gas/config/tc-xtensa.h

   1 /* tc-xtensa.h -- Header file for tc-xtensa.c.
   2    Copyright (C) 2003, 2004, 2005, 2007, 2008 Free Software Foundation, Inc.
   3
   4    This file is part of GAS, the GNU Assembler.
   5
   6    GAS is free software; you can redistribute it and/or modify
   7    it under the terms of the GNU General Public License as published by
   8    the Free Software Foundation; either version 3, or (at your option)
   9    any later version.
  10
  11    GAS is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14    GNU General Public License for more details.
  15
  16    You should have received a copy of the GNU General Public License
  17    along with GAS; see the file COPYING.  If not, write to the Free
  18    Software Foundation, 51 Franklin Street - Fifth Floor, Boston, MA
  19    02110-1301, USA.  */
  20
  21 #ifndef TC_XTENSA
  22 #define TC_XTENSA 1
  23
  24 struct fix;
  25
  26 #ifndef OBJ_ELF
  27 #error Xtensa support requires ELF object format
  28 #endif
  29
  30 #include "xtensa-isa.h"
  31 #include "xtensa-config.h"
  32
  33 #define TARGET_BYTES_BIG_ENDIAN XCHAL_HAVE_BE
  34
  35
  36 /* Maximum number of opcode slots in a VLIW instruction.  */
  37 #define MAX_SLOTS 15
  38
  39
  40 /* For all xtensa relax states except RELAX_DESIRE_ALIGN and
  41    RELAX_DESIRE_ALIGN_IF_TARGET, the amount a frag might grow is stored
  42    in the fr_var field.  For the two exceptions, fr_var is a float value
  43    that records the frequency with which the following instruction is
  44    executed as a branch target.  The aligner uses this information to
  45    tell which targets are most important to be aligned.  */
  46
  47 enum xtensa_relax_statesE
  48 {
  49   RELAX_XTENSA_NONE,
  50
  51   RELAX_ALIGN_NEXT_OPCODE,
  52   /* Use the first opcode of the next fragment to determine the
  53      alignment requirements.  This is ONLY used for LOOPs currently.  */
  54
  55   RELAX_CHECK_ALIGN_NEXT_OPCODE,
  56   /* The next non-empty frag contains a loop instruction.  Check to see
  57      if it is correctly aligned, but do not align it.  */
  58
  59   RELAX_DESIRE_ALIGN_IF_TARGET,
  60   /* These are placed in front of labels and converted to either
  61      RELAX_DESIRE_ALIGN / RELAX_LOOP_END or rs_fill of 0 before
  62      relaxation begins.  */
  63
  64   RELAX_ADD_NOP_IF_A0_B_RETW,
  65   /* These are placed in front of conditional branches.  Before
  66      relaxation begins, they are turned into either NOPs for branches
  67      immediately followed by RETW or RETW.N or rs_fills of 0.  This is
  68      used to avoid a hardware bug in some early versions of the
  69      processor.  */
  70
  71   RELAX_ADD_NOP_IF_PRE_LOOP_END,
  72   /* These are placed after JX instructions.  Before relaxation begins,
  73      they are turned into either NOPs, if the JX is one instruction
  74      before a loop end label, or rs_fills of 0.  This is used to avoid a
  75      hardware interlock issue prior to Xtensa version T1040.  */
  76
  77   RELAX_ADD_NOP_IF_SHORT_LOOP,
  78   /* These are placed after LOOP instructions and turned into NOPs when:
  79      (1) there are less than 3 instructions in the loop; we place 2 of
  80      these in a row to add up to 2 NOPS in short loops; or (2) the
  81      instructions in the loop do not include a branch or jump.
  82      Otherwise they are turned into rs_fills of 0 before relaxation
  83      begins.  This is used to avoid hardware bug PR3830.  */
  84
  85   RELAX_ADD_NOP_IF_CLOSE_LOOP_END,
  86   /* These are placed after LOOP instructions and turned into NOPs if
  87      there are less than 12 bytes to the end of some other loop's end.
  88      Otherwise they are turned into rs_fills of 0 before relaxation
  89      begins.  This is used to avoid hardware bug PR3830.  */
  90
  91   RELAX_DESIRE_ALIGN,
  92   /* The next fragment would like its first instruction to NOT cross an
  93      instruction fetch boundary.  */
  94
  95   RELAX_MAYBE_DESIRE_ALIGN,
  96   /* The next fragment might like its first instruction to NOT cross an
  97      instruction fetch boundary.  These are placed after a branch that
  98      might be relaxed.  If the branch is relaxed, then this frag will be
  99      a branch target and this frag will be changed to RELAX_DESIRE_ALIGN
 100      frag.  */
 101
 102   RELAX_LOOP_END,
 103   /* This will be turned into a NOP or NOP.N if the previous instruction
 104      is expanded to negate a loop.  */
 105
 106   RELAX_LOOP_END_ADD_NOP,
 107   /* When the code density option is available, this will generate a
 108      NOP.N marked RELAX_NARROW.  Otherwise, it will create an rs_fill
 109      fragment with a NOP in it.  Once a frag has been converted to
 110      RELAX_LOOP_END_ADD_NOP, it should never be changed back to
 111      RELAX_LOOP_END.  */
 112
 113   RELAX_LITERAL,
 114   /* Another fragment could generate an expansion here but has not yet.  */
 115
 116   RELAX_LITERAL_NR,
 117   /* Expansion has been generated by an instruction that generates a
 118      literal.  However, the stretch has NOT been reported yet in this
 119      fragment.  */
 120
 121   RELAX_LITERAL_FINAL,
 122   /* Expansion has been generated by an instruction that generates a
 123      literal.  */
 124
 125   RELAX_LITERAL_POOL_BEGIN,
 126   RELAX_LITERAL_POOL_END,
 127   /* Technically these are not relaxations at all but mark a location
 128      to store literals later.  Note that fr_var stores the frchain for
 129      BEGIN frags and fr_var stores now_seg for END frags.  */
 130
 131   RELAX_NARROW,
 132   /* The last instruction in this fragment (at->fr_opcode) can be
 133      freely replaced with a single wider instruction if a future
 134      alignment desires or needs it.  */
 135
 136   RELAX_IMMED,
 137   /* The last instruction in this fragment (at->fr_opcode) contains
 138      an immediate or symbol.  If the value does not fit, relax the
 139      opcode using expansions from the relax table.  */
 140
 141   RELAX_IMMED_STEP1,
 142   /* The last instruction in this fragment (at->fr_opcode) contains a
 143      literal.  It has already been expanded 1 step.  */
 144
 145   RELAX_IMMED_STEP2,
 146   /* The last instruction in this fragment (at->fr_opcode) contains a
 147      literal.  It has already been expanded 2 steps.  */
 148
 149   RELAX_IMMED_STEP3,
 150   /* The last instruction in this fragment (at->fr_opcode) contains a
 151      literal.  It has already been expanded 3 steps.  */
 152
 153   RELAX_SLOTS,
 154   /* There are instructions within the last VLIW instruction that need
 155      relaxation.  Find the relaxation based on the slot info in
 156      xtensa_frag_type.  Relaxations that deal with particular opcodes
 157      are slot-based (e.g., converting a MOVI to an L32R).  Relaxations
 158      that deal with entire instructions, such as alignment, are not
 159      slot-based.  */
 160
 161   RELAX_FILL_NOP,
 162   /* This marks the location of a pipeline stall.  We can fill these guys
 163      in for alignment of any size.  */
 164
 165   RELAX_UNREACHABLE,
 166   /* This marks the location as unreachable.  The assembler may widen or
 167      narrow this area to meet alignment requirements of nearby
 168      instructions.  */
 169
 170   RELAX_MAYBE_UNREACHABLE,
 171   /* This marks the location as possibly unreachable.  These are placed
 172      after a branch that may be relaxed into a branch and jump. If the
 173      branch is relaxed, then this frag will be converted to a
 174      RELAX_UNREACHABLE frag.  */
 175
 176   RELAX_ORG,
 177   /* This marks the location as having previously been an rs_org frag.
 178      rs_org frags are converted to fill-zero frags immediately after
 179      relaxation.  However, we need to remember where they were so we can
 180      prevent the linker from changing the size of any frag between the
 181      section start and the org frag.  */
 182
 183   RELAX_NONE
 184 };
 185
 186 /* This is used as a stopper to bound the number of steps that
 187    can be taken.  */
 188 #define RELAX_IMMED_MAXSTEPS (RELAX_IMMED_STEP3 - RELAX_IMMED)
 189
 190 struct xtensa_frag_type
 191 {
 192   /* Info about the current state of assembly, e.g., transform,
 193      absolute_literals, etc.  These need to be passed to the backend and
 194      then to the object file.
 195
 196      When is_assembly_state_set is false, the frag inherits some of the
 197      state settings from the previous frag in this segment.  Because it
 198      is not possible to intercept all fragment closures (frag_more and
 199      frag_append_1_char can close a frag), we use a pass after initial
 200      assembly to fill in the assembly states.  */
 201
 202   unsigned int is_assembly_state_set : 1;
 203   unsigned int is_no_density : 1;
 204   unsigned int is_no_transform : 1;
 205   unsigned int use_longcalls : 1;
 206   unsigned int use_absolute_literals : 1;
 207
 208   /* Inhibits relaxation of machine-dependent alignment frags the
 209      first time through a relaxation....  */
 210   unsigned int relax_seen : 1;
 211
 212   /* Information that is needed in the object file and set when known.  */
 213   unsigned int is_literal : 1;
 214   unsigned int is_loop_target : 1;
 215   unsigned int is_branch_target : 1;
 216   unsigned int is_insn : 1;
 217   unsigned int is_unreachable : 1;
 218
 219   unsigned int is_specific_opcode : 1; /* also implies no_transform */
 220
 221   unsigned int is_align : 1;
 222   unsigned int is_text_align : 1;
 223   unsigned int alignment : 5;
 224
 225   /* A frag with this bit set is the first in a loop that actually
 226      contains an instruction.  */
 227   unsigned int is_first_loop_insn : 1;
 228
 229   /* A frag with this bit set is a branch that we are using to
 230      align branch targets as if it were a normal narrow instruction.  */
 231   unsigned int is_aligning_branch : 1;
 232
 233   /* For text fragments that can generate literals at relax time, this
 234      variable points to the frag where the literal will be stored.  For
 235      literal frags, this variable points to the nearest literal pool
 236      location frag.  This literal frag will be moved to after this
 237      location.  For RELAX_LITERAL_POOL_BEGIN frags, this field points
 238      to the frag immediately before the corresponding RELAX_LITERAL_POOL_END
 239      frag, to make moving frags for this literal pool efficient.  */
 240   fragS *literal_frag;
 241
 242   /* The destination segment for literal frags.  (Note that this is only
 243      valid after xtensa_move_literals.)  This field is also used for
 244      LITERAL_POOL_END frags.  */
 245   segT lit_seg;
 246
 247   /* Frag chain for LITERAL_POOL_BEGIN frags.  */
 248   struct frchain *lit_frchain;
 249
 250   /* For the relaxation scheme, some literal fragments can have their
 251      expansions modified by an instruction that relaxes.  */
 252   int text_expansion[MAX_SLOTS];
 253   int literal_expansion[MAX_SLOTS];
 254   int unreported_expansion;
 255
 256   /* For slots that have a free register for relaxation, record that
 257      register.  */
 258   expressionS free_reg[MAX_SLOTS];
 259
 260   /* For text fragments that can generate literals at relax time:  */
 261   fragS *literal_frags[MAX_SLOTS];
 262   enum xtensa_relax_statesE slot_subtypes[MAX_SLOTS];
 263   symbolS *slot_symbols[MAX_SLOTS];
 264   offsetT slot_offsets[MAX_SLOTS];
 265
 266   /* The global aligner needs to walk backward through the list of
 267      frags.  This field is only valid after xtensa_end.  */
 268   fragS *fr_prev;
 269 };
 270
 271
 272 /* For VLIW support, we need to know what slot a fixup applies to.  */
 273 typedef struct xtensa_fix_data_struct
 274 {
 275   int slot;
 276   symbolS *X_add_symbol;
 277   offsetT X_add_number;
 278 } xtensa_fix_data;
 279
 280
 281 /* Structure to record xtensa-specific symbol information.  */
 282 typedef struct xtensa_symfield_type
 283 {
 284   unsigned int is_loop_target : 1;
 285   unsigned int is_branch_target : 1;
 286   symbolS *next_expr_symbol;
 287 } xtensa_symfield_type;
 288
 289
 290 /* Structure for saving information about a block of property data
 291    for frags that have the same flags.   The forward reference is
 292    in this header file.  The actual definition is in tc-xtensa.c.  */
 293 struct xtensa_block_info_struct;
 294 typedef struct xtensa_block_info_struct xtensa_block_info;
 295
 296
 297 /* Property section types.  */
 298 typedef enum
 299 {
 300   xt_literal_sec,
 301   xt_prop_sec,
 302   max_xt_sec
 303 } xt_section_type;
 304
 305 typedef struct xtensa_segment_info_struct
 306 {
 307   fragS *literal_pool_loc;
 308   xtensa_block_info *blocks[max_xt_sec];
 309 } xtensa_segment_info;
 310
 311
 312 extern const char *xtensa_target_format (void);
 313 extern void xtensa_init_fix_data (struct fix *);
 314 extern void xtensa_frag_init (fragS *);
 315 extern int xtensa_force_relocation (struct fix *);
 316 extern int xtensa_validate_fix_sub (struct fix *);
 317 extern void xtensa_frob_label (struct symbol *);
 318 extern void xtensa_end (void);
 319 extern void xtensa_post_relax_hook (void);
 320 extern void xtensa_file_arch_init (bfd *);
 321 extern void xtensa_flush_pending_output (void);
 322 extern bfd_boolean xtensa_fix_adjustable (struct fix *);
 323 extern void xtensa_symbol_new_hook (symbolS *);
 324 extern long xtensa_relax_frag (fragS *, long, int *);
 325 extern void xtensa_elf_section_change_hook (void);
 326 extern int xtensa_unrecognized_line (int);
 327 extern bfd_boolean xtensa_check_inside_bundle (void);
 328 extern void xtensa_handle_align (fragS *);
 329 extern char *xtensa_section_rename (char *);
 330
 331 #define TARGET_FORMAT                   xtensa_target_format ()
 332 #define TARGET_ARCH                     bfd_arch_xtensa
 333 #define TC_SEGMENT_INFO_TYPE            xtensa_segment_info
 334 #define TC_SYMFIELD_TYPE                struct xtensa_symfield_type
 335 #define TC_FIX_TYPE                     xtensa_fix_data
 336 #define TC_INIT_FIX_DATA(x)             xtensa_init_fix_data (x)
 337 #define TC_FRAG_TYPE                    struct xtensa_frag_type
 338 #define TC_FRAG_INIT(frag)              xtensa_frag_init (frag)
 339 #define TC_FORCE_RELOCATION(fix)        xtensa_force_relocation (fix)
 340 #define TC_FORCE_RELOCATION_SUB_SAME(fix, seg) \
 341   (! SEG_NORMAL (seg) || xtensa_force_relocation (fix))
 342 #define TC_VALIDATE_FIX_SUB(fix, seg)   xtensa_validate_fix_sub (fix)
 343 #define NO_PSEUDO_DOT                   xtensa_check_inside_bundle ()
 344 #define tc_canonicalize_symbol_name(s)  xtensa_section_rename (s)
 345 #define tc_canonicalize_section_name(s) xtensa_section_rename (s)
 346 #define tc_init_after_args()            xtensa_file_arch_init (stdoutput)
 347 #define tc_fix_adjustable(fix)          xtensa_fix_adjustable (fix)
 348 #define tc_frob_label(sym)              xtensa_frob_label (sym)
 349 #define tc_unrecognized_line(ch)        xtensa_unrecognized_line (ch)
 350 #define tc_symbol_new_hook(sym)         xtensa_symbol_new_hook (sym)
 351 #define md_do_align(a,b,c,d,e)          xtensa_flush_pending_output ()
 352 #define md_elf_section_change_hook      xtensa_elf_section_change_hook
 353 #define md_end                          xtensa_end
 354 #define md_flush_pending_output()       xtensa_flush_pending_output ()
 355 #define md_operand(x)
 356 #define TEXT_SECTION_NAME               xtensa_section_rename (".text")
 357 #define DATA_SECTION_NAME               xtensa_section_rename (".data")
 358 #define BSS_SECTION_NAME                xtensa_section_rename (".bss")
 359 #define HANDLE_ALIGN(fragP)             xtensa_handle_align (fragP)
 360 #define MAX_MEM_FOR_RS_ALIGN_CODE       1
 361
 362
 363 /* The renumber_section function must be mapped over all the sections
 364    after calling xtensa_post_relax_hook.  That function is static in
 365    write.c so it cannot be called from xtensa_post_relax_hook itself.  */
 366
 367 #define md_post_relax_hook \
 368   do \
 369     { \
 370       int i = 0; \
 371       xtensa_post_relax_hook (); \
 372       bfd_map_over_sections (stdoutput, renumber_sections, &i); \
 373     } \
 374   while (0)
 375
 376
 377 /* Because xtensa relaxation can insert a new literal into the middle of
 378    fragment and thus require re-running the relaxation pass on the
 379    section, we need an explicit flag here.  We explicitly use the name
 380    "stretched" here to avoid changing the source code in write.c.  */
 381
 382 #define md_relax_frag(segment, fragP, stretch) \
 383   xtensa_relax_frag (fragP, stretch, &stretched)
 384
 385 /* Only allow call frame debug info optimization when linker relaxation is
 386    not enabled as otherwise we could generate the DWARF directives without
 387    the relocs necessary to patch them up.  */
 388 #define md_allow_eh_opt (linkrelax == 0)
 389
 390 #define LOCAL_LABELS_FB 1
 391 #define WORKING_DOT_WORD 1
 392 #define DOUBLESLASH_LINE_COMMENTS
 393 #define TC_HANDLES_FX_DONE
 394 #define TC_FINALIZE_SYMS_BEFORE_SIZE_SEG 0
 395 #define TC_LINKRELAX_FIXUP(SEG) 0
 396 #define MD_APPLY_SYM_VALUE(FIX) 0
 397 #define SUB_SEGMENT_ALIGN(SEG, FRCHAIN) 0
 398
 399 /* Use line number format that is amenable to linker relaxation.  */
 400 #define DWARF2_USE_FIXED_ADVANCE_PC (linkrelax != 0)
 401
 402
 403 /* Resource reservation info functions.  */
 404
 405 /* Returns the number of copies of a particular unit.  */
 406 typedef int (*unit_num_copies_func) (void *, xtensa_funcUnit);
 407
 408 /* Returns the number of units the opcode uses.  */
 409 typedef int (*opcode_num_units_func) (void *, xtensa_opcode);
 410
 411 /* Given an opcode and an index into the opcode's funcUnit list,
 412    returns the unit used for the index.  */
 413 typedef int (*opcode_funcUnit_use_unit_func) (void *, xtensa_opcode, int);
 414
 415 /* Given an opcode and an index into the opcode's funcUnit list,
 416    returns the cycle during which the unit is used.  */
 417 typedef int (*opcode_funcUnit_use_stage_func) (void *, xtensa_opcode, int);
 418
 419 /* The above typedefs parameterize the resource_table so that the
 420    optional scheduler doesn't need its own resource reservation system.
 421
 422    For simple resource checking, which is all that happens normally,
 423    the functions will be as follows (with some wrapping to make the
 424    interface more convenient):
 425
 426    unit_num_copies_func = xtensa_funcUnit_num_copies
 427    opcode_num_units_func = xtensa_opcode_num_funcUnit_uses
 428    opcode_funcUnit_use_unit_func = xtensa_opcode_funcUnit_use->unit
 429    opcode_funcUnit_use_stage_func = xtensa_opcode_funcUnit_use->stage
 430
 431    Of course the optional scheduler has its own reservation table
 432    and functions.  */
 433
 434 int opcode_funcUnit_use_unit (void *, xtensa_opcode, int);
 435 int opcode_funcUnit_use_stage (void *, xtensa_opcode, int);
 436
 437 typedef struct
 438 {
 439   void *data;
 440   int cycles;
 441   int allocated_cycles;
 442   int num_units;
 443   unit_num_copies_func unit_num_copies;
 444   opcode_num_units_func opcode_num_units;
 445   opcode_funcUnit_use_unit_func opcode_unit_use;
 446   opcode_funcUnit_use_stage_func opcode_unit_stage;
 447   unsigned char **units;
 448 } resource_table;
 449
 450 resource_table *new_resource_table
 451   (void *, int, int, unit_num_copies_func, opcode_num_units_func,
 452    opcode_funcUnit_use_unit_func, opcode_funcUnit_use_stage_func);
 453 void resize_resource_table (resource_table *, int);
 454 void clear_resource_table (resource_table *);
 455 bfd_boolean resources_available (resource_table *, xtensa_opcode, int);
 456 void reserve_resources (resource_table *, xtensa_opcode, int);
 457 void release_resources (resource_table *, xtensa_opcode, int);
 458
 459 #endif /* TC_XTENSA */