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 expr_status *expr;
 166   struct emit_status *emit;
 167   struct varasm_status *varasm;
 168
 169   /* The control flow graph for this function.  */
 170   struct control_flow_graph *cfg;
 171   bool after_inlining;
 172
 173   /* For function.c.  */
 174
 175   /* Points to the FUNCTION_DECL of this function.  */
 176   tree decl;
 177
 178   /* Function containing this function, if any.  */
 179   struct function *outer;
 180
 181   /* Number of bytes of args popped by function being compiled on its return.
 182      Zero if no bytes are to be popped.
 183      May affect compilation of return insn or of function epilogue.  */
 184   int pops_args;
 185
 186   /* If function's args have a fixed size, this is that size, in bytes.
 187      Otherwise, it is -1.
 188      May affect compilation of return insn or of function epilogue.  */
 189   int args_size;
 190
 191   /* # bytes the prologue should push and pretend that the caller pushed them.
 192      The prologue must do this, but only if parms can be passed in
 193      registers.  */
 194   int pretend_args_size;
 195
 196   /* # of bytes of outgoing arguments.  If ACCUMULATE_OUTGOING_ARGS is
 197      defined, the needed space is pushed by the prologue.  */
 198   int outgoing_args_size;
 199
 200   /* This is the offset from the arg pointer to the place where the first
 201      anonymous arg can be found, if there is one.  */
 202   rtx arg_offset_rtx;
 203
 204   /* Quantities of various kinds of registers
 205      used for the current function's args.  */
 206   CUMULATIVE_ARGS args_info;
 207
 208   /* If nonzero, an RTL expression for the location at which the current
 209      function returns its result.  If the current function returns its
 210      result in a register, current_function_return_rtx will always be
 211      the hard register containing the result.  */
 212   rtx return_rtx;
 213
 214   /* The arg pointer hard register, or the pseudo into which it was copied.  */
 215   rtx internal_arg_pointer;
 216
 217   /* Opaque pointer used by get_hard_reg_initial_val and
 218      has_hard_reg_initial_val (see integrate.[hc]).  */
 219   struct initial_value_struct *hard_reg_initial_vals;
 220
 221   /* List (chain of EXPR_LIST) of labels heading the current handlers for
 222      nonlocal gotos.  */
 223   rtx x_nonlocal_goto_handler_labels;
 224
 225   /* Label that will go on function epilogue.
 226      Jumping to this label serves as a "return" instruction
 227      on machines which require execution of the epilogue on all returns.  */
 228   rtx x_return_label;
 229
 230   /* Label that will go on the end of function epilogue.
 231      Jumping to this label serves as a "naked return" instruction
 232      on machines which require execution of the epilogue on all returns.  */
 233   rtx x_naked_return_label;
 234
 235   /* List (chain of EXPR_LISTs) of all stack slots in this function.
 236      Made for the sake of unshare_all_rtl.  */
 237   rtx x_stack_slot_list;
 238
 239   /* Place after which to insert the tail_recursion_label if we need one.  */
 240   rtx x_tail_recursion_reentry;
 241
 242   /* Location at which to save the argument pointer if it will need to be
 243      referenced.  There are two cases where this is done: if nonlocal gotos
 244      exist, or if vars stored at an offset from the argument pointer will be
 245      needed by inner routines.  */
 246   rtx x_arg_pointer_save_area;
 247
 248   /* Offset to end of allocated area of stack frame.
 249      If stack grows down, this is the address of the last stack slot allocated.
 250      If stack grows up, this is the address for the next slot.  */
 251   HOST_WIDE_INT x_frame_offset;
 252
 253   /* A PARM_DECL that should contain the static chain for this function.
 254      It will be initialized at the beginning of the function.  */
 255   tree static_chain_decl;
 256
 257   /* An expression that contains the non-local goto save area.  The first
 258      word is the saved frame pointer and the second is the saved stack
 259      pointer.  */
 260   tree nonlocal_goto_save_area;
 261
 262   /* Insn after which register parms and SAVE_EXPRs are born, if nonopt.  */
 263   rtx x_parm_birth_insn;
 264
 265   /* List of all used temporaries allocated, by level.  */
 266   struct varray_head_tag * GTY((param_is (struct temp_slot))) x_used_temp_slots;
 267
 268   /* List of available temp slots.  */
 269   struct temp_slot *x_avail_temp_slots;
 270
 271   /* Current nesting level for temporaries.  */
 272   int x_temp_slot_level;
 273
 274   /* This slot is initialized as 0 and is added to
 275      during the nested function.  */
 276   struct var_refs_queue *fixup_var_refs_queue;
 277
 278   /* For integrate.c.  */
 279   int inlinable;
 280   int no_debugging_symbols;
 281   rtvec original_arg_vector;
 282   tree original_decl_initial;
 283
 284   /* Highest label number in current function.  */
 285   int inl_max_label_num;
 286
 287   /* Function sequence number for profiling, debugging, etc.  */
 288   int funcdef_no;
 289
 290   /* For flow.c.  */
 291
 292   /* Highest loop depth seen so far in loop analysis.  Used in flow.c
 293      for the "failure strategy" when doing liveness analysis starting
 294      with non-empty initial sets.  */
 295   int max_loop_depth;
 296
 297   /* For md files.  */
 298
 299   /* tm.h can use this to store whatever it likes.  */
 300   struct machine_function * GTY ((maybe_undef)) machine;
 301   /* The largest alignment of slot allocated on the stack.  */
 302   unsigned int stack_alignment_needed;
 303   /* Preferred alignment of the end of stack frame.  */
 304   unsigned int preferred_stack_boundary;
 305   /* Set when the call to function itself has been emit.  */
 306   bool recursive_call_emit;
 307   /* Set when the tail call has been produced.  */
 308   bool tail_call_emit;
 309
 310   /* Language-specific code can use this to store whatever it likes.  */
 311   struct language_function * language;
 312
 313   /* For reorg.  */
 314
 315   /* If some insns can be deferred to the delay slots of the epilogue, the
 316      delay list for them is recorded here.  */
 317   rtx epilogue_delay_list;
 318
 319   /* How commonly executed the function is.  Initialized during branch
 320      probabilities pass.  */
 321   enum function_frequency {
 322     /* This function most likely won't be executed at all.
 323        (set only when profile feedback is available).  */
 324     FUNCTION_FREQUENCY_UNLIKELY_EXECUTED,
 325     /* The default value.  */
 326     FUNCTION_FREQUENCY_NORMAL,
 327     /* Optimize this function hard
 328        (set only when profile feedback is available).  */
 329     FUNCTION_FREQUENCY_HOT
 330   } function_frequency;
 331
 332   /* Maximal number of entities in the single jumptable.  Used to estimate
 333      final flowgraph size.  */
 334   int max_jumptable_ents;
 335
 336   /* UIDs for LABEL_DECLs.  */
 337   int last_label_uid;
 338
 339   /* Line number of the end of the function.  */
 340   location_t function_end_locus;
 341
 342   /* Array mapping insn uids to blocks.  */
 343   struct varray_head_tag *ib_boundaries_block;
 344
 345   /* The variables unexpanded so far.  */
 346   tree unexpanded_var_list;
 347
 348   /* Assembly labels for the hot and cold text sections, to
 349      be used by debugger functions for determining the size of text
 350      sections.  */
 351
 352   const char *hot_section_label;
 353   const char *cold_section_label;
 354   const char *hot_section_end_label;
 355   const char *cold_section_end_label;
 356
 357   /* String to be used for name of cold text sections, via
 358      targetm.asm_out.named_section.  */
 359
 360   const char *unlikely_text_section_name;
 361
 362   /* A variable living at the top of the frame that holds a known value.
 363      Used for detecting stack clobbers.  */
 364   tree stack_protect_guard;
 365
 366   /* Collected bit flags.  */
 367
 368   /* Nonzero if function being compiled needs to be given an address
 369      where the value should be stored.  */
 370   unsigned int returns_struct : 1;
 371
 372   /* Nonzero if function being compiled needs to
 373      return the address of where it has put a structure value.  */
 374   unsigned int returns_pcc_struct : 1;
 375
 376   /* Nonzero if the current function returns a pointer type.  */
 377   unsigned int returns_pointer : 1;
 378
 379   /* Nonzero if function being compiled can call setjmp.  */
 380   unsigned int calls_setjmp : 1;
 381
 382   /* Nonzero if function being compiled can call alloca,
 383      either as a subroutine or builtin.  */
 384   unsigned int calls_alloca : 1;
 385
 386   /* Nonzero if function being compiled called builtin_return_addr or
 387      builtin_frame_address with non-zero count.  */
 388   unsigned int accesses_prior_frames : 1;
 389
 390   /* Nonzero if the function calls __builtin_eh_return.  */
 391   unsigned int calls_eh_return : 1;
 392
 393   /* Nonzero if function being compiled receives nonlocal gotos
 394      from nested functions.  */
 395   unsigned int has_nonlocal_label : 1;
 396
 397   /* Nonzero if function being compiled has nonlocal gotos to parent
 398      function.  */
 399   unsigned int has_nonlocal_goto : 1;
 400
 401   /* Nonzero if the current function is a thunk, i.e., a lightweight
 402      function implemented by the output_mi_thunk hook) that just
 403      adjusts one of its arguments and forwards to another
 404      function.  */
 405   unsigned int is_thunk : 1;
 406
 407   /* This bit is used by the exception handling logic.  It is set if all
 408      calls (if any) are sibling calls.  Such functions do not have to
 409      have EH tables generated, as they cannot throw.  A call to such a
 410      function, however, should be treated as throwing if any of its callees
 411      can throw.  */
 412   unsigned int all_throwers_are_sibcalls : 1;
 413
 414   /* Nonzero if profiling code should be generated.  */
 415   unsigned int profile : 1;
 416
 417   /* Nonzero if stack limit checking should be enabled in the current
 418      function.  */
 419   unsigned int limit_stack : 1;
 420
 421   /* Nonzero if current function uses stdarg.h or equivalent.  */
 422   unsigned int stdarg : 1;
 423
 424   /* Nonzero if the back-end should not keep track of expressions that
 425      determine the size of variable-sized objects.  Normally, such
 426      expressions are saved away, and then expanded when the next
 427      function is started.  For example, if a parameter has a
 428      variable-sized type, then the size of the parameter is computed
 429      when the function body is entered.  However, some front-ends do
 430      not desire this behavior.  */
 431   unsigned int x_dont_save_pending_sizes_p : 1;
 432
 433   /* Nonzero if the current function uses the constant pool.  */
 434   unsigned int uses_const_pool : 1;
 435
 436   /* Nonzero if the current function uses pic_offset_table_rtx.  */
 437   unsigned int uses_pic_offset_table : 1;
 438
 439   /* Nonzero if the current function needs an lsda for exception handling.  */
 440   unsigned int uses_eh_lsda : 1;
 441
 442   /* Nonzero if code to initialize arg_pointer_save_area has been emitted.  */
 443   unsigned int arg_pointer_save_area_init : 1;
 444
 445   /* Number of units of general registers that need saving in stdarg
 446      function.  What unit is depends on the backend, either it is number
 447      of bytes, or it can be number of registers.  */
 448   unsigned int va_list_gpr_size : 8;
 449
 450   /* Number of units of floating point registers that need saving in stdarg
 451      function.  */
 452   unsigned int va_list_fpr_size : 8;
 453 };
 454
 455 /* If va_list_[gf]pr_size is set to this, it means we don't know how
 456    many units need to be saved.  */
 457 #define VA_LIST_MAX_GPR_SIZE    255
 458 #define VA_LIST_MAX_FPR_SIZE    255
 459
 460 /* The function currently being compiled.  */
 461 extern GTY(()) struct function *cfun;
 462
 463 /* Pointer to chain of `struct function' for containing functions.  */
 464 extern GTY(()) struct function *outer_function_chain;
 465
 466 /* Nonzero if we've already converted virtual regs to hard regs.  */
 467 extern int virtuals_instantiated;
 468
 469 /* Nonzero if at least one trampoline has been created.  */
 470 extern int trampolines_created;
 471
 472 /* For backward compatibility... eventually these should all go away.  */
 473 #define current_function_pops_args (cfun->pops_args)
 474 #define current_function_returns_struct (cfun->returns_struct)
 475 #define current_function_returns_pcc_struct (cfun->returns_pcc_struct)
 476 #define current_function_returns_pointer (cfun->returns_pointer)
 477 #define current_function_calls_setjmp (cfun->calls_setjmp)
 478 #define current_function_calls_alloca (cfun->calls_alloca)
 479 #define current_function_accesses_prior_frames (cfun->accesses_prior_frames)
 480 #define current_function_calls_eh_return (cfun->calls_eh_return)
 481 #define current_function_is_thunk (cfun->is_thunk)
 482 #define current_function_args_info (cfun->args_info)
 483 #define current_function_args_size (cfun->args_size)
 484 #define current_function_pretend_args_size (cfun->pretend_args_size)
 485 #define current_function_outgoing_args_size (cfun->outgoing_args_size)
 486 #define current_function_arg_offset_rtx (cfun->arg_offset_rtx)
 487 #define current_function_stdarg (cfun->stdarg)
 488 #define current_function_internal_arg_pointer (cfun->internal_arg_pointer)
 489 #define current_function_return_rtx (cfun->return_rtx)
 490 #define current_function_profile (cfun->profile)
 491 #define current_function_funcdef_no (cfun->funcdef_no)
 492 #define current_function_limit_stack (cfun->limit_stack)
 493 #define current_function_uses_pic_offset_table (cfun->uses_pic_offset_table)
 494 #define current_function_uses_const_pool (cfun->uses_const_pool)
 495 #define current_function_epilogue_delay_list (cfun->epilogue_delay_list)
 496 #define current_function_has_nonlocal_label (cfun->has_nonlocal_label)
 497 #define current_function_has_nonlocal_goto (cfun->has_nonlocal_goto)
 498
 499 #define return_label (cfun->x_return_label)
 500 #define naked_return_label (cfun->x_naked_return_label)
 501 #define stack_slot_list (cfun->x_stack_slot_list)
 502 #define parm_birth_insn (cfun->x_parm_birth_insn)
 503 #define frame_offset (cfun->x_frame_offset)
 504 #define tail_recursion_reentry (cfun->x_tail_recursion_reentry)
 505 #define arg_pointer_save_area (cfun->x_arg_pointer_save_area)
 506 #define used_temp_slots (cfun->x_used_temp_slots)
 507 #define avail_temp_slots (cfun->x_avail_temp_slots)
 508 #define temp_slot_level (cfun->x_temp_slot_level)
 509 #define nonlocal_goto_handler_labels (cfun->x_nonlocal_goto_handler_labels)
 510
 511 /* Given a function decl for a containing function,
 512    return the `struct function' for it.  */
 513 struct function *find_function_data (tree);
 514
 515 /* Identify BLOCKs referenced by more than one NOTE_INSN_BLOCK_{BEG,END},
 516    and create duplicate blocks.  */
 517 extern void reorder_blocks (void);
 518
 519 /* Set BLOCK_NUMBER for all the blocks in FN.  */
 520 extern void number_blocks (tree);
 521
 522 extern void clear_block_marks (tree);
 523 extern tree blocks_nreverse (tree);
 524 extern void reset_block_changes (void);
 525 extern void record_block_change (tree);
 526 extern void finalize_block_changes (void);
 527 extern void check_block_change (rtx, tree *);
 528 extern void free_block_changes (void);
 529
 530 /* Return size needed for stack frame based on slots so far allocated.
 531    This size counts from zero.  It is not rounded to STACK_BOUNDARY;
 532    the caller may have to do that.  */
 533 extern HOST_WIDE_INT get_frame_size (void);
 534
 535 /* A pointer to a function to create target specific, per-function
 536    data structures.  */
 537 extern struct machine_function * (*init_machine_status) (void);
 538
 539 /* Save and restore status information for a nested function.  */
 540 extern void free_after_parsing (struct function *);
 541 extern void free_after_compilation (struct function *);
 542
 543 extern void init_varasm_status (struct function *);
 544
 545 #ifdef RTX_CODE
 546 extern void diddle_return_value (void (*)(rtx, void*), void*);
 547 extern void clobber_return_register (void);
 548 extern void use_return_register (void);
 549 #endif
 550
 551 extern rtx get_arg_pointer_save_area (struct function *);
 552
 553 extern void init_virtual_regs (struct emit_status *);
 554 extern void instantiate_virtual_regs (void);
 555
 556 /* Returns the name of the current function.  */
 557 extern const char *current_function_name (void);
 558
 559 extern void do_warn_unused_parameter (tree);
 560
 561 extern bool pass_by_reference (CUMULATIVE_ARGS *, enum machine_mode,
 562                                tree, bool);
 563 extern bool reference_callee_copied (CUMULATIVE_ARGS *, enum machine_mode,
 564                                      tree, bool);
 565
 566 #endif  /* GCC_FUNCTION_H */