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 eh_status *saved_eh;
 166   struct expr_status *expr;
 167   struct emit_status *emit;
 168   struct varasm_status *varasm;
 169
 170   /* The control flow graph for this function.  */
 171   struct control_flow_graph *cfg;
 172   struct control_flow_graph *saved_cfg;
 173   bool after_inlining;
 174
 175   /* For tree-optimize.c.  */
 176
 177   /* Saved tree and arguments during tree optimization.  Used later for
 178      inlining */
 179   tree saved_args;
 180   tree saved_static_chain_decl;
 181
 182   /* For function.c.  */
 183
 184   /* Points to the FUNCTION_DECL of this function.  */
 185   tree decl;
 186
 187   /* Function containing this function, if any.  */
 188   struct function *outer;
 189
 190   /* Number of bytes of args popped by function being compiled on its return.
 191      Zero if no bytes are to be popped.
 192      May affect compilation of return insn or of function epilogue.  */
 193   int pops_args;
 194
 195   /* If function's args have a fixed size, this is that size, in bytes.
 196      Otherwise, it is -1.
 197      May affect compilation of return insn or of function epilogue.  */
 198   int args_size;
 199
 200   /* # bytes the prologue should push and pretend that the caller pushed them.
 201      The prologue must do this, but only if parms can be passed in
 202      registers.  */
 203   int pretend_args_size;
 204
 205   /* # of bytes of outgoing arguments.  If ACCUMULATE_OUTGOING_ARGS is
 206      defined, the needed space is pushed by the prologue.  */
 207   int outgoing_args_size;
 208
 209   /* This is the offset from the arg pointer to the place where the first
 210      anonymous arg can be found, if there is one.  */
 211   rtx arg_offset_rtx;
 212
 213   /* Quantities of various kinds of registers
 214      used for the current function's args.  */
 215   CUMULATIVE_ARGS args_info;
 216
 217   /* If nonzero, an RTL expression for the location at which the current
 218      function returns its result.  If the current function returns its
 219      result in a register, current_function_return_rtx will always be
 220      the hard register containing the result.  */
 221   rtx return_rtx;
 222
 223   /* The arg pointer hard register, or the pseudo into which it was copied.  */
 224   rtx internal_arg_pointer;
 225
 226   /* Opaque pointer used by get_hard_reg_initial_val and
 227      has_hard_reg_initial_val (see integrate.[hc]).  */
 228   struct initial_value_struct *hard_reg_initial_vals;
 229
 230   /* List (chain of EXPR_LIST) of labels heading the current handlers for
 231      nonlocal gotos.  */
 232   rtx x_nonlocal_goto_handler_labels;
 233
 234   /* Label that will go on function epilogue.
 235      Jumping to this label serves as a "return" instruction
 236      on machines which require execution of the epilogue on all returns.  */
 237   rtx x_return_label;
 238
 239   /* Label that will go on the end of function epilogue.
 240      Jumping to this label serves as a "naked return" instruction
 241      on machines which require execution of the epilogue on all returns.  */
 242   rtx x_naked_return_label;
 243
 244   /* List (chain of EXPR_LISTs) of all stack slots in this function.
 245      Made for the sake of unshare_all_rtl.  */
 246   rtx x_stack_slot_list;
 247
 248   /* Place after which to insert the tail_recursion_label if we need one.  */
 249   rtx x_tail_recursion_reentry;
 250
 251   /* Location at which to save the argument pointer if it will need to be
 252      referenced.  There are two cases where this is done: if nonlocal gotos
 253      exist, or if vars stored at an offset from the argument pointer will be
 254      needed by inner routines.  */
 255   rtx x_arg_pointer_save_area;
 256
 257   /* Offset to end of allocated area of stack frame.
 258      If stack grows down, this is the address of the last stack slot allocated.
 259      If stack grows up, this is the address for the next slot.  */
 260   HOST_WIDE_INT x_frame_offset;
 261
 262   /* A PARM_DECL that should contain the static chain for this function.
 263      It will be initialized at the beginning of the function.  */
 264   tree static_chain_decl;
 265
 266   /* An expression that contains the non-local goto save area.  The first
 267      word is the saved frame pointer and the second is the saved stack
 268      pointer.  */
 269   tree nonlocal_goto_save_area;
 270
 271   /* Insn after which register parms and SAVE_EXPRs are born, if nonopt.  */
 272   rtx x_parm_birth_insn;
 273
 274   /* List of all used temporaries allocated, by level.  */
 275   struct varray_head_tag * GTY((param_is (struct temp_slot))) x_used_temp_slots;
 276
 277   /* List of available temp slots.  */
 278   struct temp_slot *x_avail_temp_slots;
 279
 280   /* Current nesting level for temporaries.  */
 281   int x_temp_slot_level;
 282
 283   /* This slot is initialized as 0 and is added to
 284      during the nested function.  */
 285   struct var_refs_queue *fixup_var_refs_queue;
 286
 287   /* For integrate.c.  */
 288   int inlinable;
 289   int no_debugging_symbols;
 290   rtvec original_arg_vector;
 291   tree original_decl_initial;
 292
 293   /* Highest label number in current function.  */
 294   int inl_max_label_num;
 295
 296   /* Function sequence number for profiling, debugging, etc.  */
 297   int funcdef_no;
 298
 299   /* For flow.c.  */
 300
 301   /* Highest loop depth seen so far in loop analysis.  Used in flow.c
 302      for the "failure strategy" when doing liveness analysis starting
 303      with non-empty initial sets.  */
 304   int max_loop_depth;
 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   unsigned int stack_alignment_needed;
 312   /* Preferred alignment of the end of stack frame.  */
 313   unsigned 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   /* Assembly labels for the hot and cold text sections, to
 358      be used by debugger functions for determining the size of text
 359      sections.  */
 360
 361   const char *hot_section_label;
 362   const char *cold_section_label;
 363   const char *hot_section_end_label;
 364   const char *cold_section_end_label;
 365
 366   /* String to be used for name of cold text sections, via
 367      targetm.asm_out.named_section.  */
 368
 369   const char *unlikely_text_section_name;
 370
 371   /* Collected bit flags.  */
 372
 373   /* Nonzero if function being compiled needs to be given an address
 374      where the value should be stored.  */
 375   unsigned int returns_struct : 1;
 376
 377   /* Nonzero if function being compiled needs to
 378      return the address of where it has put a structure value.  */
 379   unsigned int returns_pcc_struct : 1;
 380
 381   /* Nonzero if the current function returns a pointer type.  */
 382   unsigned int returns_pointer : 1;
 383
 384   /* Nonzero if function being compiled can call setjmp.  */
 385   unsigned int calls_setjmp : 1;
 386
 387   /* Nonzero if function being compiled can call alloca,
 388      either as a subroutine or builtin.  */
 389   unsigned int calls_alloca : 1;
 390
 391   /* Nonzero if the function calls __builtin_eh_return.  */
 392   unsigned int calls_eh_return : 1;
 393
 394   /* Nonzero if function being compiled receives nonlocal gotos
 395      from nested functions.  */
 396   unsigned int has_nonlocal_label : 1;
 397
 398   /* Nonzero if function being compiled has nonlocal gotos to parent
 399      function.  */
 400   unsigned int has_nonlocal_goto : 1;
 401
 402   /* Nonzero if the current function is a thunk, i.e., a lightweight
 403      function implemented by the output_mi_thunk hook) that just
 404      adjusts one of its arguments and forwards to another
 405      function.  */
 406   unsigned int is_thunk : 1;
 407
 408   /* This bit is used by the exception handling logic.  It is set if all
 409      calls (if any) are sibling calls.  Such functions do not have to
 410      have EH tables generated, as they cannot throw.  A call to such a
 411      function, however, should be treated as throwing if any of its callees
 412      can throw.  */
 413   unsigned int all_throwers_are_sibcalls : 1;
 414
 415   /* Nonzero if profiling code should be generated.  */
 416   unsigned int profile : 1;
 417
 418   /* Nonzero if stack limit checking should be enabled in the current
 419      function.  */
 420   unsigned int limit_stack : 1;
 421
 422   /* Nonzero if current function uses stdarg.h or equivalent.  */
 423   unsigned int stdarg : 1;
 424
 425   /* Nonzero if the back-end should not keep track of expressions that
 426      determine the size of variable-sized objects.  Normally, such
 427      expressions are saved away, and then expanded when the next
 428      function is started.  For example, if a parameter has a
 429      variable-sized type, then the size of the parameter is computed
 430      when the function body is entered.  However, some front-ends do
 431      not desire this behavior.  */
 432   unsigned int x_dont_save_pending_sizes_p : 1;
 433
 434   /* Nonzero if the current function uses the constant pool.  */
 435   unsigned int uses_const_pool : 1;
 436
 437   /* Nonzero if the current function uses pic_offset_table_rtx.  */
 438   unsigned int uses_pic_offset_table : 1;
 439
 440   /* Nonzero if the current function needs an lsda for exception handling.  */
 441   unsigned int uses_eh_lsda : 1;
 442
 443   /* Nonzero if code to initialize arg_pointer_save_area has been emitted.  */
 444   unsigned int arg_pointer_save_area_init : 1;
 445
 446   /* Number of units of general registers that need saving in stdarg
 447      function.  What unit is depends on the backend, either it is number
 448      of bytes, or it can be number of registers.  */
 449   unsigned int va_list_gpr_size : 8;
 450
 451   /* Number of units of floating point registers that need saving in stdarg
 452      function.  */
 453   unsigned int va_list_fpr_size : 8;
 454 };
 455
 456 /* If va_list_[gf]pr_size is set to this, it means we don't know how
 457    many units need to be saved.  */
 458 #define VA_LIST_MAX_GPR_SIZE    255
 459 #define VA_LIST_MAX_FPR_SIZE    255
 460
 461 /* The function currently being compiled.  */
 462 extern GTY(()) struct function *cfun;
 463
 464 /* Pointer to chain of `struct function' for containing functions.  */
 465 extern GTY(()) struct function *outer_function_chain;
 466
 467 /* Nonzero if we've already converted virtual regs to hard regs.  */
 468 extern int virtuals_instantiated;
 469
 470 /* Nonzero if at least one trampoline has been created.  */
 471 extern int trampolines_created;
 472
 473 /* For backward compatibility... eventually these should all go away.  */
 474 #define current_function_pops_args (cfun->pops_args)
 475 #define current_function_returns_struct (cfun->returns_struct)
 476 #define current_function_returns_pcc_struct (cfun->returns_pcc_struct)
 477 #define current_function_returns_pointer (cfun->returns_pointer)
 478 #define current_function_calls_setjmp (cfun->calls_setjmp)
 479 #define current_function_calls_alloca (cfun->calls_alloca)
 480 #define current_function_calls_eh_return (cfun->calls_eh_return)
 481 #define current_function_is_thunk (cfun->is_thunk)
 482 #define current_function_args_info (cfun->args_info)
 483 #define current_function_args_size (cfun->args_size)
 484 #define current_function_pretend_args_size (cfun->pretend_args_size)
 485 #define current_function_outgoing_args_size (cfun->outgoing_args_size)
 486 #define current_function_arg_offset_rtx (cfun->arg_offset_rtx)
 487 #define current_function_stdarg (cfun->stdarg)
 488 #define current_function_internal_arg_pointer (cfun->internal_arg_pointer)
 489 #define current_function_return_rtx (cfun->return_rtx)
 490 #define current_function_profile (cfun->profile)
 491 #define current_function_funcdef_no (cfun->funcdef_no)
 492 #define current_function_limit_stack (cfun->limit_stack)
 493 #define current_function_uses_pic_offset_table (cfun->uses_pic_offset_table)
 494 #define current_function_uses_const_pool (cfun->uses_const_pool)
 495 #define current_function_epilogue_delay_list (cfun->epilogue_delay_list)
 496 #define current_function_has_nonlocal_label (cfun->has_nonlocal_label)
 497 #define current_function_has_nonlocal_goto (cfun->has_nonlocal_goto)
 498
 499 #define return_label (cfun->x_return_label)
 500 #define naked_return_label (cfun->x_naked_return_label)
 501 #define stack_slot_list (cfun->x_stack_slot_list)
 502 #define parm_birth_insn (cfun->x_parm_birth_insn)
 503 #define frame_offset (cfun->x_frame_offset)
 504 #define tail_recursion_reentry (cfun->x_tail_recursion_reentry)
 505 #define arg_pointer_save_area (cfun->x_arg_pointer_save_area)
 506 #define used_temp_slots (cfun->x_used_temp_slots)
 507 #define avail_temp_slots (cfun->x_avail_temp_slots)
 508 #define temp_slot_level (cfun->x_temp_slot_level)
 509 #define nonlocal_goto_handler_labels (cfun->x_nonlocal_goto_handler_labels)
 510
 511 /* Given a function decl for a containing function,
 512    return the `struct function' for it.  */
 513 struct function *find_function_data (tree);
 514
 515 /* Identify BLOCKs referenced by more than one NOTE_INSN_BLOCK_{BEG,END},
 516    and create duplicate blocks.  */
 517 extern void reorder_blocks (void);
 518
 519 /* Set BLOCK_NUMBER for all the blocks in FN.  */
 520 extern void number_blocks (tree);
 521
 522 extern void clear_block_marks (tree);
 523 extern tree blocks_nreverse (tree);
 524 extern void reset_block_changes (void);
 525 extern void record_block_change (tree);
 526 extern void finalize_block_changes (void);
 527 extern void check_block_change (rtx, tree *);
 528 extern void free_block_changes (void);
 529
 530 /* Return size needed for stack frame based on slots so far allocated.
 531    This size counts from zero.  It is not rounded to STACK_BOUNDARY;
 532    the caller may have to do that.  */
 533 extern HOST_WIDE_INT get_frame_size (void);
 534
 535 /* A pointer to a function to create target specific, per-function
 536    data structures.  */
 537 extern struct machine_function * (*init_machine_status) (void);
 538
 539 /* Save and restore status information for a nested function.  */
 540 extern void free_after_parsing (struct function *);
 541 extern void free_after_compilation (struct function *);
 542
 543 extern void init_varasm_status (struct function *);
 544
 545 #ifdef RTX_CODE
 546 extern void diddle_return_value (void (*)(rtx, void*), void*);
 547 extern void clobber_return_register (void);
 548 extern void use_return_register (void);
 549 #endif
 550
 551 extern rtx get_arg_pointer_save_area (struct function *);
 552
 553 extern void init_virtual_regs (struct emit_status *);
 554 extern void instantiate_virtual_regs (void);
 555
 556 /* Returns the name of the current function.  */
 557 extern const char *current_function_name (void);
 558
 559 /* Called once, at initialization, to initialize function.c.  */
 560 extern void init_function_once (void);
 561
 562 extern void do_warn_unused_parameter (tree);
 563
 564 extern bool pass_by_reference (CUMULATIVE_ARGS *, enum machine_mode,
 565                                tree, bool);
 566 extern bool reference_callee_copied (CUMULATIVE_ARGS *, enum machine_mode,
 567                                      tree, bool);
 568
 569 #endif  /* GCC_FUNCTION_H */