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, 2005 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   /* The control flow graph for this function.  */
 170   struct control_flow_graph *cfg;
 171
 172   /* For tree-optimize.c.  */
 173
 174   /* Saved tree and arguments during tree optimization.  Used later for
 175      inlining */
 176   tree saved_tree;
 177   tree saved_args;
 178   tree saved_static_chain_decl;
 179
 180   /* For function.c.  */
 181
 182   /* Points to the FUNCTION_DECL of this function.  */
 183   tree decl;
 184
 185   /* Function containing this function, if any.  */
 186   struct function *outer;
 187
 188   /* Number of bytes of args popped by function being compiled on its return.
 189      Zero if no bytes are to be popped.
 190      May affect compilation of return insn or of function epilogue.  */
 191   int pops_args;
 192
 193   /* If function's args have a fixed size, this is that size, in bytes.
 194      Otherwise, it is -1.
 195      May affect compilation of return insn or of function epilogue.  */
 196   int args_size;
 197
 198   /* # bytes the prologue should push and pretend that the caller pushed them.
 199      The prologue must do this, but only if parms can be passed in
 200      registers.  */
 201   int pretend_args_size;
 202
 203   /* # of bytes of outgoing arguments.  If ACCUMULATE_OUTGOING_ARGS is
 204      defined, the needed space is pushed by the prologue.  */
 205   int outgoing_args_size;
 206
 207   /* This is the offset from the arg pointer to the place where the first
 208      anonymous arg can be found, if there is one.  */
 209   rtx arg_offset_rtx;
 210
 211   /* Quantities of various kinds of registers
 212      used for the current function's args.  */
 213   CUMULATIVE_ARGS args_info;
 214
 215   /* If nonzero, an RTL expression for the location at which the current
 216      function returns its result.  If the current function returns its
 217      result in a register, current_function_return_rtx will always be
 218      the hard register containing the result.  */
 219   rtx return_rtx;
 220
 221   /* The arg pointer hard register, or the pseudo into which it was copied.  */
 222   rtx internal_arg_pointer;
 223
 224   /* Opaque pointer used by get_hard_reg_initial_val and
 225      has_hard_reg_initial_val (see integrate.[hc]).  */
 226   struct initial_value_struct *hard_reg_initial_vals;
 227
 228   /* List (chain of EXPR_LIST) of labels heading the current handlers for
 229      nonlocal gotos.  */
 230   rtx x_nonlocal_goto_handler_labels;
 231
 232   /* Label that will go on function epilogue.
 233      Jumping to this label serves as a "return" instruction
 234      on machines which require execution of the epilogue on all returns.  */
 235   rtx x_return_label;
 236
 237   /* Label that will go on the end of function epilogue.
 238      Jumping to this label serves as a "naked return" instruction
 239      on machines which require execution of the epilogue on all returns.  */
 240   rtx x_naked_return_label;
 241
 242   /* List (chain of EXPR_LISTs) of all stack slots in this function.
 243      Made for the sake of unshare_all_rtl.  */
 244   rtx x_stack_slot_list;
 245
 246   /* Place after which to insert the tail_recursion_label if we need one.  */
 247   rtx x_tail_recursion_reentry;
 248
 249   /* Location at which to save the argument pointer if it will need to be
 250      referenced.  There are two cases where this is done: if nonlocal gotos
 251      exist, or if vars stored at an offset from the argument pointer will be
 252      needed by inner routines.  */
 253   rtx x_arg_pointer_save_area;
 254
 255   /* Offset to end of allocated area of stack frame.
 256      If stack grows down, this is the address of the last stack slot allocated.
 257      If stack grows up, this is the address for the next slot.  */
 258   HOST_WIDE_INT x_frame_offset;
 259
 260   /* A PARM_DECL that should contain the static chain for this function.
 261      It will be initialized at the beginning of the function.  */
 262   tree static_chain_decl;
 263
 264   /* An expression that contains the non-local goto save area.  The first
 265      word is the saved frame pointer and the second is the saved stack
 266      pointer.  */
 267   tree nonlocal_goto_save_area;
 268
 269   /* Insn after which register parms and SAVE_EXPRs are born, if nonopt.  */
 270   rtx x_parm_birth_insn;
 271
 272   /* List of all used temporaries allocated, by level.  */
 273   struct varray_head_tag * GTY((param_is (struct temp_slot))) x_used_temp_slots;
 274
 275   /* List of available temp slots.  */
 276   struct temp_slot *x_avail_temp_slots;
 277
 278   /* Current nesting level for temporaries.  */
 279   int x_temp_slot_level;
 280
 281   /* This slot is initialized as 0 and is added to
 282      during the nested function.  */
 283   struct var_refs_queue *fixup_var_refs_queue;
 284
 285   /* For integrate.c.  */
 286   int inlinable;
 287   int no_debugging_symbols;
 288   rtvec original_arg_vector;
 289   tree original_decl_initial;
 290
 291   /* Highest label number in current function.  */
 292   int inl_max_label_num;
 293
 294   /* Function sequence number for profiling, debugging, etc.  */
 295   int funcdef_no;
 296
 297   /* For flow.c.  */
 298
 299   /* Highest loop depth seen so far in loop analysis.  Used in flow.c
 300      for the "failure strategy" when doing liveness analysis starting
 301      with non-empty initial sets.  */
 302   int max_loop_depth;
 303
 304   /* For md files.  */
 305
 306   /* tm.h can use this to store whatever it likes.  */
 307   struct machine_function * GTY ((maybe_undef)) machine;
 308   /* The largest alignment of slot allocated on the stack.  */
 309   unsigned int stack_alignment_needed;
 310   /* Preferred alignment of the end of stack frame.  */
 311   unsigned int preferred_stack_boundary;
 312   /* Set when the call to function itself has been emit.  */
 313   bool recursive_call_emit;
 314   /* Set when the tail call has been produced.  */
 315   bool tail_call_emit;
 316
 317   /* Language-specific code can use this to store whatever it likes.  */
 318   struct language_function * language;
 319
 320   /* For reorg.  */
 321
 322   /* If some insns can be deferred to the delay slots of the epilogue, the
 323      delay list for them is recorded here.  */
 324   rtx epilogue_delay_list;
 325
 326   /* How commonly executed the function is.  Initialized during branch
 327      probabilities pass.  */
 328   enum function_frequency {
 329     /* This function most likely won't be executed at all.
 330        (set only when profile feedback is available).  */
 331     FUNCTION_FREQUENCY_UNLIKELY_EXECUTED,
 332     /* The default value.  */
 333     FUNCTION_FREQUENCY_NORMAL,
 334     /* Optimize this function hard
 335        (set only when profile feedback is available).  */
 336     FUNCTION_FREQUENCY_HOT
 337   } function_frequency;
 338
 339   /* Maximal number of entities in the single jumptable.  Used to estimate
 340      final flowgraph size.  */
 341   int max_jumptable_ents;
 342
 343   /* UIDs for LABEL_DECLs.  */
 344   int last_label_uid;
 345
 346   /* Line number of the end of the function.  */
 347   location_t function_end_locus;
 348
 349   /* Array mapping insn uids to blocks.  */
 350   struct varray_head_tag *ib_boundaries_block;
 351
 352   /* The variables unexpanded so far.  */
 353   tree unexpanded_var_list;
 354
 355   /* Collected bit flags.  */
 356
 357   /* Nonzero if function being compiled needs to be given an address
 358      where the value should be stored.  */
 359   unsigned int returns_struct : 1;
 360
 361   /* Nonzero if function being compiled needs to
 362      return the address of where it has put a structure value.  */
 363   unsigned int returns_pcc_struct : 1;
 364
 365   /* Nonzero if the current function returns a pointer type.  */
 366   unsigned int returns_pointer : 1;
 367
 368   /* Nonzero if function being compiled can call setjmp.  */
 369   unsigned int calls_setjmp : 1;
 370
 371   /* Nonzero if function being compiled can call alloca,
 372      either as a subroutine or builtin.  */
 373   unsigned int calls_alloca : 1;
 374
 375   /* Nonzero if the function calls __builtin_eh_return.  */
 376   unsigned int calls_eh_return : 1;
 377
 378   /* Nonzero if function being compiled receives nonlocal gotos
 379      from nested functions.  */
 380   unsigned int has_nonlocal_label : 1;
 381
 382   /* Nonzero if function being compiled has nonlocal gotos to parent
 383      function.  */
 384   unsigned int has_nonlocal_goto : 1;
 385
 386   /* Nonzero if the current function is a thunk, i.e., a lightweight
 387      function implemented by the output_mi_thunk hook) that just
 388      adjusts one of its arguments and forwards to another
 389      function.  */
 390   unsigned int is_thunk : 1;
 391
 392   /* This bit is used by the exception handling logic.  It is set if all
 393      calls (if any) are sibling calls.  Such functions do not have to
 394      have EH tables generated, as they cannot throw.  A call to such a
 395      function, however, should be treated as throwing if any of its callees
 396      can throw.  */
 397   unsigned int all_throwers_are_sibcalls : 1;
 398
 399   /* Nonzero if profiling code should be generated.  */
 400   unsigned int profile : 1;
 401
 402   /* Nonzero if stack limit checking should be enabled in the current
 403      function.  */
 404   unsigned int limit_stack : 1;
 405
 406   /* Nonzero if current function uses stdarg.h or equivalent.  */
 407   unsigned int stdarg : 1;
 408
 409   /* Nonzero if the back-end should not keep track of expressions that
 410      determine the size of variable-sized objects.  Normally, such
 411      expressions are saved away, and then expanded when the next
 412      function is started.  For example, if a parameter has a
 413      variable-sized type, then the size of the parameter is computed
 414      when the function body is entered.  However, some front-ends do
 415      not desire this behavior.  */
 416   unsigned int x_dont_save_pending_sizes_p : 1;
 417
 418   /* Nonzero if the current function uses the constant pool.  */
 419   unsigned int uses_const_pool : 1;
 420
 421   /* Nonzero if the current function uses pic_offset_table_rtx.  */
 422   unsigned int uses_pic_offset_table : 1;
 423
 424   /* Nonzero if the current function needs an lsda for exception handling.  */
 425   unsigned int uses_eh_lsda : 1;
 426
 427   /* Nonzero if code to initialize arg_pointer_save_area has been emitted.  */
 428   unsigned int arg_pointer_save_area_init : 1;
 429
 430   /* Number of units of general registers that need saving in stdarg
 431      function.  What unit is depends on the backend, either it is number
 432      of bytes, or it can be number of registers.  */
 433   unsigned int va_list_gpr_size : 8;
 434
 435   /* Number of units of floating point registers that need saving in stdarg
 436      function.  */
 437   unsigned int va_list_fpr_size : 8;
 438 };
 439
 440 /* If va_list_[gf]pr_size is set to this, it means we don't know how
 441    many units need to be saved.  */
 442 #define VA_LIST_MAX_GPR_SIZE    255
 443 #define VA_LIST_MAX_FPR_SIZE    255
 444
 445 /* The function currently being compiled.  */
 446 extern GTY(()) struct function *cfun;
 447
 448 /* Pointer to chain of `struct function' for containing functions.  */
 449 extern GTY(()) struct function *outer_function_chain;
 450
 451 /* Nonzero if we've already converted virtual regs to hard regs.  */
 452 extern int virtuals_instantiated;
 453
 454 /* Nonzero if at least one trampoline has been created.  */
 455 extern int trampolines_created;
 456
 457 /* For backward compatibility... eventually these should all go away.  */
 458 #define current_function_pops_args (cfun->pops_args)
 459 #define current_function_returns_struct (cfun->returns_struct)
 460 #define current_function_returns_pcc_struct (cfun->returns_pcc_struct)
 461 #define current_function_returns_pointer (cfun->returns_pointer)
 462 #define current_function_calls_setjmp (cfun->calls_setjmp)
 463 #define current_function_calls_alloca (cfun->calls_alloca)
 464 #define current_function_calls_eh_return (cfun->calls_eh_return)
 465 #define current_function_is_thunk (cfun->is_thunk)
 466 #define current_function_args_info (cfun->args_info)
 467 #define current_function_args_size (cfun->args_size)
 468 #define current_function_pretend_args_size (cfun->pretend_args_size)
 469 #define current_function_outgoing_args_size (cfun->outgoing_args_size)
 470 #define current_function_arg_offset_rtx (cfun->arg_offset_rtx)
 471 #define current_function_stdarg (cfun->stdarg)
 472 #define current_function_internal_arg_pointer (cfun->internal_arg_pointer)
 473 #define current_function_return_rtx (cfun->return_rtx)
 474 #define current_function_profile (cfun->profile)
 475 #define current_function_funcdef_no (cfun->funcdef_no)
 476 #define current_function_limit_stack (cfun->limit_stack)
 477 #define current_function_uses_pic_offset_table (cfun->uses_pic_offset_table)
 478 #define current_function_uses_const_pool (cfun->uses_const_pool)
 479 #define current_function_epilogue_delay_list (cfun->epilogue_delay_list)
 480 #define current_function_has_nonlocal_label (cfun->has_nonlocal_label)
 481 #define current_function_has_nonlocal_goto (cfun->has_nonlocal_goto)
 482
 483 #define return_label (cfun->x_return_label)
 484 #define naked_return_label (cfun->x_naked_return_label)
 485 #define stack_slot_list (cfun->x_stack_slot_list)
 486 #define parm_birth_insn (cfun->x_parm_birth_insn)
 487 #define frame_offset (cfun->x_frame_offset)
 488 #define tail_recursion_reentry (cfun->x_tail_recursion_reentry)
 489 #define arg_pointer_save_area (cfun->x_arg_pointer_save_area)
 490 #define used_temp_slots (cfun->x_used_temp_slots)
 491 #define avail_temp_slots (cfun->x_avail_temp_slots)
 492 #define temp_slot_level (cfun->x_temp_slot_level)
 493 #define nonlocal_goto_handler_labels (cfun->x_nonlocal_goto_handler_labels)
 494
 495 /* Given a function decl for a containing function,
 496    return the `struct function' for it.  */
 497 struct function *find_function_data (tree);
 498
 499 /* Identify BLOCKs referenced by more than one NOTE_INSN_BLOCK_{BEG,END},
 500    and create duplicate blocks.  */
 501 extern void reorder_blocks (void);
 502
 503 /* Set BLOCK_NUMBER for all the blocks in FN.  */
 504 extern void number_blocks (tree);
 505
 506 extern void clear_block_marks (tree);
 507 extern tree blocks_nreverse (tree);
 508 extern void reset_block_changes (void);
 509 extern void record_block_change (tree);
 510 extern void finalize_block_changes (void);
 511 extern void check_block_change (rtx, tree *);
 512 extern void free_block_changes (void);
 513
 514 /* Return size needed for stack frame based on slots so far allocated.
 515    This size counts from zero.  It is not rounded to STACK_BOUNDARY;
 516    the caller may have to do that.  */
 517 extern HOST_WIDE_INT get_frame_size (void);
 518
 519 /* A pointer to a function to create target specific, per-function
 520    data structures.  */
 521 extern struct machine_function * (*init_machine_status) (void);
 522
 523 /* Save and restore status information for a nested function.  */
 524 extern void free_after_parsing (struct function *);
 525 extern void free_after_compilation (struct function *);
 526
 527 extern void init_varasm_status (struct function *);
 528
 529 #ifdef RTX_CODE
 530 extern void diddle_return_value (void (*)(rtx, void*), void*);
 531 extern void clobber_return_register (void);
 532 extern void use_return_register (void);
 533 #endif
 534
 535 extern rtx get_arg_pointer_save_area (struct function *);
 536
 537 extern void init_virtual_regs (struct emit_status *);
 538 extern void instantiate_virtual_regs (void);
 539
 540 /* Returns the name of the current function.  */
 541 extern const char *current_function_name (void);
 542
 543 /* Called once, at initialization, to initialize function.c.  */
 544 extern void init_function_once (void);
 545
 546 extern void do_warn_unused_parameter (tree);
 547
 548 extern bool pass_by_reference (CUMULATIVE_ARGS *, enum machine_mode,
 549                                tree, bool);
 550 extern bool reference_callee_copied (CUMULATIVE_ARGS *, enum machine_mode,
 551                                      tree, bool);
 552
 553 #endif  /* GCC_FUNCTION_H */