expander: Optimize store_expr from STRING_CST [PR95052]

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

/* Register note definitions.
   Copyright (C) 2004-2020 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 3, 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 COPYING3.  If not see
<http://www.gnu.org/licenses/>.  */

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

   CFA related notes meant for RTX_FRAME_RELATED_P instructions
   should be declared with REG_CFA_NOTE macro instead of REG_NOTE.  */

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

/* REG_DEP_TRUE is used in scheduler dependencies lists to represent a
   read-after-write dependency (i.e. a true data dependency).  This is
   here, not grouped with REG_DEP_ANTI and REG_DEP_OUTPUT, because some
   passes use a literal 0 for it.  */
REG_NOTE (DEP_TRUE)

/* 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)

/* 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)

/* 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 JUMP_INSNs to say that the CODE_LABEL
   contained in the REG_LABEL_TARGET note is a possible jump target of
   this insn.  This note is an INSN_LIST.  */
REG_NOTE (LABEL_TARGET)

/* Points to a CODE_LABEL.  Used by any insn to say that the CODE_LABEL
   contained in the REG_LABEL_OPERAND note is used by the insn, but as an
   operand, not as a jump target (though it may indirectly be a jump
   target for a later jump insn).  This note is an INSN_LIST.  */
REG_NOTE (LABEL_OPERAND)

/* REG_DEP_OUTPUT and REG_DEP_ANTI are used in scheduler dependencies lists
   to represent write-after-write and write-after-read dependencies
   respectively.  */
REG_NOTE (DEP_OUTPUT)
REG_NOTE (DEP_ANTI)
REG_NOTE (DEP_CONTROL)

/* REG_BR_PROB is attached to JUMP_INSNs.  It has an
   integer value (in an INT_LIST).  For jumps, it is the probability
   that this is a taken branch. The integer represents a value of
   profile_probability type. Use to_reg_br_prob_note and from_reg_br_prob_note
   to extract the actual value.  */
REG_NOTE (BR_PROB)

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

/* REG_BR_PRED is attached to JUMP_INSNs.  It contains
   CONCAT of two integer value.  First specifies the branch predictor
   that added the note, second specifies the predicted hitrate of
   branch in a fixed point arithmetic based on REG_BR_PROB_BASE.  */
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_CFA_NOTE (FRAME_RELATED_EXPR)

/* Attached to insns that are RTX_FRAME_RELATED_P, but are too complex
   for FRAME_RELATED_EXPR intuition.  The insn's first pattern must be
   a SET, and the destination must be the CFA register.  The attached
   rtx is an expression that defines the CFA.  In the simplest case, the
   rtx could be just the stack_pointer_rtx; more common would be a PLUS
   with a base register and a constant offset.  In the most complicated
   cases, this will result in a DW_CFA_def_cfa_expression with the rtx
   expression rendered in a dwarf location expression.  */
REG_CFA_NOTE (CFA_DEF_CFA)

/* Attached to insns that are RTX_FRAME_RELATED_P, but are too complex
   for FRAME_RELATED_EXPR intuition.  This note adjusts the expression
   from which the CFA is computed.  The attached rtx defines a new CFA
   expression, relative to the old CFA expression.  This rtx must be of
   the form (SET new-cfa-reg (PLUS old-cfa-reg const_int)).  If the note
   rtx is NULL, we use the first SET of the insn.  */
REG_CFA_NOTE (CFA_ADJUST_CFA)

/* Similar to FRAME_RELATED_EXPR, with the additional information that
   this is a save to memory, i.e. will result in DW_CFA_offset or the
   like.  The pattern or the insn should be a simple store relative to
   the CFA.  */
REG_CFA_NOTE (CFA_OFFSET)

/* Similar to FRAME_RELATED_EXPR, with the additional information that this
   is a save to a register, i.e. will result in DW_CFA_register.  The insn
   or the pattern should be simple reg-reg move.  */
REG_CFA_NOTE (CFA_REGISTER)

/* Attached to insns that are RTX_FRAME_RELATED_P, but are too complex
   for FRAME_RELATED_EXPR intuition.  This is a save to memory, i.e. will
   result in a DW_CFA_expression.  The pattern or the insn should be a
   store of a register to an arbitrary (non-validated) memory address.  */
REG_CFA_NOTE (CFA_EXPRESSION)

/* Attached to insns that are RTX_FRAME_RELATED_P, but are too complex
   for FRAME_RELATED_EXPR intuition.  The DWARF expression computes the value of
   the given register.  */
REG_CFA_NOTE (CFA_VAL_EXPRESSION)

/* Attached to insns that are RTX_FRAME_RELATED_P, with the information
   that this is a restore operation, i.e. will result in DW_CFA_restore
   or the like.  Either the attached rtx, or the destination of the insn's
   first pattern is the register to be restored.  */
REG_CFA_NOTE (CFA_RESTORE)

/* Attached to insns that are RTX_FRAME_RELATED_P, marks insn that sets
   vDRAP from DRAP.  If vDRAP is a register, vdrap_reg is initalized
   to the argument, if it is a MEM, it is ignored.  */
REG_CFA_NOTE (CFA_SET_VDRAP)

/* Attached to insns that are RTX_FRAME_RELATED_P, indicating a window
   save operation, i.e. will result in a DW_CFA_GNU_window_save.
   The argument is ignored.  */
REG_CFA_NOTE (CFA_WINDOW_SAVE)

/* Attached to insns that are RTX_FRAME_RELATED_P, marks the insn as
   requiring that all queued information should be flushed *before* insn,
   regardless of what is visible in the rtl.  The argument is ignored.
   This is normally used for a call instruction which is not exposed to
   the rest of the compiler as a CALL_INSN.  */
REG_CFA_NOTE (CFA_FLUSH_QUEUE)

/* Attached to insns that are RTX_FRAME_RELATED_P, toggling the mangling status
   of return address.  Currently it's only used by AArch64.  The argument is
   ignored.  */
REG_CFA_NOTE (CFA_TOGGLE_RA_MANGLE)

/* 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 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)

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

/* This kind of note is generated at each transactional memory
   builtin, to indicate we need to generate transaction restart
   edges for this insn.  */
REG_NOTE (TM)

/* Indicates the cumulative offset of the stack pointer accounting
   for pushed arguments.  This will only be generated when
   ACCUMULATE_OUTGOING_ARGS is false.  */
REG_NOTE (ARGS_SIZE)

/* Used for communication between IRA and caller-save.c, indicates
   that the return value of a call can be used to reinitialize a
   pseudo reg.  */
REG_NOTE (RETURNED)

/* Indicates the instruction is a stack check probe that should not
   be combined with other stack adjustments.  */
REG_NOTE (STACK_CHECK)

/* Used to mark a call with the function decl called by the call.
   The decl might not be available in the call due to splitting of the call
   insn.  This note is a SYMBOL_REF.  */
REG_NOTE (CALL_DECL)

/* Indicate that a call should not be verified for control-flow consistency.
   The target address of the call is assumed as a valid address and no check
   to validate a branch to the target address is needed.  The call is marked
   when a called function has a 'notrack' attribute.  This note is used by the
   compiler when the option -fcf-protection=branch is specified.  */
REG_NOTE (CALL_NOCF_CHECK)

/* The values passed to callee, for debuginfo purposes.  */
REG_NOTE (CALL_ARG_LOCATION)