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 stmt_status *stmt;
 166   struct expr_status *expr;
 167   struct emit_status *emit;
 168   struct varasm_status *varasm;
 169
 170   /* For tree-optimize.c.  */
 171
 172   /* Saved tree and arguments during tree optimization.  Used later for
 173      inlining */
 174   tree saved_tree;
 175   tree saved_args;
 176   tree saved_static_chain_decl;
 177
 178   /* For function.c.  */
 179
 180   /* Points to the FUNCTION_DECL of this function.  */
 181   tree decl;
 182
 183   /* Function containing this function, if any.  */
 184   struct function *outer;
 185
 186   /* Number of bytes of args popped by function being compiled on its return.
 187      Zero if no bytes are to be popped.
 188      May affect compilation of return insn or of function epilogue.  */
 189   int pops_args;
 190
 191   /* If function's args have a fixed size, this is that size, in bytes.
 192      Otherwise, it is -1.
 193      May affect compilation of return insn or of function epilogue.  */
 194   int args_size;
 195
 196   /* # bytes the prologue should push and pretend that the caller pushed them.
 197      The prologue must do this, but only if parms can be passed in
 198      registers.  */
 199   int pretend_args_size;
 200
 201   /* # of bytes of outgoing arguments.  If ACCUMULATE_OUTGOING_ARGS is
 202      defined, the needed space is pushed by the prologue.  */
 203   int outgoing_args_size;
 204
 205   /* This is the offset from the arg pointer to the place where the first
 206      anonymous arg can be found, if there is one.  */
 207   rtx arg_offset_rtx;
 208
 209   /* Quantities of various kinds of registers
 210      used for the current function's args.  */
 211   CUMULATIVE_ARGS args_info;
 212
 213   /* If nonzero, an RTL expression for the location at which the current
 214      function returns its result.  If the current function returns its
 215      result in a register, current_function_return_rtx will always be
 216      the hard register containing the result.  */
 217   rtx return_rtx;
 218
 219   /* The arg pointer hard register, or the pseudo into which it was copied.  */
 220   rtx internal_arg_pointer;
 221
 222   /* Opaque pointer used by get_hard_reg_initial_val and
 223      has_hard_reg_initial_val (see integrate.[hc]).  */
 224   struct initial_value_struct *hard_reg_initial_vals;
 225
 226   /* List (chain of EXPR_LIST) of labels heading the current handlers for
 227      nonlocal gotos.  */
 228   rtx x_nonlocal_goto_handler_labels;
 229
 230   /* Label that will go on function epilogue.
 231      Jumping to this label serves as a "return" instruction
 232      on machines which require execution of the epilogue on all returns.  */
 233   rtx x_return_label;
 234
 235   /* Label that will go on the end of function epilogue.
 236      Jumping to this label serves as a "naked return" instruction
 237      on machines which require execution of the epilogue on all returns.  */
 238   rtx x_naked_return_label;
 239
 240   /* List (chain of EXPR_LISTs) of all stack slots in this function.
 241      Made for the sake of unshare_all_rtl.  */
 242   rtx x_stack_slot_list;
 243
 244   /* Place after which to insert the tail_recursion_label if we need one.  */
 245   rtx x_tail_recursion_reentry;
 246
 247   /* Location at which to save the argument pointer if it will need to be
 248      referenced.  There are two cases where this is done: if nonlocal gotos
 249      exist, or if vars stored at an offset from the argument pointer will be
 250      needed by inner routines.  */
 251   rtx x_arg_pointer_save_area;
 252
 253   /* Offset to end of allocated area of stack frame.
 254      If stack grows down, this is the address of the last stack slot allocated.
 255      If stack grows up, this is the address for the next slot.  */
 256   HOST_WIDE_INT x_frame_offset;
 257
 258   /* A PARM_DECL that should contain the static chain for this function.
 259      It will be initialized at the beginning of the function.  */
 260   tree static_chain_decl;
 261
 262   /* An expression that contains the non-local goto save area.  The first
 263      word is the saved frame pointer and the second is the saved stack
 264      pointer.  */
 265   tree nonlocal_goto_save_area;
 266
 267   /* Insn after which register parms and SAVE_EXPRs are born, if nonopt.  */
 268   rtx x_parm_birth_insn;
 269
 270   /* List of all used temporaries allocated, by level.  */
 271   struct varray_head_tag * GTY((param_is (struct temp_slot))) x_used_temp_slots;
 272
 273   /* List of available temp slots.  */
 274   struct temp_slot *x_avail_temp_slots;
 275
 276   /* Current nesting level for temporaries.  */
 277   int x_temp_slot_level;
 278
 279   /* Current nesting level for variables in a block.  */
 280   int x_var_temp_slot_level;
 281
 282   /* When temporaries are created by TARGET_EXPRs, they are created at
 283      this level of temp_slot_level, so that they can remain allocated
 284      until no longer needed.  CLEANUP_POINT_EXPRs define the lifetime
 285      of TARGET_EXPRs.  */
 286   int x_target_temp_slot_level;
 287
 288   /* This slot is initialized as 0 and is added to
 289      during the nested function.  */
 290   struct var_refs_queue *fixup_var_refs_queue;
 291
 292   /* For integrate.c.  */
 293   int inlinable;
 294   int no_debugging_symbols;
 295   rtvec original_arg_vector;
 296   tree original_decl_initial;
 297   /* Highest label number in current function.  */
 298   int inl_max_label_num;
 299
 300   /* Function sequence number for profiling, debugging, etc.  */
 301   int funcdef_no;
 302
 303   /* For md files.  */
 304
 305   /* tm.h can use this to store whatever it likes.  */
 306   struct machine_function * GTY ((maybe_undef)) machine;
 307   /* The largest alignment of slot allocated on the stack.  */
 308   unsigned int stack_alignment_needed;
 309   /* Preferred alignment of the end of stack frame.  */
 310   unsigned int preferred_stack_boundary;
 311   /* Set when the call to function itself has been emit.  */
 312   bool recursive_call_emit;
 313   /* Set when the tail call has been produced.  */
 314   bool tail_call_emit;
 315
 316   /* Language-specific code can use this to store whatever it likes.  */
 317   struct language_function * language;
 318
 319   /* For reorg.  */
 320
 321   /* If some insns can be deferred to the delay slots of the epilogue, the
 322      delay list for them is recorded here.  */
 323   rtx epilogue_delay_list;
 324
 325   /* How commonly executed the function is.  Initialized during branch
 326      probabilities pass.  */
 327   enum function_frequency {
 328     /* This function most likely won't be executed at all.
 329        (set only when profile feedback is available).  */
 330     FUNCTION_FREQUENCY_UNLIKELY_EXECUTED,
 331     /* The default value.  */
 332     FUNCTION_FREQUENCY_NORMAL,
 333     /* Optimize this function hard
 334        (set only when profile feedback is available).  */
 335     FUNCTION_FREQUENCY_HOT
 336   } function_frequency;
 337
 338   /* Maximal number of entities in the single jumptable.  Used to estimate
 339      final flowgraph size.  */
 340   int max_jumptable_ents;
 341
 342   /* UIDs for LABEL_DECLs.  */
 343   int last_label_uid;
 344
 345   /* Line number of the end of the function.  */
 346   location_t function_end_locus;
 347
 348   /* Array mapping insn uids to blocks.  */
 349   struct varray_head_tag *ib_boundaries_block;
 350
 351   /* The variables unexpanded so far.  */
 352   tree unexpanded_var_list;
 353
 354   /* Collected bit flags.  */
 355
 356   /* Nonzero if function being compiled needs to be given an address
 357      where the value should be stored.  */
 358   unsigned int returns_struct : 1;
 359
 360   /* Nonzero if function being compiled needs to
 361      return the address of where it has put a structure value.  */
 362   unsigned int returns_pcc_struct : 1;
 363
 364   /* Nonzero if the current function returns a pointer type.  */
 365   unsigned int returns_pointer : 1;
 366
 367   /* Nonzero if function being compiled can call setjmp.  */
 368   unsigned int calls_setjmp : 1;
 369
 370   /* Nonzero if function being compiled can call longjmp.  */
 371   unsigned int calls_longjmp : 1;
 372
 373   /* Nonzero if function being compiled can call alloca,
 374      either as a subroutine or builtin.  */
 375   unsigned int calls_alloca : 1;
 376
 377   /* Nonzero if the function calls __builtin_eh_return.  */
 378   unsigned int calls_eh_return : 1;
 379
 380   /* Nonzero if function being compiled receives nonlocal gotos
 381      from nested functions.  */
 382   unsigned int has_nonlocal_label : 1;
 383
 384   /* Nonzero if function being compiled has nonlocal gotos to parent
 385      function.  */
 386   unsigned int has_nonlocal_goto : 1;
 387
 388   /* Nonzero if function being compiled contains nested functions.  */
 389   unsigned int contains_functions : 1;
 390
 391   /* Nonzero if the function being compiled issues a computed jump.  */
 392   unsigned int has_computed_jump : 1;
 393
 394   /* Nonzero if the current function is a thunk, i.e., a lightweight
 395      function implemented by the output_mi_thunk hook) that just
 396      adjusts one of its arguments and forwards to another
 397      function.  */
 398   unsigned int is_thunk : 1;
 399
 400   /* This bit is used by the exception handling logic.  It is set if all
 401      calls (if any) are sibling calls.  Such functions do not have to
 402      have EH tables generated, as they cannot throw.  A call to such a
 403      function, however, should be treated as throwing if any of its callees
 404      can throw.  */
 405   unsigned int all_throwers_are_sibcalls : 1;
 406
 407   /* Nonzero if instrumentation calls for function entry and exit should be
 408      generated.  */
 409   unsigned int instrument_entry_exit : 1;
 410
 411   /* Nonzero if profiling code should be generated.  */
 412   unsigned int profile : 1;
 413
 414   /* Nonzero if stack limit checking should be enabled in the current
 415      function.  */
 416   unsigned int limit_stack : 1;
 417
 418   /* Nonzero if current function uses stdarg.h or equivalent.  */
 419   unsigned int stdarg : 1;
 420
 421   /* Nonzero if the back-end should not keep track of expressions that
 422      determine the size of variable-sized objects.  Normally, such
 423      expressions are saved away, and then expanded when the next
 424      function is started.  For example, if a parameter has a
 425      variable-sized type, then the size of the parameter is computed
 426      when the function body is entered.  However, some front-ends do
 427      not desire this behavior.  */
 428   unsigned int x_dont_save_pending_sizes_p : 1;
 429
 430   /* Nonzero if the current function uses the constant pool.  */
 431   unsigned int uses_const_pool : 1;
 432
 433   /* Nonzero if the current function uses pic_offset_table_rtx.  */
 434   unsigned int uses_pic_offset_table : 1;
 435
 436   /* Nonzero if the current function needs an lsda for exception handling.  */
 437   unsigned int uses_eh_lsda : 1;
 438
 439   /* Nonzero if code to initialize arg_pointer_save_area has been emitted.  */
 440   unsigned int arg_pointer_save_area_init : 1;
 441 };
 442
 443 /* The function currently being compiled.  */
 444 extern GTY(()) struct function *cfun;
 445
 446 /* Pointer to chain of `struct function' for containing functions.  */
 447 extern GTY(()) struct function *outer_function_chain;
 448
 449 /* Nonzero if we've already converted virtual regs to hard regs.  */
 450 extern int virtuals_instantiated;
 451
 452 /* Nonzero if at least one trampoline has been created.  */
 453 extern int trampolines_created;
 454
 455 /* For backward compatibility... eventually these should all go away.  */
 456 #define current_function_pops_args (cfun->pops_args)
 457 #define current_function_returns_struct (cfun->returns_struct)
 458 #define current_function_returns_pcc_struct (cfun->returns_pcc_struct)
 459 #define current_function_returns_pointer (cfun->returns_pointer)
 460 #define current_function_calls_setjmp (cfun->calls_setjmp)
 461 #define current_function_calls_alloca (cfun->calls_alloca)
 462 #define current_function_calls_longjmp (cfun->calls_longjmp)
 463 #define current_function_calls_eh_return (cfun->calls_eh_return)
 464 #define current_function_has_computed_jump (cfun->has_computed_jump)
 465 #define current_function_contains_functions (cfun->contains_functions)
 466 #define current_function_is_thunk (cfun->is_thunk)
 467 #define current_function_args_info (cfun->args_info)
 468 #define current_function_args_size (cfun->args_size)
 469 #define current_function_pretend_args_size (cfun->pretend_args_size)
 470 #define current_function_outgoing_args_size (cfun->outgoing_args_size)
 471 #define current_function_arg_offset_rtx (cfun->arg_offset_rtx)
 472 #define current_function_stdarg (cfun->stdarg)
 473 #define current_function_internal_arg_pointer (cfun->internal_arg_pointer)
 474 #define current_function_return_rtx (cfun->return_rtx)
 475 #define current_function_instrument_entry_exit (cfun->instrument_entry_exit)
 476 #define current_function_profile (cfun->profile)
 477 #define current_function_funcdef_no (cfun->funcdef_no)
 478 #define current_function_limit_stack (cfun->limit_stack)
 479 #define current_function_uses_pic_offset_table (cfun->uses_pic_offset_table)
 480 #define current_function_uses_const_pool (cfun->uses_const_pool)
 481 #define current_function_epilogue_delay_list (cfun->epilogue_delay_list)
 482 #define current_function_has_nonlocal_label (cfun->has_nonlocal_label)
 483 #define current_function_has_nonlocal_goto (cfun->has_nonlocal_goto)
 484
 485 #define return_label (cfun->x_return_label)
 486 #define naked_return_label (cfun->x_naked_return_label)
 487 #define stack_slot_list (cfun->x_stack_slot_list)
 488 #define parm_birth_insn (cfun->x_parm_birth_insn)
 489 #define frame_offset (cfun->x_frame_offset)
 490 #define tail_recursion_reentry (cfun->x_tail_recursion_reentry)
 491 #define arg_pointer_save_area (cfun->x_arg_pointer_save_area)
 492 #define used_temp_slots (cfun->x_used_temp_slots)
 493 #define avail_temp_slots (cfun->x_avail_temp_slots)
 494 #define temp_slot_level (cfun->x_temp_slot_level)
 495 #define target_temp_slot_level (cfun->x_target_temp_slot_level)
 496 #define var_temp_slot_level (cfun->x_var_temp_slot_level)
 497 #define nonlocal_labels (cfun->x_nonlocal_labels)
 498 #define nonlocal_goto_handler_labels (cfun->x_nonlocal_goto_handler_labels)
 499
 500 /* Given a function decl for a containing function,
 501    return the `struct function' for it.  */
 502 struct function *find_function_data (tree);
 503
 504 /* Identify BLOCKs referenced by more than one NOTE_INSN_BLOCK_{BEG,END},
 505    and create duplicate blocks.  */
 506 extern void reorder_blocks (void);
 507
 508 /* Set BLOCK_NUMBER for all the blocks in FN.  */
 509 extern void number_blocks (tree);
 510
 511 extern void clear_block_marks (tree);
 512 extern tree blocks_nreverse (tree);
 513 extern void reset_block_changes (void);
 514 extern void record_block_change (tree);
 515 extern void finalize_block_changes (void);
 516 extern void check_block_change (rtx, tree *);
 517 extern void free_block_changes (void);
 518
 519 /* Return size needed for stack frame based on slots so far allocated.
 520    This size counts from zero.  It is not rounded to STACK_BOUNDARY;
 521    the caller may have to do that.  */
 522 extern HOST_WIDE_INT get_frame_size (void);
 523 /* Likewise, but for a different than the current function.  */
 524 extern HOST_WIDE_INT get_func_frame_size (struct function *);
 525
 526 /* A pointer to a function to create target specific, per-function
 527    data structures.  */
 528 extern struct machine_function * (*init_machine_status) (void);
 529
 530 /* Save and restore status information for a nested function.  */
 531 extern void restore_emit_status (struct function *);
 532 extern void free_after_parsing (struct function *);
 533 extern void free_after_compilation (struct function *);
 534
 535 extern void init_varasm_status (struct function *);
 536
 537 #ifdef RTX_CODE
 538 extern void diddle_return_value (void (*)(rtx, void*), void*);
 539 extern void clobber_return_register (void);
 540 extern void use_return_register (void);
 541 #endif
 542
 543 extern rtx get_arg_pointer_save_area (struct function *);
 544
 545 extern void init_virtual_regs (struct emit_status *);
 546 extern void instantiate_virtual_regs (void);
 547
 548 /* Returns the name of the current function.  */
 549 extern const char *current_function_name (void);
 550
 551 /* Called once, at initialization, to initialize function.c.  */
 552 extern void init_function_once (void);
 553
 554 extern void do_warn_unused_parameter (tree);
 555
 556 extern bool pass_by_reference (CUMULATIVE_ARGS *, enum machine_mode,
 557                                tree, bool);
 558
 559 #endif  /* GCC_FUNCTION_H */