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/* Data structure definitions for a generic GCC target.

   Copyright (C) 2001, 2002, 2003, 2004, 2005, 2006, 2007

   Free Software Foundation, Inc.

   This program 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.

   This program 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 this program; see the file COPYING3.  If not see

   <http://www.gnu.org/licenses/>.

   In other words, you are welcome to use, share and improve this program.

   You are forbidden to forbid anyone else to use, share and improve

   what you give them.   Help stamp out software-hoarding!  */

/* This file contains a data structure that describes a GCC target.

   At present it is incomplete, but in future it should grow to

   contain most or all target machine and target O/S specific

   information.

   This structure has its initializer declared in target-def.h in the

   form of large macro TARGET_INITIALIZER that expands to many smaller

   macros.

   The smaller macros each initialize one component of the structure,

   and each has a default.  Each target should have a file that

   includes target.h and target-def.h, and overrides any inappropriate

   defaults by undefining the relevant macro and defining a suitable

   replacement.  That file should then contain the definition of

   "targetm" like so:

   struct gcc_target targetm = TARGET_INITIALIZER;

   Doing things this way allows us to bring together everything that

   defines a GCC target.  By supplying a default that is appropriate

   to most targets, we can easily add new items without needing to

   edit dozens of target configuration files.  It should also allow us

   to gradually reduce the amount of conditional compilation that is

   scattered throughout GCC.  */

#ifndef GCC_TARGET_H

#define GCC_TARGET_H

#include "tm.h"

#include "insn-modes.h"

struct stdarg_info;

struct spec_info_def;

/* The struct used by the secondary_reload target hook.  */

typedef struct secondary_reload_info

{

  /* icode is actually an enum insn_code, but we don't want to force every

     file that includes target.h to include optabs.h .  */

  int icode;

  int extra_cost; /* Cost for using (a) scratch register(s) to be taken

                     into account by copy_cost.  */

  /* The next two members are for the use of the backward

     compatibility hook.  */

  struct secondary_reload_info *prev_sri;

  int t_icode; /* Actually an enum insn_code - see above.  */

} secondary_reload_info;

struct gcc_target

{

  /* Functions that output assembler for the target.  */

  struct asm_out

  {

    /* Opening and closing parentheses for asm expression grouping.  */

    const char *open_paren, *close_paren;

    /* Assembler instructions for creating various kinds of integer object.  */

    const char *byte_op;

    struct asm_int_op

    {

      const char *hi;

      const char *si;

      const char *di;

      const char *ti;

    } aligned_op, unaligned_op;

    /* Try to output the assembler code for an integer object whose

       value is given by X.  SIZE is the size of the object in bytes and

       ALIGNED_P indicates whether it is aligned.  Return true if

       successful.  Only handles cases for which BYTE_OP, ALIGNED_OP

       and UNALIGNED_OP are NULL.  */

    bool (* integer) (rtx x, unsigned int size, int aligned_p);

    /* Output code that will globalize a label.  */

    void (* globalize_label) (FILE *, const char *);

    /* Output code that will emit a label for unwind info, if this

       target requires such labels.  Second argument is the decl the

       unwind info is associated with, third is a boolean: true if

       this is for exception handling, fourth is a boolean: true if

       this is only a placeholder for an omitted FDE.  */

    void (* unwind_label) (FILE *, tree, int, int);

    /* Output code that will emit a label to divide up the exception

       table.  */

    void (* except_table_label) (FILE *);

    /* Emit any directives required to unwind this instruction.  */

    void (* unwind_emit) (FILE *, rtx);

    /* Output an internal label.  */

    void (* internal_label) (FILE *, const char *, unsigned long);

    /* Emit a ttype table reference to a typeinfo object.  */

    bool (* ttype) (rtx);

    /* Emit an assembler directive to set visibility for the symbol

       associated with the tree decl.  */

    void (* visibility) (tree, int);

    /* Output the assembler code for entry to a function.  */

    void (* function_prologue) (FILE *, HOST_WIDE_INT);

    /* Output the assembler code for end of prologue.  */

    void (* function_end_prologue) (FILE *);

    /* Output the assembler code for start of epilogue.  */

    void (* function_begin_epilogue) (FILE *);

    /* Output the assembler code for function exit.  */

    void (* function_epilogue) (FILE *, HOST_WIDE_INT);

    /* Initialize target-specific sections.  */

    void (* init_sections) (void);

    /* Tell assembler to change to section NAME with attributes FLAGS.

       If DECL is non-NULL, it is the VAR_DECL or FUNCTION_DECL with

       which this section is associated.  */

    void (* named_section) (const char *name, unsigned int flags, tree decl);

    /* Return a mask describing how relocations should be treated when

       selecting sections.  Bit 1 should be set if global relocations

       should be placed in a read-write section; bit 0 should be set if

       local relocations should be placed in a read-write section.  */

    int (*reloc_rw_mask) (void);

    /* Return a section for EXP.  It may be a DECL or a constant.  RELOC

       is nonzero if runtime relocations must be applied; bit 1 will be

       set if the runtime relocations require non-local name resolution.

       ALIGN is the required alignment of the data.  */

    section *(* select_section) (tree, int, unsigned HOST_WIDE_INT);

    /* Return a section for X.  MODE is X's mode and ALIGN is its

       alignment in bits.  */

    section *(* select_rtx_section) (enum machine_mode, rtx,

                                     unsigned HOST_WIDE_INT);

    /* Select a unique section name for DECL.  RELOC is the same as

       for SELECT_SECTION.  */

    void (* unique_section) (tree, int);

    /* Return the readonly data section associated with function DECL.  */

    section *(* function_rodata_section) (tree);

    /* Output a constructor for a symbol with a given priority.  */

    void (* constructor) (rtx, int);

    /* Output a destructor for a symbol with a given priority.  */

    void (* destructor) (rtx, int);

    /* Output the assembler code for a thunk function.  THUNK_DECL is the

       declaration for the thunk function itself, FUNCTION is the decl for

       the target function.  DELTA is an immediate constant offset to be

       added to THIS.  If VCALL_OFFSET is nonzero, the word at

       *(*this + vcall_offset) should be added to THIS.  */

    void (* output_mi_thunk) (FILE *file, tree thunk_decl,

                              HOST_WIDE_INT delta, HOST_WIDE_INT vcall_offset,

                              tree function_decl);

    /* Determine whether output_mi_thunk would succeed.  */

    /* ??? Ideally, this hook would not exist, and success or failure

       would be returned from output_mi_thunk directly.  But there's

       too much undo-able setup involved in invoking output_mi_thunk.

       Could be fixed by making output_mi_thunk emit rtl instead of

       text to the output file.  */

    bool (* can_output_mi_thunk) (tree thunk_decl, HOST_WIDE_INT delta,

                                  HOST_WIDE_INT vcall_offset,

                                  tree function_decl);

    /* Output any boilerplate text needed at the beginning of a

       translation unit.  */

    void (*file_start) (void);

    /* Output any boilerplate text needed at the end of a

       translation unit.  */

    void (*file_end) (void);

    /* Output an assembler pseudo-op to declare a library function name

       external.  */

    void (*external_libcall) (rtx);

     /* Output an assembler directive to mark decl live. This instructs

        linker to not dead code strip this symbol.  */

    void (*mark_decl_preserved) (const char *);

    /* Output the definition of a section anchor.  */

    void (*output_anchor) (rtx);

    /* Output a DTP-relative reference to a TLS symbol.  */

    void (*output_dwarf_dtprel) (FILE *file, int size, rtx x);

  } asm_out;

  /* Functions relating to instruction scheduling.  */

  struct sched

  {

    /* Given the current cost, COST, of an insn, INSN, calculate and

       return a new cost based on its relationship to DEP_INSN through

       the dependence LINK.  The default is to make no adjustment.  */

    int (* adjust_cost) (rtx insn, rtx link, rtx def_insn, int cost);

    /* Adjust the priority of an insn as you see fit.  Returns the new

       priority.  */

    int (* adjust_priority) (rtx, int);

    /* Function which returns the maximum number of insns that can be

       scheduled in the same machine cycle.  This must be constant

       over an entire compilation.  The default is 1.  */

    int (* issue_rate) (void);

    /* Calculate how much this insn affects how many more insns we

       can emit this cycle.  Default is they all cost the same.  */

    int (* variable_issue) (FILE *, int, rtx, int);

    /* Initialize machine-dependent scheduling code.  */

    void (* md_init) (FILE *, int, int);

    /* Finalize machine-dependent scheduling code.  */

    void (* md_finish) (FILE *, int);

    /* Initialize machine-dependent function while scheduling code.  */

    void (* md_init_global) (FILE *, int, int);

    /* Finalize machine-dependent function wide scheduling code.  */

    void (* md_finish_global) (FILE *, int);

    /* Reorder insns in a machine-dependent fashion, in two different

       places.  Default does nothing.  */

    int (* reorder) (FILE *, int, rtx *, int *, int);

    int (* reorder2) (FILE *, int, rtx *, int *, int);

    /* The following member value is a pointer to a function called

       after evaluation forward dependencies of insns in chain given

       by two parameter values (head and tail correspondingly).  */

    void (* dependencies_evaluation_hook) (rtx, rtx);

    /* The values of the following four members are pointers to

       functions used to simplify the automaton descriptions.

       dfa_pre_cycle_insn and dfa_post_cycle_insn give functions

       returning insns which are used to change the pipeline hazard

       recognizer state when the new simulated processor cycle

       correspondingly starts and finishes.  The function defined by

       init_dfa_pre_cycle_insn and init_dfa_post_cycle_insn are used

       to initialize the corresponding insns.  The default values of

       the members result in not changing the automaton state when

       the new simulated processor cycle correspondingly starts and

       finishes.  */

    void (* init_dfa_pre_cycle_insn) (void);

    rtx (* dfa_pre_cycle_insn) (void);

    void (* init_dfa_post_cycle_insn) (void);

    rtx (* dfa_post_cycle_insn) (void);

    /* The following member value is a pointer to a function returning value

       which defines how many insns in queue `ready' will we try for

       multi-pass scheduling.  If the member value is nonzero and the

       function returns positive value, the DFA based scheduler will make

       multi-pass scheduling for the first cycle.  In other words, we will

       try to choose ready insn which permits to start maximum number of

       insns on the same cycle.  */

    int (* first_cycle_multipass_dfa_lookahead) (void);

    /* The following member value is pointer to a function controlling

       what insns from the ready insn queue will be considered for the

       multipass insn scheduling.  If the hook returns zero for insn

       passed as the parameter, the insn will be not chosen to be

       issued.  */

    int (* first_cycle_multipass_dfa_lookahead_guard) (rtx);

    /* The following member value is pointer to a function called by

       the insn scheduler before issuing insn passed as the third

       parameter on given cycle.  If the hook returns nonzero, the

       insn is not issued on given processors cycle.  Instead of that,

       the processor cycle is advanced.  If the value passed through

       the last parameter is zero, the insn ready queue is not sorted

       on the new cycle start as usually.  The first parameter passes

       file for debugging output.  The second one passes the scheduler

       verbose level of the debugging output.  The forth and the fifth

       parameter values are correspondingly processor cycle on which

       the previous insn has been issued and the current processor

       cycle.  */

    int (* dfa_new_cycle) (FILE *, int, rtx, int, int, int *);

    /* The following member value is a pointer to a function called

       by the insn scheduler.  It should return true if there exists a

       dependence which is considered costly by the target, between

       the insn passed as the first parameter, and the insn passed as

       the second parameter.  The third parameter is the INSN_DEPEND

       link that represents the dependence between the two insns.  The

       fourth argument is the cost of the dependence as estimated by

       the scheduler.  The last argument is the distance in cycles

       between the already scheduled insn (first parameter) and the

       the second insn (second parameter).  */

    bool (* is_costly_dependence) (rtx, rtx, rtx, int, int);

    /* Given the current cost, COST, of an insn, INSN, calculate and

       return a new cost based on its relationship to DEP_INSN through the

       dependence of type DEP_TYPE.  The default is to make no adjustment.  */

    int (* adjust_cost_2) (rtx insn, int, rtx def_insn, int cost);

    /* The following member value is a pointer to a function called

       by the insn scheduler. This hook is called to notify the backend

       that new instructions were emitted.  */

    void (* h_i_d_extended) (void);

    /* The following member value is a pointer to a function called

       by the insn scheduler.

       The first parameter is an instruction, the second parameter is the type

       of the requested speculation, and the third parameter is a pointer to the

       speculative pattern of the corresponding type (set if return value == 1).

       It should return

       -1, if there is no pattern, that will satisfy the requested speculation

       type,

       0, if current pattern satisfies the requested speculation type,

       1, if pattern of the instruction should be changed to the newly

       generated one.  */

    int (* speculate_insn) (rtx, int, rtx *);

    /* The following member value is a pointer to a function called

       by the insn scheduler.  It should return true if the check instruction

       corresponding to the instruction passed as the parameter needs a

       recovery block.  */

    bool (* needs_block_p) (rtx);

    /* The following member value is a pointer to a function called

       by the insn scheduler.  It should return a pattern for the check

       instruction.

       The first parameter is a speculative instruction, the second parameter

       is the label of the corresponding recovery block (or null, if it is a

       simple check).  If the mutation of the check is requested (e.g. from

       ld.c to chk.a), the third parameter is true - in this case the first

       parameter is the previous check.  */

    rtx (* gen_check) (rtx, rtx, bool);

    /* The following member value is a pointer to a function controlling

       what insns from the ready insn queue will be considered for the

       multipass insn scheduling.  If the hook returns zero for the insn

       passed as the parameter, the insn will not be chosen to be

       issued.  This hook is used to discard speculative instructions,

       that stand at the first position of the ready list.  */

    bool (* first_cycle_multipass_dfa_lookahead_guard_spec) (rtx);

    /* The following member value is a pointer to a function that provides

       information about the speculation capabilities of the target.

       The parameter is a pointer to spec_info variable.  */

    void (* set_sched_flags) (struct spec_info_def *);

  } sched;

  /* Functions relating to vectorization.  */

  struct vectorize

  {

    /* The following member value is a pointer to a function called

       by the vectorizer, and return the decl of the target builtin

       function.  */

    tree (* builtin_mask_for_load) (void);

    /* Return true if vector alignment is reachable (by peeling N

      interations) for the given type.  */

     bool (* vector_alignment_reachable) (tree, bool);

  } vectorize;

  /* The initial value of target_flags.  */

  int default_target_flags;

  /* Handle target switch CODE (an OPT_* value).  ARG is the argument

     passed to the switch; it is NULL if no argument was.  VALUE is the

     value of ARG if CODE specifies a UInteger option, otherwise it is

     1 if the positive form of the switch was used and 0 if the negative

     form was.  Return true if the switch was valid.  */

  bool (* handle_option) (size_t code, const char *arg, int value);

  /* Return machine mode for filter value.  */

  enum machine_mode (* eh_return_filter_mode) (void);

  /* Given two decls, merge their attributes and return the result.  */

  tree (* merge_decl_attributes) (tree, tree);

  /* Given two types, merge their attributes and return the result.  */

  tree (* merge_type_attributes) (tree, tree);

  /* Table of machine attributes and functions to handle them.

     Ignored if NULL.  */

  const struct attribute_spec *attribute_table;

  /* Return zero if the attributes on TYPE1 and TYPE2 are incompatible,

     one if they are compatible and two if they are nearly compatible

     (which causes a warning to be generated).  */

  int (* comp_type_attributes) (tree type1, tree type2);

  /* Assign default attributes to the newly defined TYPE.  */

  void (* set_default_type_attributes) (tree type);

  /* Insert attributes on the newly created DECL.  */

  void (* insert_attributes) (tree decl, tree *attributes);

  /* Return true if FNDECL (which has at least one machine attribute)

     can be inlined despite its machine attributes, false otherwise.  */

  bool (* function_attribute_inlinable_p) (tree fndecl);

  /* Return true if bitfields in RECORD_TYPE should follow the

     Microsoft Visual C++ bitfield layout rules.  */

  bool (* ms_bitfield_layout_p) (tree record_type);

  /* True if the target supports decimal floating point.  */

  bool (* decimal_float_supported_p) (void);

  /* Return true if anonymous bitfields affect structure alignment.  */

  bool (* align_anon_bitfield) (void);

  /* Return true if volatile bitfields should use the narrowest type possible.

     Return false if they should use the container type.  */

  bool (* narrow_volatile_bitfield) (void);

  /* Set up target-specific built-in functions.  */

  void (* init_builtins) (void);

  /* Expand a target-specific builtin.  */

  rtx (* expand_builtin) (tree exp, rtx target, rtx subtarget,

                          enum machine_mode mode, int ignore);

  /* Select a replacement for a target-specific builtin.  This is done

     *before* regular type checking, and so allows the target to implement

     a crude form of function overloading.  The result is a complete

     expression that implements the operation.  */

  tree (*resolve_overloaded_builtin) (tree decl, tree params);

  /* Fold a target-specific builtin.  */

  tree (* fold_builtin) (tree fndecl, tree arglist, bool ignore);

  /* For a vendor-specific fundamental TYPE, return a pointer to

     a statically-allocated string containing the C++ mangling for

     TYPE.  In all other cases, return NULL.  */

  const char * (* mangle_fundamental_type) (tree type);

  /* Make any adjustments to libfunc names needed for this target.  */

  void (* init_libfuncs) (void);

  /* Given a decl, a section name, and whether the decl initializer

     has relocs, choose attributes for the section.  */

  /* ??? Should be merged with SELECT_SECTION and UNIQUE_SECTION.  */

  unsigned int (* section_type_flags) (tree, const char *, int);

  /* True if new jumps cannot be created, to replace existing ones or

     not, at the current point in the compilation.  */

  bool (* cannot_modify_jumps_p) (void);

  /* Return a register class for which branch target register

     optimizations should be applied.  */

  int (* branch_target_register_class) (void);

  /* Return true if branch target register optimizations should include

     callee-saved registers that are not already live during the current

     function.  AFTER_PE_GEN is true if prologues and epilogues have

     already been generated.  */

  bool (* branch_target_register_callee_saved) (bool after_pe_gen);

  /* True if the constant X cannot be placed in the constant pool.  */

  bool (* cannot_force_const_mem) (rtx);

  /* True if the insn X cannot be duplicated.  */

  bool (* cannot_copy_insn_p) (rtx);

  /* True if X is considered to be commutative.  */

  bool (* commutative_p) (rtx, int);

  /* Given an address RTX, undo the effects of LEGITIMIZE_ADDRESS.  */

  rtx (* delegitimize_address) (rtx);

  /* True if the given constant can be put into an object_block.  */

  bool (* use_blocks_for_constant_p) (enum machine_mode, rtx);

  /* The minimum and maximum byte offsets for anchored addresses.  */

  HOST_WIDE_INT min_anchor_offset;

  HOST_WIDE_INT max_anchor_offset;

  /* True if section anchors can be used to access the given symbol.  */

  bool (* use_anchors_for_symbol_p) (rtx);

  /* True if it is OK to do sibling call optimization for the specified

     call expression EXP.  DECL will be the called function, or NULL if

     this is an indirect call.  */

  bool (*function_ok_for_sibcall) (tree decl, tree exp);

  /* True if EXP should be placed in a "small data" section.  */

  bool (* in_small_data_p) (tree);

  /* True if EXP names an object for which name resolution must resolve

     to the current module.  */

  bool (* binds_local_p) (tree);

  /* Do something target-specific to record properties of the DECL into

     the associated SYMBOL_REF.  */

  void (* encode_section_info) (tree, rtx, int);

  /* Undo the effects of encode_section_info on the symbol string.  */

  const char * (* strip_name_encoding) (const char *);

  /* If shift optabs for MODE are known to always truncate the shift count,

     return the mask that they apply.  Return 0 otherwise.  */

  unsigned HOST_WIDE_INT (* shift_truncation_mask) (enum machine_mode mode);

  /* Return the number of divisions in the given MODE that should be present,

     so that it is profitable to turn the division into a multiplication by

     the reciprocal.  */

  unsigned int (* min_divisions_for_recip_mul) (enum machine_mode mode);

  /* If the representation of integral MODE is such that values are

     always sign-extended to a wider mode MODE_REP then return

     SIGN_EXTEND.  Return UNKNOWN otherwise.  */

  /* Note that the return type ought to be RTX_CODE, but that's not

     necessarily defined at this point.  */

  int (* mode_rep_extended) (enum machine_mode mode,

                             enum machine_mode mode_rep);

  /* True if MODE is valid for a pointer in __attribute__((mode("MODE"))).  */

  bool (* valid_pointer_mode) (enum machine_mode mode);

  /* True if MODE is valid for the target.  By "valid", we mean able to

     be manipulated in non-trivial ways.  In particular, this means all

     the arithmetic is supported.  */

  bool (* scalar_mode_supported_p) (enum machine_mode mode);

  /* Similarly for vector modes.  "Supported" here is less strict.  At

     least some operations are supported; need to check optabs or builtins

     for further details.  */

  bool (* vector_mode_supported_p) (enum machine_mode mode);

  /* True if a vector is opaque.  */

  bool (* vector_opaque_p) (tree);

  /* Compute a (partial) cost for rtx X.  Return true if the complete

     cost has been computed, and false if subexpressions should be

     scanned.  In either case, *TOTAL contains the cost result.  */

  /* Note that CODE and OUTER_CODE ought to be RTX_CODE, but that's

     not necessarily defined at this point.  */

  bool (* rtx_costs) (rtx x, int code, int outer_code, int *total);

  /* Compute the cost of X, used as an address.  Never called with

     invalid addresses.  */

  int (* address_cost) (rtx x);

  /* Return where to allocate pseudo for a given hard register initial

     value.  */

  rtx (* allocate_initial_value) (rtx x);

  /* Given a register, this hook should return a parallel of registers

     to represent where to find the register pieces.  Define this hook

     if the register and its mode are represented in Dwarf in

     non-contiguous locations, or if the register should be

     represented in more than one register in Dwarf.  Otherwise, this

     hook should return NULL_RTX.  */

  rtx (* dwarf_register_span) (rtx);

  /* Fetch the fixed register(s) which hold condition codes, for

     targets where it makes sense to look for duplicate assignments to

     the condition codes.  This should return true if there is such a

     register, false otherwise.  The arguments should be set to the

     fixed register numbers.  Up to two condition code registers are

     supported.  If there is only one for this target, the int pointed

     at by the second argument should be set to -1.  */

  bool (* fixed_condition_code_regs) (unsigned int *, unsigned int *);

  /* If two condition code modes are compatible, return a condition

     code mode which is compatible with both, such that a comparison

     done in the returned mode will work for both of the original

     modes.  If the condition code modes are not compatible, return

     VOIDmode.  */

  enum machine_mode (* cc_modes_compatible) (enum machine_mode,

                                             enum machine_mode);

  /* Do machine-dependent code transformations.  Called just before

     delayed-branch scheduling.  */

  void (* machine_dependent_reorg) (void);

  /* Create the __builtin_va_list type.  */

  tree (* build_builtin_va_list) (void);

  /* Gimplifies a VA_ARG_EXPR.  */

  tree (* gimplify_va_arg_expr) (tree valist, tree type, tree *pre_p,

                                 tree *post_p);

  /* Validity-checking routines for PCH files, target-specific.

     get_pch_validity returns a pointer to the data to be stored,

     and stores the size in its argument.  pch_valid_p gets the same

     information back and returns NULL if the PCH is valid,

     or an error message if not.

  */

  void * (* get_pch_validity) (size_t *);

  const char * (* pch_valid_p) (const void *, size_t);

  /* If nonnull, this function checks whether a PCH file with the

     given set of target flags can be used.  It returns NULL if so,

     otherwise it returns an error message.  */

  const char *(*check_pch_target_flags) (int);

  /* True if the compiler should give an enum type only as many

     bytes as it takes to represent the range of possible values of

     that type.  */

  bool (* default_short_enums) (void);

  /* This target hook returns an rtx that is used to store the address

     of the current frame into the built-in setjmp buffer.  */

  rtx (* builtin_setjmp_frame_value) (void);

  /* This target hook should add STRING_CST trees for any hard regs

     the port wishes to automatically clobber for an asm.  */

  tree (* md_asm_clobbers) (tree, tree, tree);

  /* This target hook allows the backend to specify a calling convention

     in the debug information.  This function actually returns an

     enum dwarf_calling_convention, but because of forward declarations

     and not wanting to include dwarf2.h everywhere target.h is included

     the function is being declared as an int.  */

  int (* dwarf_calling_convention) (tree);

  /* This target hook allows the backend to emit frame-related insns that

     contain UNSPECs or UNSPEC_VOLATILEs.  The call frame debugging info

     engine will invoke it on insns of the form

       (set (reg) (unspec [...] UNSPEC_INDEX))

     and

       (set (reg) (unspec_volatile [...] UNSPECV_INDEX))

     to let the backend emit the call frame instructions.  */

  void (* dwarf_handle_frame_unspec) (const char *, rtx, int);

  /* Perform architecture specific checking of statements gimplified

     from VA_ARG_EXPR.  LHS is left hand side of MODIFY_EXPR, RHS

     is right hand side.  Returns true if the statements doesn't need

     to be checked for va_list references.  */

  bool (* stdarg_optimize_hook) (struct stdarg_info *ai, tree lhs, tree rhs);

  /* This target hook allows the operating system to override the DECL

     that represents the external variable that contains the stack

     protection guard variable.  The type of this DECL is ptr_type_node.  */

  tree (* stack_protect_guard) (void);

  /* This target hook allows the operating system to override the CALL_EXPR

     that is invoked when a check vs the guard variable fails.  */

  tree (* stack_protect_fail) (void);

  /* Returns NULL if target supports the insn within a doloop block,

     otherwise it returns an error message.  */

  const char * (*invalid_within_doloop) (rtx);

  /* DECL is a variable or function with __attribute__((dllimport))

     specified.  Use this hook if the target needs to add extra validation

     checks to  handle_dll_attribute ().  */

  bool (* valid_dllimport_attribute_p) (tree decl);

  /* Functions relating to calls - argument passing, returns, etc.  */

  struct calls {

    bool (*promote_function_args) (tree fntype);

    bool (*promote_function_return) (tree fntype);

    bool (*promote_prototypes) (tree fntype);

    rtx (*struct_value_rtx) (tree fndecl, int incoming);

    bool (*return_in_memory) (tree type, tree fndecl);

    bool (*return_in_msb) (tree type);

    /* Return true if a parameter must be passed by reference.  TYPE may

       be null if this is a libcall.  CA may be null if this query is

       from __builtin_va_arg.  */

    bool (*pass_by_reference) (CUMULATIVE_ARGS *ca, enum machine_mode mode,

                               tree type, bool named_arg);

    rtx (*expand_builtin_saveregs) (void);

    /* Returns pretend_argument_size.  */

    void (*setup_incoming_varargs) (CUMULATIVE_ARGS *ca, enum machine_mode mode,

                                    tree type, int *pretend_arg_size,

                                    int second_time);

    bool (*strict_argument_naming) (CUMULATIVE_ARGS *ca);

    /* Returns true if we should use

       targetm.calls.setup_incoming_varargs() and/or

       targetm.calls.strict_argument_naming().  */

    bool (*pretend_outgoing_varargs_named) (CUMULATIVE_ARGS *ca);

    /* Given a complex type T, return true if a parameter of type T

       should be passed as two scalars.  */

    bool (* split_complex_arg) (tree type);

    /* Return true if type T, mode MODE, may not be passed in registers,

       but must be passed on the stack.  */

    /* ??? This predicate should be applied strictly after pass-by-reference.

       Need audit to verify that this is the case.  */

    bool (* must_pass_in_stack) (enum machine_mode mode, tree t);

    /* Return true if type TYPE, mode MODE, which is passed by reference,

       should have the object copy generated by the callee rather than

       the caller.  It is never called for TYPE requiring constructors.  */

    bool (* callee_copies) (CUMULATIVE_ARGS *ca, enum machine_mode mode,

                            tree type, bool named);

    /* Return zero for arguments passed entirely on the stack or entirely

       in registers.  If passed in both, return the number of bytes passed

       in registers; the balance is therefore passed on the stack.  */

    int (* arg_partial_bytes) (CUMULATIVE_ARGS *ca, enum machine_mode mode,

                               tree type, bool named);

    /* Return the diagnostic message string if function without a prototype

       is not allowed for this 'val' argument; NULL otherwise. */

    const char *(*invalid_arg_for_unprototyped_fn) (tree typelist,

                                                    tree funcdecl, tree val);

    /* Return an rtx for the return value location of the function

       specified by FN_DECL_OR_TYPE with a return type of RET_TYPE.  */

    rtx (*function_value) (tree ret_type, tree fn_decl_or_type,

                           bool outgoing);

    /* Return an rtx for the argument pointer incoming to the

       current function.  */

    rtx (*internal_arg_pointer) (void);

  } calls;

  /* Return the diagnostic message string if conversion from FROMTYPE

     to TOTYPE is not allowed, NULL otherwise.  */

  const char *(*invalid_conversion) (tree fromtype, tree totype);