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 gimple_df;
 163 struct temp_slot;
 164 typedef struct temp_slot *temp_slot_p;
 165
 166 DEF_VEC_P(temp_slot_p);
 167 DEF_VEC_ALLOC_P(temp_slot_p,gc);
 168
 169 enum function_frequency {
 170   /* This function most likely won't be executed at all.
 171      (set only when profile feedback is available).  */
 172   FUNCTION_FREQUENCY_UNLIKELY_EXECUTED,
 173   /* The default value.  */
 174   FUNCTION_FREQUENCY_NORMAL,
 175   /* Optimize this function hard
 176      (set only when profile feedback is available).  */
 177   FUNCTION_FREQUENCY_HOT
 178 };
 179
 180 /* This structure can save all the important global and static variables
 181    describing the status of the current function.  */
 182
 183 struct function GTY(())
 184 {
 185   struct eh_status *eh;
 186   struct expr_status *expr;
 187   struct emit_status *emit;
 188   struct varasm_status *varasm;
 189
 190   /* The control flow graph for this function.  */
 191   struct control_flow_graph *cfg;
 192   /* SSA and dataflow information.  */
 193   struct gimple_df *gimple_df;
 194
 195   /* The loops in this function.  */
 196   struct loops * GTY((skip)) x_current_loops;
 197
 198   /* For function.c.  */
 199
 200   /* Points to the FUNCTION_DECL of this function.  */
 201   tree decl;
 202
 203   /* Function containing this function, if any.  */
 204   struct function *outer;
 205
 206   /* Number of bytes of args popped by function being compiled on its return.
 207      Zero if no bytes are to be popped.
 208      May affect compilation of return insn or of function epilogue.  */
 209   int pops_args;
 210
 211   /* If function's args have a fixed size, this is that size, in bytes.
 212      Otherwise, it is -1.
 213      May affect compilation of return insn or of function epilogue.  */
 214   int args_size;
 215
 216   /* # bytes the prologue should push and pretend that the caller pushed them.
 217      The prologue must do this, but only if parms can be passed in
 218      registers.  */
 219   int pretend_args_size;
 220
 221   /* # of bytes of outgoing arguments.  If ACCUMULATE_OUTGOING_ARGS is
 222      defined, the needed space is pushed by the prologue.  */
 223   int outgoing_args_size;
 224
 225   /* This is the offset from the arg pointer to the place where the first
 226      anonymous arg can be found, if there is one.  */
 227   rtx arg_offset_rtx;
 228
 229   /* Quantities of various kinds of registers
 230      used for the current function's args.  */
 231   CUMULATIVE_ARGS args_info;
 232
 233   /* If nonzero, an RTL expression for the location at which the current
 234      function returns its result.  If the current function returns its
 235      result in a register, current_function_return_rtx will always be
 236      the hard register containing the result.  */
 237   rtx return_rtx;
 238
 239   /* The arg pointer hard register, or the pseudo into which it was copied.  */
 240   rtx internal_arg_pointer;
 241
 242   /* Opaque pointer used by get_hard_reg_initial_val and
 243      has_hard_reg_initial_val (see integrate.[hc]).  */
 244   struct initial_value_struct *hard_reg_initial_vals;
 245
 246   /* List (chain of EXPR_LIST) of labels heading the current handlers for
 247      nonlocal gotos.  */
 248   rtx x_nonlocal_goto_handler_labels;
 249
 250   /* Label that will go on function epilogue.
 251      Jumping to this label serves as a "return" instruction
 252      on machines which require execution of the epilogue on all returns.  */
 253   rtx x_return_label;
 254
 255   /* Label that will go on the end of function epilogue.
 256      Jumping to this label serves as a "naked return" instruction
 257      on machines which require execution of the epilogue on all returns.  */
 258   rtx x_naked_return_label;
 259
 260   /* List (chain of EXPR_LISTs) of all stack slots in this function.
 261      Made for the sake of unshare_all_rtl.  */
 262   rtx x_stack_slot_list;
 263
 264   /* Place after which to insert the tail_recursion_label if we need one.  */
 265   rtx x_stack_check_probe_note;
 266
 267   /* Location at which to save the argument pointer if it will need to be
 268      referenced.  There are two cases where this is done: if nonlocal gotos
 269      exist, or if vars stored at an offset from the argument pointer will be
 270      needed by inner routines.  */
 271   rtx x_arg_pointer_save_area;
 272
 273   /* Offset to end of allocated area of stack frame.
 274      If stack grows down, this is the address of the last stack slot allocated.
 275      If stack grows up, this is the address for the next slot.  */
 276   HOST_WIDE_INT x_frame_offset;
 277
 278   /* A PARM_DECL that should contain the static chain for this function.
 279      It will be initialized at the beginning of the function.  */
 280   tree static_chain_decl;
 281
 282   /* An expression that contains the non-local goto save area.  The first
 283      word is the saved frame pointer and the second is the saved stack
 284      pointer.  */
 285   tree nonlocal_goto_save_area;
 286
 287   /* Insn after which register parms and SAVE_EXPRs are born, if nonopt.  */
 288   rtx x_parm_birth_insn;
 289
 290   /* List of all used temporaries allocated, by level.  */
 291   VEC(temp_slot_p,gc) *x_used_temp_slots;
 292
 293   /* List of available temp slots.  */
 294   struct temp_slot *x_avail_temp_slots;
 295
 296   /* This slot is initialized as 0 and is added to
 297      during the nested function.  */
 298   struct var_refs_queue *fixup_var_refs_queue;
 299
 300   /* Current nesting level for temporaries.  */
 301   int x_temp_slot_level;
 302
 303   /* Highest label number in current function.  */
 304   int inl_max_label_num;
 305
 306   /* Function sequence number for profiling, debugging, etc.  */
 307   int funcdef_no;
 308
 309   /* For flow.c.  */
 310
 311   /* Highest loop depth seen so far in loop analysis.  Used in flow.c
 312      for the "failure strategy" when doing liveness analysis starting
 313      with non-empty initial sets.  */
 314   int max_loop_depth;
 315
 316   /* For md files.  */
 317
 318   /* tm.h can use this to store whatever it likes.  */
 319   struct machine_function * GTY ((maybe_undef)) machine;
 320
 321   /* The largest alignment of slot allocated on the stack.  */
 322   unsigned int stack_alignment_needed;
 323
 324   /* Preferred alignment of the end of stack frame.  */
 325   unsigned int preferred_stack_boundary;
 326
 327   /* Language-specific code can use this to store whatever it likes.  */
 328   struct language_function * language;
 329
 330   /* Used types hash table.  */
 331   htab_t GTY ((param_is (union tree_node))) used_types_hash;
 332
 333   /* For reorg.  */
 334
 335   /* If some insns can be deferred to the delay slots of the epilogue, the
 336      delay list for them is recorded here.  */
 337   rtx epilogue_delay_list;
 338
 339   /* Maximal number of entities in the single jumptable.  Used to estimate
 340      final flowgraph size.  */
 341   int max_jumptable_ents;
 342
 343   /* UIDs for LABEL_DECLs.  */
 344   int last_label_uid;
 345
 346   /* Line number of the end of the function.  */
 347   location_t function_end_locus;
 348
 349   /* Array mapping insn uids to blocks.  */
 350   VEC(tree,gc) *ib_boundaries_block;
 351
 352   /* The variables unexpanded so far.  */
 353   tree unexpanded_var_list;
 354
 355   /* Assembly labels for the hot and cold text sections, to
 356      be used by debugger functions for determining the size of text
 357      sections.  */
 358
 359   const char *hot_section_label;
 360   const char *cold_section_label;
 361   const char *hot_section_end_label;
 362   const char *cold_section_end_label;
 363
 364   /* String to be used for name of cold text sections, via
 365      targetm.asm_out.named_section.  */
 366
 367   const char *unlikely_text_section_name;
 368
 369   /* A variable living at the top of the frame that holds a known value.
 370      Used for detecting stack clobbers.  */
 371   tree stack_protect_guard;
 372
 373   /* Collected bit flags.  */
 374
 375   /* Nonzero if function being compiled needs to be given an address
 376      where the value should be stored.  */
 377   unsigned int returns_struct : 1;
 378
 379   /* Nonzero if function being compiled needs to
 380      return the address of where it has put a structure value.  */
 381   unsigned int returns_pcc_struct : 1;
 382
 383   /* Nonzero if the current function returns a pointer type.  */
 384   unsigned int returns_pointer : 1;
 385
 386   /* Nonzero if function being compiled can call setjmp.  */
 387   unsigned int calls_setjmp : 1;
 388
 389   /* Nonzero if function being compiled can call alloca,
 390      either as a subroutine or builtin.  */
 391   unsigned int calls_alloca : 1;
 392
 393   /* Nonzero if function being compiled called builtin_return_addr or
 394      builtin_frame_address with nonzero count.  */
 395   unsigned int accesses_prior_frames : 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   unsigned int after_inlining : 1;
 453
 454   /* Set when the call to function itself has been emit.  */
 455   unsigned int recursive_call_emit : 1;
 456
 457   /* Set when the tail call has been produced.  */
 458   unsigned int tail_call_emit : 1;
 459
 460   /* How commonly executed the function is.  Initialized during branch
 461      probabilities pass.  */
 462   ENUM_BITFIELD (function_frequency) function_frequency : 2;
 463
 464   /* Number of units of general registers that need saving in stdarg
 465      function.  What unit is depends on the backend, either it is number
 466      of bytes, or it can be number of registers.  */
 467   unsigned int va_list_gpr_size : 8;
 468
 469   /* Number of units of floating point registers that need saving in stdarg
 470      function.  */
 471   unsigned int va_list_fpr_size : 8;
 472 };
 473
 474 /* If va_list_[gf]pr_size is set to this, it means we don't know how
 475    many units need to be saved.  */
 476 #define VA_LIST_MAX_GPR_SIZE    255
 477 #define VA_LIST_MAX_FPR_SIZE    255
 478
 479 /* The function currently being compiled.  */
 480 extern GTY(()) struct function *cfun;
 481
 482 /* Pointer to chain of `struct function' for containing functions.  */
 483 extern GTY(()) struct function *outer_function_chain;
 484
 485 /* Nonzero if we've already converted virtual regs to hard regs.  */
 486 extern int virtuals_instantiated;
 487
 488 /* Nonzero if at least one trampoline has been created.  */
 489 extern int trampolines_created;
 490
 491 /* For backward compatibility... eventually these should all go away.  */
 492 #define current_function_pops_args (cfun->pops_args)
 493 #define current_function_returns_struct (cfun->returns_struct)
 494 #define current_function_returns_pcc_struct (cfun->returns_pcc_struct)
 495 #define current_function_returns_pointer (cfun->returns_pointer)
 496 #define current_function_calls_setjmp (cfun->calls_setjmp)
 497 #define current_function_calls_alloca (cfun->calls_alloca)
 498 #define current_function_accesses_prior_frames (cfun->accesses_prior_frames)
 499 #define current_function_calls_eh_return (cfun->calls_eh_return)
 500 #define current_function_is_thunk (cfun->is_thunk)
 501 #define current_function_args_info (cfun->args_info)
 502 #define current_function_args_size (cfun->args_size)
 503 #define current_function_pretend_args_size (cfun->pretend_args_size)
 504 #define current_function_outgoing_args_size (cfun->outgoing_args_size)
 505 #define current_function_arg_offset_rtx (cfun->arg_offset_rtx)
 506 #define current_function_stdarg (cfun->stdarg)
 507 #define current_function_internal_arg_pointer (cfun->internal_arg_pointer)
 508 #define current_function_return_rtx (cfun->return_rtx)
 509 #define current_function_profile (cfun->profile)
 510 #define current_function_funcdef_no (cfun->funcdef_no)
 511 #define current_function_limit_stack (cfun->limit_stack)
 512 #define current_function_uses_pic_offset_table (cfun->uses_pic_offset_table)
 513 #define current_function_uses_const_pool (cfun->uses_const_pool)
 514 #define current_function_epilogue_delay_list (cfun->epilogue_delay_list)
 515 #define current_function_has_nonlocal_label (cfun->has_nonlocal_label)
 516 #define current_function_has_nonlocal_goto (cfun->has_nonlocal_goto)
 517
 518 #define return_label (cfun->x_return_label)
 519 #define naked_return_label (cfun->x_naked_return_label)
 520 #define stack_slot_list (cfun->x_stack_slot_list)
 521 #define parm_birth_insn (cfun->x_parm_birth_insn)
 522 #define frame_offset (cfun->x_frame_offset)
 523 #define stack_check_probe_note (cfun->x_stack_check_probe_note)
 524 #define arg_pointer_save_area (cfun->x_arg_pointer_save_area)
 525 #define used_temp_slots (cfun->x_used_temp_slots)
 526 #define avail_temp_slots (cfun->x_avail_temp_slots)
 527 #define temp_slot_level (cfun->x_temp_slot_level)
 528 #define nonlocal_goto_handler_labels (cfun->x_nonlocal_goto_handler_labels)
 529 #define current_loops (cfun->x_current_loops)
 530
 531 /* Given a function decl for a containing function,
 532    return the `struct function' for it.  */
 533 struct function *find_function_data (tree);
 534
 535 /* Identify BLOCKs referenced by more than one NOTE_INSN_BLOCK_{BEG,END},
 536    and create duplicate blocks.  */
 537 extern void reorder_blocks (void);
 538
 539 /* Set BLOCK_NUMBER for all the blocks in FN.  */
 540 extern void number_blocks (tree);
 541
 542 extern void clear_block_marks (tree);
 543 extern tree blocks_nreverse (tree);
 544 extern void reset_block_changes (void);
 545 extern void record_block_change (tree);
 546 extern void finalize_block_changes (void);
 547 extern void check_block_change (rtx, tree *);
 548 extern void free_block_changes (void);
 549
 550 /* Return size needed for stack frame based on slots so far allocated.
 551    This size counts from zero.  It is not rounded to STACK_BOUNDARY;
 552    the caller may have to do that.  */
 553 extern HOST_WIDE_INT get_frame_size (void);
 554
 555 /* Issue an error message and return TRUE if frame OFFSET overflows in
 556    the signed target pointer arithmetics for function FUNC.  Otherwise
 557    return FALSE.  */
 558 extern bool frame_offset_overflow (HOST_WIDE_INT, tree);
 559
 560 /* A pointer to a function to create target specific, per-function
 561    data structures.  */
 562 extern struct machine_function * (*init_machine_status) (void);
 563
 564 /* Save and restore status information for a nested function.  */
 565 extern void free_after_parsing (struct function *);
 566 extern void free_after_compilation (struct function *);
 567
 568 extern void init_varasm_status (struct function *);
 569
 570 #ifdef RTX_CODE
 571 extern void diddle_return_value (void (*)(rtx, void*), void*);
 572 extern void clobber_return_register (void);
 573 #endif
 574
 575 extern rtx get_arg_pointer_save_area (struct function *);
 576
 577 /* Returns the name of the current function.  */
 578 extern const char *current_function_name (void);
 579
 580 extern void do_warn_unused_parameter (tree);
 581
 582 extern bool pass_by_reference (CUMULATIVE_ARGS *, enum machine_mode,
 583                                tree, bool);
 584 extern bool reference_callee_copied (CUMULATIVE_ARGS *, enum machine_mode,
 585                                      tree, bool);
 586
 587 extern void used_types_insert (tree);
 588
 589 #endif  /* GCC_FUNCTION_H */