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, 2006, 2007 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 3, 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 COPYING3.  If not see
  19 <http://www.gnu.org/licenses/>.  */
  20
  21 #ifndef GCC_FUNCTION_H
  22 #define GCC_FUNCTION_H
  23
  24 #include "tree.h"
  25 #include "hashtab.h"
  26
  27 /* Stack of pending (incomplete) sequences saved by `start_sequence'.
  28    Each element describes one pending sequence.
  29    The main insn-chain is saved in the last element of the chain,
  30    unless the chain is empty.  */
  31
  32 struct sequence_stack GTY(())
  33 {
  34   /* First and last insns in the chain of the saved sequence.  */
  35   rtx first;
  36   rtx last;
  37   struct sequence_stack *next;
  38 };
  39 \f
  40 struct emit_status GTY(())
  41 {
  42   /* This is reset to LAST_VIRTUAL_REGISTER + 1 at the start of each function.
  43      After rtl generation, it is 1 plus the largest register number used.  */
  44   int x_reg_rtx_no;
  45
  46   /* Lowest label number in current function.  */
  47   int x_first_label_num;
  48
  49   /* The ends of the doubly-linked chain of rtl for the current function.
  50      Both are reset to null at the start of rtl generation for the function.
  51
  52      start_sequence saves both of these on `sequence_stack' and then starts
  53      a new, nested sequence of insns.  */
  54   rtx x_first_insn;
  55   rtx x_last_insn;
  56
  57   /* Stack of pending (incomplete) sequences saved by `start_sequence'.
  58      Each element describes one pending sequence.
  59      The main insn-chain is saved in the last element of the chain,
  60      unless the chain is empty.  */
  61   struct sequence_stack *sequence_stack;
  62
  63   /* INSN_UID for next insn emitted.
  64      Reset to 1 for each function compiled.  */
  65   int x_cur_insn_uid;
  66
  67   /* Location the last line-number NOTE emitted.
  68      This is used to avoid generating duplicates.  */
  69   location_t x_last_location;
  70
  71   /* The length of the regno_pointer_align, regno_decl, and x_regno_reg_rtx
  72      vectors.  Since these vectors are needed during the expansion phase when
  73      the total number of registers in the function is not yet known, the
  74      vectors are copied and made bigger when necessary.  */
  75   int regno_pointer_align_length;
  76
  77   /* Indexed by pseudo register number, if nonzero gives the known alignment
  78      for that pseudo (if REG_POINTER is set in x_regno_reg_rtx).
  79      Allocated in parallel with x_regno_reg_rtx.  */
  80   unsigned char * GTY ((length ("%h.x_reg_rtx_no")))
  81     regno_pointer_align;
  82
  83   /* Indexed by pseudo register number, gives the rtx for that pseudo.
  84      Allocated in parallel with regno_pointer_align.  */
  85   rtx * GTY ((length ("%h.x_reg_rtx_no"))) x_regno_reg_rtx;
  86 };
  87
  88 /* For backward compatibility... eventually these should all go away.  */
  89 #define reg_rtx_no (cfun->emit->x_reg_rtx_no)
  90 #define regno_reg_rtx (cfun->emit->x_regno_reg_rtx)
  91 #define seq_stack (cfun->emit->sequence_stack)
  92
  93 #define REGNO_POINTER_ALIGN(REGNO) (cfun->emit->regno_pointer_align[REGNO])
  94
  95 struct expr_status GTY(())
  96 {
  97   /* Number of units that we should eventually pop off the stack.
  98      These are the arguments to function calls that have already returned.  */
  99   int x_pending_stack_adjust;
 100
 101   /* Under some ABIs, it is the caller's responsibility to pop arguments
 102      pushed for function calls.  A naive implementation would simply pop
 103      the arguments immediately after each call.  However, if several
 104      function calls are made in a row, it is typically cheaper to pop
 105      all the arguments after all of the calls are complete since a
 106      single pop instruction can be used.  Therefore, GCC attempts to
 107      defer popping the arguments until absolutely necessary.  (For
 108      example, at the end of a conditional, the arguments must be popped,
 109      since code outside the conditional won't know whether or not the
 110      arguments need to be popped.)
 111
 112      When INHIBIT_DEFER_POP is nonzero, however, the compiler does not
 113      attempt to defer pops.  Instead, the stack is popped immediately
 114      after each call.  Rather then setting this variable directly, use
 115      NO_DEFER_POP and OK_DEFER_POP.  */
 116   int x_inhibit_defer_pop;
 117
 118   /* If PREFERRED_STACK_BOUNDARY and PUSH_ROUNDING are defined, the stack
 119      boundary can be momentarily unaligned while pushing the arguments.
 120      Record the delta since last aligned boundary here in order to get
 121      stack alignment in the nested function calls working right.  */
 122   int x_stack_pointer_delta;
 123
 124   /* Nonzero means __builtin_saveregs has already been done in this function.
 125      The value is the pseudoreg containing the value __builtin_saveregs
 126      returned.  */
 127   rtx x_saveregs_value;
 128
 129   /* Similarly for __builtin_apply_args.  */
 130   rtx x_apply_args_value;
 131
 132   /* List of labels that must never be deleted.  */
 133   rtx x_forced_labels;
 134 };
 135
 136 #define pending_stack_adjust (cfun->expr->x_pending_stack_adjust)
 137 #define inhibit_defer_pop (cfun->expr->x_inhibit_defer_pop)
 138 #define saveregs_value (cfun->expr->x_saveregs_value)
 139 #define apply_args_value (cfun->expr->x_apply_args_value)
 140 #define forced_labels (cfun->expr->x_forced_labels)
 141 #define stack_pointer_delta (cfun->expr->x_stack_pointer_delta)
 142
 143 struct gimple_df;
 144 struct temp_slot;
 145 typedef struct temp_slot *temp_slot_p;
 146
 147 DEF_VEC_P(temp_slot_p);
 148 DEF_VEC_ALLOC_P(temp_slot_p,gc);
 149
 150 enum function_frequency {
 151   /* This function most likely won't be executed at all.
 152      (set only when profile feedback is available or via function attribute). */
 153   FUNCTION_FREQUENCY_UNLIKELY_EXECUTED,
 154   /* The default value.  */
 155   FUNCTION_FREQUENCY_NORMAL,
 156   /* Optimize this function hard
 157      (set only when profile feedback is available or via function attribute). */
 158   FUNCTION_FREQUENCY_HOT
 159 };
 160
 161 /* This structure can save all the important global and static variables
 162    describing the status of the current function.  */
 163
 164 struct function GTY(())
 165 {
 166   struct eh_status *eh;
 167   struct expr_status *expr;
 168   struct emit_status *emit;
 169   struct varasm_status *varasm;
 170
 171   /* The control flow graph for this function.  */
 172   struct control_flow_graph *cfg;
 173   /* SSA and dataflow information.  */
 174   struct gimple_df *gimple_df;
 175
 176   /* The loops in this function.  */
 177   struct loops *x_current_loops;
 178
 179   /* Value histograms attached to particular statements.  */
 180   htab_t GTY((skip)) value_histograms;
 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_stack_check_probe_note;
 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   VEC(temp_slot_p,gc) *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   /* Highest label number in current function.  */
 284   int inl_max_label_num;
 285
 286   /* Function sequence number for profiling, debugging, etc.  */
 287   int funcdef_no;
 288
 289   /* For md files.  */
 290
 291   /* tm.h can use this to store whatever it likes.  */
 292   struct machine_function * GTY ((maybe_undef)) machine;
 293
 294   /* The largest alignment of slot allocated on the stack.  */
 295   unsigned int stack_alignment_needed;
 296
 297   /* Preferred alignment of the end of stack frame.  */
 298   unsigned int preferred_stack_boundary;
 299
 300   /* Language-specific code can use this to store whatever it likes.  */
 301   struct language_function * language;
 302
 303   /* Used types hash table.  */
 304   htab_t GTY ((param_is (union tree_node))) used_types_hash;
 305
 306   /* For reorg.  */
 307
 308   /* If some insns can be deferred to the delay slots of the epilogue, the
 309      delay list for them is recorded here.  */
 310   rtx epilogue_delay_list;
 311
 312   /* Maximal number of entities in the single jumptable.  Used to estimate
 313      final flowgraph size.  */
 314   int max_jumptable_ents;
 315
 316   /* UIDs for LABEL_DECLs.  */
 317   int last_label_uid;
 318
 319   /* Line number of the end of the function.  */
 320   location_t function_end_locus;
 321
 322   /* The variables unexpanded so far.  */
 323   tree unexpanded_var_list;
 324
 325   /* Assembly labels for the hot and cold text sections, to
 326      be used by debugger functions for determining the size of text
 327      sections.  */
 328
 329   const char *hot_section_label;
 330   const char *cold_section_label;
 331   const char *hot_section_end_label;
 332   const char *cold_section_end_label;
 333
 334   /* String to be used for name of cold text sections, via
 335      targetm.asm_out.named_section.  */
 336
 337   const char *unlikely_text_section_name;
 338
 339   /* A variable living at the top of the frame that holds a known value.
 340      Used for detecting stack clobbers.  */
 341   tree stack_protect_guard;
 342
 343   /* Properties used by the pass manager.  */
 344   unsigned int curr_properties;
 345   unsigned int last_verified;
 346
 347   /* Collected bit flags.  */
 348
 349   /* Number of units of general registers that need saving in stdarg
 350      function.  What unit is depends on the backend, either it is number
 351      of bytes, or it can be number of registers.  */
 352   unsigned int va_list_gpr_size : 8;
 353
 354   /* Number of units of floating point registers that need saving in stdarg
 355      function.  */
 356   unsigned int va_list_fpr_size : 8;
 357
 358
 359   /* How commonly executed the function is.  Initialized during branch
 360      probabilities pass.  */
 361   ENUM_BITFIELD (function_frequency) function_frequency : 2;
 362
 363   /* Nonzero if function being compiled needs to be given an address
 364      where the value should be stored.  */
 365   unsigned int returns_struct : 1;
 366
 367   /* Nonzero if function being compiled needs to
 368      return the address of where it has put a structure value.  */
 369   unsigned int returns_pcc_struct : 1;
 370
 371   /* Nonzero if function being compiled can call setjmp.  */
 372   unsigned int calls_setjmp : 1;
 373
 374   /* Nonzero if function being compiled can call alloca,
 375      either as a subroutine or builtin.  */
 376   unsigned int calls_alloca : 1;
 377
 378   /* Nonzero if function being compiled called builtin_return_addr or
 379      builtin_frame_address with nonzero count.  */
 380   unsigned int accesses_prior_frames : 1;
 381
 382   /* Nonzero if the function calls __builtin_eh_return.  */
 383   unsigned int calls_eh_return : 1;
 384
 385
 386   /* Nonzero if function being compiled receives nonlocal gotos
 387      from nested functions.  */
 388   unsigned int has_nonlocal_label : 1;
 389
 390   /* Nonzero if function saves all registers, e.g. if it has a nonlocal
 391      label that can reach the exit block via non-exceptional paths. */
 392   unsigned int saves_all_registers : 1;
 393
 394   /* Nonzero if function being compiled has nonlocal gotos to parent
 395      function.  */
 396   unsigned int has_nonlocal_goto : 1;
 397
 398   /* Nonzero if function being compiled has an asm statement.  */
 399   unsigned int has_asm_statement : 1;
 400
 401   /* Nonzero if the current function is a thunk, i.e., a lightweight
 402      function implemented by the output_mi_thunk hook) that just
 403      adjusts one of its arguments and forwards to another
 404      function.  */
 405   unsigned int is_thunk : 1;
 406
 407   /* This bit is used by the exception handling logic.  It is set if all
 408      calls (if any) are sibling calls.  Such functions do not have to
 409      have EH tables generated, as they cannot throw.  A call to such a
 410      function, however, should be treated as throwing if any of its callees
 411      can throw.  */
 412   unsigned int all_throwers_are_sibcalls : 1;
 413
 414   /* Nonzero if profiling code should be generated.  */
 415   unsigned int profile : 1;
 416
 417   /* Nonzero if stack limit checking should be enabled in the current
 418      function.  */
 419   unsigned int limit_stack : 1;
 420
 421
 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   unsigned int after_inlining : 1;
 447
 448   /* Set when the call to function itself has been emit.  */
 449   unsigned int recursive_call_emit : 1;
 450
 451
 452   /* Set when the tail call has been produced.  */
 453   unsigned int tail_call_emit : 1;
 454
 455   /* FIXME tuples: This bit is temporarily here to mark when a
 456      function has been gimplified, so we can make sure we're not
 457      creating non GIMPLE tuples after gimplification.  */
 458   unsigned int gimplified : 1;
 459 };
 460
 461 /* If va_list_[gf]pr_size is set to this, it means we don't know how
 462    many units need to be saved.  */
 463 #define VA_LIST_MAX_GPR_SIZE    255
 464 #define VA_LIST_MAX_FPR_SIZE    255
 465
 466 /* The function currently being compiled.  */
 467 extern GTY(()) struct function *cfun;
 468
 469 /* Pointer to chain of `struct function' for containing functions.  */
 470 extern GTY(()) struct function *outer_function_chain;
 471
 472 /* Nonzero if we've already converted virtual regs to hard regs.  */
 473 extern int virtuals_instantiated;
 474
 475 /* Nonzero if at least one trampoline has been created.  */
 476 extern int trampolines_created;
 477
 478 /* cfun shouldn't be set directly; use one of these functions instead.  */
 479 extern void set_cfun (struct function *new_cfun);
 480 extern void push_cfun (struct function *new_cfun);
 481 extern void pop_cfun (void);
 482
 483 /* For backward compatibility... eventually these should all go away.  */
 484 #define current_function_pops_args (cfun->pops_args)
 485 #define current_function_returns_struct (cfun->returns_struct)
 486 #define current_function_returns_pcc_struct (cfun->returns_pcc_struct)
 487 #define current_function_calls_setjmp (cfun->calls_setjmp)
 488 #define current_function_calls_alloca (cfun->calls_alloca)
 489 #define current_function_accesses_prior_frames (cfun->accesses_prior_frames)
 490 #define current_function_calls_eh_return (cfun->calls_eh_return)
 491 #define current_function_is_thunk (cfun->is_thunk)
 492 #define current_function_args_info (cfun->args_info)
 493 #define current_function_args_size (cfun->args_size)
 494 #define current_function_pretend_args_size (cfun->pretend_args_size)
 495 #define current_function_outgoing_args_size (cfun->outgoing_args_size)
 496 #define current_function_arg_offset_rtx (cfun->arg_offset_rtx)
 497 #define current_function_stdarg (cfun->stdarg)
 498 #define current_function_internal_arg_pointer (cfun->internal_arg_pointer)
 499 #define current_function_return_rtx (cfun->return_rtx)
 500 #define current_function_profile (cfun->profile)
 501 #define current_function_funcdef_no (cfun->funcdef_no)
 502 #define current_function_limit_stack (cfun->limit_stack)
 503 #define current_function_uses_pic_offset_table (cfun->uses_pic_offset_table)
 504 #define current_function_uses_const_pool (cfun->uses_const_pool)
 505 #define current_function_epilogue_delay_list (cfun->epilogue_delay_list)
 506 #define current_function_has_nonlocal_label (cfun->has_nonlocal_label)
 507 #define current_function_saves_all_registers (cfun->saves_all_registers)
 508 #define current_function_has_nonlocal_goto (cfun->has_nonlocal_goto)
 509 #define current_function_has_asm_statement (cfun->has_asm_statement)
 510
 511 #define return_label (cfun->x_return_label)
 512 #define naked_return_label (cfun->x_naked_return_label)
 513 #define stack_slot_list (cfun->x_stack_slot_list)
 514 #define parm_birth_insn (cfun->x_parm_birth_insn)
 515 #define frame_offset (cfun->x_frame_offset)
 516 #define stack_check_probe_note (cfun->x_stack_check_probe_note)
 517 #define arg_pointer_save_area (cfun->x_arg_pointer_save_area)
 518 #define used_temp_slots (cfun->x_used_temp_slots)
 519 #define avail_temp_slots (cfun->x_avail_temp_slots)
 520 #define temp_slot_level (cfun->x_temp_slot_level)
 521 #define nonlocal_goto_handler_labels (cfun->x_nonlocal_goto_handler_labels)
 522 #define rtl_df (cfun->df)
 523 #define current_loops (cfun->x_current_loops)
 524 #define dom_computed (cfun->cfg->x_dom_computed)
 525 #define n_bbs_in_dom_tree (cfun->cfg->x_n_bbs_in_dom_tree)
 526 #define VALUE_HISTOGRAMS(fun) (fun)->value_histograms
 527
 528 /* Given a function decl for a containing function,
 529    return the `struct function' for it.  */
 530 struct function *find_function_data (tree);
 531
 532 /* Identify BLOCKs referenced by more than one NOTE_INSN_BLOCK_{BEG,END},
 533    and create duplicate blocks.  */
 534 extern void reorder_blocks (void);
 535
 536 /* Set BLOCK_NUMBER for all the blocks in FN.  */
 537 extern void number_blocks (tree);
 538
 539 extern void clear_block_marks (tree);
 540 extern tree blocks_nreverse (tree);
 541
 542 /* Return size needed for stack frame based on slots so far allocated.
 543    This size counts from zero.  It is not rounded to STACK_BOUNDARY;
 544    the caller may have to do that.  */
 545 extern HOST_WIDE_INT get_frame_size (void);
 546
 547 /* Issue an error message and return TRUE if frame OFFSET overflows in
 548    the signed target pointer arithmetics for function FUNC.  Otherwise
 549    return FALSE.  */
 550 extern bool frame_offset_overflow (HOST_WIDE_INT, tree);
 551
 552 /* A pointer to a function to create target specific, per-function
 553    data structures.  */
 554 extern struct machine_function * (*init_machine_status) (void);
 555
 556 /* Save and restore status information for a nested function.  */
 557 extern void free_after_parsing (struct function *);
 558 extern void free_after_compilation (struct function *);
 559
 560 extern void init_varasm_status (struct function *);
 561
 562 #ifdef RTX_CODE
 563 extern void diddle_return_value (void (*)(rtx, void*), void*);
 564 extern void clobber_return_register (void);
 565 #endif
 566
 567 extern rtx get_arg_pointer_save_area (struct function *);
 568
 569 /* Returns the name of the current function.  */
 570 extern const char *current_function_name (void);
 571 /* Returns the assembler name (raw, mangled) of the current function.  */
 572 extern const char *current_function_assembler_name (void);
 573
 574 extern void do_warn_unused_parameter (tree);
 575
 576 extern bool pass_by_reference (CUMULATIVE_ARGS *, enum machine_mode,
 577                                tree, bool);
 578 extern bool reference_callee_copied (CUMULATIVE_ARGS *, enum machine_mode,
 579                                      tree, bool);
 580
 581 extern void used_types_insert (tree);
 582
 583 extern int get_next_funcdef_no (void);
 584 #endif  /* GCC_FUNCTION_H */