gcc/function.h

   1 /* Structure for saving state for a nested function.
   2    Copyright (C) 1989, 92-97, 1998 Free Software Foundation, Inc.
   3
   4 This file is part of GNU CC.
   5
   6 GNU CC is free software; you can redistribute it and/or modify
   7 it under the terms of the GNU General Public License as published by
   8 the Free Software Foundation; either version 2, or (at your option)
   9 any later version.
  10
  11 GNU CC is distributed in the hope that it will be useful,
  12 but WITHOUT ANY WARRANTY; without even the implied warranty of
  13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14 GNU General Public License for more details.
  15
  16 You should have received a copy of the GNU General Public License
  17 along with GNU CC; see the file COPYING.  If not, write to
  18 the Free Software Foundation, 59 Temple Place - Suite 330,
  19 Boston, MA 02111-1307, USA.  */
  20
  21
  22 #if !defined(NULL_TREE) && !defined(tree)
  23 typedef union union_node *_function_tree;
  24 #define tree _function_tree
  25 #endif
  26 #if !defined(NULL_RTX) && !defined(rtx)
  27 typedef struct rtx_def *_function_rtx;
  28 #define rtx _function_rtx
  29 #endif
  30
  31 struct var_refs_queue
  32 {
  33   rtx modified;
  34   enum machine_mode promoted_mode;
  35   int unsignedp;
  36   struct var_refs_queue *next;
  37 };
  38
  39 /* Stack of pending (incomplete) sequences saved by `start_sequence'.
  40    Each element describes one pending sequence.
  41    The main insn-chain is saved in the last element of the chain,
  42    unless the chain is empty.  */
  43
  44 struct sequence_stack
  45 {
  46   /* First and last insns in the chain of the saved sequence.  */
  47   rtx first, last;
  48   tree sequence_rtl_expr;
  49   struct sequence_stack *next;
  50 };
  51
  52 extern struct sequence_stack *sequence_stack;
  53
  54 /* Stack of single obstacks.  */
  55
  56 struct simple_obstack_stack
  57 {
  58   struct obstack *obstack;
  59   struct simple_obstack_stack *next;
  60 };
  61 \f
  62 struct emit_status
  63 {
  64   /* This is reset to LAST_VIRTUAL_REGISTER + 1 at the start of each function.
  65      After rtl generation, it is 1 plus the largest register number used.  */
  66   int x_reg_rtx_no;
  67
  68   /* Lowest label number in current function.  */
  69   int x_first_label_num;
  70
  71   /* The ends of the doubly-linked chain of rtl for the current function.
  72      Both are reset to null at the start of rtl generation for the function.
  73
  74      start_sequence saves both of these on `sequence_stack' along with
  75      `sequence_rtl_expr' and then starts a new, nested sequence of insns.  */
  76   rtx x_first_insn;
  77   rtx x_last_insn;
  78
  79   /* RTL_EXPR within which the current sequence will be placed.  Use to
  80      prevent reuse of any temporaries within the sequence until after the
  81      RTL_EXPR is emitted.  */
  82   tree sequence_rtl_expr;
  83
  84   /* Stack of pending (incomplete) sequences saved by `start_sequence'.
  85      Each element describes one pending sequence.
  86      The main insn-chain is saved in the last element of the chain,
  87      unless the chain is empty.  */
  88   struct sequence_stack *sequence_stack;
  89
  90   /* INSN_UID for next insn emitted.
  91      Reset to 1 for each function compiled.  */
  92   int x_cur_insn_uid;
  93
  94   /* Line number and source file of the last line-number NOTE emitted.
  95      This is used to avoid generating duplicates.  */
  96   int x_last_linenum;
  97   char *x_last_filename;
  98
  99   /* A vector indexed by pseudo reg number.  The allocated length
 100      of this vector is regno_pointer_flag_length.  Since this
 101      vector is needed during the expansion phase when the total
 102      number of registers in the function is not yet known,
 103      it is copied and made bigger when necessary.  */
 104   char *regno_pointer_flag;
 105   int regno_pointer_flag_length;
 106
 107   /* Indexed by pseudo register number, if nonzero gives the known alignment
 108      for that pseudo (if regno_pointer_flag is set).
 109      Allocated in parallel with regno_pointer_flag.  */
 110   char *regno_pointer_align;
 111
 112   /* Indexed by pseudo register number, gives the rtx for that pseudo.
 113      Allocated in parallel with regno_pointer_flag.  */
 114   rtx *x_regno_reg_rtx;
 115 };
 116
 117 /* For backward compatibility... eventually these should all go away.  */
 118 #define reg_rtx_no (current_function->emit->x_reg_rtx_no)
 119 #define seq_rtl_expr (current_function->emit->sequence_rtl_expr)
 120 #define regno_reg_rtx (current_function->emit->x_regno_reg_rtx)
 121 #define seq_stack (current_function->emit->sequence_stack)
 122
 123 #define REGNO_POINTER_ALIGN(REGNO) \
 124   (current_function->emit->regno_pointer_align[REGNO])
 125 #define REGNO_POINTER_FLAG(REGNO) \
 126   (current_function->emit->regno_pointer_flag[REGNO])
 127
 128 struct expr_status
 129 {
 130   /* Number of units that we should eventually pop off the stack.
 131      These are the arguments to function calls that have already returned.  */
 132   int x_pending_stack_adjust;
 133
 134   /* Under some ABIs, it is the caller's responsibility to pop arguments
 135      pushed for function calls.  A naive implementation would simply pop
 136      the arguments immediately after each call.  However, if several
 137      function calls are made in a row, it is typically cheaper to pop
 138      all the arguments after all of the calls are complete since a
 139      single pop instruction can be used.  Therefore, GCC attempts to
 140      defer popping the arguments until absolutely necessary.  (For
 141      example, at the end of a conditional, the arguments must be popped,
 142      since code outside the conditional won't know whether or not the
 143      arguments need to be popped.)
 144
 145      When INHIBIT_DEFER_POP is non-zero, however, the compiler does not
 146      attempt to defer pops.  Instead, the stack is popped immediately
 147      after each call.  Rather then setting this variable directly, use
 148      NO_DEFER_POP and OK_DEFER_POP.  */
 149   int x_inhibit_defer_pop;
 150
 151   /* Nonzero means __builtin_saveregs has already been done in this function.
 152      The value is the pseudoreg containing the value __builtin_saveregs
 153      returned.  */
 154   rtx x_saveregs_value;
 155
 156   /* Similarly for __builtin_apply_args.  */
 157   rtx x_apply_args_value;
 158
 159   /* List of labels that must never be deleted.  */
 160   rtx x_forced_labels;
 161
 162   /* Postincrements that still need to be expanded.  */
 163   rtx x_pending_chain;
 164 };
 165
 166 #define pending_stack_adjust (current_function->expr->x_pending_stack_adjust)
 167 #define inhibit_defer_pop (current_function->expr->x_inhibit_defer_pop)
 168 #define saveregs_value (current_function->expr->x_saveregs_value)
 169 #define apply_args_value (current_function->expr->x_apply_args_value)
 170 #define forced_labels (current_function->expr->x_forced_labels)
 171 #define pending_chain (current_function->expr->x_pending_chain)
 172
 173 /* This structure can save all the important global and static variables
 174    describing the status of the current function.  */
 175
 176 struct function
 177 {
 178   struct function *next_global;
 179   struct function *next;
 180
 181   struct eh_status *eh;
 182   struct stmt_status *stmt;
 183   struct expr_status *expr;
 184   struct emit_status *emit;
 185   struct varasm_status *varasm;
 186
 187   /* Nonzero if we are done compiling this function.  */
 188   int can_garbage_collect;
 189
 190   /* For function.c.  */
 191
 192   /* Name of this function.  */
 193   const char *name;
 194   /* Points to the FUNCTION_DECL of this function. */
 195   tree decl;
 196
 197   /* Number of bytes of args popped by function being compiled on its return.
 198      Zero if no bytes are to be popped.
 199      May affect compilation of return insn or of function epilogue.  */
 200   int pops_args;
 201
 202   /* Nonzero if function being compiled needs to be given an address
 203      where the value should be stored.  */
 204   int returns_struct;
 205
 206   /* Nonzero if function being compiled needs to
 207      return the address of where it has put a structure value.  */
 208   int returns_pcc_struct;
 209
 210   /* Nonzero if the current function returns a pointer type.  */
 211   int returns_pointer;
 212
 213   /* Nonzero if function being compiled needs to be passed a static chain.  */
 214   int needs_context;
 215
 216   /* Nonzero if function being compiled can call setjmp.  */
 217   int calls_setjmp;
 218
 219   /* Nonzero if function being compiled can call longjmp.  */
 220   int calls_longjmp;
 221
 222   /* Nonzero if function being compiled can call alloca,
 223      either as a subroutine or builtin.  */
 224   int calls_alloca;
 225
 226   /* Nonzero if function being compiled receives nonlocal gotos
 227      from nested functions.  */
 228
 229   int has_nonlocal_label;
 230
 231   /* Nonzero if function being compiled has nonlocal gotos to parent
 232      function.  */
 233   int has_nonlocal_goto;
 234
 235   /* Nonzero if function being compiled contains nested functions.  */
 236   int contains_functions;
 237
 238   /* Nonzero if the function being compiled issues a computed jump.  */
 239   int has_computed_jump;
 240
 241   /* Nonzero if the current function is a thunk (a lightweight function that
 242      just adjusts one of its arguments and forwards to another function), so
 243      we should try to cut corners where we can.  */
 244   int is_thunk;
 245
 246   /* If function's args have a fixed size, this is that size, in bytes.
 247      Otherwise, it is -1.
 248      May affect compilation of return insn or of function epilogue.  */
 249   int args_size;
 250
 251   /* # bytes the prologue should push and pretend that the caller pushed them.
 252      The prologue must do this, but only if parms can be passed in
 253      registers.  */
 254   int pretend_args_size;
 255
 256   /* # of bytes of outgoing arguments.  If ACCUMULATE_OUTGOING_ARGS is
 257      defined, the needed space is pushed by the prologue.  */
 258   int outgoing_args_size;
 259
 260   /* This is the offset from the arg pointer to the place where the first
 261      anonymous arg can be found, if there is one.  */
 262   rtx arg_offset_rtx;
 263
 264   /* Nonzero if current function uses varargs.h or equivalent.
 265      Zero for functions that use stdarg.h.  */
 266   int varargs;
 267
 268   /* Nonzero if current function uses stdarg.h or equivalent.
 269      Zero for functions that use varargs.h.  */
 270   int stdarg;
 271
 272   /* Quantities of various kinds of registers
 273      used for the current function's args.  */
 274   CUMULATIVE_ARGS args_info;
 275
 276   /* If non-zero, an RTL expression for the location at which the current
 277      function returns its result.  If the current function returns its
 278      result in a register, current_function_return_rtx will always be
 279      the hard register containing the result.  */
 280   rtx return_rtx;
 281
 282   /* The arg pointer hard register, or the pseudo into which it was copied.  */
 283   rtx internal_arg_pointer;
 284
 285   /* Language-specific reason why the current function cannot be made
 286      inline.  */
 287   const char *cannot_inline;
 288
 289   /* Nonzero if instrumentation calls for function entry and exit should be
 290      generated.  */
 291   int instrument_entry_exit;
 292
 293   /* Nonzero if memory access checking be enabled in the current function.  */
 294   int check_memory_usage;
 295
 296   /* Number of function calls seen so far in current function.  */
 297   int x_function_call_count;
 298
 299   /* List (chain of TREE_LIST) of LABEL_DECLs for all nonlocal labels
 300      (labels to which there can be nonlocal gotos from nested functions)
 301      in this function.  */
 302   tree x_nonlocal_labels;
 303
 304   /* List (chain of EXPR_LIST) of stack slots that hold the current handlers
 305      for nonlocal gotos.  There is one for every nonlocal label in the
 306      function; this list matches the one in nonlocal_labels.
 307      Zero when function does not have nonlocal labels.  */
 308   rtx x_nonlocal_goto_handler_slots;
 309
 310   /* List (chain of EXPR_LIST) of labels heading the current handlers for
 311      nonlocal gotos.  */
 312   rtx x_nonlocal_goto_handler_labels;
 313
 314   /* RTX for stack slot that holds the stack pointer value to restore
 315      for a nonlocal goto.
 316      Zero when function does not have nonlocal labels.  */
 317   rtx x_nonlocal_goto_stack_level;
 318
 319   /* Label that will go on parm cleanup code, if any.
 320      Jumping to this label runs cleanup code for parameters, if
 321      such code must be run.  Following this code is the logical return
 322      label.  */
 323   rtx x_cleanup_label;
 324
 325   /* Label that will go on function epilogue.
 326      Jumping to this label serves as a "return" instruction
 327      on machines which require execution of the epilogue on all returns.  */
 328   rtx x_return_label;
 329
 330   /* List (chain of EXPR_LISTs) of pseudo-regs of SAVE_EXPRs.
 331      So we can mark them all live at the end of the function, if nonopt.  */
 332   rtx x_save_expr_regs;
 333
 334   /* List (chain of EXPR_LISTs) of all stack slots in this function.
 335      Made for the sake of unshare_all_rtl.  */
 336   rtx x_stack_slot_list;
 337
 338   /* Chain of all RTL_EXPRs that have insns in them.  */
 339   tree x_rtl_expr_chain;
 340
 341   /* Label to jump back to for tail recursion, or 0 if we have
 342      not yet needed one for this function.  */
 343   rtx x_tail_recursion_label;
 344
 345   /* Place after which to insert the tail_recursion_label if we need one.  */
 346   rtx x_tail_recursion_reentry;
 347
 348   /* Location at which to save the argument pointer if it will need to be
 349      referenced.  There are two cases where this is done: if nonlocal gotos
 350      exist, or if vars stored at an offset from the argument pointer will be
 351      needed by inner routines.  */
 352   rtx x_arg_pointer_save_area;
 353
 354   /* Offset to end of allocated area of stack frame.
 355      If stack grows down, this is the address of the last stack slot allocated.
 356      If stack grows up, this is the address for the next slot.  */
 357   HOST_WIDE_INT x_frame_offset;
 358
 359   /* List (chain of TREE_LISTs) of static chains for containing functions.
 360      Each link has a FUNCTION_DECL in the TREE_PURPOSE and a reg rtx
 361      in an RTL_EXPR in the TREE_VALUE.  */
 362   tree x_context_display;
 363
 364   /* List (chain of TREE_LISTs) of trampolines for nested functions.
 365      The trampoline sets up the static chain and jumps to the function.
 366      We supply the trampoline's address when the function's address is
 367      requested.
 368
 369      Each link has a FUNCTION_DECL in the TREE_PURPOSE and a reg rtx
 370      in an RTL_EXPR in the TREE_VALUE.  */
 371   tree x_trampoline_list;
 372
 373   /* Insn after which register parms and SAVE_EXPRs are born, if nonopt.  */
 374   rtx x_parm_birth_insn;
 375
 376   /* Last insn of those whose job was to put parms into their nominal
 377      homes.  */
 378   rtx x_last_parm_insn;
 379
 380   /* 1 + last pseudo register number possibly used for loading a copy
 381      of a parameter of this function. */
 382   int x_max_parm_reg;
 383
 384   /* Vector indexed by REGNO, containing location on stack in which
 385      to put the parm which is nominally in pseudo register REGNO,
 386      if we discover that that parm must go in the stack.  The highest
 387      element in this vector is one less than MAX_PARM_REG, above.  */
 388   rtx *x_parm_reg_stack_loc;
 389
 390   /* List of all temporaries allocated, both available and in use.  */
 391   struct temp_slot *x_temp_slots;
 392
 393   /* Current nesting level for temporaries.  */
 394   int x_temp_slot_level;
 395
 396   /* Current nesting level for variables in a block.  */
 397   int x_var_temp_slot_level;
 398
 399   /* When temporaries are created by TARGET_EXPRs, they are created at
 400      this level of temp_slot_level, so that they can remain allocated
 401      until no longer needed.  CLEANUP_POINT_EXPRs define the lifetime
 402      of TARGET_EXPRs.  */
 403   int x_target_temp_slot_level;
 404
 405   /* This slot is initialized as 0 and is added to
 406      during the nested function.  */
 407   struct var_refs_queue *fixup_var_refs_queue;
 408
 409   /* For tree.c.  */
 410   int all_types_permanent;
 411   struct momentary_level *momentary_stack;
 412   char *maybepermanent_firstobj;
 413   char *temporary_firstobj;
 414   char *momentary_firstobj;
 415   char *momentary_function_firstobj;
 416   struct obstack *current_obstack;
 417   struct obstack *function_obstack;
 418   struct obstack *function_maybepermanent_obstack;
 419   struct obstack *expression_obstack;
 420   struct obstack *saveable_obstack;
 421   struct obstack *rtl_obstack;
 422
 423   /* For integrate.c.  */
 424   int inlinable;
 425   /* This is in fact an rtvec.  */
 426   void *original_arg_vector;
 427   tree original_decl_initial;
 428   /* Last insn of those whose job was to put parms into their nominal
 429      homes.  */
 430   rtx inl_last_parm_insn;
 431   /* Highest label number in current function.  */
 432   int inl_max_label_num;
 433
 434   /* Nonzero if the current function uses the constant pool.  */
 435   int uses_const_pool;
 436
 437   /* For md files.  */
 438
 439   /* Nonzero if the current function uses pic_offset_table_rtx.  */
 440   int uses_pic_offset_table;
 441   /* tm.h can use this to store whatever it likes.  */
 442   struct machine_function *machine;
 443
 444   /* Language-specific code can use this to store whatever it likes.  */
 445   struct language_function *language;
 446
 447   /* For reorg.  */
 448
 449   /* If some insns can be deferred to the delay slots of the epilogue, the
 450      delay list for them is recorded here.  */
 451   rtx epilogue_delay_list;
 452 };
 453
 454 extern struct function *current_function;
 455 extern struct function *all_functions;
 456
 457 /* For backward compatibility... eventually these should all go away.  */
 458 #define current_function_name (current_function->name)
 459 #define current_function_pops_args (current_function->pops_args)
 460 #define current_function_returns_struct (current_function->returns_struct)
 461 #define current_function_returns_pcc_struct (current_function->returns_pcc_struct)
 462 #define current_function_returns_pointer (current_function->returns_pointer)
 463 #define current_function_needs_context (current_function->needs_context)
 464 #define current_function_calls_setjmp (current_function->calls_setjmp)
 465 #define current_function_calls_alloca (current_function->calls_alloca)
 466 #define current_function_calls_longjmp (current_function->calls_longjmp)
 467 #define current_function_has_computed_jump (current_function->has_computed_jump)
 468 #define current_function_contains_functions (current_function->contains_functions)
 469 #define current_function_is_thunk (current_function->is_thunk)
 470 #define current_function_args_info (current_function->args_info)
 471 #define current_function_args_size (current_function->args_size)
 472 #define current_function_pretend_args_size (current_function->pretend_args_size)
 473 #define current_function_outgoing_args_size (current_function->outgoing_args_size)
 474 #define current_function_arg_offset_rtx (current_function->arg_offset_rtx)
 475 #define current_function_varargs (current_function->varargs)
 476 #define current_function_stdarg (current_function->stdarg)
 477 #define current_function_internal_arg_pointer (current_function->internal_arg_pointer)
 478 #define current_function_return_rtx (current_function->return_rtx)
 479 #define current_function_instrument_entry_exit (current_function->instrument_entry_exit)
 480 #define current_function_check_memory_usage (current_function->check_memory_usage)
 481 #define current_function_uses_pic_offset_table (current_function->uses_pic_offset_table)
 482 #define current_function_uses_const_pool (current_function->uses_const_pool)
 483 #define current_function_cannot_inline (current_function->cannot_inline)
 484 #define current_function_epilogue_delay_list (current_function->epilogue_delay_list)
 485 #define current_function_has_nonlocal_label (current_function->has_nonlocal_label)
 486 #define current_function_has_nonlocal_goto (current_function->has_nonlocal_goto)
 487
 488 #define max_parm_reg (current_function->x_max_parm_reg)
 489 #define parm_reg_stack_loc (current_function->x_parm_reg_stack_loc)
 490 #define cleanup_label (current_function->x_cleanup_label)
 491 #define return_label (current_function->x_return_label)
 492 #define save_expr_regs (current_function->x_save_expr_regs)
 493 #define stack_slot_list (current_function->x_stack_slot_list)
 494 #define parm_birth_insn (current_function->x_parm_birth_insn)
 495 #define frame_offset (current_function->x_frame_offset)
 496 #define tail_recursion_label (current_function->x_tail_recursion_label)
 497 #define tail_recursion_reentry (current_function->x_tail_recursion_reentry)
 498 #define arg_pointer_save_area (current_function->x_arg_pointer_save_area)
 499 #define rtl_expr_chain (current_function->x_rtl_expr_chain)
 500 #define last_parm_insn (current_function->x_last_parm_insn)
 501 #define context_display (current_function->x_context_display)
 502 #define trampoline_list (current_function->x_trampoline_list)
 503 #define function_call_count (current_function->x_function_call_count)
 504 #define temp_slots (current_function->x_temp_slots)
 505 #define temp_slot_level (current_function->x_temp_slot_level)
 506 #define target_temp_slot_level (current_function->x_target_temp_slot_level)
 507 #define var_temp_slot_level (current_function->x_var_temp_slot_level)
 508 #define nonlocal_labels (current_function->x_nonlocal_labels)
 509 #define nonlocal_goto_handler_slots (current_function->x_nonlocal_goto_handler_slots)
 510 #define nonlocal_goto_handler_labels (current_function->x_nonlocal_goto_handler_labels)
 511 #define nonlocal_goto_stack_level (current_function->x_nonlocal_goto_stack_level)
 512
 513 /* The FUNCTION_DECL for an inline function currently being expanded.  */
 514 extern tree inline_function_decl;
 515
 516 /* Given a function decl for a containing function,
 517    return the `struct function' for it.  */
 518 struct function *find_function_data PROTO((tree));
 519
 520 /* Pointer to chain of `struct function' for containing functions.  */
 521 extern struct function *outer_function_chain;
 522
 523 /* Put all this function's BLOCK nodes into a vector and return it.
 524    Also store in each NOTE for the beginning or end of a block
 525    the index of that block in the vector.  */
 526 extern tree *identify_blocks PROTO((tree, rtx));
 527
 528 /* Return size needed for stack frame based on slots so far allocated.
 529    This size counts from zero.  It is not rounded to STACK_BOUNDARY;
 530    the caller may have to do that.  */
 531 extern HOST_WIDE_INT get_frame_size     PROTO((void));
 532 /* Likewise, but for a different than the current function.  */
 533 extern HOST_WIDE_INT get_func_frame_size        PROTO((struct function *));
 534
 535 /* These variables hold pointers to functions to
 536    save and restore machine-specific data,
 537    in push_function_context and pop_function_context.  */
 538 extern void (*init_machine_status)      PROTO((struct function *));
 539 extern void (*mark_machine_status)      PROTO((struct function *));
 540 extern void (*save_machine_status)      PROTO((struct function *));
 541 extern void (*restore_machine_status)   PROTO((struct function *));
 542
 543 /* Likewise, but for language-specific data.  */
 544 extern void (*mark_lang_status)         PROTO((struct function *));
 545 extern void (*save_lang_status)         PROTO((struct function *));
 546 extern void (*restore_lang_status)      PROTO((struct function *));
 547
 548 /* Save and restore status information for a nested function.  */
 549 extern void save_tree_status            PROTO((struct function *));
 550 extern void restore_tree_status         PROTO((struct function *));
 551 extern void restore_emit_status         PROTO((struct function *));
 552 extern void free_after_compilation      PROTO((struct function *,
 553                                                tree));
 554
 555 extern void init_varasm_status          PROTO((struct function *));
 556 extern void free_varasm_status          PROTO((struct function *,
 557                                                tree));
 558 extern void free_emit_status            PROTO((struct function *,
 559                                                tree));
 560 extern void free_stmt_status            PROTO((struct function *,
 561                                                tree));
 562 extern rtx get_first_block_beg          PROTO((void));
 563
 564 extern void init_virtual_regs           PROTO((struct emit_status *));
 565
 566 /* Called once, at initialization, to initialize function.c.  */
 567 extern void init_function_once          PROTO((void));
 568
 569 #ifdef rtx
 570 #undef rtx
 571 #endif
 572
 573 #ifdef tree
 574 #undef tree
 575 #endif