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, 51 Franklin Street, Fifth Floor, Boston, MA
  20 02110-1301, USA.  */
  21
  22 #ifndef GCC_FUNCTION_H
  23 #define GCC_FUNCTION_H
  24
  25 #include "tree.h"
  26 #include "hashtab.h"
  27
  28 struct var_refs_queue GTY(())
  29 {
  30   rtx modified;
  31   enum machine_mode promoted_mode;
  32   int unsignedp;
  33   struct var_refs_queue *next;
  34 };
  35
  36 /* Stack of pending (incomplete) sequences saved by `start_sequence'.
  37    Each element describes one pending sequence.
  38    The main insn-chain is saved in the last element of the chain,
  39    unless the chain is empty.  */
  40
  41 struct sequence_stack GTY(())
  42 {
  43   /* First and last insns in the chain of the saved sequence.  */
  44   rtx first;
  45   rtx last;
  46   struct sequence_stack *next;
  47 };
  48
  49 extern struct sequence_stack *sequence_stack;
  50
  51 /* Stack of single obstacks.  */
  52
  53 struct simple_obstack_stack
  54 {
  55   struct obstack *obstack;
  56   struct simple_obstack_stack *next;
  57 };
  58 \f
  59 struct emit_status GTY(())
  60 {
  61   /* This is reset to LAST_VIRTUAL_REGISTER + 1 at the start of each function.
  62      After rtl generation, it is 1 plus the largest register number used.  */
  63   int x_reg_rtx_no;
  64
  65   /* Lowest label number in current function.  */
  66   int x_first_label_num;
  67
  68   /* The ends of the doubly-linked chain of rtl for the current function.
  69      Both are reset to null at the start of rtl generation for the function.
  70
  71      start_sequence saves both of these on `sequence_stack' and then starts
  72      a new, nested sequence of insns.  */
  73   rtx x_first_insn;
  74   rtx x_last_insn;
  75
  76   /* Stack of pending (incomplete) sequences saved by `start_sequence'.
  77      Each element describes one pending sequence.
  78      The main insn-chain is saved in the last element of the chain,
  79      unless the chain is empty.  */
  80   struct sequence_stack *sequence_stack;
  81
  82   /* INSN_UID for next insn emitted.
  83      Reset to 1 for each function compiled.  */
  84   int x_cur_insn_uid;
  85
  86   /* Location the last line-number NOTE emitted.
  87      This is used to avoid generating duplicates.  */
  88   location_t x_last_location;
  89
  90   /* The length of the regno_pointer_align, regno_decl, and x_regno_reg_rtx
  91      vectors.  Since these vectors are needed during the expansion phase when
  92      the total number of registers in the function is not yet known, the
  93      vectors are copied and made bigger when necessary.  */
  94   int regno_pointer_align_length;
  95
  96   /* Indexed by pseudo register number, if nonzero gives the known alignment
  97      for that pseudo (if REG_POINTER is set in x_regno_reg_rtx).
  98      Allocated in parallel with x_regno_reg_rtx.  */
  99   unsigned char * GTY ((length ("%h.x_reg_rtx_no")))
 100     regno_pointer_align;
 101
 102   /* Indexed by pseudo register number, gives the rtx for that pseudo.
 103      Allocated in parallel with regno_pointer_align.  */
 104   rtx * GTY ((length ("%h.x_reg_rtx_no"))) x_regno_reg_rtx;
 105 };
 106
 107 /* For backward compatibility... eventually these should all go away.  */
 108 #define reg_rtx_no (cfun->emit->x_reg_rtx_no)
 109 #define regno_reg_rtx (cfun->emit->x_regno_reg_rtx)
 110 #define seq_stack (cfun->emit->sequence_stack)
 111
 112 #define REGNO_POINTER_ALIGN(REGNO) (cfun->emit->regno_pointer_align[REGNO])
 113
 114 struct expr_status GTY(())
 115 {
 116   /* Number of units that we should eventually pop off the stack.
 117      These are the arguments to function calls that have already returned.  */
 118   int x_pending_stack_adjust;
 119
 120   /* Under some ABIs, it is the caller's responsibility to pop arguments
 121      pushed for function calls.  A naive implementation would simply pop
 122      the arguments immediately after each call.  However, if several
 123      function calls are made in a row, it is typically cheaper to pop
 124      all the arguments after all of the calls are complete since a
 125      single pop instruction can be used.  Therefore, GCC attempts to
 126      defer popping the arguments until absolutely necessary.  (For
 127      example, at the end of a conditional, the arguments must be popped,
 128      since code outside the conditional won't know whether or not the
 129      arguments need to be popped.)
 130
 131      When INHIBIT_DEFER_POP is nonzero, however, the compiler does not
 132      attempt to defer pops.  Instead, the stack is popped immediately
 133      after each call.  Rather then setting this variable directly, use
 134      NO_DEFER_POP and OK_DEFER_POP.  */
 135   int x_inhibit_defer_pop;
 136
 137   /* If PREFERRED_STACK_BOUNDARY and PUSH_ROUNDING are defined, the stack
 138      boundary can be momentarily unaligned while pushing the arguments.
 139      Record the delta since last aligned boundary here in order to get
 140      stack alignment in the nested function calls working right.  */
 141   int x_stack_pointer_delta;
 142
 143   /* Nonzero means __builtin_saveregs has already been done in this function.
 144      The value is the pseudoreg containing the value __builtin_saveregs
 145      returned.  */
 146   rtx x_saveregs_value;
 147
 148   /* Similarly for __builtin_apply_args.  */
 149   rtx x_apply_args_value;
 150
 151   /* List of labels that must never be deleted.  */
 152   rtx x_forced_labels;
 153 };
 154
 155 #define pending_stack_adjust (cfun->expr->x_pending_stack_adjust)
 156 #define inhibit_defer_pop (cfun->expr->x_inhibit_defer_pop)
 157 #define saveregs_value (cfun->expr->x_saveregs_value)
 158 #define apply_args_value (cfun->expr->x_apply_args_value)
 159 #define forced_labels (cfun->expr->x_forced_labels)
 160 #define stack_pointer_delta (cfun->expr->x_stack_pointer_delta)
 161
 162 struct temp_slot;
 163 typedef struct temp_slot *temp_slot_p;
 164
 165 DEF_VEC_P(temp_slot_p);
 166 DEF_VEC_ALLOC_P(temp_slot_p,gc);
 167
 168 enum function_frequency {
 169   /* This function most likely won't be executed at all.
 170      (set only when profile feedback is available).  */
 171   FUNCTION_FREQUENCY_UNLIKELY_EXECUTED,
 172   /* The default value.  */
 173   FUNCTION_FREQUENCY_NORMAL,
 174   /* Optimize this function hard
 175      (set only when profile feedback is available).  */
 176   FUNCTION_FREQUENCY_HOT
 177 };
 178
 179 /* This structure can save all the important global and static variables
 180    describing the status of the current function.  */
 181
 182 struct function GTY(())
 183 {
 184   struct eh_status *eh;
 185   struct expr_status *expr;
 186   struct emit_status *emit;
 187   struct varasm_status *varasm;
 188
 189   /* The control flow graph for this function.  */
 190   struct control_flow_graph *cfg;
 191
 192   /* For function.c.  */
 193
 194   /* Points to the FUNCTION_DECL of this function.  */
 195   tree decl;
 196
 197   /* Function containing this function, if any.  */
 198   struct function *outer;
 199
 200   /* Number of bytes of args popped by function being compiled on its return.
 201      Zero if no bytes are to be popped.
 202      May affect compilation of return insn or of function epilogue.  */
 203   int pops_args;
 204
 205   /* If function's args have a fixed size, this is that size, in bytes.
 206      Otherwise, it is -1.
 207      May affect compilation of return insn or of function epilogue.  */
 208   int args_size;
 209
 210   /* # bytes the prologue should push and pretend that the caller pushed them.
 211      The prologue must do this, but only if parms can be passed in
 212      registers.  */
 213   int pretend_args_size;
 214
 215   /* # of bytes of outgoing arguments.  If ACCUMULATE_OUTGOING_ARGS is
 216      defined, the needed space is pushed by the prologue.  */
 217   int outgoing_args_size;
 218
 219   /* This is the offset from the arg pointer to the place where the first
 220      anonymous arg can be found, if there is one.  */
 221   rtx arg_offset_rtx;
 222
 223   /* Quantities of various kinds of registers
 224      used for the current function's args.  */
 225   CUMULATIVE_ARGS args_info;
 226
 227   /* If nonzero, an RTL expression for the location at which the current
 228      function returns its result.  If the current function returns its
 229      result in a register, current_function_return_rtx will always be
 230      the hard register containing the result.  */
 231   rtx return_rtx;
 232
 233   /* The arg pointer hard register, or the pseudo into which it was copied.  */
 234   rtx internal_arg_pointer;
 235
 236   /* Opaque pointer used by get_hard_reg_initial_val and
 237      has_hard_reg_initial_val (see integrate.[hc]).  */
 238   struct initial_value_struct *hard_reg_initial_vals;
 239
 240   /* List (chain of EXPR_LIST) of labels heading the current handlers for
 241      nonlocal gotos.  */
 242   rtx x_nonlocal_goto_handler_labels;
 243
 244   /* Label that will go on function epilogue.
 245      Jumping to this label serves as a "return" instruction
 246      on machines which require execution of the epilogue on all returns.  */
 247   rtx x_return_label;
 248
 249   /* Label that will go on the end of function epilogue.
 250      Jumping to this label serves as a "naked return" instruction
 251      on machines which require execution of the epilogue on all returns.  */
 252   rtx x_naked_return_label;
 253
 254   /* List (chain of EXPR_LISTs) of all stack slots in this function.
 255      Made for the sake of unshare_all_rtl.  */
 256   rtx x_stack_slot_list;
 257
 258   /* Place after which to insert the tail_recursion_label if we need one.  */
 259   rtx x_stack_check_probe_note;
 260
 261   /* Location at which to save the argument pointer if it will need to be
 262      referenced.  There are two cases where this is done: if nonlocal gotos
 263      exist, or if vars stored at an offset from the argument pointer will be
 264      needed by inner routines.  */
 265   rtx x_arg_pointer_save_area;
 266
 267   /* Offset to end of allocated area of stack frame.
 268      If stack grows down, this is the address of the last stack slot allocated.
 269      If stack grows up, this is the address for the next slot.  */
 270   HOST_WIDE_INT x_frame_offset;
 271
 272   /* A PARM_DECL that should contain the static chain for this function.
 273      It will be initialized at the beginning of the function.  */
 274   tree static_chain_decl;
 275
 276   /* An expression that contains the non-local goto save area.  The first
 277      word is the saved frame pointer and the second is the saved stack
 278      pointer.  */
 279   tree nonlocal_goto_save_area;
 280
 281   /* Insn after which register parms and SAVE_EXPRs are born, if nonopt.  */
 282   rtx x_parm_birth_insn;
 283
 284   /* List of all used temporaries allocated, by level.  */
 285   VEC(temp_slot_p,gc) *x_used_temp_slots;
 286
 287   /* List of available temp slots.  */
 288   struct temp_slot *x_avail_temp_slots;
 289
 290   /* This slot is initialized as 0 and is added to
 291      during the nested function.  */
 292   struct var_refs_queue *fixup_var_refs_queue;
 293
 294   /* Current nesting level for temporaries.  */
 295   int x_temp_slot_level;
 296
 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 flow.c.  */
 304
 305   /* Highest loop depth seen so far in loop analysis.  Used in flow.c
 306      for the "failure strategy" when doing liveness analysis starting
 307      with non-empty initial sets.  */
 308   int max_loop_depth;
 309
 310   /* For md files.  */
 311
 312   /* tm.h can use this to store whatever it likes.  */
 313   struct machine_function * GTY ((maybe_undef)) machine;
 314
 315   /* The largest alignment of slot allocated on the stack.  */
 316   unsigned int stack_alignment_needed;
 317
 318   /* Preferred alignment of the end of stack frame.  */
 319   unsigned int preferred_stack_boundary;
 320
 321   /* Language-specific code can use this to store whatever it likes.  */
 322   struct language_function * language;
 323
 324   /* Used types hash table.  */
 325   htab_t GTY ((param_is (union tree_node))) used_types_hash;
 326
 327   /* For reorg.  */
 328
 329   /* If some insns can be deferred to the delay slots of the epilogue, the
 330      delay list for them is recorded here.  */
 331   rtx epilogue_delay_list;
 332
 333   /* Maximal number of entities in the single jumptable.  Used to estimate
 334      final flowgraph size.  */
 335   int max_jumptable_ents;
 336
 337   /* UIDs for LABEL_DECLs.  */
 338   int last_label_uid;
 339
 340   /* Line number of the end of the function.  */
 341   location_t function_end_locus;
 342
 343   /* Array mapping insn uids to blocks.  */
 344   VEC(tree,gc) *ib_boundaries_block;
 345
 346   /* The variables unexpanded so far.  */
 347   tree unexpanded_var_list;
 348
 349   /* Assembly labels for the hot and cold text sections, to
 350      be used by debugger functions for determining the size of text
 351      sections.  */
 352
 353   const char *hot_section_label;
 354   const char *cold_section_label;
 355   const char *hot_section_end_label;
 356   const char *cold_section_end_label;
 357
 358   /* String to be used for name of cold text sections, via
 359      targetm.asm_out.named_section.  */
 360
 361   const char *unlikely_text_section_name;
 362
 363   /* A variable living at the top of the frame that holds a known value.
 364      Used for detecting stack clobbers.  */
 365   tree stack_protect_guard;
 366
 367   /* Collected bit flags.  */
 368
 369   /* Nonzero if function being compiled needs to be given an address
 370      where the value should be stored.  */
 371   unsigned int returns_struct : 1;
 372
 373   /* Nonzero if function being compiled needs to
 374      return the address of where it has put a structure value.  */
 375   unsigned int returns_pcc_struct : 1;
 376
 377   /* Nonzero if the current function returns a pointer type.  */
 378   unsigned int returns_pointer : 1;
 379
 380   /* Nonzero if function being compiled can call setjmp.  */
 381   unsigned int calls_setjmp : 1;
 382
 383   /* Nonzero if function being compiled can call alloca,
 384      either as a subroutine or builtin.  */
 385   unsigned int calls_alloca : 1;
 386
 387   /* Nonzero if function being compiled called builtin_return_addr or
 388      builtin_frame_address with nonzero count.  */
 389   unsigned int accesses_prior_frames : 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   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   /* Set when the tail call has been produced.  */
 452   unsigned int tail_call_emit : 1;
 453
 454   /* How commonly executed the function is.  Initialized during branch
 455      probabilities pass.  */
 456   ENUM_BITFIELD (function_frequency) function_frequency : 2;
 457
 458   /* Number of units of general registers that need saving in stdarg
 459      function.  What unit is depends on the backend, either it is number
 460      of bytes, or it can be number of registers.  */
 461   unsigned int va_list_gpr_size : 8;
 462
 463   /* Number of units of floating point registers that need saving in stdarg
 464      function.  */
 465   unsigned int va_list_fpr_size : 8;
 466 };
 467
 468 /* If va_list_[gf]pr_size is set to this, it means we don't know how
 469    many units need to be saved.  */
 470 #define VA_LIST_MAX_GPR_SIZE    255
 471 #define VA_LIST_MAX_FPR_SIZE    255
 472
 473 /* The function currently being compiled.  */
 474 extern GTY(()) struct function *cfun;
 475
 476 /* Pointer to chain of `struct function' for containing functions.  */
 477 extern GTY(()) struct function *outer_function_chain;
 478
 479 /* Nonzero if we've already converted virtual regs to hard regs.  */
 480 extern int virtuals_instantiated;
 481
 482 /* Nonzero if at least one trampoline has been created.  */
 483 extern int trampolines_created;
 484
 485 /* For backward compatibility... eventually these should all go away.  */
 486 #define current_function_pops_args (cfun->pops_args)
 487 #define current_function_returns_struct (cfun->returns_struct)
 488 #define current_function_returns_pcc_struct (cfun->returns_pcc_struct)
 489 #define current_function_returns_pointer (cfun->returns_pointer)
 490 #define current_function_calls_setjmp (cfun->calls_setjmp)
 491 #define current_function_calls_alloca (cfun->calls_alloca)
 492 #define current_function_accesses_prior_frames (cfun->accesses_prior_frames)
 493 #define current_function_calls_eh_return (cfun->calls_eh_return)
 494 #define current_function_is_thunk (cfun->is_thunk)
 495 #define current_function_args_info (cfun->args_info)
 496 #define current_function_args_size (cfun->args_size)
 497 #define current_function_pretend_args_size (cfun->pretend_args_size)
 498 #define current_function_outgoing_args_size (cfun->outgoing_args_size)
 499 #define current_function_arg_offset_rtx (cfun->arg_offset_rtx)
 500 #define current_function_stdarg (cfun->stdarg)
 501 #define current_function_internal_arg_pointer (cfun->internal_arg_pointer)
 502 #define current_function_return_rtx (cfun->return_rtx)
 503 #define current_function_profile (cfun->profile)
 504 #define current_function_funcdef_no (cfun->funcdef_no)
 505 #define current_function_limit_stack (cfun->limit_stack)
 506 #define current_function_uses_pic_offset_table (cfun->uses_pic_offset_table)
 507 #define current_function_uses_const_pool (cfun->uses_const_pool)
 508 #define current_function_epilogue_delay_list (cfun->epilogue_delay_list)
 509 #define current_function_has_nonlocal_label (cfun->has_nonlocal_label)
 510 #define current_function_has_nonlocal_goto (cfun->has_nonlocal_goto)
 511
 512 #define return_label (cfun->x_return_label)
 513 #define naked_return_label (cfun->x_naked_return_label)
 514 #define stack_slot_list (cfun->x_stack_slot_list)
 515 #define parm_birth_insn (cfun->x_parm_birth_insn)
 516 #define frame_offset (cfun->x_frame_offset)
 517 #define stack_check_probe_note (cfun->x_stack_check_probe_note)
 518 #define arg_pointer_save_area (cfun->x_arg_pointer_save_area)
 519 #define used_temp_slots (cfun->x_used_temp_slots)
 520 #define avail_temp_slots (cfun->x_avail_temp_slots)
 521 #define temp_slot_level (cfun->x_temp_slot_level)
 522 #define nonlocal_goto_handler_labels (cfun->x_nonlocal_goto_handler_labels)
 523
 524 /* Given a function decl for a containing function,
 525    return the `struct function' for it.  */
 526 struct function *find_function_data (tree);
 527
 528 /* Identify BLOCKs referenced by more than one NOTE_INSN_BLOCK_{BEG,END},
 529    and create duplicate blocks.  */
 530 extern void reorder_blocks (void);
 531
 532 /* Set BLOCK_NUMBER for all the blocks in FN.  */
 533 extern void number_blocks (tree);
 534
 535 extern void clear_block_marks (tree);
 536 extern tree blocks_nreverse (tree);
 537 extern void reset_block_changes (void);
 538 extern void record_block_change (tree);
 539 extern void finalize_block_changes (void);
 540 extern void check_block_change (rtx, tree *);
 541 extern void free_block_changes (void);
 542
 543 /* Return size needed for stack frame based on slots so far allocated.
 544    This size counts from zero.  It is not rounded to STACK_BOUNDARY;
 545    the caller may have to do that.  */
 546 extern HOST_WIDE_INT get_frame_size (void);
 547
 548 /* Issue an error message and return TRUE if frame OFFSET overflows in
 549    the signed target pointer arithmetics for function FUNC.  Otherwise
 550    return FALSE.  */
 551 extern bool frame_offset_overflow (HOST_WIDE_INT, tree);
 552
 553 /* A pointer to a function to create target specific, per-function
 554    data structures.  */
 555 extern struct machine_function * (*init_machine_status) (void);
 556
 557 /* Save and restore status information for a nested function.  */
 558 extern void free_after_parsing (struct function *);
 559 extern void free_after_compilation (struct function *);
 560
 561 extern void init_varasm_status (struct function *);
 562
 563 #ifdef RTX_CODE
 564 extern void diddle_return_value (void (*)(rtx, void*), void*);
 565 extern void clobber_return_register (void);
 566 #endif
 567
 568 extern rtx get_arg_pointer_save_area (struct function *);
 569
 570 /* Returns the name of the current function.  */
 571 extern const char *current_function_name (void);
 572
 573 extern void do_warn_unused_parameter (tree);
 574
 575 extern bool pass_by_reference (CUMULATIVE_ARGS *, enum machine_mode,
 576                                tree, bool);
 577 extern bool reference_callee_copied (CUMULATIVE_ARGS *, enum machine_mode,
 578                                      tree, bool);
 579
 580 extern void used_types_insert (tree);
 581
 582 #endif  /* GCC_FUNCTION_H */