gcc/config/rs6000/darwin.h

   1 /* Target definitions for PowerPC running Darwin (Mac OS X).
   2    Copyright (C) 1997-2019 Free Software Foundation, Inc.
   3    Contributed by Apple Computer Inc.
   4
   5    This file is part of GCC.
   6
   7    GCC is free software; you can redistribute it and/or modify it
   8    under the terms of the GNU General Public License as published
   9    by the Free Software Foundation; either version 3, or (at your
  10    option) any later version.
  11
  12    GCC is distributed in the hope that it will be useful, but WITHOUT
  13    ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
  14    or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public
  15    License for more details.
  16
  17    You should have received a copy of the GNU General Public License
  18    along with GCC; see the file COPYING3.  If not see
  19    <http://www.gnu.org/licenses/>.  */
  20
  21 #undef DARWIN_PPC
  22 #define DARWIN_PPC 1
  23
  24 /* The "Darwin ABI" is mostly like AIX, but with some key differences.  */
  25
  26 #define DEFAULT_ABI ABI_DARWIN
  27
  28 #ifdef IN_LIBGCC2
  29 #undef TARGET_64BIT
  30 #ifdef __powerpc64__
  31 #define TARGET_64BIT 1
  32 #else
  33 #define TARGET_64BIT 0
  34 #endif
  35 #endif
  36
  37 /* The object file format is Mach-O.  */
  38
  39 #define TARGET_OBJECT_FORMAT OBJECT_MACHO
  40
  41 /* Size of the Obj-C jump buffer.  */
  42 #define OBJC_JBLEN ((TARGET_64BIT) ? (26*2 + 18*2 + 129 + 1) : (26 + 18*2 + 129 + 1))
  43
  44 /* We're not ever going to do TOCs.  */
  45
  46 #define TARGET_HAS_TOC 0
  47
  48 /* Override the default rs6000 definition.  */
  49 #undef  PTRDIFF_TYPE
  50 #define PTRDIFF_TYPE (TARGET_64BIT ? "long int" : "int")
  51
  52 #define TARGET_OS_CPP_BUILTINS()                        \
  53   do                                                    \
  54     {                                                   \
  55       builtin_define ("__POWERPC__");                   \
  56       builtin_define ("__PPC__");                       \
  57       if (TARGET_64BIT)                                 \
  58         {                                               \
  59           builtin_define ("__ppc64__");                 \
  60           builtin_define ("__PPC64__");                 \
  61           builtin_define ("__powerpc64__");             \
  62           builtin_assert ("cpu=powerpc64");             \
  63           builtin_assert ("machine=powerpc64");         \
  64         }                                               \
  65       else                                              \
  66         {                                               \
  67           builtin_define ("__ppc__");                   \
  68           builtin_define_std ("PPC");                   \
  69           builtin_assert ("cpu=powerpc");               \
  70           builtin_assert ("machine=powerpc");           \
  71         }                                               \
  72       builtin_define ("__NATURAL_ALIGNMENT__");         \
  73       darwin_cpp_builtins (pfile);                      \
  74     }                                                   \
  75   while (0)
  76
  77 #define SUBTARGET_OVERRIDE_OPTIONS darwin_rs6000_override_options ()
  78
  79 #define C_COMMON_OVERRIDE_OPTIONS do {                                  \
  80   /* On powerpc, __cxa_get_exception_ptr is available starting in the   \
  81      10.4.6 libstdc++.dylib.  */                                        \
  82   if (strverscmp (darwin_macosx_version_min, "10.4.6") < 0              \
  83       && flag_use_cxa_get_exception_ptr == 2)                           \
  84     flag_use_cxa_get_exception_ptr = 0;                                 \
  85   if (flag_mkernel)                                                     \
  86     flag_no_builtin = 1;                                                \
  87   SUBTARGET_C_COMMON_OVERRIDE_OPTIONS;                                  \
  88 } while (0)
  89
  90 /* Darwin has 128-bit long double support in libc in 10.4 and later.
  91    Default to 128-bit long doubles even on earlier platforms for ABI
  92    consistency; arithmetic will work even if libc and libm support is
  93    not available.  */
  94
  95 #define RS6000_DEFAULT_LONG_DOUBLE_SIZE 128
  96
  97 /* Machine dependent libraries.
  98    Include libmx when targeting Darwin 7.0 and above, but before libSystem,
  99    since the functions are actually in libSystem but for 7.x compatibility
 100    we want them to be looked for in libmx first.
 101    Include libSystemStubs when compiling against 10.3 - 10.5 SDKs (we assume
 102    this is the case when targetting these) - but not for 64-bit long double.
 103    Don't do either for m64, the library is either a dummy or non-existent.
 104 */
 105
 106 #undef LIB_SPEC
 107 #define LIB_SPEC \
 108 "%{!static:                                                             \
 109   %{!m64:%{!mlong-double-64:                                            \
 110     %{pg:%:version-compare(>< 10.3 10.5 mmacosx-version-min= -lSystemStubs_profile)} \
 111     %{!pg:%:version-compare(>< 10.3 10.5 mmacosx-version-min= -lSystemStubs)} \
 112      %:version-compare(>< 10.3 10.4 mmacosx-version-min= -lmx)}}        \
 113   -lSystem                                                              \
 114 }"
 115
 116 /* We want -fPIC by default, unless we're using -static to compile for
 117    the kernel or some such.  The "-faltivec" option should have been
 118    called "-maltivec" all along.  */
 119
 120 #define CC1_SPEC "\
 121   %(cc1_cpu) \
 122   %{g: %{!fno-eliminate-unused-debug-symbols: -feliminate-unused-debug-symbols }} \
 123   %{static: %{Zdynamic: %e conflicting code gen style switches are used}}\
 124   %{!mkernel:%{!static:%{!mdynamic-no-pic:-fPIC}}} \
 125   %{faltivec:-maltivec -include altivec.h} %{fno-altivec:-mno-altivec} \
 126   %<faltivec %<fno-altivec " \
 127   DARWIN_CC1_SPEC
 128
 129 /* Default to PPC for single arch builds.  */
 130 #define DARWIN_ARCH_SPEC "ppc"
 131
 132 #define DARWIN_SUBARCH_SPEC "                   \
 133  %{mcpu=601:ppc601;                             \
 134    mcpu=603:ppc603;                             \
 135    mcpu=603e:ppc603;                            \
 136    mcpu=604:ppc604;                             \
 137    mcpu=604e:ppc604e;                           \
 138    mcpu=740:ppc750;                             \
 139    mcpu=750:ppc750;                             \
 140    mcpu=G3:ppc750;                              \
 141    mcpu=7400:ppc7400;                           \
 142    mcpu=G4:ppc7400;                             \
 143    mcpu=7450:ppc7450;                           \
 144    mcpu=970:ppc970;                             \
 145    mcpu=power4:ppc970;                          \
 146    mcpu=G5:ppc970;                              \
 147    :ppc}"
 148
 149 /* We need to jam the crt to 10.5 for 10.6 (Rosetta) use.  */
 150 #undef DARWIN_CRT1_SPEC
 151 #define DARWIN_CRT1_SPEC                                                \
 152   "%:version-compare(!> 10.5 mmacosx-version-min= -lcrt1.o)             \
 153    %:version-compare(>< 10.5 10.7 mmacosx-version-min= -lcrt1.10.5.o)   \
 154    %{fgnu-tm: -lcrttms.o}"
 155
 156 /* crt2.o is at least partially required for 10.3.x and earlier.
 157    It deals with registration of the unwind frames, where this is not
 158    automatically provided by the system.  So we need it for any case that
 159    might use exceptions.  */
 160 #undef DARWIN_CRT2_SPEC
 161 #define DARWIN_CRT2_SPEC \
 162 "%{!m64:%{shared-libgcc|static-libstdc++|fexceptions|fobjc-exceptions|fgnu-runtime: \
 163    %:version-compare(!> 10.4 mmacosx-version-min= crt2.o%s) \
 164   }}"
 165
 166 /* crt3 deals with providing cxa_atexit on earlier systems (or fixing it up,
 167    for broken versions).  It's only needed for c++ code, so we can make it
 168    conditional on shared-libgcc since that's forced on for c++.  */
 169 #undef DARWIN_CRT3_SPEC
 170 #define DARWIN_CRT3_SPEC \
 171 "%{!m64:%{shared-libgcc|static-libstdc++:                                                       \
 172    %:version-compare(>< 10.4 10.5 mmacosx-version-min= crt3.o%s) \
 173    %:version-compare(!> 10.4 mmacosx-version-min= crt3_2.o%s) \
 174   }}"
 175
 176 /* As for crt1, we need to force the dylib crt for 10.6.  */
 177 #undef DARWIN_DYLIB1_SPEC
 178 #define DARWIN_DYLIB1_SPEC                                              \
 179   "%:version-compare(!> 10.5 mmacosx-version-min= -ldylib1.o)           \
 180    %:version-compare(>< 10.5 10.7 mmacosx-version-min= -ldylib1.10.5.o)"
 181
 182 /* Likewise, the bundle crt.  */
 183 #undef DARWIN_BUNDLE1_SPEC
 184 #define DARWIN_BUNDLE1_SPEC \
 185 "%{!static:%:version-compare(< 10.7 mmacosx-version-min= -lbundle1.o)   \
 186            %{fgnu-tm: -lcrttms.o}}"
 187
 188 /* The PPC regs save/restore functions are leaves and could, conceivably
 189    be used by the tm destructor.  */
 190 #undef ENDFILE_SPEC
 191 #define ENDFILE_SPEC TM_DESTRUCTOR " -lef_ppc"
 192
 193 #undef SUBTARGET_EXTRA_SPECS
 194 #define SUBTARGET_EXTRA_SPECS                   \
 195   DARWIN_EXTRA_SPECS                            \
 196   { "darwin_arch", DARWIN_ARCH_SPEC },          \
 197   { "darwin_crt2", DARWIN_CRT2_SPEC },          \
 198   { "darwin_subarch", DARWIN_SUBARCH_SPEC },
 199
 200 /* Output a .machine directive.  */
 201 #undef TARGET_ASM_FILE_START
 202 #define TARGET_ASM_FILE_START rs6000_darwin_file_start
 203
 204 /* Make both r2 and r13 available for allocation.  */
 205 #define FIXED_R2 0
 206 #define FIXED_R13 0
 207
 208 /* Base register for access to local variables of the function.  */
 209
 210 #undef  HARD_FRAME_POINTER_REGNUM
 211 #define HARD_FRAME_POINTER_REGNUM 30
 212
 213 #undef  RS6000_PIC_OFFSET_TABLE_REGNUM
 214 #define RS6000_PIC_OFFSET_TABLE_REGNUM 31
 215
 216 /* Darwin's stack must remain 16-byte aligned for both 32 and 64 bit
 217    ABIs.  */
 218
 219 #undef  STACK_BOUNDARY
 220 #define STACK_BOUNDARY 128
 221
 222 /* Offset within stack frame to start allocating local variables at.
 223    For supported Darwin versions, FRAME_GROWS_DOWNWARD is true, therefore
 224    this value is the offset to the END of the first local allocated.
 225
 226    On the RS/6000, the frame pointer is the same as the stack pointer,
 227    except for dynamic allocations.  So we start after the fixed area and
 228    outgoing parameter area.
 229
 230    If the function uses dynamic stack space (CALLS_ALLOCA is set), that
 231    space needs to be aligned to STACK_BOUNDARY, i.e. the sum of the
 232    sizes of the fixed area and the parameter area must be a multiple of
 233    STACK_BOUNDARY.  */
 234
 235 #undef RS6000_STARTING_FRAME_OFFSET
 236 #define RS6000_STARTING_FRAME_OFFSET                                    \
 237   (cfun->calls_alloca                                                   \
 238    ? RS6000_ALIGN (crtl->outgoing_args_size + RS6000_SAVE_AREA, 16)     \
 239    : (RS6000_ALIGN (crtl->outgoing_args_size, 16) + RS6000_SAVE_AREA))
 240
 241 /* Offset from the stack pointer register to an item dynamically
 242    allocated on the stack, e.g., by `alloca'.
 243
 244    The default value for this macro is `STACK_POINTER_OFFSET' plus the
 245    length of the outgoing arguments.  The default is correct for most
 246    machines.  See `function.c' for details.
 247
 248    This value must be a multiple of STACK_BOUNDARY (hard coded in
 249    `emit-rtl.c').  */
 250
 251 #undef STACK_DYNAMIC_OFFSET
 252 #define STACK_DYNAMIC_OFFSET(FUNDECL)                                   \
 253   RS6000_ALIGN (crtl->outgoing_args_size.to_constant()                  \
 254                 + STACK_POINTER_OFFSET, 16)
 255
 256 /* Darwin uses a function call if everything needs to be saved/restored.  */
 257
 258 #undef WORLD_SAVE_P
 259 #define WORLD_SAVE_P(INFO) ((INFO)->world_save_p)
 260
 261 /* We don't use these on Darwin, they are just place-holders.  */
 262 #define SAVE_FP_PREFIX ""
 263 #define SAVE_FP_SUFFIX ""
 264 #define RESTORE_FP_PREFIX ""
 265 #define RESTORE_FP_SUFFIX ""
 266
 267 /* The assembler wants the alternate register names, but without
 268    leading percent sign.  */
 269 #undef REGISTER_NAMES
 270 #define REGISTER_NAMES                                                  \
 271 {                                                                       \
 272   /* GPRs */                                                            \
 273      "r0",  "r1",  "r2",  "r3",  "r4",  "r5",  "r6",  "r7",             \
 274      "r8",  "r9", "r10", "r11", "r12", "r13", "r14", "r15",             \
 275     "r16", "r17", "r18", "r19", "r20", "r21", "r22", "r23",             \
 276     "r24", "r25", "r26", "r27", "r28", "r29", "r30", "r31",             \
 277   /* FPRs */                                                            \
 278      "f0",  "f1",  "f2",  "f3",  "f4",  "f5",  "f6",  "f7",             \
 279      "f8",  "f9", "f10", "f11", "f12", "f13", "f14", "f15",             \
 280     "f16", "f17", "f18", "f19", "f20", "f21", "f22", "f23",             \
 281     "f24", "f25", "f26", "f27", "f28", "f29", "f30", "f31",             \
 282   /* VRs */                                                             \
 283      "v0",  "v1",  "v2",  "v3",  "v4",  "v5",  "v6",  "v7",             \
 284      "v8",  "v9", "v10", "v11", "v12", "v13", "v14", "v15",             \
 285     "v16", "v17", "v18", "v19", "v20", "v21", "v22", "v23",             \
 286     "v24", "v25", "v26", "v27", "v28", "v29", "v30", "v31",             \
 287   /* lr ctr ca ap */                                                    \
 288      "lr", "ctr", "xer",  "ap",                                         \
 289   /* cr0..cr7 */                                                        \
 290     "cr0", "cr1", "cr2", "cr3", "cr4", "cr5", "cr6", "cr7",             \
 291   /* vrsave vscr sfp */                                                 \
 292     "vrsave", "vscr", "sfp"                                             \
 293 }
 294
 295 /* This outputs NAME to FILE.  */
 296
 297 #undef  RS6000_OUTPUT_BASENAME
 298 #define RS6000_OUTPUT_BASENAME(FILE, NAME)      \
 299     assemble_name (FILE, NAME)
 300
 301 /* Globalizing directive for a label.  */
 302 #undef GLOBAL_ASM_OP
 303 #define GLOBAL_ASM_OP "\t.globl "
 304 #undef TARGET_ASM_GLOBALIZE_LABEL
 305
 306 /* This is how to output an internal label prefix.  rs6000.c uses this
 307    when generating traceback tables.  */
 308 /* Not really used for Darwin?  */
 309
 310 #undef ASM_OUTPUT_INTERNAL_LABEL_PREFIX
 311 #define ASM_OUTPUT_INTERNAL_LABEL_PREFIX(FILE,PREFIX)   \
 312   fprintf (FILE, "%s", PREFIX)
 313
 314 /* Override the standard rs6000 definition.  */
 315
 316 #undef ASM_COMMENT_START
 317 #define ASM_COMMENT_START ";"
 318
 319 /* This is how to output an assembler line that says to advance
 320    the location counter to a multiple of 2**LOG bytes using the
 321    "nop" instruction as padding.  */
 322
 323 #define ASM_OUTPUT_ALIGN_WITH_NOP(FILE,LOG)                   \
 324   do                                                          \
 325     {                                                         \
 326       if ((LOG) < 3)                                          \
 327         {                                                     \
 328           ASM_OUTPUT_ALIGN (FILE,LOG);                        \
 329         }                                                     \
 330       else /* nop == ori r0,r0,0 */                           \
 331         fprintf (FILE, "\t.align32 %d,0x60000000\n", (LOG));  \
 332     } while (0)
 333
 334 #ifdef HAVE_GAS_MAX_SKIP_P2ALIGN
 335 /* This is supported in cctools 465 and later.  The macro test
 336    above prevents using it in earlier build environments.  */
 337 #define ASM_OUTPUT_MAX_SKIP_ALIGN(FILE,LOG,MAX_SKIP)          \
 338   if ((LOG) > 0)                                             \
 339     {                                                         \
 340       if ((MAX_SKIP) <= 0)                                    \
 341         fprintf ((FILE), "\t.p2align %d\n", (LOG));           \
 342       else                                                    \
 343         fprintf ((FILE), "\t.p2align %d,,%d\n", (LOG), (MAX_SKIP)); \
 344     }
 345 #endif
 346
 347 /* Generate insns to call the profiler.  */
 348
 349 #define PROFILE_HOOK(LABEL)   output_profile_hook (LABEL)
 350
 351 /* Function name to call to do profiling.  */
 352
 353 #define RS6000_MCOUNT "*mcount"
 354
 355 /* Default processor: G4, and G5 for 64-bit.  */
 356
 357 #undef PROCESSOR_DEFAULT
 358 #define PROCESSOR_DEFAULT  PROCESSOR_PPC7400
 359 #undef PROCESSOR_DEFAULT64
 360 #define PROCESSOR_DEFAULT64  PROCESSOR_POWER4
 361
 362 /* Default target flag settings.  Despite the fact that STMW/LMW
 363    serializes, it's still a big code size win to use them.  Use FSEL by
 364    default as well.  */
 365
 366 #undef  TARGET_DEFAULT
 367 #define TARGET_DEFAULT (MASK_MULTIPLE | MASK_PPC_GFXOPT)
 368
 369 /* Darwin always uses IBM long double, never IEEE long double.  */
 370 #undef  TARGET_IEEEQUAD
 371 #define TARGET_IEEEQUAD 0
 372
 373 #undef  TARGET_IEEEQUAD_DEFAULT
 374 #define TARGET_IEEEQUAD_DEFAULT 0
 375
 376 /* Since Darwin doesn't do TOCs, stub this out.  */
 377
 378 #define ASM_OUTPUT_SPECIAL_POOL_ENTRY_P(X, MODE)  ((void)X, (void)MODE, 0)
 379
 380 /* Unlike most other PowerPC targets, chars are signed, for
 381    consistency with other Darwin architectures.  */
 382
 383 #undef DEFAULT_SIGNED_CHAR
 384 #define DEFAULT_SIGNED_CHAR (1)
 385
 386 /* Given an rtx X being reloaded into a reg required to be
 387    in class CLASS, return the class of reg to actually use.
 388    In general this is just CLASS; but on some machines
 389    in some cases it is preferable to use a more restrictive class.
 390
 391    On the RS/6000, we have to return NO_REGS when we want to reload a
 392    floating-point CONST_DOUBLE to force it to be copied to memory.
 393
 394    Don't allow R0 when loading the address of, or otherwise furtling with,
 395    a SYMBOL_REF.  */
 396
 397 #undef PREFERRED_RELOAD_CLASS
 398 #define PREFERRED_RELOAD_CLASS(X,CLASS)                         \
 399   ((CONSTANT_P (X)                                              \
 400     && reg_classes_intersect_p ((CLASS), FLOAT_REGS))           \
 401    ? NO_REGS                                                    \
 402    : ((SYMBOL_REF_P (X) || GET_CODE (X) == HIGH)                \
 403       && reg_class_subset_p (BASE_REGS, (CLASS)))               \
 404    ? BASE_REGS                                                  \
 405    : (GET_MODE_CLASS (GET_MODE (X)) == MODE_INT                 \
 406       && (CLASS) == GEN_OR_FLOAT_REGS)                          \
 407    ? GENERAL_REGS                                               \
 408    : (CLASS))
 409
 410 /* Compute field alignment.
 411    This implements the 'power' alignment rule by pegging the alignment of
 412    items (beyond the first aggregate field) to 32 bits.  The pegging is
 413    suppressed for vector and long double items (both 128 in size).
 414    There is a dummy use of the FIELD argument to avoid an unused variable
 415    warning (see PR59496).  */
 416 #define ADJUST_FIELD_ALIGN(FIELD, TYPE, COMPUTED)               \
 417   ((void) (FIELD),                                              \
 418     (TARGET_ALIGN_NATURAL                                       \
 419      ? (COMPUTED)                                               \
 420      : (COMPUTED) == 128                                        \
 421         ? 128                                                   \
 422         : MIN ((COMPUTED), 32)))
 423
 424 /* Darwin increases natural record alignment to doubleword if the first
 425    field is an FP double while the FP fields remain word aligned.  */
 426 #define ROUND_TYPE_ALIGN(STRUCT, COMPUTED, SPECIFIED)                     \
 427   ((TREE_CODE (STRUCT) == RECORD_TYPE                                     \
 428     || TREE_CODE (STRUCT) == UNION_TYPE                                   \
 429     || TREE_CODE (STRUCT) == QUAL_UNION_TYPE)                             \
 430    && TARGET_ALIGN_NATURAL == 0                                           \
 431    ? darwin_rs6000_special_round_type_align (STRUCT, COMPUTED, SPECIFIED) \
 432    : (TREE_CODE (STRUCT) == VECTOR_TYPE                                   \
 433       && ALTIVEC_VECTOR_MODE (TYPE_MODE (STRUCT)))                        \
 434    ? MAX (MAX ((COMPUTED), (SPECIFIED)), 128)                             \
 435    : MAX ((COMPUTED), (SPECIFIED)))
 436
 437 /* Specify padding for the last element of a block move between
 438    registers and memory.  FIRST is nonzero if this is the only
 439    element.  */
 440 #define BLOCK_REG_PADDING(MODE, TYPE, FIRST) \
 441   (!(FIRST) ? PAD_UPWARD : targetm.calls.function_arg_padding (MODE, TYPE))
 442
 443 #define DOUBLE_INT_ASM_OP "\t.quad\t"
 444
 445 /* For binary compatibility with 2.95; Darwin C APIs use bool from
 446    stdbool.h, which was an int-sized enum in 2.95.  Users can explicitly
 447    choose to have sizeof(bool)==1 with the -mone-byte-bool switch. */
 448 #define BOOL_TYPE_SIZE (darwin_one_byte_bool ? CHAR_TYPE_SIZE : INT_TYPE_SIZE)
 449
 450 #undef REGISTER_TARGET_PRAGMAS
 451 #define REGISTER_TARGET_PRAGMAS() \
 452   do \
 453     { \
 454       DARWIN_REGISTER_TARGET_PRAGMAS(); \
 455       targetm.target_option.pragma_parse = rs6000_pragma_target_parse; \
 456       targetm.resolve_overloaded_builtin = altivec_resolve_overloaded_builtin; \
 457     } \
 458   while (0)
 459
 460 #ifdef IN_LIBGCC2
 461 #include <stdbool.h>
 462 #endif
 463
 464 /* True, iff we're generating fast turn around debugging code.  When
 465    true, we arrange for function prologues to start with 5 nops so
 466    that gdb may insert code to redirect them, and for data to be
 467    accessed indirectly.  The runtime uses this indirection to forward
 468    references for data to the original instance of that data.  */
 469
 470 #define TARGET_FIX_AND_CONTINUE (darwin_fix_and_continue)
 471
 472 /* This is the reserved direct dispatch address for Objective-C.  */
 473 #define OFFS_MSGSEND_FAST               0xFFFEFF00
 474
 475 /* This is the reserved ivar address Objective-C.  */
 476 #define OFFS_ASSIGNIVAR_FAST            0xFFFEFEC0
 477
 478 /* Old versions of Mac OS/Darwin don't have C99 functions available.  */
 479 #undef TARGET_LIBC_HAS_FUNCTION
 480 #define TARGET_LIBC_HAS_FUNCTION darwin_libc_has_function
 481
 482 /* When generating kernel code or kexts, we don't use Altivec by
 483    default, as kernel code doesn't save/restore those registers.  */
 484 #define OS_MISSING_ALTIVEC (flag_mkernel || flag_apple_kext)
 485
 486 /* Darwin has support for section anchors on powerpc*.
 487    It is disabled for any section containing a "zero-sized item" (because these
 488    are re-written as size=1 to be compatible with the OSX ld64).
 489    The re-writing would interfere with the computation of anchor offsets.
 490    Therefore, we place zero-sized items in their own sections and make such
 491    sections unavailable to section anchoring.  */
 492
 493 #undef TARGET_ASM_OUTPUT_ANCHOR
 494 #define TARGET_ASM_OUTPUT_ANCHOR darwin_asm_output_anchor
 495
 496 #undef TARGET_USE_ANCHORS_FOR_SYMBOL_P
 497 #define TARGET_USE_ANCHORS_FOR_SYMBOL_P darwin_use_anchors_for_symbol_p
 498
 499 #undef DARWIN_SECTION_ANCHORS
 500 #define DARWIN_SECTION_ANCHORS 1
 501
 502 /* PPC Darwin has to rename some of the long double builtins.  */
 503 #undef  SUBTARGET_INIT_BUILTINS
 504 #define SUBTARGET_INIT_BUILTINS                                         \
 505 do {                                                                    \
 506   darwin_patch_builtins ();                                             \
 507   rs6000_builtin_decls[(unsigned) (RS6000_BUILTIN_CFSTRING)]            \
 508     = darwin_init_cfstring_builtins ((unsigned) (RS6000_BUILTIN_CFSTRING)); \
 509 } while(0)
 510
 511 /* So far, there is no rs6000_fold_builtin, if one is introduced, then
 512    this will need to be modified similar to the x86 case.  */
 513 #define TARGET_FOLD_BUILTIN SUBTARGET_FOLD_BUILTIN
 514
 515 /* First available SYMBOL flag bit for use by subtargets.  */
 516 #define SYMBOL_FLAG_SUBT_DEP (SYMBOL_FLAG_MACH_DEP)
 517
 518 /* Use standard DWARF numbering for DWARF debugging information.  */
 519 #define RS6000_USE_DWARF_NUMBERING
 520