gas/config/tc-xtensa.h

   1 /* tc-xtensa.h -- Header file for tc-xtensa.c.
   2    Copyright (C) 2003-2021 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 0
  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   RELAX_LITERAL_POOL_CANDIDATE_BEGIN,
 128   /* Technically these are not relaxations at all but mark a location
 129      to store literals later.  Note that fr_var stores the frchain for
 130      BEGIN frags and fr_var stores now_seg for END frags.  */
 131
 132   RELAX_NARROW,
 133   /* The last instruction in this fragment (at->fr_opcode) can be
 134      freely replaced with a single wider instruction if a future
 135      alignment desires or needs it.  */
 136
 137   RELAX_IMMED,
 138   /* The last instruction in this fragment (at->fr_opcode) contains
 139      an immediate or symbol.  If the value does not fit, relax the
 140      opcode using expansions from the relax table.  */
 141
 142   RELAX_IMMED_STEP1,
 143   /* The last instruction in this fragment (at->fr_opcode) contains a
 144      literal.  It has already been expanded 1 step.  */
 145
 146   RELAX_IMMED_STEP2,
 147   /* The last instruction in this fragment (at->fr_opcode) contains a
 148      literal.  It has already been expanded 2 steps.  */
 149
 150   RELAX_IMMED_STEP3,
 151   /* The last instruction in this fragment (at->fr_opcode) contains a
 152      literal.  It has already been expanded 3 steps.  */
 153
 154   RELAX_SLOTS,
 155   /* There are instructions within the last VLIW instruction that need
 156      relaxation.  Find the relaxation based on the slot info in
 157      xtensa_frag_type.  Relaxations that deal with particular opcodes
 158      are slot-based (e.g., converting a MOVI to an L32R).  Relaxations
 159      that deal with entire instructions, such as alignment, are not
 160      slot-based.  */
 161
 162   RELAX_FILL_NOP,
 163   /* This marks the location of a pipeline stall.  We can fill these guys
 164      in for alignment of any size.  */
 165
 166   RELAX_UNREACHABLE,
 167   /* This marks the location as unreachable.  The assembler may widen or
 168      narrow this area to meet alignment requirements of nearby
 169      instructions.  */
 170
 171   RELAX_MAYBE_UNREACHABLE,
 172   /* This marks the location as possibly unreachable.  These are placed
 173      after a branch that may be relaxed into a branch and jump. If the
 174      branch is relaxed, then this frag will be converted to a
 175      RELAX_UNREACHABLE frag.  */
 176
 177   RELAX_ORG,
 178   /* This marks the location as having previously been an rs_org frag.
 179      rs_org frags are converted to fill-zero frags immediately after
 180      relaxation.  However, we need to remember where they were so we can
 181      prevent the linker from changing the size of any frag between the
 182      section start and the org frag.  */
 183
 184   RELAX_TRAMPOLINE,
 185   /* Every few thousand frags, we insert one of these, just in case we may
 186      need some space for a trampoline (jump to a jump) because the function
 187      has gotten too big. If not needed, it disappears. */
 188
 189   RELAX_NONE
 190 };
 191
 192 /* This is used as a stopper to bound the number of steps that
 193    can be taken.  */
 194 #define RELAX_IMMED_MAXSTEPS (RELAX_IMMED_STEP3 - RELAX_IMMED)
 195
 196 struct xtensa_frag_type
 197 {
 198   /* Info about the current state of assembly, e.g., transform,
 199      absolute_literals, etc.  These need to be passed to the backend and
 200      then to the object file.
 201
 202      When is_assembly_state_set is false, the frag inherits some of the
 203      state settings from the previous frag in this segment.  Because it
 204      is not possible to intercept all fragment closures (frag_more and
 205      frag_append_1_char can close a frag), we use a pass after initial
 206      assembly to fill in the assembly states.  */
 207
 208   unsigned int is_assembly_state_set : 1;
 209   unsigned int is_no_density : 1;
 210   unsigned int is_no_transform : 1;
 211   unsigned int use_longcalls : 1;
 212   unsigned int use_absolute_literals : 1;
 213
 214   /* Inhibits relaxation of machine-dependent alignment frags the
 215      first time through a relaxation....  */
 216   unsigned int relax_seen : 1;
 217
 218   /* Information that is needed in the object file and set when known.  */
 219   unsigned int is_literal : 1;
 220   unsigned int is_loop_target : 1;
 221   unsigned int is_branch_target : 1;
 222   unsigned int is_insn : 1;
 223   unsigned int is_unreachable : 1;
 224
 225   unsigned int is_specific_opcode : 1; /* also implies no_transform */
 226
 227   unsigned int is_align : 1;
 228   unsigned int is_text_align : 1;
 229   unsigned int alignment : 5;
 230
 231   /* A frag with this bit set is the first in a loop that actually
 232      contains an instruction.  */
 233   unsigned int is_first_loop_insn : 1;
 234
 235   /* A frag with this bit set is a branch that we are using to
 236      align branch targets as if it were a normal narrow instruction.  */
 237   unsigned int is_aligning_branch : 1;
 238
 239   /* A trampoline frag that is located in the middle of code and thus
 240      needs a jump around.  */
 241   unsigned int needs_jump_around : 1;
 242
 243   /* For text fragments that can generate literals at relax time, this
 244      variable points to the frag where the literal will be stored.  For
 245      literal frags, this variable points to the nearest literal pool
 246      location frag.  This literal frag will be moved to after this
 247      location.  For RELAX_LITERAL_POOL_BEGIN frags, this field points
 248      to the frag immediately before the corresponding RELAX_LITERAL_POOL_END
 249      frag, to make moving frags for this literal pool efficient.  */
 250   fragS *literal_frag;
 251
 252   /* The destination segment for literal frags.  (Note that this is only
 253      valid after xtensa_move_literals.)  This field is also used for
 254      LITERAL_POOL_END frags.  */
 255   segT lit_seg;
 256
 257   /* Frag chain for LITERAL_POOL_BEGIN frags.  */
 258   struct frchain *lit_frchain;
 259
 260   /* For the relaxation scheme, some literal fragments can have their
 261      expansions modified by an instruction that relaxes.  */
 262   int text_expansion[MAX_SLOTS];
 263   int literal_expansion[MAX_SLOTS];
 264   int unreported_expansion;
 265
 266   /* For slots that have a free register for relaxation, record that
 267      register.  */
 268   expressionS free_reg[MAX_SLOTS];
 269
 270   /* For text fragments that can generate literals at relax time:  */
 271   fragS *literal_frags[MAX_SLOTS];
 272   enum xtensa_relax_statesE slot_subtypes[MAX_SLOTS];
 273   symbolS *slot_symbols[MAX_SLOTS];
 274   offsetT slot_offsets[MAX_SLOTS];
 275
 276   /* For trampoline fragments.  */
 277   struct fix *jump_around_fix;
 278
 279   /* When marking frags after this one in the chain as no transform,
 280      cache the last one in the chain, so that we can skip to the
 281      end of the chain.  */
 282   fragS *no_transform_end;
 283 };
 284
 285
 286 /* For VLIW support, we need to know what slot a fixup applies to.  */
 287 typedef struct xtensa_fix_data_struct
 288 {
 289   int slot;
 290   symbolS *X_add_symbol;
 291   offsetT X_add_number;
 292 } xtensa_fix_data;
 293
 294
 295 /* Structure to record xtensa-specific symbol information.  */
 296 typedef struct xtensa_symfield_type
 297 {
 298   unsigned int is_loop_target : 1;
 299   unsigned int is_branch_target : 1;
 300   symbolS *next_expr_symbol;
 301 } xtensa_symfield_type;
 302
 303
 304 /* Structure for saving information about a block of property data
 305    for frags that have the same flags.   The forward reference is
 306    in this header file.  The actual definition is in tc-xtensa.c.  */
 307 struct xtensa_block_info_struct;
 308 typedef struct xtensa_block_info_struct xtensa_block_info;
 309
 310
 311 /* Property section types.  */
 312 typedef enum
 313 {
 314   xt_literal_sec,
 315   xt_prop_sec,
 316   max_xt_sec
 317 } xt_section_type;
 318
 319 typedef struct xtensa_segment_info_struct
 320 {
 321   fragS *literal_pool_loc;
 322   xtensa_block_info *blocks[max_xt_sec];
 323 } xtensa_segment_info;
 324
 325
 326 extern const char *xtensa_target_format (void);
 327 extern void xtensa_init_fix_data (struct fix *);
 328 extern void xtensa_frag_init (fragS *);
 329 extern int xtensa_force_relocation (struct fix *);
 330 extern int xtensa_validate_fix_sub (struct fix *);
 331 extern void xtensa_frob_label (struct symbol *);
 332 extern void xtensa_end (void);
 333 extern void xtensa_post_relax_hook (void);
 334 extern void xtensa_file_arch_init (bfd *);
 335 extern void xtensa_flush_pending_output (void);
 336 extern bfd_boolean xtensa_fix_adjustable (struct fix *);
 337 extern void xtensa_symbol_new_hook (symbolS *);
 338 extern long xtensa_relax_frag (fragS *, long, int *);
 339 extern void xtensa_elf_section_change_hook (void);
 340 extern int xtensa_unrecognized_line (int);
 341 extern bfd_boolean xtensa_check_inside_bundle (void);
 342 extern void xtensa_handle_align (fragS *);
 343 extern char *xtensa_section_rename (const char *);
 344
 345 /* We need to set the target endianness in xtensa_init and not in md_begin.
 346    This is because xtensa_target_format is called before md_begin, and we
 347    want to have all non-statically initialized fields initialized.  */
 348
 349 #define HOST_SPECIAL_INIT xtensa_init
 350 extern void xtensa_init (int, char **);
 351
 352 #define TARGET_FORMAT                   xtensa_target_format ()
 353 #define TARGET_ARCH                     bfd_arch_xtensa
 354 #define TC_SEGMENT_INFO_TYPE            xtensa_segment_info
 355 #define TC_SYMFIELD_TYPE                struct xtensa_symfield_type
 356 #define TC_FIX_TYPE                     xtensa_fix_data
 357 #define TC_INIT_FIX_DATA(x)             xtensa_init_fix_data (x)
 358 #define TC_FRAG_TYPE                    struct xtensa_frag_type
 359 #define TC_FRAG_INIT(frag, max_bytes)   xtensa_frag_init (frag)
 360 #define TC_FORCE_RELOCATION(fix)        xtensa_force_relocation (fix)
 361 #define TC_FORCE_RELOCATION_SUB_SAME(fix, seg) \
 362   (GENERIC_FORCE_RELOCATION_SUB_SAME (fix, seg) \
 363    || xtensa_force_relocation (fix))
 364 #define TC_VALIDATE_FIX_SUB(fix, seg)   xtensa_validate_fix_sub (fix)
 365 #define NO_PSEUDO_DOT                   xtensa_check_inside_bundle ()
 366 #define tc_canonicalize_symbol_name(s)  xtensa_section_rename (s)
 367 #define tc_canonicalize_section_name(s) xtensa_section_rename (s)
 368 #define tc_init_after_args()            xtensa_file_arch_init (stdoutput)
 369 #define tc_fix_adjustable(fix)          xtensa_fix_adjustable (fix)
 370 #define tc_frob_label(sym)              xtensa_frob_label (sym)
 371 #define tc_unrecognized_line(ch)        xtensa_unrecognized_line (ch)
 372 #define tc_symbol_new_hook(sym)         xtensa_symbol_new_hook (sym)
 373 #define md_do_align(a,b,c,d,e)          xtensa_flush_pending_output ()
 374 #define md_elf_section_change_hook      xtensa_elf_section_change_hook
 375 #define md_end                          xtensa_end
 376 #define md_flush_pending_output()       xtensa_flush_pending_output ()
 377 #define md_operand(x)
 378 #define TEXT_SECTION_NAME               xtensa_section_rename (".text")
 379 #define DATA_SECTION_NAME               xtensa_section_rename (".data")
 380 #define BSS_SECTION_NAME                xtensa_section_rename (".bss")
 381 #define HANDLE_ALIGN(fragP)             xtensa_handle_align (fragP)
 382 #define MAX_MEM_FOR_RS_ALIGN_CODE       1
 383
 384
 385 /* The renumber_section function must be mapped over all the sections
 386    after calling xtensa_post_relax_hook.  That function is static in
 387    write.c so it cannot be called from xtensa_post_relax_hook itself.  */
 388
 389 #define md_post_relax_hook \
 390   do \
 391     { \
 392       int i = 0; \
 393       xtensa_post_relax_hook (); \
 394       bfd_map_over_sections (stdoutput, renumber_sections, &i); \
 395     } \
 396   while (0)
 397
 398
 399 /* Because xtensa relaxation can insert a new literal into the middle of
 400    fragment and thus require re-running the relaxation pass on the
 401    section, we need an explicit flag here.  We explicitly use the name
 402    "stretched" here to avoid changing the source code in write.c.  */
 403
 404 #define md_relax_frag(segment, fragP, stretch) \
 405   xtensa_relax_frag (fragP, stretch, &stretched)
 406
 407 /* Only allow call frame debug info optimization when linker relaxation is
 408    not enabled as otherwise we could generate the DWARF directives without
 409    the relocs necessary to patch them up.  */
 410 #define md_allow_eh_opt (linkrelax == 0)
 411
 412 #define LOCAL_LABELS_FB 1
 413 #define WORKING_DOT_WORD 1
 414 #define DOUBLESLASH_LINE_COMMENTS
 415 #define TC_HANDLES_FX_DONE
 416 #define TC_FINALIZE_SYMS_BEFORE_SIZE_SEG 0
 417 #define TC_LINKRELAX_FIXUP(SEG) 0
 418 #define MD_APPLY_SYM_VALUE(FIX) 0
 419 #define SUB_SEGMENT_ALIGN(SEG, FRCHAIN) 0
 420
 421 /* Use line number format that is amenable to linker relaxation.  */
 422 #define DWARF2_USE_FIXED_ADVANCE_PC (linkrelax != 0)
 423
 424
 425 /* Resource reservation info functions.  */
 426
 427 /* Returns the number of copies of a particular unit.  */
 428 typedef int (*unit_num_copies_func) (void *, xtensa_funcUnit);
 429
 430 /* Returns the number of units the opcode uses.  */
 431 typedef int (*opcode_num_units_func) (void *, xtensa_opcode);
 432
 433 /* Given an opcode and an index into the opcode's funcUnit list,
 434    returns the unit used for the index.  */
 435 typedef int (*opcode_funcUnit_use_unit_func) (void *, xtensa_opcode, int);
 436
 437 /* Given an opcode and an index into the opcode's funcUnit list,
 438    returns the cycle during which the unit is used.  */
 439 typedef int (*opcode_funcUnit_use_stage_func) (void *, xtensa_opcode, int);
 440
 441 /* The above typedefs parameterize the resource_table so that the
 442    optional scheduler doesn't need its own resource reservation system.
 443
 444    For simple resource checking, which is all that happens normally,
 445    the functions will be as follows (with some wrapping to make the
 446    interface more convenient):
 447
 448    unit_num_copies_func = xtensa_funcUnit_num_copies
 449    opcode_num_units_func = xtensa_opcode_num_funcUnit_uses
 450    opcode_funcUnit_use_unit_func = xtensa_opcode_funcUnit_use->unit
 451    opcode_funcUnit_use_stage_func = xtensa_opcode_funcUnit_use->stage
 452
 453    Of course the optional scheduler has its own reservation table
 454    and functions.  */
 455
 456 int opcode_funcUnit_use_unit (void *, xtensa_opcode, int);
 457 int opcode_funcUnit_use_stage (void *, xtensa_opcode, int);
 458
 459 typedef struct
 460 {
 461   void *data;
 462   int cycles;
 463   int allocated_cycles;
 464   int num_units;
 465   unit_num_copies_func unit_num_copies;
 466   opcode_num_units_func opcode_num_units;
 467   opcode_funcUnit_use_unit_func opcode_unit_use;
 468   opcode_funcUnit_use_stage_func opcode_unit_stage;
 469   unsigned char **units;
 470 } resource_table;
 471
 472 resource_table *new_resource_table
 473   (void *, int, int, unit_num_copies_func, opcode_num_units_func,
 474    opcode_funcUnit_use_unit_func, opcode_funcUnit_use_stage_func);
 475 void resize_resource_table (resource_table *, int);
 476 void clear_resource_table (resource_table *);
 477 bfd_boolean resources_available (resource_table *, xtensa_opcode, int);
 478 void reserve_resources (resource_table *, xtensa_opcode, int);
 479 void release_resources (resource_table *, xtensa_opcode, int);
 480
 481 #endif /* TC_XTENSA */