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 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   tree saved_blocks;
 182   tree saved_unexpanded_var_list;
 183
 184   /* For function.c.  */
 185
 186   /* Points to the FUNCTION_DECL of this function.  */
 187   tree decl;
 188
 189   /* Function containing this function, if any.  */
 190   struct function *outer;
 191
 192   /* Number of bytes of args popped by function being compiled on its return.
 193      Zero if no bytes are to be popped.
 194      May affect compilation of return insn or of function epilogue.  */
 195   int pops_args;
 196
 197   /* If function's args have a fixed size, this is that size, in bytes.
 198      Otherwise, it is -1.
 199      May affect compilation of return insn or of function epilogue.  */
 200   int args_size;
 201
 202   /* # bytes the prologue should push and pretend that the caller pushed them.
 203      The prologue must do this, but only if parms can be passed in
 204      registers.  */
 205   int pretend_args_size;
 206
 207   /* # of bytes of outgoing arguments.  If ACCUMULATE_OUTGOING_ARGS is
 208      defined, the needed space is pushed by the prologue.  */
 209   int outgoing_args_size;
 210
 211   /* This is the offset from the arg pointer to the place where the first
 212      anonymous arg can be found, if there is one.  */
 213   rtx arg_offset_rtx;
 214
 215   /* Quantities of various kinds of registers
 216      used for the current function's args.  */
 217   CUMULATIVE_ARGS args_info;
 218
 219   /* If nonzero, an RTL expression for the location at which the current
 220      function returns its result.  If the current function returns its
 221      result in a register, current_function_return_rtx will always be
 222      the hard register containing the result.  */
 223   rtx return_rtx;
 224
 225   /* The arg pointer hard register, or the pseudo into which it was copied.  */
 226   rtx internal_arg_pointer;
 227
 228   /* Opaque pointer used by get_hard_reg_initial_val and
 229      has_hard_reg_initial_val (see integrate.[hc]).  */
 230   struct initial_value_struct *hard_reg_initial_vals;
 231
 232   /* List (chain of EXPR_LIST) of labels heading the current handlers for
 233      nonlocal gotos.  */
 234   rtx x_nonlocal_goto_handler_labels;
 235
 236   /* Label that will go on function epilogue.
 237      Jumping to this label serves as a "return" instruction
 238      on machines which require execution of the epilogue on all returns.  */
 239   rtx x_return_label;
 240
 241   /* Label that will go on the end of function epilogue.
 242      Jumping to this label serves as a "naked return" instruction
 243      on machines which require execution of the epilogue on all returns.  */
 244   rtx x_naked_return_label;
 245
 246   /* List (chain of EXPR_LISTs) of all stack slots in this function.
 247      Made for the sake of unshare_all_rtl.  */
 248   rtx x_stack_slot_list;
 249
 250   /* Place after which to insert the tail_recursion_label if we need one.  */
 251   rtx x_tail_recursion_reentry;
 252
 253   /* Location at which to save the argument pointer if it will need to be
 254      referenced.  There are two cases where this is done: if nonlocal gotos
 255      exist, or if vars stored at an offset from the argument pointer will be
 256      needed by inner routines.  */
 257   rtx x_arg_pointer_save_area;
 258
 259   /* Offset to end of allocated area of stack frame.
 260      If stack grows down, this is the address of the last stack slot allocated.
 261      If stack grows up, this is the address for the next slot.  */
 262   HOST_WIDE_INT x_frame_offset;
 263
 264   /* A PARM_DECL that should contain the static chain for this function.
 265      It will be initialized at the beginning of the function.  */
 266   tree static_chain_decl;
 267
 268   /* An expression that contains the non-local goto save area.  The first
 269      word is the saved frame pointer and the second is the saved stack
 270      pointer.  */
 271   tree nonlocal_goto_save_area;
 272
 273   /* Insn after which register parms and SAVE_EXPRs are born, if nonopt.  */
 274   rtx x_parm_birth_insn;
 275
 276   /* List of all used temporaries allocated, by level.  */
 277   struct varray_head_tag * GTY((param_is (struct temp_slot))) x_used_temp_slots;
 278
 279   /* List of available temp slots.  */
 280   struct temp_slot *x_avail_temp_slots;
 281
 282   /* Current nesting level for temporaries.  */
 283   int x_temp_slot_level;
 284
 285   /* This slot is initialized as 0 and is added to
 286      during the nested function.  */
 287   struct var_refs_queue *fixup_var_refs_queue;
 288
 289   /* For integrate.c.  */
 290   int inlinable;
 291   int no_debugging_symbols;
 292   rtvec original_arg_vector;
 293   tree original_decl_initial;
 294
 295   /* Highest label number in current function.  */
 296   int inl_max_label_num;
 297
 298   /* Function sequence number for profiling, debugging, etc.  */
 299   int funcdef_no;
 300
 301   /* For flow.c.  */
 302
 303   /* Highest loop depth seen so far in loop analysis.  Used in flow.c
 304      for the "failure strategy" when doing liveness analysis starting
 305      with non-empty initial sets.  */
 306   int max_loop_depth;
 307
 308   /* For md files.  */
 309
 310   /* tm.h can use this to store whatever it likes.  */
 311   struct machine_function * GTY ((maybe_undef)) machine;
 312   /* The largest alignment of slot allocated on the stack.  */
 313   unsigned int stack_alignment_needed;
 314   /* Preferred alignment of the end of stack frame.  */
 315   unsigned int preferred_stack_boundary;
 316   /* Set when the call to function itself has been emit.  */
 317   bool recursive_call_emit;
 318   /* Set when the tail call has been produced.  */
 319   bool tail_call_emit;
 320
 321   /* Language-specific code can use this to store whatever it likes.  */
 322   struct language_function * language;
 323
 324   /* For reorg.  */
 325
 326   /* If some insns can be deferred to the delay slots of the epilogue, the
 327      delay list for them is recorded here.  */
 328   rtx epilogue_delay_list;
 329
 330   /* How commonly executed the function is.  Initialized during branch
 331      probabilities pass.  */
 332   enum function_frequency {
 333     /* This function most likely won't be executed at all.
 334        (set only when profile feedback is available).  */
 335     FUNCTION_FREQUENCY_UNLIKELY_EXECUTED,
 336     /* The default value.  */
 337     FUNCTION_FREQUENCY_NORMAL,
 338     /* Optimize this function hard
 339        (set only when profile feedback is available).  */
 340     FUNCTION_FREQUENCY_HOT
 341   } function_frequency;
 342
 343   /* Maximal number of entities in the single jumptable.  Used to estimate
 344      final flowgraph size.  */
 345   int max_jumptable_ents;
 346
 347   /* UIDs for LABEL_DECLs.  */
 348   int last_label_uid;
 349
 350   /* Line number of the end of the function.  */
 351   location_t function_end_locus;
 352
 353   /* Array mapping insn uids to blocks.  */
 354   struct varray_head_tag *ib_boundaries_block;
 355
 356   /* The variables unexpanded so far.  */
 357   tree unexpanded_var_list;
 358
 359   /* Assembly labels for the hot and cold text sections, to
 360      be used by debugger functions for determining the size of text
 361      sections.  */
 362
 363   const char *hot_section_label;
 364   const char *cold_section_label;
 365   const char *hot_section_end_label;
 366   const char *cold_section_end_label;
 367
 368   /* String to be used for name of cold text sections, via
 369      targetm.asm_out.named_section.  */
 370
 371   const char *unlikely_text_section_name;
 372
 373   /* A variable living at the top of the frame that holds a known value.
 374      Used for detecting stack clobbers.  */
 375   tree stack_protect_guard;
 376
 377   /* Collected bit flags.  */
 378
 379   /* Nonzero if function being compiled needs to be given an address
 380      where the value should be stored.  */
 381   unsigned int returns_struct : 1;
 382
 383   /* Nonzero if function being compiled needs to
 384      return the address of where it has put a structure value.  */
 385   unsigned int returns_pcc_struct : 1;
 386
 387   /* Nonzero if the current function returns a pointer type.  */
 388   unsigned int returns_pointer : 1;
 389
 390   /* Nonzero if function being compiled can call setjmp.  */
 391   unsigned int calls_setjmp : 1;
 392
 393   /* Nonzero if function being compiled can call alloca,
 394      either as a subroutine or builtin.  */
 395   unsigned int calls_alloca : 1;
 396
 397   /* Nonzero if the function calls __builtin_eh_return.  */
 398   unsigned int calls_eh_return : 1;
 399
 400   /* Nonzero if function being compiled receives nonlocal gotos
 401      from nested functions.  */
 402   unsigned int has_nonlocal_label : 1;
 403
 404   /* Nonzero if function being compiled has nonlocal gotos to parent
 405      function.  */
 406   unsigned int has_nonlocal_goto : 1;
 407
 408   /* Nonzero if the current function is a thunk, i.e., a lightweight
 409      function implemented by the output_mi_thunk hook) that just
 410      adjusts one of its arguments and forwards to another
 411      function.  */
 412   unsigned int is_thunk : 1;
 413
 414   /* This bit is used by the exception handling logic.  It is set if all
 415      calls (if any) are sibling calls.  Such functions do not have to
 416      have EH tables generated, as they cannot throw.  A call to such a
 417      function, however, should be treated as throwing if any of its callees
 418      can throw.  */
 419   unsigned int all_throwers_are_sibcalls : 1;
 420
 421   /* Nonzero if profiling code should be generated.  */
 422   unsigned int profile : 1;
 423
 424   /* Nonzero if stack limit checking should be enabled in the current
 425      function.  */
 426   unsigned int limit_stack : 1;
 427
 428   /* Nonzero if current function uses stdarg.h or equivalent.  */
 429   unsigned int stdarg : 1;
 430
 431   /* Nonzero if the back-end should not keep track of expressions that
 432      determine the size of variable-sized objects.  Normally, such
 433      expressions are saved away, and then expanded when the next
 434      function is started.  For example, if a parameter has a
 435      variable-sized type, then the size of the parameter is computed
 436      when the function body is entered.  However, some front-ends do
 437      not desire this behavior.  */
 438   unsigned int x_dont_save_pending_sizes_p : 1;
 439
 440   /* Nonzero if the current function uses the constant pool.  */
 441   unsigned int uses_const_pool : 1;
 442
 443   /* Nonzero if the current function uses pic_offset_table_rtx.  */
 444   unsigned int uses_pic_offset_table : 1;
 445
 446   /* Nonzero if the current function needs an lsda for exception handling.  */
 447   unsigned int uses_eh_lsda : 1;
 448
 449   /* Nonzero if code to initialize arg_pointer_save_area has been emitted.  */
 450   unsigned int arg_pointer_save_area_init : 1;
 451
 452   /* Number of units of general registers that need saving in stdarg
 453      function.  What unit is depends on the backend, either it is number
 454      of bytes, or it can be number of registers.  */
 455   unsigned int va_list_gpr_size : 8;
 456
 457   /* Number of units of floating point registers that need saving in stdarg
 458      function.  */
 459   unsigned int va_list_fpr_size : 8;
 460 };
 461
 462 /* If va_list_[gf]pr_size is set to this, it means we don't know how
 463    many units need to be saved.  */
 464 #define VA_LIST_MAX_GPR_SIZE    255
 465 #define VA_LIST_MAX_FPR_SIZE    255
 466
 467 /* The function currently being compiled.  */
 468 extern GTY(()) struct function *cfun;
 469
 470 /* Pointer to chain of `struct function' for containing functions.  */
 471 extern GTY(()) struct function *outer_function_chain;
 472
 473 /* Nonzero if we've already converted virtual regs to hard regs.  */
 474 extern int virtuals_instantiated;
 475
 476 /* Nonzero if at least one trampoline has been created.  */
 477 extern int trampolines_created;
 478
 479 /* For backward compatibility... eventually these should all go away.  */
 480 #define current_function_pops_args (cfun->pops_args)
 481 #define current_function_returns_struct (cfun->returns_struct)
 482 #define current_function_returns_pcc_struct (cfun->returns_pcc_struct)
 483 #define current_function_returns_pointer (cfun->returns_pointer)
 484 #define current_function_calls_setjmp (cfun->calls_setjmp)
 485 #define current_function_calls_alloca (cfun->calls_alloca)
 486 #define current_function_calls_eh_return (cfun->calls_eh_return)
 487 #define current_function_is_thunk (cfun->is_thunk)
 488 #define current_function_args_info (cfun->args_info)
 489 #define current_function_args_size (cfun->args_size)
 490 #define current_function_pretend_args_size (cfun->pretend_args_size)
 491 #define current_function_outgoing_args_size (cfun->outgoing_args_size)
 492 #define current_function_arg_offset_rtx (cfun->arg_offset_rtx)
 493 #define current_function_stdarg (cfun->stdarg)
 494 #define current_function_internal_arg_pointer (cfun->internal_arg_pointer)
 495 #define current_function_return_rtx (cfun->return_rtx)
 496 #define current_function_profile (cfun->profile)
 497 #define current_function_funcdef_no (cfun->funcdef_no)
 498 #define current_function_limit_stack (cfun->limit_stack)
 499 #define current_function_uses_pic_offset_table (cfun->uses_pic_offset_table)
 500 #define current_function_uses_const_pool (cfun->uses_const_pool)
 501 #define current_function_epilogue_delay_list (cfun->epilogue_delay_list)
 502 #define current_function_has_nonlocal_label (cfun->has_nonlocal_label)
 503 #define current_function_has_nonlocal_goto (cfun->has_nonlocal_goto)
 504
 505 #define return_label (cfun->x_return_label)
 506 #define naked_return_label (cfun->x_naked_return_label)
 507 #define stack_slot_list (cfun->x_stack_slot_list)
 508 #define parm_birth_insn (cfun->x_parm_birth_insn)
 509 #define frame_offset (cfun->x_frame_offset)
 510 #define tail_recursion_reentry (cfun->x_tail_recursion_reentry)
 511 #define arg_pointer_save_area (cfun->x_arg_pointer_save_area)
 512 #define used_temp_slots (cfun->x_used_temp_slots)
 513 #define avail_temp_slots (cfun->x_avail_temp_slots)
 514 #define temp_slot_level (cfun->x_temp_slot_level)
 515 #define nonlocal_goto_handler_labels (cfun->x_nonlocal_goto_handler_labels)
 516
 517 /* Given a function decl for a containing function,
 518    return the `struct function' for it.  */
 519 struct function *find_function_data (tree);
 520
 521 /* Identify BLOCKs referenced by more than one NOTE_INSN_BLOCK_{BEG,END},
 522    and create duplicate blocks.  */
 523 extern void reorder_blocks (void);
 524
 525 /* Set BLOCK_NUMBER for all the blocks in FN.  */
 526 extern void number_blocks (tree);
 527
 528 extern void clear_block_marks (tree);
 529 extern tree blocks_nreverse (tree);
 530 extern void reset_block_changes (void);
 531 extern void record_block_change (tree);
 532 extern void finalize_block_changes (void);
 533 extern void check_block_change (rtx, tree *);
 534 extern void free_block_changes (void);
 535
 536 /* Return size needed for stack frame based on slots so far allocated.
 537    This size counts from zero.  It is not rounded to STACK_BOUNDARY;
 538    the caller may have to do that.  */
 539 extern HOST_WIDE_INT get_frame_size (void);
 540
 541 /* A pointer to a function to create target specific, per-function
 542    data structures.  */
 543 extern struct machine_function * (*init_machine_status) (void);
 544
 545 /* Save and restore status information for a nested function.  */
 546 extern void free_after_parsing (struct function *);
 547 extern void free_after_compilation (struct function *);
 548
 549 extern void init_varasm_status (struct function *);
 550
 551 #ifdef RTX_CODE
 552 extern void diddle_return_value (void (*)(rtx, void*), void*);
 553 extern void clobber_return_register (void);
 554 extern void use_return_register (void);
 555 #endif
 556
 557 extern rtx get_arg_pointer_save_area (struct function *);
 558
 559 extern void init_virtual_regs (struct emit_status *);
 560 extern void instantiate_virtual_regs (void);
 561
 562 /* Returns the name of the current function.  */
 563 extern const char *current_function_name (void);
 564
 565 extern void do_warn_unused_parameter (tree);
 566
 567 extern bool pass_by_reference (CUMULATIVE_ARGS *, enum machine_mode,
 568                                tree, bool);
 569 extern bool reference_callee_copied (CUMULATIVE_ARGS *, enum machine_mode,
 570                                      tree, bool);
 571
 572 #endif  /* GCC_FUNCTION_H */