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
  27 struct var_refs_queue GTY(())
  28 {
  29   rtx modified;
  30   enum machine_mode promoted_mode;
  31   int unsignedp;
  32   struct var_refs_queue *next;
  33 };
  34
  35 /* Stack of pending (incomplete) sequences saved by `start_sequence'.
  36    Each element describes one pending sequence.
  37    The main insn-chain is saved in the last element of the chain,
  38    unless the chain is empty.  */
  39
  40 struct sequence_stack GTY(())
  41 {
  42   /* First and last insns in the chain of the saved sequence.  */
  43   rtx first;
  44   rtx last;
  45   struct sequence_stack *next;
  46 };
  47
  48 extern struct sequence_stack *sequence_stack;
  49
  50 /* Stack of single obstacks.  */
  51
  52 struct simple_obstack_stack
  53 {
  54   struct obstack *obstack;
  55   struct simple_obstack_stack *next;
  56 };
  57 \f
  58 struct emit_status GTY(())
  59 {
  60   /* This is reset to LAST_VIRTUAL_REGISTER + 1 at the start of each function.
  61      After rtl generation, it is 1 plus the largest register number used.  */
  62   int x_reg_rtx_no;
  63
  64   /* Lowest label number in current function.  */
  65   int x_first_label_num;
  66
  67   /* The ends of the doubly-linked chain of rtl for the current function.
  68      Both are reset to null at the start of rtl generation for the function.
  69
  70      start_sequence saves both of these on `sequence_stack' and then starts
  71      a new, nested sequence of insns.  */
  72   rtx x_first_insn;
  73   rtx x_last_insn;
  74
  75   /* Stack of pending (incomplete) sequences saved by `start_sequence'.
  76      Each element describes one pending sequence.
  77      The main insn-chain is saved in the last element of the chain,
  78      unless the chain is empty.  */
  79   struct sequence_stack *sequence_stack;
  80
  81   /* INSN_UID for next insn emitted.
  82      Reset to 1 for each function compiled.  */
  83   int x_cur_insn_uid;
  84
  85   /* Location the last line-number NOTE emitted.
  86      This is used to avoid generating duplicates.  */
  87   location_t x_last_location;
  88
  89   /* The length of the regno_pointer_align, regno_decl, and x_regno_reg_rtx
  90      vectors.  Since these vectors are needed during the expansion phase when
  91      the total number of registers in the function is not yet known, the
  92      vectors are copied and made bigger when necessary.  */
  93   int regno_pointer_align_length;
  94
  95   /* Indexed by pseudo register number, if nonzero gives the known alignment
  96      for that pseudo (if REG_POINTER is set in x_regno_reg_rtx).
  97      Allocated in parallel with x_regno_reg_rtx.  */
  98   unsigned char * GTY ((length ("%h.x_reg_rtx_no")))
  99     regno_pointer_align;
 100
 101   /* Indexed by pseudo register number, gives the rtx for that pseudo.
 102      Allocated in parallel with regno_pointer_align.  */
 103   rtx * GTY ((length ("%h.x_reg_rtx_no"))) x_regno_reg_rtx;
 104 };
 105
 106 /* For backward compatibility... eventually these should all go away.  */
 107 #define reg_rtx_no (cfun->emit->x_reg_rtx_no)
 108 #define regno_reg_rtx (cfun->emit->x_regno_reg_rtx)
 109 #define seq_stack (cfun->emit->sequence_stack)
 110
 111 #define REGNO_POINTER_ALIGN(REGNO) (cfun->emit->regno_pointer_align[REGNO])
 112
 113 struct expr_status GTY(())
 114 {
 115   /* Number of units that we should eventually pop off the stack.
 116      These are the arguments to function calls that have already returned.  */
 117   int x_pending_stack_adjust;
 118
 119   /* Under some ABIs, it is the caller's responsibility to pop arguments
 120      pushed for function calls.  A naive implementation would simply pop
 121      the arguments immediately after each call.  However, if several
 122      function calls are made in a row, it is typically cheaper to pop
 123      all the arguments after all of the calls are complete since a
 124      single pop instruction can be used.  Therefore, GCC attempts to
 125      defer popping the arguments until absolutely necessary.  (For
 126      example, at the end of a conditional, the arguments must be popped,
 127      since code outside the conditional won't know whether or not the
 128      arguments need to be popped.)
 129
 130      When INHIBIT_DEFER_POP is nonzero, however, the compiler does not
 131      attempt to defer pops.  Instead, the stack is popped immediately
 132      after each call.  Rather then setting this variable directly, use
 133      NO_DEFER_POP and OK_DEFER_POP.  */
 134   int x_inhibit_defer_pop;
 135
 136   /* If PREFERRED_STACK_BOUNDARY and PUSH_ROUNDING are defined, the stack
 137      boundary can be momentarily unaligned while pushing the arguments.
 138      Record the delta since last aligned boundary here in order to get
 139      stack alignment in the nested function calls working right.  */
 140   int x_stack_pointer_delta;
 141
 142   /* Nonzero means __builtin_saveregs has already been done in this function.
 143      The value is the pseudoreg containing the value __builtin_saveregs
 144      returned.  */
 145   rtx x_saveregs_value;
 146
 147   /* Similarly for __builtin_apply_args.  */
 148   rtx x_apply_args_value;
 149
 150   /* List of labels that must never be deleted.  */
 151   rtx x_forced_labels;
 152 };
 153
 154 #define pending_stack_adjust (cfun->expr->x_pending_stack_adjust)
 155 #define inhibit_defer_pop (cfun->expr->x_inhibit_defer_pop)
 156 #define saveregs_value (cfun->expr->x_saveregs_value)
 157 #define apply_args_value (cfun->expr->x_apply_args_value)
 158 #define forced_labels (cfun->expr->x_forced_labels)
 159 #define stack_pointer_delta (cfun->expr->x_stack_pointer_delta)
 160
 161 /* This structure can save all the important global and static variables
 162    describing the status of the current function.  */
 163
 164 struct function GTY(())
 165 {
 166   struct eh_status *eh;
 167   struct expr_status *expr;
 168   struct emit_status *emit;
 169   struct varasm_status *varasm;
 170
 171   /* The control flow graph for this function.  */
 172   struct control_flow_graph *cfg;
 173   bool after_inlining;
 174
 175   /* For function.c.  */
 176
 177   /* Points to the FUNCTION_DECL of this function.  */
 178   tree decl;
 179
 180   /* Function containing this function, if any.  */
 181   struct function *outer;
 182
 183   /* Number of bytes of args popped by function being compiled on its return.
 184      Zero if no bytes are to be popped.
 185      May affect compilation of return insn or of function epilogue.  */
 186   int pops_args;
 187
 188   /* If function's args have a fixed size, this is that size, in bytes.
 189      Otherwise, it is -1.
 190      May affect compilation of return insn or of function epilogue.  */
 191   int args_size;
 192
 193   /* # bytes the prologue should push and pretend that the caller pushed them.
 194      The prologue must do this, but only if parms can be passed in
 195      registers.  */
 196   int pretend_args_size;
 197
 198   /* # of bytes of outgoing arguments.  If ACCUMULATE_OUTGOING_ARGS is
 199      defined, the needed space is pushed by the prologue.  */
 200   int outgoing_args_size;
 201
 202   /* This is the offset from the arg pointer to the place where the first
 203      anonymous arg can be found, if there is one.  */
 204   rtx arg_offset_rtx;
 205
 206   /* Quantities of various kinds of registers
 207      used for the current function's args.  */
 208   CUMULATIVE_ARGS args_info;
 209
 210   /* If nonzero, an RTL expression for the location at which the current
 211      function returns its result.  If the current function returns its
 212      result in a register, current_function_return_rtx will always be
 213      the hard register containing the result.  */
 214   rtx return_rtx;
 215
 216   /* The arg pointer hard register, or the pseudo into which it was copied.  */
 217   rtx internal_arg_pointer;
 218
 219   /* Opaque pointer used by get_hard_reg_initial_val and
 220      has_hard_reg_initial_val (see integrate.[hc]).  */
 221   struct initial_value_struct *hard_reg_initial_vals;
 222
 223   /* List (chain of EXPR_LIST) of labels heading the current handlers for
 224      nonlocal gotos.  */
 225   rtx x_nonlocal_goto_handler_labels;
 226
 227   /* Label that will go on function epilogue.
 228      Jumping to this label serves as a "return" instruction
 229      on machines which require execution of the epilogue on all returns.  */
 230   rtx x_return_label;
 231
 232   /* Label that will go on the end of function epilogue.
 233      Jumping to this label serves as a "naked return" instruction
 234      on machines which require execution of the epilogue on all returns.  */
 235   rtx x_naked_return_label;
 236
 237   /* List (chain of EXPR_LISTs) of all stack slots in this function.
 238      Made for the sake of unshare_all_rtl.  */
 239   rtx x_stack_slot_list;
 240
 241   /* Place after which to insert the tail_recursion_label if we need one.  */
 242   rtx x_tail_recursion_reentry;
 243
 244   /* Location at which to save the argument pointer if it will need to be
 245      referenced.  There are two cases where this is done: if nonlocal gotos
 246      exist, or if vars stored at an offset from the argument pointer will be
 247      needed by inner routines.  */
 248   rtx x_arg_pointer_save_area;
 249
 250   /* Offset to end of allocated area of stack frame.
 251      If stack grows down, this is the address of the last stack slot allocated.
 252      If stack grows up, this is the address for the next slot.  */
 253   HOST_WIDE_INT x_frame_offset;
 254
 255   /* A PARM_DECL that should contain the static chain for this function.
 256      It will be initialized at the beginning of the function.  */
 257   tree static_chain_decl;
 258
 259   /* An expression that contains the non-local goto save area.  The first
 260      word is the saved frame pointer and the second is the saved stack
 261      pointer.  */
 262   tree nonlocal_goto_save_area;
 263
 264   /* Insn after which register parms and SAVE_EXPRs are born, if nonopt.  */
 265   rtx x_parm_birth_insn;
 266
 267   /* List of all used temporaries allocated, by level.  */
 268   struct varray_head_tag * GTY((param_is (struct temp_slot))) x_used_temp_slots;
 269
 270   /* List of available temp slots.  */
 271   struct temp_slot *x_avail_temp_slots;
 272
 273   /* Current nesting level for temporaries.  */
 274   int x_temp_slot_level;
 275
 276   /* This slot is initialized as 0 and is added to
 277      during the nested function.  */
 278   struct var_refs_queue *fixup_var_refs_queue;
 279
 280   /* For integrate.c.  */
 281   int inlinable;
 282   int no_debugging_symbols;
 283   rtvec original_arg_vector;
 284   tree original_decl_initial;
 285
 286   /* Highest label number in current function.  */
 287   int inl_max_label_num;
 288
 289   /* Function sequence number for profiling, debugging, etc.  */
 290   int funcdef_no;
 291
 292   /* For flow.c.  */
 293
 294   /* Highest loop depth seen so far in loop analysis.  Used in flow.c
 295      for the "failure strategy" when doing liveness analysis starting
 296      with non-empty initial sets.  */
 297   int max_loop_depth;
 298
 299   /* For md files.  */
 300
 301   /* tm.h can use this to store whatever it likes.  */
 302   struct machine_function * GTY ((maybe_undef)) machine;
 303   /* The largest alignment of slot allocated on the stack.  */
 304   unsigned int stack_alignment_needed;
 305   /* Preferred alignment of the end of stack frame.  */
 306   unsigned int preferred_stack_boundary;
 307   /* Set when the call to function itself has been emit.  */
 308   bool recursive_call_emit;
 309   /* Set when the tail call has been produced.  */
 310   bool tail_call_emit;
 311
 312   /* Language-specific code can use this to store whatever it likes.  */
 313   struct language_function * language;
 314
 315   /* For reorg.  */
 316
 317   /* If some insns can be deferred to the delay slots of the epilogue, the
 318      delay list for them is recorded here.  */
 319   rtx epilogue_delay_list;
 320
 321   /* How commonly executed the function is.  Initialized during branch
 322      probabilities pass.  */
 323   enum function_frequency {
 324     /* This function most likely won't be executed at all.
 325        (set only when profile feedback is available).  */
 326     FUNCTION_FREQUENCY_UNLIKELY_EXECUTED,
 327     /* The default value.  */
 328     FUNCTION_FREQUENCY_NORMAL,
 329     /* Optimize this function hard
 330        (set only when profile feedback is available).  */
 331     FUNCTION_FREQUENCY_HOT
 332   } function_frequency;
 333
 334   /* Maximal number of entities in the single jumptable.  Used to estimate
 335      final flowgraph size.  */
 336   int max_jumptable_ents;
 337
 338   /* UIDs for LABEL_DECLs.  */
 339   int last_label_uid;
 340
 341   /* Line number of the end of the function.  */
 342   location_t function_end_locus;
 343
 344   /* Array mapping insn uids to blocks.  */
 345   struct varray_head_tag *ib_boundaries_block;
 346
 347   /* The variables unexpanded so far.  */
 348   tree unexpanded_var_list;
 349
 350   /* Assembly labels for the hot and cold text sections, to
 351      be used by debugger functions for determining the size of text
 352      sections.  */
 353
 354   const char *hot_section_label;
 355   const char *cold_section_label;
 356   const char *hot_section_end_label;
 357   const char *cold_section_end_label;
 358
 359   /* String to be used for name of cold text sections, via
 360      targetm.asm_out.named_section.  */
 361
 362   const char *unlikely_text_section_name;
 363
 364   /* A variable living at the top of the frame that holds a known value.
 365      Used for detecting stack clobbers.  */
 366   tree stack_protect_guard;
 367
 368   /* Collected bit flags.  */
 369
 370   /* Nonzero if function being compiled needs to be given an address
 371      where the value should be stored.  */
 372   unsigned int returns_struct : 1;
 373
 374   /* Nonzero if function being compiled needs to
 375      return the address of where it has put a structure value.  */
 376   unsigned int returns_pcc_struct : 1;
 377
 378   /* Nonzero if the current function returns a pointer type.  */
 379   unsigned int returns_pointer : 1;
 380
 381   /* Nonzero if function being compiled can call setjmp.  */
 382   unsigned int calls_setjmp : 1;
 383
 384   /* Nonzero if function being compiled can call alloca,
 385      either as a subroutine or builtin.  */
 386   unsigned int calls_alloca : 1;
 387
 388   /* Nonzero if function being compiled called builtin_return_addr or
 389      builtin_frame_address with non-zero count.  */
 390   unsigned int accesses_prior_frames : 1;
 391
 392   /* Nonzero if the function calls __builtin_eh_return.  */
 393   unsigned int calls_eh_return : 1;
 394
 395   /* Nonzero if function being compiled receives nonlocal gotos
 396      from nested functions.  */
 397   unsigned int has_nonlocal_label : 1;
 398
 399   /* Nonzero if function being compiled has nonlocal gotos to parent
 400      function.  */
 401   unsigned int has_nonlocal_goto : 1;
 402
 403   /* Nonzero if the current function is a thunk, i.e., a lightweight
 404      function implemented by the output_mi_thunk hook) that just
 405      adjusts one of its arguments and forwards to another
 406      function.  */
 407   unsigned int is_thunk : 1;
 408
 409   /* This bit is used by the exception handling logic.  It is set if all
 410      calls (if any) are sibling calls.  Such functions do not have to
 411      have EH tables generated, as they cannot throw.  A call to such a
 412      function, however, should be treated as throwing if any of its callees
 413      can throw.  */
 414   unsigned int all_throwers_are_sibcalls : 1;
 415
 416   /* Nonzero if profiling code should be generated.  */
 417   unsigned int profile : 1;
 418
 419   /* Nonzero if stack limit checking should be enabled in the current
 420      function.  */
 421   unsigned int limit_stack : 1;
 422
 423   /* Nonzero if current function uses stdarg.h or equivalent.  */
 424   unsigned int stdarg : 1;
 425
 426   /* Nonzero if the back-end should not keep track of expressions that
 427      determine the size of variable-sized objects.  Normally, such
 428      expressions are saved away, and then expanded when the next
 429      function is started.  For example, if a parameter has a
 430      variable-sized type, then the size of the parameter is computed
 431      when the function body is entered.  However, some front-ends do
 432      not desire this behavior.  */
 433   unsigned int x_dont_save_pending_sizes_p : 1;
 434
 435   /* Nonzero if the current function uses the constant pool.  */
 436   unsigned int uses_const_pool : 1;
 437
 438   /* Nonzero if the current function uses pic_offset_table_rtx.  */
 439   unsigned int uses_pic_offset_table : 1;
 440
 441   /* Nonzero if the current function needs an lsda for exception handling.  */
 442   unsigned int uses_eh_lsda : 1;
 443
 444   /* Nonzero if code to initialize arg_pointer_save_area has been emitted.  */
 445   unsigned int arg_pointer_save_area_init : 1;
 446
 447   /* Number of units of general registers that need saving in stdarg
 448      function.  What unit is depends on the backend, either it is number
 449      of bytes, or it can be number of registers.  */
 450   unsigned int va_list_gpr_size : 8;
 451
 452   /* Number of units of floating point registers that need saving in stdarg
 453      function.  */
 454   unsigned int va_list_fpr_size : 8;
 455 };
 456
 457 /* If va_list_[gf]pr_size is set to this, it means we don't know how
 458    many units need to be saved.  */
 459 #define VA_LIST_MAX_GPR_SIZE    255
 460 #define VA_LIST_MAX_FPR_SIZE    255
 461
 462 /* The function currently being compiled.  */
 463 extern GTY(()) struct function *cfun;
 464
 465 /* Pointer to chain of `struct function' for containing functions.  */
 466 extern GTY(()) struct function *outer_function_chain;
 467
 468 /* Nonzero if we've already converted virtual regs to hard regs.  */
 469 extern int virtuals_instantiated;
 470
 471 /* Nonzero if at least one trampoline has been created.  */
 472 extern int trampolines_created;
 473
 474 /* For backward compatibility... eventually these should all go away.  */
 475 #define current_function_pops_args (cfun->pops_args)
 476 #define current_function_returns_struct (cfun->returns_struct)
 477 #define current_function_returns_pcc_struct (cfun->returns_pcc_struct)
 478 #define current_function_returns_pointer (cfun->returns_pointer)
 479 #define current_function_calls_setjmp (cfun->calls_setjmp)
 480 #define current_function_calls_alloca (cfun->calls_alloca)
 481 #define current_function_accesses_prior_frames (cfun->accesses_prior_frames)
 482 #define current_function_calls_eh_return (cfun->calls_eh_return)
 483 #define current_function_is_thunk (cfun->is_thunk)
 484 #define current_function_args_info (cfun->args_info)
 485 #define current_function_args_size (cfun->args_size)
 486 #define current_function_pretend_args_size (cfun->pretend_args_size)
 487 #define current_function_outgoing_args_size (cfun->outgoing_args_size)
 488 #define current_function_arg_offset_rtx (cfun->arg_offset_rtx)
 489 #define current_function_stdarg (cfun->stdarg)
 490 #define current_function_internal_arg_pointer (cfun->internal_arg_pointer)
 491 #define current_function_return_rtx (cfun->return_rtx)
 492 #define current_function_profile (cfun->profile)
 493 #define current_function_funcdef_no (cfun->funcdef_no)
 494 #define current_function_limit_stack (cfun->limit_stack)
 495 #define current_function_uses_pic_offset_table (cfun->uses_pic_offset_table)
 496 #define current_function_uses_const_pool (cfun->uses_const_pool)
 497 #define current_function_epilogue_delay_list (cfun->epilogue_delay_list)
 498 #define current_function_has_nonlocal_label (cfun->has_nonlocal_label)
 499 #define current_function_has_nonlocal_goto (cfun->has_nonlocal_goto)
 500
 501 #define return_label (cfun->x_return_label)
 502 #define naked_return_label (cfun->x_naked_return_label)
 503 #define stack_slot_list (cfun->x_stack_slot_list)
 504 #define parm_birth_insn (cfun->x_parm_birth_insn)
 505 #define frame_offset (cfun->x_frame_offset)
 506 #define tail_recursion_reentry (cfun->x_tail_recursion_reentry)
 507 #define arg_pointer_save_area (cfun->x_arg_pointer_save_area)
 508 #define used_temp_slots (cfun->x_used_temp_slots)
 509 #define avail_temp_slots (cfun->x_avail_temp_slots)
 510 #define temp_slot_level (cfun->x_temp_slot_level)
 511 #define nonlocal_goto_handler_labels (cfun->x_nonlocal_goto_handler_labels)
 512
 513 /* Given a function decl for a containing function,
 514    return the `struct function' for it.  */
 515 struct function *find_function_data (tree);
 516
 517 /* Identify BLOCKs referenced by more than one NOTE_INSN_BLOCK_{BEG,END},
 518    and create duplicate blocks.  */
 519 extern void reorder_blocks (void);
 520
 521 /* Set BLOCK_NUMBER for all the blocks in FN.  */
 522 extern void number_blocks (tree);
 523
 524 extern void clear_block_marks (tree);
 525 extern tree blocks_nreverse (tree);
 526 extern void reset_block_changes (void);
 527 extern void record_block_change (tree);
 528 extern void finalize_block_changes (void);
 529 extern void check_block_change (rtx, tree *);
 530 extern void free_block_changes (void);
 531
 532 /* Return size needed for stack frame based on slots so far allocated.
 533    This size counts from zero.  It is not rounded to STACK_BOUNDARY;
 534    the caller may have to do that.  */
 535 extern HOST_WIDE_INT get_frame_size (void);
 536
 537 /* A pointer to a function to create target specific, per-function
 538    data structures.  */
 539 extern struct machine_function * (*init_machine_status) (void);
 540
 541 /* Save and restore status information for a nested function.  */
 542 extern void free_after_parsing (struct function *);
 543 extern void free_after_compilation (struct function *);
 544
 545 extern void init_varasm_status (struct function *);
 546
 547 #ifdef RTX_CODE
 548 extern void diddle_return_value (void (*)(rtx, void*), void*);
 549 extern void clobber_return_register (void);
 550 extern void use_return_register (void);
 551 #endif
 552
 553 extern rtx get_arg_pointer_save_area (struct function *);
 554
 555 /* Returns the name of the current function.  */
 556 extern const char *current_function_name (void);
 557
 558 extern void do_warn_unused_parameter (tree);
 559
 560 extern bool pass_by_reference (CUMULATIVE_ARGS *, enum machine_mode,
 561                                tree, bool);
 562 extern bool reference_callee_copied (CUMULATIVE_ARGS *, enum machine_mode,
 563                                      tree, bool);
 564
 565 #endif  /* GCC_FUNCTION_H */