
   but need not, be omitted.  */
REG_NOTE (DEAD)

/* The REG is autoincremented or autodecremented in this insn.  */
REG_NOTE (INC)

/* Describes the insn as a whole; it says that the insn sets a
   register to a constant value or to be equivalent to a memory
   address.  If the register is spilled to the stack then the constant
   value should be substituted for it.  The contents of the REG_EQUIV
   is the constant value or memory address, which may be different
   from the source of the SET although it has the same value.  A
   REG_EQUIV note may also appear on an insn which copies a register
   parameter to a pseudo-register, if there is a memory address which
   could be used to hold that pseudo-register throughout the function.  */
REG_NOTE (EQUIV)

/* Like REG_EQUIV except that the destination is only momentarily
   equal to the specified rtx.  Therefore, it cannot be used for
   substitution; but it can be used for cse.  */
REG_NOTE (EQUAL)

/* This insn copies the return-value of a library call out of the hard
   reg for return values.  This note is actually an INSN_LIST and it
   points to the first insn involved in setting up arguments for the
   call.  flow.c uses this to delete the entire library call when its
   result is dead.  */
REG_NOTE (RETVAL)

/* The inverse of REG_RETVAL: it goes on the first insn of the library
   call and points at the one that has the REG_RETVAL.  This note is
   also an INSN_LIST.  */
REG_NOTE (LIBCALL)

/* The register is always nonnegative during the containing loop.
   This is used in branches so that decrement and branch instructions
   terminating on zero can be matched.  There must be an insn pattern
   in the md file named `decrement_and_branch_until_zero' or else this
   will never be added to any instructions.  */
REG_NOTE (NONNEG)

/* There is no conflict *after this insn* between the register in the
   note and the destination of this insn.  */
REG_NOTE (NO_CONFLICT)

/* Identifies a register set in this insn and never used.  */
REG_NOTE (UNUSED)

/* REG_CC_SETTER and REG_CC_USER link a pair of insns that set and use
   CC0, respectively.  Normally, these are required to be consecutive
   insns, but we permit putting a cc0-setting insn in the delay slot
   of a branch as long as only one copy of the insn exists.  In that
   case, these notes point from one to the other to allow code
   generation to determine what any require information and to
   properly update CC_STATUS.  These notes are INSN_LISTs.  */
REG_NOTE (CC_SETTER)
REG_NOTE (CC_USER)

/* Points to a CODE_LABEL.  Used by non-JUMP_INSNs to say that the
   CODE_LABEL contained in the REG_LABEL note is used by the insn.
   This note is an INSN_LIST.  */
REG_NOTE (LABEL)

/* REG_DEP_ANTI and REG_DEP_OUTPUT are used in LOG_LINKS to represent
   write-after-read and write-after-write dependencies respectively.
   Data dependencies, which are the only type of LOG_LINK created by
   flow, are represented by a 0 reg note kind.  */
REG_NOTE (DEP_ANTI)
REG_NOTE (DEP_OUTPUT)

/* REG_BR_PROB is attached to JUMP_INSNs and CALL_INSNs.  It has an
   integer value.  For jumps, it is the probability that this is a
   taken branch.  For calls, it is the probability that this call
   won't return.  */
REG_NOTE (BR_PROB)

/* REG_VALUE_PROFILE is attached when the profile is read in to an
   insn before that the code to profile the value is inserted.  It
   contains the results of profiling.  */
REG_NOTE (VALUE_PROFILE)

/* Attached to a call insn; indicates that the call is malloc-like and
   that the pointer returned cannot alias anything else.  */
REG_NOTE (NOALIAS)

/* Used to optimize rtl generated by dynamic stack allocations for
   targets where SETJMP_VIA_SAVE_AREA is true.  */
REG_NOTE (SAVE_AREA)

/* REG_BR_PRED is attached to JUMP_INSNs and CALL_INSNSs.  It contains
   CONCAT of two integer value.  First specifies the branch predictor
   that added the note, second specifies the predicted hitrate of
   branch in the same format as REG_BR_PROB note uses.  */
REG_NOTE (BR_PRED)

/* Attached to insns that are RTX_FRAME_RELATED_P, but are too complex
   for DWARF to interpret what they imply.  The attached rtx is used
   instead of intuition.  */
REG_NOTE (FRAME_RELATED_EXPR)

/* Indicates that REG holds the exception context for the function.
   This context is shared by inline functions, so the code to acquire
   the real exception context is delayed until after inlining.  */
REG_NOTE (EH_CONTEXT)

/* Indicates what exception region an INSN belongs in.  This is used
   to indicate what region to which a call may throw.  REGION 0
   indicates that a call cannot throw at all.  REGION -1 indicates
   that it cannot throw, nor will it execute a non-local goto.  */
REG_NOTE (EH_REGION)

/* Used by haifa-sched to save NOTE_INSN notes across scheduling.  */
REG_NOTE (SAVE_NOTE)

/* Indicates that this insn (which is part of the prologue) computes a
   value which might not be used later, and if so it's OK to delete
   the insn.  Normally, deleting any insn in the prologue is an error.
   At present the parameter is unused and set to (const_int 0).  */
REG_NOTE (MAYBE_DEAD)

/* Indicates that a call does not return.  */
REG_NOTE (NORETURN)

/* Indicates that an indirect jump is a non-local goto instead of a
   computed goto.  */
REG_NOTE (NON_LOCAL_GOTO)

/* Indicates that a jump crosses between hot and cold sections in a
   (partitioned) assembly or .o file, and therefore should not be
   reduced to a simpler jump by optimizations.  */
REG_NOTE (CROSSING_JUMP)

/* This kind of note is generated at each to `setjmp', and similar
   functions that can return twice.  */
REG_NOTE (SETJMP)

/* Indicate calls that always returns.  */
REG_NOTE (ALWAYS_RETURN)
Commit	Line	Data
826c9564 ZW	1	/* Register note definitions.
	2	Copyright (C) 2004 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 2, 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 COPYING. If not, write to the Free
	18	Software Foundation, 59 Temple Place - Suite 330, Boston, MA
	19	02111-1307, USA. */
	20
	21	/* This file defines all the codes that may appear on individual
	22	EXPR_LIST rtxes in the REG_NOTES chain of an insn. The codes are
	23	stored in the mode field of the EXPR_LIST. Source files define
a2fe1975	24	DEF_REG_NOTE appropriately before including this file. */
826c9564 ZW	25
	26	/* Shorthand. */
	27	#define REG_NOTE(NAME) DEF_REG_NOTE (REG_##NAME)
	28
	29	/* The value in REG dies in this insn (i.e., it is not needed past
	30	this insn). If REG is set in this insn, the REG_DEAD note may,
	31	but need not, be omitted. */
	32	REG_NOTE (DEAD)
	33
	34	/* The REG is autoincremented or autodecremented in this insn. */
	35	REG_NOTE (INC)
	36
	37	/* Describes the insn as a whole; it says that the insn sets a
	38	register to a constant value or to be equivalent to a memory
	39	address. If the register is spilled to the stack then the constant
	40	value should be substituted for it. The contents of the REG_EQUIV
	41	is the constant value or memory address, which may be different
	42	from the source of the SET although it has the same value. A
	43	REG_EQUIV note may also appear on an insn which copies a register
	44	parameter to a pseudo-register, if there is a memory address which
	45	could be used to hold that pseudo-register throughout the function. */
	46	REG_NOTE (EQUIV)
	47
	48	/* Like REG_EQUIV except that the destination is only momentarily
	49	equal to the specified rtx. Therefore, it cannot be used for
	50	substitution; but it can be used for cse. */
	51	REG_NOTE (EQUAL)
	52
	53	/* This insn copies the return-value of a library call out of the hard
	54	reg for return values. This note is actually an INSN_LIST and it
	55	points to the first insn involved in setting up arguments for the
	56	call. flow.c uses this to delete the entire library call when its
	57	result is dead. */
	58	REG_NOTE (RETVAL)
	59
	60	/* The inverse of REG_RETVAL: it goes on the first insn of the library
	61	call and points at the one that has the REG_RETVAL. This note is
	62	also an INSN_LIST. */
	63	REG_NOTE (LIBCALL)
	64
	65	/* The register is always nonnegative during the containing loop.
	66	This is used in branches so that decrement and branch instructions
	67	terminating on zero can be matched. There must be an insn pattern
	68	in the md file named `decrement_and_branch_until_zero' or else this
	69	will never be added to any instructions. */
	70	REG_NOTE (NONNEG)
	71
	72	/* There is no conflict after this insn between the register in the
	73	note and the destination of this insn. */
	74	REG_NOTE (NO_CONFLICT)
	75
	76	/* Identifies a register set in this insn and never used. */
	77	REG_NOTE (UNUSED)
	78
	79	/* REG_CC_SETTER and REG_CC_USER link a pair of insns that set and use
	80	CC0, respectively. Normally, these are required to be consecutive
	81	insns, but we permit putting a cc0-setting insn in the delay slot
	82	of a branch as long as only one copy of the insn exists. In that
	83	case, these notes point from one to the other to allow code
	84	generation to determine what any require information and to
	85	properly update CC_STATUS. These notes are INSN_LISTs. */
	86	REG_NOTE (CC_SETTER)
	87	REG_NOTE (CC_USER)
	88
89	/* Points to a CODE_LABEL. Used by non-JUMP_INSNs to say that the
90	CODE_LABEL contained in the REG_LABEL note is used by the insn.
91	This note is an INSN_LIST. */
92	REG_NOTE (LABEL)
93
94	/* REG_DEP_ANTI and REG_DEP_OUTPUT are used in LOG_LINKS to represent
95	write-after-read and write-after-write dependencies respectively.
96	Data dependencies, which are the only type of LOG_LINK created by
97	flow, are represented by a 0 reg note kind. */
98	REG_NOTE (DEP_ANTI)
99	REG_NOTE (DEP_OUTPUT)
100
101	/* REG_BR_PROB is attached to JUMP_INSNs and CALL_INSNs. It has an
102	integer value. For jumps, it is the probability that this is a
103	taken branch. For calls, it is the probability that this call
104	won't return. */
105	REG_NOTE (BR_PROB)
106
107	/* REG_VALUE_PROFILE is attached when the profile is read in to an
108	insn before that the code to profile the value is inserted. It
109	contains the results of profiling. */
110	REG_NOTE (VALUE_PROFILE)
111
112	/* Attached to a call insn; indicates that the call is malloc-like and
113	that the pointer returned cannot alias anything else. */
114	REG_NOTE (NOALIAS)
115
116	/* Used to optimize rtl generated by dynamic stack allocations for
117	targets where SETJMP_VIA_SAVE_AREA is true. */
118	REG_NOTE (SAVE_AREA)
119
120	/* REG_BR_PRED is attached to JUMP_INSNs and CALL_INSNSs. It contains
121	CONCAT of two integer value. First specifies the branch predictor
122	that added the note, second specifies the predicted hitrate of
123	branch in the same format as REG_BR_PROB note uses. */
124	REG_NOTE (BR_PRED)
125
126	/* Attached to insns that are RTX_FRAME_RELATED_P, but are too complex
127	for DWARF to interpret what they imply. The attached rtx is used
128	instead of intuition. */
129	REG_NOTE (FRAME_RELATED_EXPR)
130
131	/* Indicates that REG holds the exception context for the function.
132	This context is shared by inline functions, so the code to acquire
133	the real exception context is delayed until after inlining. */
134	REG_NOTE (EH_CONTEXT)
135
136	/* Indicates what exception region an INSN belongs in. This is used
137	to indicate what region to which a call may throw. REGION 0
138	indicates that a call cannot throw at all. REGION -1 indicates
139	that it cannot throw, nor will it execute a non-local goto. */
140	REG_NOTE (EH_REGION)
141
142	/* Used by haifa-sched to save NOTE_INSN notes across scheduling. */
143	REG_NOTE (SAVE_NOTE)
144
145	/* Indicates that this insn (which is part of the prologue) computes a
146	value which might not be used later, and if so it's OK to delete
147	the insn. Normally, deleting any insn in the prologue is an error.
148	At present the parameter is unused and set to (const_int 0). */
149	REG_NOTE (MAYBE_DEAD)
150
151	/* Indicates that a call does not return. */
152	REG_NOTE (NORETURN)
153
154	/* Indicates that an indirect jump is a non-local goto instead of a
155	computed goto. */
156	REG_NOTE (NON_LOCAL_GOTO)
157
158	/* Indicates that a jump crosses between hot and cold sections in a
159	(partitioned) assembly or .o file, and therefore should not be
160	reduced to a simpler jump by optimizations. */
161	REG_NOTE (CROSSING_JUMP)
162
163	/* This kind of note is generated at each to `setjmp', and similar
164	functions that can return twice. */
165	REG_NOTE (SETJMP)
166
167	/* Indicate calls that always returns. */
168	REG_NOTE (ALWAYS_RETURN)