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
 152 #define pending_stack_adjust (cfun->expr->x_pending_stack_adjust)
 153 #define inhibit_defer_pop (cfun->expr->x_inhibit_defer_pop)
 154 #define saveregs_value (cfun->expr->x_saveregs_value)
 155 #define apply_args_value (cfun->expr->x_apply_args_value)
 156 #define forced_labels (cfun->expr->x_forced_labels)
 157 #define stack_pointer_delta (cfun->expr->x_stack_pointer_delta)
 158
 159 /* This structure can save all the important global and static variables
 160    describing the status of the current function.  */
 161
 162 struct function GTY(())
 163 {
 164   struct eh_status *eh;
 165   struct expr_status *expr;
 166   struct emit_status *emit;
 167   struct varasm_status *varasm;
 168
 169   /* For tree-optimize.c.  */
 170
 171   /* Saved tree and arguments during tree optimization.  Used later for
 172      inlining */
 173   tree saved_tree;
 174   tree saved_args;
 175   tree saved_static_chain_decl;
 176
 177   /* For function.c.  */
 178
 179   /* Points to the FUNCTION_DECL of this function.  */
 180   tree decl;
 181
 182   /* Function containing this function, if any.  */
 183   struct function *outer;
 184
 185   /* Number of bytes of args popped by function being compiled on its return.
 186      Zero if no bytes are to be popped.
 187      May affect compilation of return insn or of function epilogue.  */
 188   int pops_args;
 189
 190   /* If function's args have a fixed size, this is that size, in bytes.
 191      Otherwise, it is -1.
 192      May affect compilation of return insn or of function epilogue.  */
 193   int args_size;
 194
 195   /* # bytes the prologue should push and pretend that the caller pushed them.
 196      The prologue must do this, but only if parms can be passed in
 197      registers.  */
 198   int pretend_args_size;
 199
 200   /* # of bytes of outgoing arguments.  If ACCUMULATE_OUTGOING_ARGS is
 201      defined, the needed space is pushed by the prologue.  */
 202   int outgoing_args_size;
 203
 204   /* This is the offset from the arg pointer to the place where the first
 205      anonymous arg can be found, if there is one.  */
 206   rtx arg_offset_rtx;
 207
 208   /* Quantities of various kinds of registers
 209      used for the current function's args.  */
 210   CUMULATIVE_ARGS args_info;
 211
 212   /* If nonzero, an RTL expression for the location at which the current
 213      function returns its result.  If the current function returns its
 214      result in a register, current_function_return_rtx will always be
 215      the hard register containing the result.  */
 216   rtx return_rtx;
 217
 218   /* The arg pointer hard register, or the pseudo into which it was copied.  */
 219   rtx internal_arg_pointer;
 220
 221   /* Opaque pointer used by get_hard_reg_initial_val and
 222      has_hard_reg_initial_val (see integrate.[hc]).  */
 223   struct initial_value_struct *hard_reg_initial_vals;
 224
 225   /* List (chain of EXPR_LIST) of labels heading the current handlers for
 226      nonlocal gotos.  */
 227   rtx x_nonlocal_goto_handler_labels;
 228
 229   /* Label that will go on function epilogue.
 230      Jumping to this label serves as a "return" instruction
 231      on machines which require execution of the epilogue on all returns.  */
 232   rtx x_return_label;
 233
 234   /* Label that will go on the end of function epilogue.
 235      Jumping to this label serves as a "naked return" instruction
 236      on machines which require execution of the epilogue on all returns.  */
 237   rtx x_naked_return_label;
 238
 239   /* List (chain of EXPR_LISTs) of all stack slots in this function.
 240      Made for the sake of unshare_all_rtl.  */
 241   rtx x_stack_slot_list;
 242
 243   /* Place after which to insert the tail_recursion_label if we need one.  */
 244   rtx x_tail_recursion_reentry;
 245
 246   /* Location at which to save the argument pointer if it will need to be
 247      referenced.  There are two cases where this is done: if nonlocal gotos
 248      exist, or if vars stored at an offset from the argument pointer will be
 249      needed by inner routines.  */
 250   rtx x_arg_pointer_save_area;
 251
 252   /* Offset to end of allocated area of stack frame.
 253      If stack grows down, this is the address of the last stack slot allocated.
 254      If stack grows up, this is the address for the next slot.  */
 255   HOST_WIDE_INT x_frame_offset;
 256
 257   /* A PARM_DECL that should contain the static chain for this function.
 258      It will be initialized at the beginning of the function.  */
 259   tree static_chain_decl;
 260
 261   /* An expression that contains the non-local goto save area.  The first
 262      word is the saved frame pointer and the second is the saved stack
 263      pointer.  */
 264   tree nonlocal_goto_save_area;
 265
 266   /* Insn after which register parms and SAVE_EXPRs are born, if nonopt.  */
 267   rtx x_parm_birth_insn;
 268
 269   /* List of all used temporaries allocated, by level.  */
 270   struct varray_head_tag * GTY((param_is (struct temp_slot))) x_used_temp_slots;
 271
 272   /* List of available temp slots.  */
 273   struct temp_slot *x_avail_temp_slots;
 274
 275   /* Current nesting level for temporaries.  */
 276   int x_temp_slot_level;
 277
 278   /* This slot is initialized as 0 and is added to
 279      during the nested function.  */
 280   struct var_refs_queue *fixup_var_refs_queue;
 281
 282   /* For integrate.c.  */
 283   int inlinable;
 284   int no_debugging_symbols;
 285   rtvec original_arg_vector;
 286   tree original_decl_initial;
 287   /* Highest label number in current function.  */
 288   int inl_max_label_num;
 289
 290   /* Function sequence number for profiling, debugging, etc.  */
 291   int funcdef_no;
 292
 293   /* For md files.  */
 294
 295   /* tm.h can use this to store whatever it likes.  */
 296   struct machine_function * GTY ((maybe_undef)) machine;
 297   /* The largest alignment of slot allocated on the stack.  */
 298   unsigned int stack_alignment_needed;
 299   /* Preferred alignment of the end of stack frame.  */
 300   unsigned int preferred_stack_boundary;
 301   /* Set when the call to function itself has been emit.  */
 302   bool recursive_call_emit;
 303   /* Set when the tail call has been produced.  */
 304   bool tail_call_emit;
 305
 306   /* Language-specific code can use this to store whatever it likes.  */
 307   struct language_function * language;
 308
 309   /* For reorg.  */
 310
 311   /* If some insns can be deferred to the delay slots of the epilogue, the
 312      delay list for them is recorded here.  */
 313   rtx epilogue_delay_list;
 314
 315   /* How commonly executed the function is.  Initialized during branch
 316      probabilities pass.  */
 317   enum function_frequency {
 318     /* This function most likely won't be executed at all.
 319        (set only when profile feedback is available).  */
 320     FUNCTION_FREQUENCY_UNLIKELY_EXECUTED,
 321     /* The default value.  */
 322     FUNCTION_FREQUENCY_NORMAL,
 323     /* Optimize this function hard
 324        (set only when profile feedback is available).  */
 325     FUNCTION_FREQUENCY_HOT
 326   } function_frequency;
 327
 328   /* Maximal number of entities in the single jumptable.  Used to estimate
 329      final flowgraph size.  */
 330   int max_jumptable_ents;
 331
 332   /* UIDs for LABEL_DECLs.  */
 333   int last_label_uid;
 334
 335   /* Line number of the end of the function.  */
 336   location_t function_end_locus;
 337
 338   /* Array mapping insn uids to blocks.  */
 339   struct varray_head_tag *ib_boundaries_block;
 340
 341   /* The variables unexpanded so far.  */
 342   tree unexpanded_var_list;
 343
 344   /* Collected bit flags.  */
 345
 346   /* Nonzero if function being compiled needs to be given an address
 347      where the value should be stored.  */
 348   unsigned int returns_struct : 1;
 349
 350   /* Nonzero if function being compiled needs to
 351      return the address of where it has put a structure value.  */
 352   unsigned int returns_pcc_struct : 1;
 353
 354   /* Nonzero if the current function returns a pointer type.  */
 355   unsigned int returns_pointer : 1;
 356
 357   /* Nonzero if function being compiled can call setjmp.  */
 358   unsigned int calls_setjmp : 1;
 359
 360   /* Nonzero if function being compiled can call longjmp.  */
 361   unsigned int calls_longjmp : 1;
 362
 363   /* Nonzero if function being compiled can call alloca,
 364      either as a subroutine or builtin.  */
 365   unsigned int calls_alloca : 1;
 366
 367   /* Nonzero if the function calls __builtin_eh_return.  */
 368   unsigned int calls_eh_return : 1;
 369
 370   /* Nonzero if function being compiled receives nonlocal gotos
 371      from nested functions.  */
 372   unsigned int has_nonlocal_label : 1;
 373
 374   /* Nonzero if function being compiled has nonlocal gotos to parent
 375      function.  */
 376   unsigned int has_nonlocal_goto : 1;
 377
 378   /* Nonzero if function being compiled contains nested functions.  */
 379   unsigned int contains_functions : 1;
 380
 381   /* Nonzero if the function being compiled issues a computed jump.  */
 382   unsigned int has_computed_jump : 1;
 383
 384   /* Nonzero if the current function is a thunk, i.e., a lightweight
 385      function implemented by the output_mi_thunk hook) that just
 386      adjusts one of its arguments and forwards to another
 387      function.  */
 388   unsigned int is_thunk : 1;
 389
 390   /* This bit is used by the exception handling logic.  It is set if all
 391      calls (if any) are sibling calls.  Such functions do not have to
 392      have EH tables generated, as they cannot throw.  A call to such a
 393      function, however, should be treated as throwing if any of its callees
 394      can throw.  */
 395   unsigned int all_throwers_are_sibcalls : 1;
 396
 397   /* Nonzero if instrumentation calls for function entry and exit should be
 398      generated.  */
 399   unsigned int instrument_entry_exit : 1;
 400
 401   /* Nonzero if profiling code should be generated.  */
 402   unsigned int profile : 1;
 403
 404   /* Nonzero if stack limit checking should be enabled in the current
 405      function.  */
 406   unsigned int limit_stack : 1;
 407
 408   /* Nonzero if current function uses stdarg.h or equivalent.  */
 409   unsigned int stdarg : 1;
 410
 411   /* Nonzero if the back-end should not keep track of expressions that
 412      determine the size of variable-sized objects.  Normally, such
 413      expressions are saved away, and then expanded when the next
 414      function is started.  For example, if a parameter has a
 415      variable-sized type, then the size of the parameter is computed
 416      when the function body is entered.  However, some front-ends do
 417      not desire this behavior.  */
 418   unsigned int x_dont_save_pending_sizes_p : 1;
 419
 420   /* Nonzero if the current function uses the constant pool.  */
 421   unsigned int uses_const_pool : 1;
 422
 423   /* Nonzero if the current function uses pic_offset_table_rtx.  */
 424   unsigned int uses_pic_offset_table : 1;
 425
 426   /* Nonzero if the current function needs an lsda for exception handling.  */
 427   unsigned int uses_eh_lsda : 1;
 428
 429   /* Nonzero if code to initialize arg_pointer_save_area has been emitted.  */
 430   unsigned int arg_pointer_save_area_init : 1;
 431 };
 432
 433 /* The function currently being compiled.  */
 434 extern GTY(()) struct function *cfun;
 435
 436 /* Pointer to chain of `struct function' for containing functions.  */
 437 extern GTY(()) struct function *outer_function_chain;
 438
 439 /* Nonzero if we've already converted virtual regs to hard regs.  */
 440 extern int virtuals_instantiated;
 441
 442 /* Nonzero if at least one trampoline has been created.  */
 443 extern int trampolines_created;
 444
 445 /* For backward compatibility... eventually these should all go away.  */
 446 #define current_function_pops_args (cfun->pops_args)
 447 #define current_function_returns_struct (cfun->returns_struct)
 448 #define current_function_returns_pcc_struct (cfun->returns_pcc_struct)
 449 #define current_function_returns_pointer (cfun->returns_pointer)
 450 #define current_function_calls_setjmp (cfun->calls_setjmp)
 451 #define current_function_calls_alloca (cfun->calls_alloca)
 452 #define current_function_calls_longjmp (cfun->calls_longjmp)
 453 #define current_function_calls_eh_return (cfun->calls_eh_return)
 454 #define current_function_has_computed_jump (cfun->has_computed_jump)
 455 #define current_function_contains_functions (cfun->contains_functions)
 456 #define current_function_is_thunk (cfun->is_thunk)
 457 #define current_function_args_info (cfun->args_info)
 458 #define current_function_args_size (cfun->args_size)
 459 #define current_function_pretend_args_size (cfun->pretend_args_size)
 460 #define current_function_outgoing_args_size (cfun->outgoing_args_size)
 461 #define current_function_arg_offset_rtx (cfun->arg_offset_rtx)
 462 #define current_function_stdarg (cfun->stdarg)
 463 #define current_function_internal_arg_pointer (cfun->internal_arg_pointer)
 464 #define current_function_return_rtx (cfun->return_rtx)
 465 #define current_function_instrument_entry_exit (cfun->instrument_entry_exit)
 466 #define current_function_profile (cfun->profile)
 467 #define current_function_funcdef_no (cfun->funcdef_no)
 468 #define current_function_limit_stack (cfun->limit_stack)
 469 #define current_function_uses_pic_offset_table (cfun->uses_pic_offset_table)
 470 #define current_function_uses_const_pool (cfun->uses_const_pool)
 471 #define current_function_epilogue_delay_list (cfun->epilogue_delay_list)
 472 #define current_function_has_nonlocal_label (cfun->has_nonlocal_label)
 473 #define current_function_has_nonlocal_goto (cfun->has_nonlocal_goto)
 474
 475 #define return_label (cfun->x_return_label)
 476 #define naked_return_label (cfun->x_naked_return_label)
 477 #define stack_slot_list (cfun->x_stack_slot_list)
 478 #define parm_birth_insn (cfun->x_parm_birth_insn)
 479 #define frame_offset (cfun->x_frame_offset)
 480 #define tail_recursion_reentry (cfun->x_tail_recursion_reentry)
 481 #define arg_pointer_save_area (cfun->x_arg_pointer_save_area)
 482 #define used_temp_slots (cfun->x_used_temp_slots)
 483 #define avail_temp_slots (cfun->x_avail_temp_slots)
 484 #define temp_slot_level (cfun->x_temp_slot_level)
 485 #define nonlocal_labels (cfun->x_nonlocal_labels)
 486 #define nonlocal_goto_handler_labels (cfun->x_nonlocal_goto_handler_labels)
 487
 488 /* Given a function decl for a containing function,
 489    return the `struct function' for it.  */
 490 struct function *find_function_data (tree);
 491
 492 /* Identify BLOCKs referenced by more than one NOTE_INSN_BLOCK_{BEG,END},
 493    and create duplicate blocks.  */
 494 extern void reorder_blocks (void);
 495
 496 /* Set BLOCK_NUMBER for all the blocks in FN.  */
 497 extern void number_blocks (tree);
 498
 499 extern void clear_block_marks (tree);
 500 extern tree blocks_nreverse (tree);
 501 extern void reset_block_changes (void);
 502 extern void record_block_change (tree);
 503 extern void finalize_block_changes (void);
 504 extern void check_block_change (rtx, tree *);
 505 extern void free_block_changes (void);
 506
 507 /* Return size needed for stack frame based on slots so far allocated.
 508    This size counts from zero.  It is not rounded to STACK_BOUNDARY;
 509    the caller may have to do that.  */
 510 extern HOST_WIDE_INT get_frame_size (void);
 511 /* Likewise, but for a different than the current function.  */
 512 extern HOST_WIDE_INT get_func_frame_size (struct function *);
 513
 514 /* A pointer to a function to create target specific, per-function
 515    data structures.  */
 516 extern struct machine_function * (*init_machine_status) (void);
 517
 518 /* Save and restore status information for a nested function.  */
 519 extern void restore_emit_status (struct function *);
 520 extern void free_after_parsing (struct function *);
 521 extern void free_after_compilation (struct function *);
 522
 523 extern void init_varasm_status (struct function *);
 524
 525 #ifdef RTX_CODE
 526 extern void diddle_return_value (void (*)(rtx, void*), void*);
 527 extern void clobber_return_register (void);
 528 extern void use_return_register (void);
 529 #endif
 530
 531 extern rtx get_arg_pointer_save_area (struct function *);
 532
 533 extern void init_virtual_regs (struct emit_status *);
 534 extern void instantiate_virtual_regs (void);
 535
 536 /* Returns the name of the current function.  */
 537 extern const char *current_function_name (void);
 538
 539 /* Called once, at initialization, to initialize function.c.  */
 540 extern void init_function_once (void);
 541
 542 extern void do_warn_unused_parameter (tree);
 543
 544 extern bool pass_by_reference (CUMULATIVE_ARGS *, enum machine_mode,
 545                                tree, bool);
 546 extern bool reference_callee_copied (CUMULATIVE_ARGS *, enum machine_mode,
 547                                      tree, bool);
 548
 549 #endif  /* GCC_FUNCTION_H */