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   /* The loops in this function.  */
 193   struct loops * GTY((skip)) x_current_loops;
 194
 195   /* For function.c.  */
 196
 197   /* Points to the FUNCTION_DECL of this function.  */
 198   tree decl;
 199
 200   /* Function containing this function, if any.  */
 201   struct function *outer;
 202
 203   /* Number of bytes of args popped by function being compiled on its return.
 204      Zero if no bytes are to be popped.
 205      May affect compilation of return insn or of function epilogue.  */
 206   int pops_args;
 207
 208   /* If function's args have a fixed size, this is that size, in bytes.
 209      Otherwise, it is -1.
 210      May affect compilation of return insn or of function epilogue.  */
 211   int args_size;
 212
 213   /* # bytes the prologue should push and pretend that the caller pushed them.
 214      The prologue must do this, but only if parms can be passed in
 215      registers.  */
 216   int pretend_args_size;
 217
 218   /* # of bytes of outgoing arguments.  If ACCUMULATE_OUTGOING_ARGS is
 219      defined, the needed space is pushed by the prologue.  */
 220   int outgoing_args_size;
 221
 222   /* This is the offset from the arg pointer to the place where the first
 223      anonymous arg can be found, if there is one.  */
 224   rtx arg_offset_rtx;
 225
 226   /* Quantities of various kinds of registers
 227      used for the current function's args.  */
 228   CUMULATIVE_ARGS args_info;
 229
 230   /* If nonzero, an RTL expression for the location at which the current
 231      function returns its result.  If the current function returns its
 232      result in a register, current_function_return_rtx will always be
 233      the hard register containing the result.  */
 234   rtx return_rtx;
 235
 236   /* The arg pointer hard register, or the pseudo into which it was copied.  */
 237   rtx internal_arg_pointer;
 238
 239   /* Opaque pointer used by get_hard_reg_initial_val and
 240      has_hard_reg_initial_val (see integrate.[hc]).  */
 241   struct initial_value_struct *hard_reg_initial_vals;
 242
 243   /* List (chain of EXPR_LIST) of labels heading the current handlers for
 244      nonlocal gotos.  */
 245   rtx x_nonlocal_goto_handler_labels;
 246
 247   /* Label that will go on function epilogue.
 248      Jumping to this label serves as a "return" instruction
 249      on machines which require execution of the epilogue on all returns.  */
 250   rtx x_return_label;
 251
 252   /* Label that will go on the end of function epilogue.
 253      Jumping to this label serves as a "naked return" instruction
 254      on machines which require execution of the epilogue on all returns.  */
 255   rtx x_naked_return_label;
 256
 257   /* List (chain of EXPR_LISTs) of all stack slots in this function.
 258      Made for the sake of unshare_all_rtl.  */
 259   rtx x_stack_slot_list;
 260
 261   /* Place after which to insert the tail_recursion_label if we need one.  */
 262   rtx x_stack_check_probe_note;
 263
 264   /* Location at which to save the argument pointer if it will need to be
 265      referenced.  There are two cases where this is done: if nonlocal gotos
 266      exist, or if vars stored at an offset from the argument pointer will be
 267      needed by inner routines.  */
 268   rtx x_arg_pointer_save_area;
 269
 270   /* Offset to end of allocated area of stack frame.
 271      If stack grows down, this is the address of the last stack slot allocated.
 272      If stack grows up, this is the address for the next slot.  */
 273   HOST_WIDE_INT x_frame_offset;
 274
 275   /* A PARM_DECL that should contain the static chain for this function.
 276      It will be initialized at the beginning of the function.  */
 277   tree static_chain_decl;
 278
 279   /* An expression that contains the non-local goto save area.  The first
 280      word is the saved frame pointer and the second is the saved stack
 281      pointer.  */
 282   tree nonlocal_goto_save_area;
 283
 284   /* Insn after which register parms and SAVE_EXPRs are born, if nonopt.  */
 285   rtx x_parm_birth_insn;
 286
 287   /* List of all used temporaries allocated, by level.  */
 288   VEC(temp_slot_p,gc) *x_used_temp_slots;
 289
 290   /* List of available temp slots.  */
 291   struct temp_slot *x_avail_temp_slots;
 292
 293   /* This slot is initialized as 0 and is added to
 294      during the nested function.  */
 295   struct var_refs_queue *fixup_var_refs_queue;
 296
 297   /* Current nesting level for temporaries.  */
 298   int x_temp_slot_level;
 299
 300   /* Highest label number in current function.  */
 301   int inl_max_label_num;
 302
 303   /* Function sequence number for profiling, debugging, etc.  */
 304   int funcdef_no;
 305
 306   /* For flow.c.  */
 307
 308   /* Highest loop depth seen so far in loop analysis.  Used in flow.c
 309      for the "failure strategy" when doing liveness analysis starting
 310      with non-empty initial sets.  */
 311   int max_loop_depth;
 312
 313   /* For md files.  */
 314
 315   /* tm.h can use this to store whatever it likes.  */
 316   struct machine_function * GTY ((maybe_undef)) machine;
 317
 318   /* The largest alignment of slot allocated on the stack.  */
 319   unsigned int stack_alignment_needed;
 320
 321   /* Preferred alignment of the end of stack frame.  */
 322   unsigned int preferred_stack_boundary;
 323
 324   /* Language-specific code can use this to store whatever it likes.  */
 325   struct language_function * language;
 326
 327   /* Used types hash table.  */
 328   htab_t GTY ((param_is (union tree_node))) used_types_hash;
 329
 330   /* For reorg.  */
 331
 332   /* If some insns can be deferred to the delay slots of the epilogue, the
 333      delay list for them is recorded here.  */
 334   rtx epilogue_delay_list;
 335
 336   /* Maximal number of entities in the single jumptable.  Used to estimate
 337      final flowgraph size.  */
 338   int max_jumptable_ents;
 339
 340   /* UIDs for LABEL_DECLs.  */
 341   int last_label_uid;
 342
 343   /* Line number of the end of the function.  */
 344   location_t function_end_locus;
 345
 346   /* Array mapping insn uids to blocks.  */
 347   VEC(tree,gc) *ib_boundaries_block;
 348
 349   /* The variables unexpanded so far.  */
 350   tree unexpanded_var_list;
 351
 352   /* Assembly labels for the hot and cold text sections, to
 353      be used by debugger functions for determining the size of text
 354      sections.  */
 355
 356   const char *hot_section_label;
 357   const char *cold_section_label;
 358   const char *hot_section_end_label;
 359   const char *cold_section_end_label;
 360
 361   /* String to be used for name of cold text sections, via
 362      targetm.asm_out.named_section.  */
 363
 364   const char *unlikely_text_section_name;
 365
 366   /* A variable living at the top of the frame that holds a known value.
 367      Used for detecting stack clobbers.  */
 368   tree stack_protect_guard;
 369
 370   /* Collected bit flags.  */
 371
 372   /* Nonzero if function being compiled needs to be given an address
 373      where the value should be stored.  */
 374   unsigned int returns_struct : 1;
 375
 376   /* Nonzero if function being compiled needs to
 377      return the address of where it has put a structure value.  */
 378   unsigned int returns_pcc_struct : 1;
 379
 380   /* Nonzero if the current function returns a pointer type.  */
 381   unsigned int returns_pointer : 1;
 382
 383   /* Nonzero if function being compiled can call setjmp.  */
 384   unsigned int calls_setjmp : 1;
 385
 386   /* Nonzero if function being compiled can call alloca,
 387      either as a subroutine or builtin.  */
 388   unsigned int calls_alloca : 1;
 389
 390   /* Nonzero if function being compiled called builtin_return_addr or
 391      builtin_frame_address with nonzero count.  */
 392   unsigned int accesses_prior_frames : 1;
 393
 394   /* Nonzero if the function calls __builtin_eh_return.  */
 395   unsigned int calls_eh_return : 1;
 396
 397   /* Nonzero if function being compiled receives nonlocal gotos
 398      from nested functions.  */
 399   unsigned int has_nonlocal_label : 1;
 400
 401   /* Nonzero if function being compiled has nonlocal gotos to parent
 402      function.  */
 403   unsigned int has_nonlocal_goto : 1;
 404
 405   /* Nonzero if the current function is a thunk, i.e., a lightweight
 406      function implemented by the output_mi_thunk hook) that just
 407      adjusts one of its arguments and forwards to another
 408      function.  */
 409   unsigned int is_thunk : 1;
 410
 411   /* This bit is used by the exception handling logic.  It is set if all
 412      calls (if any) are sibling calls.  Such functions do not have to
 413      have EH tables generated, as they cannot throw.  A call to such a
 414      function, however, should be treated as throwing if any of its callees
 415      can throw.  */
 416   unsigned int all_throwers_are_sibcalls : 1;
 417
 418   /* Nonzero if profiling code should be generated.  */
 419   unsigned int profile : 1;
 420
 421   /* Nonzero if stack limit checking should be enabled in the current
 422      function.  */
 423   unsigned int limit_stack : 1;
 424
 425   /* Nonzero if current function uses stdarg.h or equivalent.  */
 426   unsigned int stdarg : 1;
 427
 428   /* Nonzero if the back-end should not keep track of expressions that
 429      determine the size of variable-sized objects.  Normally, such
 430      expressions are saved away, and then expanded when the next
 431      function is started.  For example, if a parameter has a
 432      variable-sized type, then the size of the parameter is computed
 433      when the function body is entered.  However, some front-ends do
 434      not desire this behavior.  */
 435   unsigned int x_dont_save_pending_sizes_p : 1;
 436
 437   /* Nonzero if the current function uses the constant pool.  */
 438   unsigned int uses_const_pool : 1;
 439
 440   /* Nonzero if the current function uses pic_offset_table_rtx.  */
 441   unsigned int uses_pic_offset_table : 1;
 442
 443   /* Nonzero if the current function needs an lsda for exception handling.  */
 444   unsigned int uses_eh_lsda : 1;
 445
 446   /* Nonzero if code to initialize arg_pointer_save_area has been emitted.  */
 447   unsigned int arg_pointer_save_area_init : 1;
 448
 449   unsigned int after_inlining : 1;
 450
 451   /* Set when the call to function itself has been emit.  */
 452   unsigned int recursive_call_emit : 1;
 453
 454   /* Set when the tail call has been produced.  */
 455   unsigned int tail_call_emit : 1;
 456
 457   /* How commonly executed the function is.  Initialized during branch
 458      probabilities pass.  */
 459   ENUM_BITFIELD (function_frequency) function_frequency : 2;
 460
 461   /* Number of units of general registers that need saving in stdarg
 462      function.  What unit is depends on the backend, either it is number
 463      of bytes, or it can be number of registers.  */
 464   unsigned int va_list_gpr_size : 8;
 465
 466   /* Number of units of floating point registers that need saving in stdarg
 467      function.  */
 468   unsigned int va_list_fpr_size : 8;
 469 };
 470
 471 /* If va_list_[gf]pr_size is set to this, it means we don't know how
 472    many units need to be saved.  */
 473 #define VA_LIST_MAX_GPR_SIZE    255
 474 #define VA_LIST_MAX_FPR_SIZE    255
 475
 476 /* The function currently being compiled.  */
 477 extern GTY(()) struct function *cfun;
 478
 479 /* Pointer to chain of `struct function' for containing functions.  */
 480 extern GTY(()) struct function *outer_function_chain;
 481
 482 /* Nonzero if we've already converted virtual regs to hard regs.  */
 483 extern int virtuals_instantiated;
 484
 485 /* Nonzero if at least one trampoline has been created.  */
 486 extern int trampolines_created;
 487
 488 /* For backward compatibility... eventually these should all go away.  */
 489 #define current_function_pops_args (cfun->pops_args)
 490 #define current_function_returns_struct (cfun->returns_struct)
 491 #define current_function_returns_pcc_struct (cfun->returns_pcc_struct)
 492 #define current_function_returns_pointer (cfun->returns_pointer)
 493 #define current_function_calls_setjmp (cfun->calls_setjmp)
 494 #define current_function_calls_alloca (cfun->calls_alloca)
 495 #define current_function_accesses_prior_frames (cfun->accesses_prior_frames)
 496 #define current_function_calls_eh_return (cfun->calls_eh_return)
 497 #define current_function_is_thunk (cfun->is_thunk)
 498 #define current_function_args_info (cfun->args_info)
 499 #define current_function_args_size (cfun->args_size)
 500 #define current_function_pretend_args_size (cfun->pretend_args_size)
 501 #define current_function_outgoing_args_size (cfun->outgoing_args_size)
 502 #define current_function_arg_offset_rtx (cfun->arg_offset_rtx)
 503 #define current_function_stdarg (cfun->stdarg)
 504 #define current_function_internal_arg_pointer (cfun->internal_arg_pointer)
 505 #define current_function_return_rtx (cfun->return_rtx)
 506 #define current_function_profile (cfun->profile)
 507 #define current_function_funcdef_no (cfun->funcdef_no)
 508 #define current_function_limit_stack (cfun->limit_stack)
 509 #define current_function_uses_pic_offset_table (cfun->uses_pic_offset_table)
 510 #define current_function_uses_const_pool (cfun->uses_const_pool)
 511 #define current_function_epilogue_delay_list (cfun->epilogue_delay_list)
 512 #define current_function_has_nonlocal_label (cfun->has_nonlocal_label)
 513 #define current_function_has_nonlocal_goto (cfun->has_nonlocal_goto)
 514
 515 #define return_label (cfun->x_return_label)
 516 #define naked_return_label (cfun->x_naked_return_label)
 517 #define stack_slot_list (cfun->x_stack_slot_list)
 518 #define parm_birth_insn (cfun->x_parm_birth_insn)
 519 #define frame_offset (cfun->x_frame_offset)
 520 #define stack_check_probe_note (cfun->x_stack_check_probe_note)
 521 #define arg_pointer_save_area (cfun->x_arg_pointer_save_area)
 522 #define used_temp_slots (cfun->x_used_temp_slots)
 523 #define avail_temp_slots (cfun->x_avail_temp_slots)
 524 #define temp_slot_level (cfun->x_temp_slot_level)
 525 #define nonlocal_goto_handler_labels (cfun->x_nonlocal_goto_handler_labels)
 526 #define current_loops (cfun->x_current_loops)
 527
 528 /* Given a function decl for a containing function,
 529    return the `struct function' for it.  */
 530 struct function *find_function_data (tree);
 531
 532 /* Identify BLOCKs referenced by more than one NOTE_INSN_BLOCK_{BEG,END},
 533    and create duplicate blocks.  */
 534 extern void reorder_blocks (void);
 535
 536 /* Set BLOCK_NUMBER for all the blocks in FN.  */
 537 extern void number_blocks (tree);
 538
 539 extern void clear_block_marks (tree);
 540 extern tree blocks_nreverse (tree);
 541 extern void reset_block_changes (void);
 542 extern void record_block_change (tree);
 543 extern void finalize_block_changes (void);
 544 extern void check_block_change (rtx, tree *);
 545 extern void free_block_changes (void);
 546
 547 /* Return size needed for stack frame based on slots so far allocated.
 548    This size counts from zero.  It is not rounded to STACK_BOUNDARY;
 549    the caller may have to do that.  */
 550 extern HOST_WIDE_INT get_frame_size (void);
 551
 552 /* Issue an error message and return TRUE if frame OFFSET overflows in
 553    the signed target pointer arithmetics for function FUNC.  Otherwise
 554    return FALSE.  */
 555 extern bool frame_offset_overflow (HOST_WIDE_INT, tree);
 556
 557 /* A pointer to a function to create target specific, per-function
 558    data structures.  */
 559 extern struct machine_function * (*init_machine_status) (void);
 560
 561 /* Save and restore status information for a nested function.  */
 562 extern void free_after_parsing (struct function *);
 563 extern void free_after_compilation (struct function *);
 564
 565 extern void init_varasm_status (struct function *);
 566
 567 #ifdef RTX_CODE
 568 extern void diddle_return_value (void (*)(rtx, void*), void*);
 569 extern void clobber_return_register (void);
 570 #endif
 571
 572 extern rtx get_arg_pointer_save_area (struct function *);
 573
 574 /* Returns the name of the current function.  */
 575 extern const char *current_function_name (void);
 576
 577 extern void do_warn_unused_parameter (tree);
 578
 579 extern bool pass_by_reference (CUMULATIVE_ARGS *, enum machine_mode,
 580                                tree, bool);
 581 extern bool reference_callee_copied (CUMULATIVE_ARGS *, enum machine_mode,
 582                                      tree, bool);
 583
 584 extern void used_types_insert (tree);
 585
 586 #endif  /* GCC_FUNCTION_H */