gcc/function.h

   1 /* Structure for saving state for a nested function.
   2    Copyright (C) 1989, 1992, 1993, 1994, 1995, 1996, 1997, 1998,
   3    1999, 2000, 2003, 2004 Free Software Foundation, Inc.
   4
   5 This file is part of GCC.
   6
   7 GCC is free software; you can redistribute it and/or modify it under
   8 the terms of the GNU General Public License as published by the Free
   9 Software Foundation; either version 2, or (at your option) any later
  10 version.
  11
  12 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
  13 WARRANTY; without even the implied warranty of MERCHANTABILITY or
  14 FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  15 for more details.
  16
  17 You should have received a copy of the GNU General Public License
  18 along with GCC; see the file COPYING.  If not, write to the Free
  19 Software Foundation, 59 Temple Place - Suite 330, Boston, MA
  20 02111-1307, USA.  */
  21
  22 #ifndef GCC_FUNCTION_H
  23 #define GCC_FUNCTION_H
  24
  25 struct var_refs_queue GTY(())
  26 {
  27   rtx modified;
  28   enum machine_mode promoted_mode;
  29   int unsignedp;
  30   struct var_refs_queue *next;
  31 };
  32
  33 /* Stack of pending (incomplete) sequences saved by `start_sequence'.
  34    Each element describes one pending sequence.
  35    The main insn-chain is saved in the last element of the chain,
  36    unless the chain is empty.  */
  37
  38 struct sequence_stack GTY(())
  39 {
  40   /* First and last insns in the chain of the saved sequence.  */
  41   rtx first;
  42   rtx last;
  43   struct sequence_stack *next;
  44 };
  45
  46 extern struct sequence_stack *sequence_stack;
  47
  48 /* Stack of single obstacks.  */
  49
  50 struct simple_obstack_stack
  51 {
  52   struct obstack *obstack;
  53   struct simple_obstack_stack *next;
  54 };
  55 \f
  56 struct emit_status GTY(())
  57 {
  58   /* This is reset to LAST_VIRTUAL_REGISTER + 1 at the start of each function.
  59      After rtl generation, it is 1 plus the largest register number used.  */
  60   int x_reg_rtx_no;
  61
  62   /* Lowest label number in current function.  */
  63   int x_first_label_num;
  64
  65   /* The ends of the doubly-linked chain of rtl for the current function.
  66      Both are reset to null at the start of rtl generation for the function.
  67
  68      start_sequence saves both of these on `sequence_stack' and then starts
  69      a new, nested sequence of insns.  */
  70   rtx x_first_insn;
  71   rtx x_last_insn;
  72
  73   /* Stack of pending (incomplete) sequences saved by `start_sequence'.
  74      Each element describes one pending sequence.
  75      The main insn-chain is saved in the last element of the chain,
  76      unless the chain is empty.  */
  77   struct sequence_stack *sequence_stack;
  78
  79   /* INSN_UID for next insn emitted.
  80      Reset to 1 for each function compiled.  */
  81   int x_cur_insn_uid;
  82
  83   /* Location the last line-number NOTE emitted.
  84      This is used to avoid generating duplicates.  */
  85   location_t x_last_location;
  86
  87   /* The length of the regno_pointer_align, regno_decl, and x_regno_reg_rtx
  88      vectors.  Since these vectors are needed during the expansion phase when
  89      the total number of registers in the function is not yet known, the
  90      vectors are copied and made bigger when necessary.  */
  91   int regno_pointer_align_length;
  92
  93   /* Indexed by pseudo register number, if nonzero gives the known alignment
  94      for that pseudo (if REG_POINTER is set in x_regno_reg_rtx).
  95      Allocated in parallel with x_regno_reg_rtx.  */
  96   unsigned char * GTY ((length ("%h.x_reg_rtx_no")))
  97     regno_pointer_align;
  98
  99   /* Indexed by pseudo register number, gives the rtx for that pseudo.
 100      Allocated in parallel with regno_pointer_align.  */
 101   rtx * GTY ((length ("%h.x_reg_rtx_no"))) x_regno_reg_rtx;
 102 };
 103
 104 /* For backward compatibility... eventually these should all go away.  */
 105 #define reg_rtx_no (cfun->emit->x_reg_rtx_no)
 106 #define regno_reg_rtx (cfun->emit->x_regno_reg_rtx)
 107 #define seq_stack (cfun->emit->sequence_stack)
 108
 109 #define REGNO_POINTER_ALIGN(REGNO) (cfun->emit->regno_pointer_align[REGNO])
 110
 111 struct expr_status GTY(())
 112 {
 113   /* Number of units that we should eventually pop off the stack.
 114      These are the arguments to function calls that have already returned.  */
 115   int x_pending_stack_adjust;
 116
 117   /* Under some ABIs, it is the caller's responsibility to pop arguments
 118      pushed for function calls.  A naive implementation would simply pop
 119      the arguments immediately after each call.  However, if several
 120      function calls are made in a row, it is typically cheaper to pop
 121      all the arguments after all of the calls are complete since a
 122      single pop instruction can be used.  Therefore, GCC attempts to
 123      defer popping the arguments until absolutely necessary.  (For
 124      example, at the end of a conditional, the arguments must be popped,
 125      since code outside the conditional won't know whether or not the
 126      arguments need to be popped.)
 127
 128      When INHIBIT_DEFER_POP is nonzero, however, the compiler does not
 129      attempt to defer pops.  Instead, the stack is popped immediately
 130      after each call.  Rather then setting this variable directly, use
 131      NO_DEFER_POP and OK_DEFER_POP.  */
 132   int x_inhibit_defer_pop;
 133
 134   /* If PREFERRED_STACK_BOUNDARY and PUSH_ROUNDING are defined, the stack
 135      boundary can be momentarily unaligned while pushing the arguments.
 136      Record the delta since last aligned boundary here in order to get
 137      stack alignment in the nested function calls working right.  */
 138   int x_stack_pointer_delta;
 139
 140   /* Nonzero means __builtin_saveregs has already been done in this function.
 141      The value is the pseudoreg containing the value __builtin_saveregs
 142      returned.  */
 143   rtx x_saveregs_value;
 144
 145   /* Similarly for __builtin_apply_args.  */
 146   rtx x_apply_args_value;
 147
 148   /* List of labels that must never be deleted.  */
 149   rtx x_forced_labels;
 150
 151   /* Postincrements that still need to be expanded.  */
 152   rtx x_pending_chain;
 153 };
 154
 155 #define pending_stack_adjust (cfun->expr->x_pending_stack_adjust)
 156 #define inhibit_defer_pop (cfun->expr->x_inhibit_defer_pop)
 157 #define saveregs_value (cfun->expr->x_saveregs_value)
 158 #define apply_args_value (cfun->expr->x_apply_args_value)
 159 #define forced_labels (cfun->expr->x_forced_labels)
 160 #define pending_chain (cfun->expr->x_pending_chain)
 161 #define stack_pointer_delta (cfun->expr->x_stack_pointer_delta)
 162
 163 /* This structure can save all the important global and static variables
 164    describing the status of the current function.  */
 165
 166 struct function GTY(())
 167 {
 168   struct eh_status *eh;
 169   struct stmt_status *stmt;
 170   struct expr_status *expr;
 171   struct emit_status *emit;
 172   struct varasm_status *varasm;
 173
 174   /* For tree-optimize.c.  */
 175
 176   /* Saved tree and arguments during tree optimization.  Used later for
 177      inlining */
 178   tree saved_tree;
 179   tree saved_args;
 180
 181   /* For function.c.  */
 182
 183   /* Points to the FUNCTION_DECL of this function.  */
 184   tree decl;
 185
 186   /* Function containing this function, if any.  */
 187   struct function *outer;
 188
 189   /* Number of bytes of args popped by function being compiled on its return.
 190      Zero if no bytes are to be popped.
 191      May affect compilation of return insn or of function epilogue.  */
 192   int pops_args;
 193
 194   /* If function's args have a fixed size, this is that size, in bytes.
 195      Otherwise, it is -1.
 196      May affect compilation of return insn or of function epilogue.  */
 197   int args_size;
 198
 199   /* # bytes the prologue should push and pretend that the caller pushed them.
 200      The prologue must do this, but only if parms can be passed in
 201      registers.  */
 202   int pretend_args_size;
 203
 204   /* # of bytes of outgoing arguments.  If ACCUMULATE_OUTGOING_ARGS is
 205      defined, the needed space is pushed by the prologue.  */
 206   int outgoing_args_size;
 207
 208   /* This is the offset from the arg pointer to the place where the first
 209      anonymous arg can be found, if there is one.  */
 210   rtx arg_offset_rtx;
 211
 212   /* Quantities of various kinds of registers
 213      used for the current function's args.  */
 214   CUMULATIVE_ARGS args_info;
 215
 216   /* If nonzero, an RTL expression for the location at which the current
 217      function returns its result.  If the current function returns its
 218      result in a register, current_function_return_rtx will always be
 219      the hard register containing the result.  */
 220   rtx return_rtx;
 221
 222   /* The arg pointer hard register, or the pseudo into which it was copied.  */
 223   rtx internal_arg_pointer;
 224
 225   /* Opaque pointer used by get_hard_reg_initial_val and
 226      has_hard_reg_initial_val (see integrate.[hc]).  */
 227   struct initial_value_struct *hard_reg_initial_vals;
 228
 229   /* List (chain of EXPR_LIST) of labels heading the current handlers for
 230      nonlocal gotos.  */
 231   rtx x_nonlocal_goto_handler_labels;
 232
 233   /* Label that will go on function epilogue.
 234      Jumping to this label serves as a "return" instruction
 235      on machines which require execution of the epilogue on all returns.  */
 236   rtx x_return_label;
 237
 238   /* Label that will go on the end of function epilogue.
 239      Jumping to this label serves as a "naked return" instruction
 240      on machines which require execution of the epilogue on all returns.  */
 241   rtx x_naked_return_label;
 242
 243   /* List (chain of EXPR_LISTs) of all stack slots in this function.
 244      Made for the sake of unshare_all_rtl.  */
 245   rtx x_stack_slot_list;
 246
 247   /* Place after which to insert the tail_recursion_label if we need one.  */
 248   rtx x_tail_recursion_reentry;
 249
 250   /* Location at which to save the argument pointer if it will need to be
 251      referenced.  There are two cases where this is done: if nonlocal gotos
 252      exist, or if vars stored at an offset from the argument pointer will be
 253      needed by inner routines.  */
 254   rtx x_arg_pointer_save_area;
 255
 256   /* Offset to end of allocated area of stack frame.
 257      If stack grows down, this is the address of the last stack slot allocated.
 258      If stack grows up, this is the address for the next slot.  */
 259   HOST_WIDE_INT x_frame_offset;
 260
 261   /* A VAR_DECL that should contain the static chain for this function.
 262      It will be initialized at the beginning of the function.  */
 263   tree static_chain_decl;
 264
 265   /* An expression that contains the non-local goto save area.  The first
 266      word is the saved frame pointer and the second is the saved stack
 267      pointer.  */
 268   tree nonlocal_goto_save_area;
 269
 270   /* Insn after which register parms and SAVE_EXPRs are born, if nonopt.  */
 271   rtx x_parm_birth_insn;
 272
 273   /* List of all used temporaries allocated, by level.  */
 274   struct varray_head_tag * GTY((param_is (struct temp_slot))) x_used_temp_slots;
 275
 276   /* List of available temp slots.  */
 277   struct temp_slot *x_avail_temp_slots;
 278
 279   /* Current nesting level for temporaries.  */
 280   int x_temp_slot_level;
 281
 282   /* Current nesting level for variables in a block.  */
 283   int x_var_temp_slot_level;
 284
 285   /* When temporaries are created by TARGET_EXPRs, they are created at
 286      this level of temp_slot_level, so that they can remain allocated
 287      until no longer needed.  CLEANUP_POINT_EXPRs define the lifetime
 288      of TARGET_EXPRs.  */
 289   int x_target_temp_slot_level;
 290
 291   /* This slot is initialized as 0 and is added to
 292      during the nested function.  */
 293   struct var_refs_queue *fixup_var_refs_queue;
 294
 295   /* For integrate.c.  */
 296   int inlinable;
 297   int no_debugging_symbols;
 298   rtvec original_arg_vector;
 299   tree original_decl_initial;
 300   /* Highest label number in current function.  */
 301   int inl_max_label_num;
 302
 303   /* Function sequence number for profiling, debugging, etc.  */
 304   int funcdef_no;
 305
 306   /* For md files.  */
 307
 308   /* tm.h can use this to store whatever it likes.  */
 309   struct machine_function * GTY ((maybe_undef)) machine;
 310   /* The largest alignment of slot allocated on the stack.  */
 311   int stack_alignment_needed;
 312   /* Preferred alignment of the end of stack frame.  */
 313   int preferred_stack_boundary;
 314   /* Set when the call to function itself has been emit.  */
 315   bool recursive_call_emit;
 316   /* Set when the tail call has been produced.  */
 317   bool tail_call_emit;
 318
 319   /* Language-specific code can use this to store whatever it likes.  */
 320   struct language_function * language;
 321
 322   /* For reorg.  */
 323
 324   /* If some insns can be deferred to the delay slots of the epilogue, the
 325      delay list for them is recorded here.  */
 326   rtx epilogue_delay_list;
 327
 328   /* How commonly executed the function is.  Initialized during branch
 329      probabilities pass.  */
 330   enum function_frequency {
 331     /* This function most likely won't be executed at all.
 332        (set only when profile feedback is available).  */
 333     FUNCTION_FREQUENCY_UNLIKELY_EXECUTED,
 334     /* The default value.  */
 335     FUNCTION_FREQUENCY_NORMAL,
 336     /* Optimize this function hard
 337        (set only when profile feedback is available).  */
 338     FUNCTION_FREQUENCY_HOT
 339   } function_frequency;
 340
 341   /* Maximal number of entities in the single jumptable.  Used to estimate
 342      final flowgraph size.  */
 343   int max_jumptable_ents;
 344
 345   /* UIDs for LABEL_DECLs.  */
 346   int last_label_uid;
 347
 348   /* Line number of the end of the function.  */
 349   location_t function_end_locus;
 350
 351   /* Array mapping insn uids to blocks.  */
 352   struct varray_head_tag *ib_boundaries_block;
 353
 354   /* The variables unexpanded so far.  */
 355   tree unexpanded_var_list;
 356
 357   /* Collected bit flags.  */
 358
 359   /* Nonzero if function being compiled needs to be given an address
 360      where the value should be stored.  */
 361   unsigned int returns_struct : 1;
 362
 363   /* Nonzero if function being compiled needs to
 364      return the address of where it has put a structure value.  */
 365   unsigned int returns_pcc_struct : 1;
 366
 367   /* Nonzero if the current function returns a pointer type.  */
 368   unsigned int returns_pointer : 1;
 369
 370   /* Nonzero if function being compiled can call setjmp.  */
 371   unsigned int calls_setjmp : 1;
 372
 373   /* Nonzero if function being compiled can call longjmp.  */
 374   unsigned int calls_longjmp : 1;
 375
 376   /* Nonzero if function being compiled can call alloca,
 377      either as a subroutine or builtin.  */
 378   unsigned int calls_alloca : 1;
 379
 380   /* Nonzero if the function calls __builtin_eh_return.  */
 381   unsigned int calls_eh_return : 1;
 382
 383   /* Nonzero if function being compiled receives nonlocal gotos
 384      from nested functions.  */
 385   unsigned int has_nonlocal_label : 1;
 386
 387   /* Nonzero if function being compiled has nonlocal gotos to parent
 388      function.  */
 389   unsigned int has_nonlocal_goto : 1;
 390
 391   /* Nonzero if function being compiled contains nested functions.  */
 392   unsigned int contains_functions : 1;
 393
 394   /* Nonzero if the function being compiled issues a computed jump.  */
 395   unsigned int has_computed_jump : 1;
 396
 397   /* Nonzero if the current function is a thunk, i.e., a lightweight
 398      function implemented by the output_mi_thunk hook) that just
 399      adjusts one of its arguments and forwards to another
 400      function.  */
 401   unsigned int is_thunk : 1;
 402
 403   /* This bit is used by the exception handling logic.  It is set if all
 404      calls (if any) are sibling calls.  Such functions do not have to
 405      have EH tables generated, as they cannot throw.  A call to such a
 406      function, however, should be treated as throwing if any of its callees
 407      can throw.  */
 408   unsigned int all_throwers_are_sibcalls : 1;
 409
 410   /* Nonzero if instrumentation calls for function entry and exit should be
 411      generated.  */
 412   unsigned int instrument_entry_exit : 1;
 413
 414   /* Nonzero if profiling code should be generated.  */
 415   unsigned int profile : 1;
 416
 417   /* Nonzero if stack limit checking should be enabled in the current
 418      function.  */
 419   unsigned int limit_stack : 1;
 420
 421   /* Nonzero if current function uses stdarg.h or equivalent.  */
 422   unsigned int stdarg : 1;
 423
 424   /* Nonzero if the back-end should not keep track of expressions that
 425      determine the size of variable-sized objects.  Normally, such
 426      expressions are saved away, and then expanded when the next
 427      function is started.  For example, if a parameter has a
 428      variable-sized type, then the size of the parameter is computed
 429      when the function body is entered.  However, some front-ends do
 430      not desire this behavior.  */
 431   unsigned int x_dont_save_pending_sizes_p : 1;
 432
 433   /* Nonzero if the current function uses the constant pool.  */
 434   unsigned int uses_const_pool : 1;
 435
 436   /* Nonzero if the current function uses pic_offset_table_rtx.  */
 437   unsigned int uses_pic_offset_table : 1;
 438
 439   /* Nonzero if the current function needs an lsda for exception handling.  */
 440   unsigned int uses_eh_lsda : 1;
 441
 442   /* Nonzero if code to initialize arg_pointer_save_area has been emitted.  */
 443   unsigned int arg_pointer_save_area_init : 1;
 444 };
 445
 446 /* The function currently being compiled.  */
 447 extern GTY(()) struct function *cfun;
 448
 449 /* Pointer to chain of `struct function' for containing functions.  */
 450 extern GTY(()) struct function *outer_function_chain;
 451
 452 /* Nonzero if we've already converted virtual regs to hard regs.  */
 453 extern int virtuals_instantiated;
 454
 455 /* Nonzero if at least one trampoline has been created.  */
 456 extern int trampolines_created;
 457
 458 /* For backward compatibility... eventually these should all go away.  */
 459 #define current_function_pops_args (cfun->pops_args)
 460 #define current_function_returns_struct (cfun->returns_struct)
 461 #define current_function_returns_pcc_struct (cfun->returns_pcc_struct)
 462 #define current_function_returns_pointer (cfun->returns_pointer)
 463 #define current_function_calls_setjmp (cfun->calls_setjmp)
 464 #define current_function_calls_alloca (cfun->calls_alloca)
 465 #define current_function_calls_longjmp (cfun->calls_longjmp)
 466 #define current_function_calls_eh_return (cfun->calls_eh_return)
 467 #define current_function_has_computed_jump (cfun->has_computed_jump)
 468 #define current_function_contains_functions (cfun->contains_functions)
 469 #define current_function_is_thunk (cfun->is_thunk)
 470 #define current_function_args_info (cfun->args_info)
 471 #define current_function_args_size (cfun->args_size)
 472 #define current_function_pretend_args_size (cfun->pretend_args_size)
 473 #define current_function_outgoing_args_size (cfun->outgoing_args_size)
 474 #define current_function_arg_offset_rtx (cfun->arg_offset_rtx)
 475 #define current_function_stdarg (cfun->stdarg)
 476 #define current_function_internal_arg_pointer (cfun->internal_arg_pointer)
 477 #define current_function_return_rtx (cfun->return_rtx)
 478 #define current_function_instrument_entry_exit (cfun->instrument_entry_exit)
 479 #define current_function_profile (cfun->profile)
 480 #define current_function_funcdef_no (cfun->funcdef_no)
 481 #define current_function_limit_stack (cfun->limit_stack)
 482 #define current_function_uses_pic_offset_table (cfun->uses_pic_offset_table)
 483 #define current_function_uses_const_pool (cfun->uses_const_pool)
 484 #define current_function_epilogue_delay_list (cfun->epilogue_delay_list)
 485 #define current_function_has_nonlocal_label (cfun->has_nonlocal_label)
 486 #define current_function_has_nonlocal_goto (cfun->has_nonlocal_goto)
 487
 488 #define return_label (cfun->x_return_label)
 489 #define naked_return_label (cfun->x_naked_return_label)
 490 #define stack_slot_list (cfun->x_stack_slot_list)
 491 #define parm_birth_insn (cfun->x_parm_birth_insn)
 492 #define frame_offset (cfun->x_frame_offset)
 493 #define tail_recursion_reentry (cfun->x_tail_recursion_reentry)
 494 #define arg_pointer_save_area (cfun->x_arg_pointer_save_area)
 495 #define used_temp_slots (cfun->x_used_temp_slots)
 496 #define avail_temp_slots (cfun->x_avail_temp_slots)
 497 #define temp_slot_level (cfun->x_temp_slot_level)
 498 #define target_temp_slot_level (cfun->x_target_temp_slot_level)
 499 #define var_temp_slot_level (cfun->x_var_temp_slot_level)
 500 #define nonlocal_labels (cfun->x_nonlocal_labels)
 501 #define nonlocal_goto_handler_labels (cfun->x_nonlocal_goto_handler_labels)
 502
 503 /* Given a function decl for a containing function,
 504    return the `struct function' for it.  */
 505 struct function *find_function_data (tree);
 506
 507 /* Identify BLOCKs referenced by more than one NOTE_INSN_BLOCK_{BEG,END},
 508    and create duplicate blocks.  */
 509 extern void reorder_blocks (void);
 510
 511 /* Set BLOCK_NUMBER for all the blocks in FN.  */
 512 extern void number_blocks (tree);
 513
 514 extern void clear_block_marks (tree);
 515 extern tree blocks_nreverse (tree);
 516 extern void reset_block_changes (void);
 517 extern void record_block_change (tree);
 518 extern void finalize_block_changes (void);
 519 extern void check_block_change (rtx, tree *);
 520 extern void free_block_changes (void);
 521
 522 /* Return size needed for stack frame based on slots so far allocated.
 523    This size counts from zero.  It is not rounded to STACK_BOUNDARY;
 524    the caller may have to do that.  */
 525 extern HOST_WIDE_INT get_frame_size (void);
 526 /* Likewise, but for a different than the current function.  */
 527 extern HOST_WIDE_INT get_func_frame_size (struct function *);
 528
 529 /* A pointer to a function to create target specific, per-function
 530    data structures.  */
 531 extern struct machine_function * (*init_machine_status) (void);
 532
 533 /* Save and restore status information for a nested function.  */
 534 extern void restore_emit_status (struct function *);
 535 extern void free_after_parsing (struct function *);
 536 extern void free_after_compilation (struct function *);
 537
 538 extern void init_varasm_status (struct function *);
 539
 540 #ifdef RTX_CODE
 541 extern void diddle_return_value (void (*)(rtx, void*), void*);
 542 extern void clobber_return_register (void);
 543 extern void use_return_register (void);
 544 #endif
 545
 546 extern rtx get_arg_pointer_save_area (struct function *);
 547
 548 extern void init_virtual_regs (struct emit_status *);
 549 extern void instantiate_virtual_regs (void);
 550
 551 /* Returns the name of the current function.  */
 552 extern const char *current_function_name (void);
 553
 554 /* Called once, at initialization, to initialize function.c.  */
 555 extern void init_function_once (void);
 556
 557 extern void do_warn_unused_parameter (tree);
 558
 559 #endif  /* GCC_FUNCTION_H */