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
 186   /* For function.c.  */
 187
 188   /* Name of this function.  */
 189   const char *name;
 190   /* Points to the FUNCTION_DECL of this function. */
 191   tree decl;
 192
 193   /* Number of bytes of args popped by function being compiled on its return.
 194      Zero if no bytes are to be popped.
 195      May affect compilation of return insn or of function epilogue.  */
 196   int pops_args;
 197
 198   /* Nonzero if function being compiled needs to be given an address
 199      where the value should be stored.  */
 200   int returns_struct;
 201
 202   /* Nonzero if function being compiled needs to
 203      return the address of where it has put a structure value.  */
 204   int returns_pcc_struct;
 205
 206   /* Nonzero if the current function returns a pointer type.  */
 207   int returns_pointer;
 208
 209   /* Nonzero if function being compiled needs to be passed a static chain.  */
 210   int needs_context;
 211
 212   /* Nonzero if function being compiled can call setjmp.  */
 213   int calls_setjmp;
 214
 215   /* Nonzero if function being compiled can call longjmp.  */
 216   int calls_longjmp;
 217
 218   /* Nonzero if function being compiled can call alloca,
 219      either as a subroutine or builtin.  */
 220   int calls_alloca;
 221
 222   /* Nonzero if function being compiled receives nonlocal gotos
 223      from nested functions.  */
 224
 225   int has_nonlocal_label;
 226
 227   /* Nonzero if function being compiled has nonlocal gotos to parent
 228      function.  */
 229   int has_nonlocal_goto;
 230
 231   /* Nonzero if function being compiled contains nested functions.  */
 232   int contains_functions;
 233
 234   /* Nonzero if the function being compiled issues a computed jump.  */
 235   int has_computed_jump;
 236
 237   /* Nonzero if the current function is a thunk (a lightweight function that
 238      just adjusts one of its arguments and forwards to another function), so
 239      we should try to cut corners where we can.  */
 240   int is_thunk;
 241
 242   /* If function's args have a fixed size, this is that size, in bytes.
 243      Otherwise, it is -1.
 244      May affect compilation of return insn or of function epilogue.  */
 245   int args_size;
 246
 247   /* # bytes the prologue should push and pretend that the caller pushed them.
 248      The prologue must do this, but only if parms can be passed in
 249      registers.  */
 250   int pretend_args_size;
 251
 252   /* # of bytes of outgoing arguments.  If ACCUMULATE_OUTGOING_ARGS is
 253      defined, the needed space is pushed by the prologue.  */
 254   int outgoing_args_size;
 255
 256   /* This is the offset from the arg pointer to the place where the first
 257      anonymous arg can be found, if there is one.  */
 258   rtx arg_offset_rtx;
 259
 260   /* Nonzero if current function uses varargs.h or equivalent.
 261      Zero for functions that use stdarg.h.  */
 262   int varargs;
 263
 264   /* Nonzero if current function uses stdarg.h or equivalent.
 265      Zero for functions that use varargs.h.  */
 266   int stdarg;
 267
 268   /* Quantities of various kinds of registers
 269      used for the current function's args.  */
 270   CUMULATIVE_ARGS args_info;
 271
 272   /* If non-zero, an RTL expression for the location at which the current
 273      function returns its result.  If the current function returns its
 274      result in a register, current_function_return_rtx will always be
 275      the hard register containing the result.  */
 276   rtx return_rtx;
 277
 278   /* The arg pointer hard register, or the pseudo into which it was copied.  */
 279   rtx internal_arg_pointer;
 280
 281   /* Language-specific reason why the current function cannot be made
 282      inline.  */
 283   const char *cannot_inline;
 284
 285   /* Nonzero if instrumentation calls for function entry and exit should be
 286      generated.  */
 287   int instrument_entry_exit;
 288
 289   /* Nonzero if memory access checking be enabled in the current function.  */
 290   int check_memory_usage;
 291
 292   /* Number of function calls seen so far in current function.  */
 293   int x_function_call_count;
 294
 295   /* List (chain of TREE_LIST) of LABEL_DECLs for all nonlocal labels
 296      (labels to which there can be nonlocal gotos from nested functions)
 297      in this function.  */
 298   tree x_nonlocal_labels;
 299
 300   /* List (chain of EXPR_LIST) of stack slots that hold the current handlers
 301      for nonlocal gotos.  There is one for every nonlocal label in the
 302      function; this list matches the one in nonlocal_labels.
 303      Zero when function does not have nonlocal labels.  */
 304   rtx x_nonlocal_goto_handler_slots;
 305
 306   /* List (chain of EXPR_LIST) of labels heading the current handlers for
 307      nonlocal gotos.  */
 308   rtx x_nonlocal_goto_handler_labels;
 309
 310   /* RTX for stack slot that holds the stack pointer value to restore
 311      for a nonlocal goto.
 312      Zero when function does not have nonlocal labels.  */
 313   rtx x_nonlocal_goto_stack_level;
 314
 315   /* Label that will go on parm cleanup code, if any.
 316      Jumping to this label runs cleanup code for parameters, if
 317      such code must be run.  Following this code is the logical return
 318      label.  */
 319   rtx x_cleanup_label;
 320
 321   /* Label that will go on function epilogue.
 322      Jumping to this label serves as a "return" instruction
 323      on machines which require execution of the epilogue on all returns.  */
 324   rtx x_return_label;
 325
 326   /* List (chain of EXPR_LISTs) of pseudo-regs of SAVE_EXPRs.
 327      So we can mark them all live at the end of the function, if nonopt.  */
 328   rtx x_save_expr_regs;
 329
 330   /* List (chain of EXPR_LISTs) of all stack slots in this function.
 331      Made for the sake of unshare_all_rtl.  */
 332   rtx x_stack_slot_list;
 333
 334   /* Chain of all RTL_EXPRs that have insns in them.  */
 335   tree x_rtl_expr_chain;
 336
 337   /* Label to jump back to for tail recursion, or 0 if we have
 338      not yet needed one for this function.  */
 339   rtx x_tail_recursion_label;
 340
 341   /* Place after which to insert the tail_recursion_label if we need one.  */
 342   rtx x_tail_recursion_reentry;
 343
 344   /* Location at which to save the argument pointer if it will need to be
 345      referenced.  There are two cases where this is done: if nonlocal gotos
 346      exist, or if vars stored at an offset from the argument pointer will be
 347      needed by inner routines.  */
 348   rtx x_arg_pointer_save_area;
 349
 350   /* Offset to end of allocated area of stack frame.
 351      If stack grows down, this is the address of the last stack slot allocated.
 352      If stack grows up, this is the address for the next slot.  */
 353   HOST_WIDE_INT x_frame_offset;
 354
 355   /* List (chain of TREE_LISTs) of static chains for containing functions.
 356      Each link has a FUNCTION_DECL in the TREE_PURPOSE and a reg rtx
 357      in an RTL_EXPR in the TREE_VALUE.  */
 358   tree x_context_display;
 359
 360   /* List (chain of TREE_LISTs) of trampolines for nested functions.
 361      The trampoline sets up the static chain and jumps to the function.
 362      We supply the trampoline's address when the function's address is
 363      requested.
 364
 365      Each link has a FUNCTION_DECL in the TREE_PURPOSE and a reg rtx
 366      in an RTL_EXPR in the TREE_VALUE.  */
 367   tree x_trampoline_list;
 368
 369   /* Insn after which register parms and SAVE_EXPRs are born, if nonopt.  */
 370   rtx x_parm_birth_insn;
 371
 372   /* Last insn of those whose job was to put parms into their nominal
 373      homes.  */
 374   rtx x_last_parm_insn;
 375
 376   /* 1 + last pseudo register number possibly used for loading a copy
 377      of a parameter of this function. */
 378   int x_max_parm_reg;
 379
 380   /* Vector indexed by REGNO, containing location on stack in which
 381      to put the parm which is nominally in pseudo register REGNO,
 382      if we discover that that parm must go in the stack.  The highest
 383      element in this vector is one less than MAX_PARM_REG, above.  */
 384   rtx *x_parm_reg_stack_loc;
 385
 386   /* List of all temporaries allocated, both available and in use.  */
 387   struct temp_slot *x_temp_slots;
 388
 389   /* Current nesting level for temporaries.  */
 390   int x_temp_slot_level;
 391
 392   /* Current nesting level for variables in a block.  */
 393   int x_var_temp_slot_level;
 394
 395   /* When temporaries are created by TARGET_EXPRs, they are created at
 396      this level of temp_slot_level, so that they can remain allocated
 397      until no longer needed.  CLEANUP_POINT_EXPRs define the lifetime
 398      of TARGET_EXPRs.  */
 399   int x_target_temp_slot_level;
 400
 401   /* This slot is initialized as 0 and is added to
 402      during the nested function.  */
 403   struct var_refs_queue *fixup_var_refs_queue;
 404
 405   /* For tree.c.  */
 406   int all_types_permanent;
 407   struct momentary_level *momentary_stack;
 408   char *maybepermanent_firstobj;
 409   char *temporary_firstobj;
 410   char *momentary_firstobj;
 411   char *momentary_function_firstobj;
 412   struct obstack *current_obstack;
 413   struct obstack *function_obstack;
 414   struct obstack *function_maybepermanent_obstack;
 415   struct obstack *expression_obstack;
 416   struct obstack *saveable_obstack;
 417   struct obstack *rtl_obstack;
 418   struct simple_obstack_stack *inline_obstacks;
 419
 420   /* For integrate.c.  We duplicate some of the fields so that
 421      save_for_inline_copying can keep two versions.  */
 422   int inlinable;
 423   struct emit_status *inl_emit;
 424   /* This is in fact an rtvec.  */
 425   void *original_arg_vector;
 426   tree original_decl_initial;
 427   /* Last insn of those whose job was to put parms into their nominal
 428      homes.  */
 429   rtx inl_last_parm_insn;
 430   /* Highest label number in current function.  */
 431   int inl_max_label_num;
 432
 433   /* Nonzero if the current function uses the constant pool.  */
 434   int uses_const_pool;
 435
 436   /* For md files.  */
 437
 438   /* Nonzero if the current function uses pic_offset_table_rtx.  */
 439   int uses_pic_offset_table;
 440   /* tm.h can use this to store whatever it likes.  */
 441   struct machine_function *machine;
 442
 443   /* Language-specific code can use this to store whatever it likes.  */
 444   struct language_function *language;
 445
 446   /* For reorg.  */
 447
 448   /* If some insns can be deferred to the delay slots of the epilogue, the
 449      delay list for them is recorded here.  */
 450   rtx epilogue_delay_list;
 451
 452   /* For varasm.  */
 453   struct constant_descriptor **const_rtx_hash_table;
 454   struct pool_sym **const_rtx_sym_hash_table;
 455   struct pool_constant *first_pool, *last_pool;
 456   int pool_offset;
 457   rtx const_double_chain;
 458 };
 459
 460 extern struct function *current_function;
 461 extern struct function *all_functions;
 462
 463 /* For backward compatibility... eventually these should all go away.  */
 464 #define current_function_name (current_function->name)
 465 #define current_function_pops_args (current_function->pops_args)
 466 #define current_function_returns_struct (current_function->returns_struct)
 467 #define current_function_returns_pcc_struct (current_function->returns_pcc_struct)
 468 #define current_function_returns_pointer (current_function->returns_pointer)
 469 #define current_function_needs_context (current_function->needs_context)
 470 #define current_function_calls_setjmp (current_function->calls_setjmp)
 471 #define current_function_calls_alloca (current_function->calls_alloca)
 472 #define current_function_calls_longjmp (current_function->calls_longjmp)
 473 #define current_function_has_computed_jump (current_function->has_computed_jump)
 474 #define current_function_contains_functions (current_function->contains_functions)
 475 #define current_function_is_thunk (current_function->is_thunk)
 476 #define current_function_args_info (current_function->args_info)
 477 #define current_function_args_size (current_function->args_size)
 478 #define current_function_pretend_args_size (current_function->pretend_args_size)
 479 #define current_function_outgoing_args_size (current_function->outgoing_args_size)
 480 #define current_function_arg_offset_rtx (current_function->arg_offset_rtx)
 481 #define current_function_varargs (current_function->varargs)
 482 #define current_function_stdarg (current_function->stdarg)
 483 #define current_function_internal_arg_pointer (current_function->internal_arg_pointer)
 484 #define current_function_return_rtx (current_function->return_rtx)
 485 #define current_function_instrument_entry_exit (current_function->instrument_entry_exit)
 486 #define current_function_check_memory_usage (current_function->check_memory_usage)
 487 #define current_function_uses_pic_offset_table (current_function->uses_pic_offset_table)
 488 #define current_function_uses_const_pool (current_function->uses_const_pool)
 489 #define current_function_cannot_inline (current_function->cannot_inline)
 490 #define current_function_epilogue_delay_list (current_function->epilogue_delay_list)
 491 #define current_function_has_nonlocal_label (current_function->has_nonlocal_label)
 492 #define current_function_has_nonlocal_goto (current_function->has_nonlocal_goto)
 493
 494 #define max_parm_reg (current_function->x_max_parm_reg)
 495 #define parm_reg_stack_loc (current_function->x_parm_reg_stack_loc)
 496 #define cleanup_label (current_function->x_cleanup_label)
 497 #define return_label (current_function->x_return_label)
 498 #define save_expr_regs (current_function->x_save_expr_regs)
 499 #define stack_slot_list (current_function->x_stack_slot_list)
 500 #define parm_birth_insn (current_function->x_parm_birth_insn)
 501 #define frame_offset (current_function->x_frame_offset)
 502 #define tail_recursion_label (current_function->x_tail_recursion_label)
 503 #define tail_recursion_reentry (current_function->x_tail_recursion_reentry)
 504 #define arg_pointer_save_area (current_function->x_arg_pointer_save_area)
 505 #define rtl_expr_chain (current_function->x_rtl_expr_chain)
 506 #define last_parm_insn (current_function->x_last_parm_insn)
 507 #define context_display (current_function->x_context_display)
 508 #define trampoline_list (current_function->x_trampoline_list)
 509 #define function_call_count (current_function->x_function_call_count)
 510 #define temp_slots (current_function->x_temp_slots)
 511 #define temp_slot_level (current_function->x_temp_slot_level)
 512 #define target_temp_slot_level (current_function->x_target_temp_slot_level)
 513 #define var_temp_slot_level (current_function->x_var_temp_slot_level)
 514 #define nonlocal_labels (current_function->x_nonlocal_labels)
 515 #define nonlocal_goto_handler_slots (current_function->x_nonlocal_goto_handler_slots)
 516 #define nonlocal_goto_handler_labels (current_function->x_nonlocal_goto_handler_labels)
 517 #define nonlocal_goto_stack_level (current_function->x_nonlocal_goto_stack_level)
 518
 519 /* The FUNCTION_DECL for an inline function currently being expanded.  */
 520 extern tree inline_function_decl;
 521
 522 /* Given a function decl for a containing function,
 523    return the `struct function' for it.  */
 524 struct function *find_function_data PROTO((tree));
 525
 526 /* Pointer to chain of `struct function' for containing functions.  */
 527 extern struct function *outer_function_chain;
 528
 529 /* Put all this function's BLOCK nodes into a vector and return it.
 530    Also store in each NOTE for the beginning or end of a block
 531    the index of that block in the vector.  */
 532 extern tree *identify_blocks PROTO((tree, rtx));
 533
 534 /* Return size needed for stack frame based on slots so far allocated.
 535    This size counts from zero.  It is not rounded to STACK_BOUNDARY;
 536    the caller may have to do that.  */
 537 extern HOST_WIDE_INT get_frame_size PROTO((void));
 538 /* Likewise, but for a different than the current function.  */
 539 extern HOST_WIDE_INT get_func_frame_size PROTO((struct function *));
 540
 541 /* These variables hold pointers to functions to
 542    save and restore machine-specific data,
 543    in push_function_context and pop_function_context.  */
 544 extern void (*save_machine_status) PROTO((struct function *));
 545 extern void (*restore_machine_status) PROTO((struct function *));
 546
 547 /* Likewise, but for language-specific data.  */
 548 extern void (*save_lang_status)         PROTO((struct function *));
 549 extern void (*restore_lang_status)      PROTO((struct function *));
 550
 551 /* Save and restore status information for a nested function.  */
 552 extern void save_tree_status            PROTO((struct function *, tree));
 553 extern void restore_tree_status         PROTO((struct function *, tree));
 554 extern void save_varasm_status          PROTO((struct function *, tree));
 555 extern void restore_varasm_status       PROTO((struct function *));
 556 extern void restore_emit_status         PROTO((struct function *));
 557
 558 extern rtx get_first_block_beg          PROTO((void));
 559
 560 extern void init_virtual_regs           PROTO((struct emit_status *));
 561
 562 #ifdef rtx
 563 #undef rtx
 564 #endif
 565
 566 #ifdef tree
 567 #undef tree
 568 #endif