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 /* This structure can save all the important global and static variables
 169    describing the status of the current function.  */
 170
 171 struct function GTY(())
 172 {
 173   struct eh_status *eh;
 174   struct expr_status *expr;
 175   struct emit_status *emit;
 176   struct varasm_status *varasm;
 177
 178   /* The control flow graph for this function.  */
 179   struct control_flow_graph *cfg;
 180   bool after_inlining;
 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   /* 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   /* Used types hash table.  */
 323   htab_t GTY ((param_is (union tree_node))) used_types_hash;
 324
 325   /* For reorg.  */
 326
 327   /* If some insns can be deferred to the delay slots of the epilogue, the
 328      delay list for them is recorded here.  */
 329   rtx epilogue_delay_list;
 330
 331   /* How commonly executed the function is.  Initialized during branch
 332      probabilities pass.  */
 333   enum function_frequency {
 334     /* This function most likely won't be executed at all.
 335        (set only when profile feedback is available).  */
 336     FUNCTION_FREQUENCY_UNLIKELY_EXECUTED,
 337     /* The default value.  */
 338     FUNCTION_FREQUENCY_NORMAL,
 339     /* Optimize this function hard
 340        (set only when profile feedback is available).  */
 341     FUNCTION_FREQUENCY_HOT
 342   } function_frequency;
 343
 344   /* Maximal number of entities in the single jumptable.  Used to estimate
 345      final flowgraph size.  */
 346   int max_jumptable_ents;
 347
 348   /* UIDs for LABEL_DECLs.  */
 349   int last_label_uid;
 350
 351   /* Line number of the end of the function.  */
 352   location_t function_end_locus;
 353
 354   /* Array mapping insn uids to blocks.  */
 355   VEC(tree,gc) *ib_boundaries_block;
 356
 357   /* The variables unexpanded so far.  */
 358   tree unexpanded_var_list;
 359
 360   /* Assembly labels for the hot and cold text sections, to
 361      be used by debugger functions for determining the size of text
 362      sections.  */
 363
 364   const char *hot_section_label;
 365   const char *cold_section_label;
 366   const char *hot_section_end_label;
 367   const char *cold_section_end_label;
 368
 369   /* String to be used for name of cold text sections, via
 370      targetm.asm_out.named_section.  */
 371
 372   const char *unlikely_text_section_name;
 373
 374   /* A variable living at the top of the frame that holds a known value.
 375      Used for detecting stack clobbers.  */
 376   tree stack_protect_guard;
 377
 378   /* Collected bit flags.  */
 379
 380   /* Nonzero if function being compiled needs to be given an address
 381      where the value should be stored.  */
 382   unsigned int returns_struct : 1;
 383
 384   /* Nonzero if function being compiled needs to
 385      return the address of where it has put a structure value.  */
 386   unsigned int returns_pcc_struct : 1;
 387
 388   /* Nonzero if the current function returns a pointer type.  */
 389   unsigned int returns_pointer : 1;
 390
 391   /* Nonzero if function being compiled can call setjmp.  */
 392   unsigned int calls_setjmp : 1;
 393
 394   /* Nonzero if function being compiled can call alloca,
 395      either as a subroutine or builtin.  */
 396   unsigned int calls_alloca : 1;
 397
 398   /* Nonzero if function being compiled called builtin_return_addr or
 399      builtin_frame_address with nonzero count.  */
 400   unsigned int accesses_prior_frames : 1;
 401
 402   /* Nonzero if the function calls __builtin_eh_return.  */
 403   unsigned int calls_eh_return : 1;
 404
 405   /* Nonzero if function being compiled receives nonlocal gotos
 406      from nested functions.  */
 407   unsigned int has_nonlocal_label : 1;
 408
 409   /* Nonzero if function being compiled has nonlocal gotos to parent
 410      function.  */
 411   unsigned int has_nonlocal_goto : 1;
 412
 413   /* Nonzero if the current function is a thunk, i.e., a lightweight
 414      function implemented by the output_mi_thunk hook) that just
 415      adjusts one of its arguments and forwards to another
 416      function.  */
 417   unsigned int is_thunk : 1;
 418
 419   /* This bit is used by the exception handling logic.  It is set if all
 420      calls (if any) are sibling calls.  Such functions do not have to
 421      have EH tables generated, as they cannot throw.  A call to such a
 422      function, however, should be treated as throwing if any of its callees
 423      can throw.  */
 424   unsigned int all_throwers_are_sibcalls : 1;
 425
 426   /* Nonzero if profiling code should be generated.  */
 427   unsigned int profile : 1;
 428
 429   /* Nonzero if stack limit checking should be enabled in the current
 430      function.  */
 431   unsigned int limit_stack : 1;
 432
 433   /* Nonzero if current function uses stdarg.h or equivalent.  */
 434   unsigned int stdarg : 1;
 435
 436   /* Nonzero if the back-end should not keep track of expressions that
 437      determine the size of variable-sized objects.  Normally, such
 438      expressions are saved away, and then expanded when the next
 439      function is started.  For example, if a parameter has a
 440      variable-sized type, then the size of the parameter is computed
 441      when the function body is entered.  However, some front-ends do
 442      not desire this behavior.  */
 443   unsigned int x_dont_save_pending_sizes_p : 1;
 444
 445   /* Nonzero if the current function uses the constant pool.  */
 446   unsigned int uses_const_pool : 1;
 447
 448   /* Nonzero if the current function uses pic_offset_table_rtx.  */
 449   unsigned int uses_pic_offset_table : 1;
 450
 451   /* Nonzero if the current function needs an lsda for exception handling.  */
 452   unsigned int uses_eh_lsda : 1;
 453
 454   /* Nonzero if code to initialize arg_pointer_save_area has been emitted.  */
 455   unsigned int arg_pointer_save_area_init : 1;
 456
 457   /* Number of units of general registers that need saving in stdarg
 458      function.  What unit is depends on the backend, either it is number
 459      of bytes, or it can be number of registers.  */
 460   unsigned int va_list_gpr_size : 8;
 461
 462   /* Number of units of floating point registers that need saving in stdarg
 463      function.  */
 464   unsigned int va_list_fpr_size : 8;
 465 };
 466
 467 /* If va_list_[gf]pr_size is set to this, it means we don't know how
 468    many units need to be saved.  */
 469 #define VA_LIST_MAX_GPR_SIZE    255
 470 #define VA_LIST_MAX_FPR_SIZE    255
 471
 472 /* The function currently being compiled.  */
 473 extern GTY(()) struct function *cfun;
 474
 475 /* Pointer to chain of `struct function' for containing functions.  */
 476 extern GTY(()) struct function *outer_function_chain;
 477
 478 /* Nonzero if we've already converted virtual regs to hard regs.  */
 479 extern int virtuals_instantiated;
 480
 481 /* Nonzero if at least one trampoline has been created.  */
 482 extern int trampolines_created;
 483
 484 /* For backward compatibility... eventually these should all go away.  */
 485 #define current_function_pops_args (cfun->pops_args)
 486 #define current_function_returns_struct (cfun->returns_struct)
 487 #define current_function_returns_pcc_struct (cfun->returns_pcc_struct)
 488 #define current_function_returns_pointer (cfun->returns_pointer)
 489 #define current_function_calls_setjmp (cfun->calls_setjmp)
 490 #define current_function_calls_alloca (cfun->calls_alloca)
 491 #define current_function_accesses_prior_frames (cfun->accesses_prior_frames)
 492 #define current_function_calls_eh_return (cfun->calls_eh_return)
 493 #define current_function_is_thunk (cfun->is_thunk)
 494 #define current_function_args_info (cfun->args_info)
 495 #define current_function_args_size (cfun->args_size)
 496 #define current_function_pretend_args_size (cfun->pretend_args_size)
 497 #define current_function_outgoing_args_size (cfun->outgoing_args_size)
 498 #define current_function_arg_offset_rtx (cfun->arg_offset_rtx)
 499 #define current_function_stdarg (cfun->stdarg)
 500 #define current_function_internal_arg_pointer (cfun->internal_arg_pointer)
 501 #define current_function_return_rtx (cfun->return_rtx)
 502 #define current_function_profile (cfun->profile)
 503 #define current_function_funcdef_no (cfun->funcdef_no)
 504 #define current_function_limit_stack (cfun->limit_stack)
 505 #define current_function_uses_pic_offset_table (cfun->uses_pic_offset_table)
 506 #define current_function_uses_const_pool (cfun->uses_const_pool)
 507 #define current_function_epilogue_delay_list (cfun->epilogue_delay_list)
 508 #define current_function_has_nonlocal_label (cfun->has_nonlocal_label)
 509 #define current_function_has_nonlocal_goto (cfun->has_nonlocal_goto)
 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
 523 /* Given a function decl for a containing function,
 524    return the `struct function' for it.  */
 525 struct function *find_function_data (tree);
 526
 527 /* Identify BLOCKs referenced by more than one NOTE_INSN_BLOCK_{BEG,END},
 528    and create duplicate blocks.  */
 529 extern void reorder_blocks (void);
 530
 531 /* Set BLOCK_NUMBER for all the blocks in FN.  */
 532 extern void number_blocks (tree);
 533
 534 extern void clear_block_marks (tree);
 535 extern tree blocks_nreverse (tree);
 536 extern void reset_block_changes (void);
 537 extern void record_block_change (tree);
 538 extern void finalize_block_changes (void);
 539 extern void check_block_change (rtx, tree *);
 540 extern void free_block_changes (void);
 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
 572 extern void do_warn_unused_parameter (tree);
 573
 574 extern bool pass_by_reference (CUMULATIVE_ARGS *, enum machine_mode,
 575                                tree, bool);
 576 extern bool reference_callee_copied (CUMULATIVE_ARGS *, enum machine_mode,
 577                                      tree, bool);
 578
 579 extern void used_types_insert (tree);
 580
 581 #endif  /* GCC_FUNCTION_H */