target.h revision 132718
1/* Data structure definitions for a generic GCC target. 2 Copyright (C) 2001, 2002, 2003, 2004 Free Software Foundation, Inc. 3 4This program is free software; you can redistribute it and/or modify it 5under the terms of the GNU General Public License as published by the 6Free Software Foundation; either version 2, or (at your option) any 7later version. 8 9This program is distributed in the hope that it will be useful, 10but WITHOUT ANY WARRANTY; without even the implied warranty of 11MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 12GNU General Public License for more details. 13 14You should have received a copy of the GNU General Public License 15along with this program; if not, write to the Free Software 16Foundation, 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. 17 18 In other words, you are welcome to use, share and improve this program. 19 You are forbidden to forbid anyone else to use, share and improve 20 what you give them. Help stamp out software-hoarding! */ 21 22/* This file contains a data structure that describes a GCC target. 23 At present it is incomplete, but in future it should grow to 24 contain most or all target machine and target O/S specific 25 information. 26 27 This structure has its initializer declared in target-def.h in the 28 form of large macro TARGET_INITIALIZER that expands to many smaller 29 macros. 30 31 The smaller macros each initialize one component of the structure, 32 and each has a default. Each target should have a file that 33 includes target.h and target-def.h, and overrides any inappropriate 34 defaults by undefining the relevant macro and defining a suitable 35 replacement. That file should then contain the definition of 36 "targetm" like so: 37 38 struct gcc_target targetm = TARGET_INITIALIZER; 39 40 Doing things this way allows us to bring together everything that 41 defines a GCC target. By supplying a default that is appropriate 42 to most targets, we can easily add new items without needing to 43 edit dozens of target configuration files. It should also allow us 44 to gradually reduce the amount of conditional compilation that is 45 scattered throughout GCC. */ 46 47#include "tm.h" 48 49struct gcc_target 50{ 51 /* Functions that output assembler for the target. */ 52 struct asm_out 53 { 54 /* Opening and closing parentheses for asm expression grouping. */ 55 const char *open_paren, *close_paren; 56 57 /* Assembler instructions for creating various kinds of integer object. */ 58 const char *byte_op; 59 struct asm_int_op 60 { 61 const char *hi; 62 const char *si; 63 const char *di; 64 const char *ti; 65 } aligned_op, unaligned_op; 66 67 /* Try to output the assembler code for an integer object whose 68 value is given by X. SIZE is the size of the object in bytes and 69 ALIGNED_P indicates whether it is aligned. Return true if 70 successful. Only handles cases for which BYTE_OP, ALIGNED_OP 71 and UNALIGNED_OP are NULL. */ 72 bool (* integer) (rtx x, unsigned int size, int aligned_p); 73 74 /* Output code that will globalize a label. */ 75 void (* globalize_label) (FILE *, const char *); 76 77 /* Output an internal label. */ 78 void (* internal_label) (FILE *, const char *, unsigned long); 79 80 /* Emit an assembler directive to set visibility for the symbol 81 associated with the tree decl. */ 82 void (* visibility) (tree, int); 83 84 /* Output the assembler code for entry to a function. */ 85 void (* function_prologue) (FILE *, HOST_WIDE_INT); 86 87 /* Output the assembler code for end of prologue. */ 88 void (* function_end_prologue) (FILE *); 89 90 /* Output the assembler code for start of epilogue. */ 91 void (* function_begin_epilogue) (FILE *); 92 93 /* Output the assembler code for function exit. */ 94 void (* function_epilogue) (FILE *, HOST_WIDE_INT); 95 96 /* Switch to an arbitrary section NAME with attributes as 97 specified by FLAGS. */ 98 void (* named_section) (const char *, unsigned int); 99 100 /* Switch to the section that holds the exception table. */ 101 void (* exception_section) (void); 102 103 /* Switch to the section that holds the exception frames. */ 104 void (* eh_frame_section) (void); 105 106 /* Select and switch to a section for EXP. It may be a DECL or a 107 constant. RELOC is nonzero if runtime relocations must be applied; 108 bit 1 will be set if the runtime relocations require non-local 109 name resolution. ALIGN is the required alignment of the data. */ 110 void (* select_section) (tree, int, unsigned HOST_WIDE_INT); 111 112 /* Select and switch to a section for X with MODE. ALIGN is 113 the desired alignment of the data. */ 114 void (* select_rtx_section) (enum machine_mode, rtx, 115 unsigned HOST_WIDE_INT); 116 117 /* Select a unique section name for DECL. RELOC is the same as 118 for SELECT_SECTION. */ 119 void (* unique_section) (tree, int); 120 121 /* Output a constructor for a symbol with a given priority. */ 122 void (* constructor) (rtx, int); 123 124 /* Output a destructor for a symbol with a given priority. */ 125 void (* destructor) (rtx, int); 126 127 /* Output the assembler code for a thunk function. THUNK_DECL is the 128 declaration for the thunk function itself, FUNCTION is the decl for 129 the target function. DELTA is an immediate constant offset to be 130 added to THIS. If VCALL_OFFSET is nonzero, the word at 131 *(*this + vcall_offset) should be added to THIS. */ 132 void (* output_mi_thunk) (FILE *file, tree thunk_decl, 133 HOST_WIDE_INT delta, HOST_WIDE_INT vcall_offset, 134 tree function_decl); 135 136 /* Determine whether output_mi_thunk would succeed. */ 137 /* ??? Ideally, this hook would not exist, and success or failure 138 would be returned from output_mi_thunk directly. But there's 139 too much undo-able setup involved in invoking output_mi_thunk. 140 Could be fixed by making output_mi_thunk emit rtl instead of 141 text to the output file. */ 142 bool (* can_output_mi_thunk) (tree thunk_decl, HOST_WIDE_INT delta, 143 HOST_WIDE_INT vcall_offset, 144 tree function_decl); 145 146 /* Output any boilerplate text needed at the beginning of a 147 translation unit. */ 148 void (*file_start) (void); 149 150 /* Output any boilerplate text needed at the end of a 151 translation unit. */ 152 void (*file_end) (void); 153 154 /* Output an assembler pseudo-op to declare a library function name 155 external. */ 156 void (*external_libcall) (rtx); 157 } asm_out; 158 159 /* Functions relating to instruction scheduling. */ 160 struct sched 161 { 162 /* Given the current cost, COST, of an insn, INSN, calculate and 163 return a new cost based on its relationship to DEP_INSN through 164 the dependence LINK. The default is to make no adjustment. */ 165 int (* adjust_cost) (rtx insn, rtx link, rtx def_insn, int cost); 166 167 /* Adjust the priority of an insn as you see fit. Returns the new 168 priority. */ 169 int (* adjust_priority) (rtx, int); 170 171 /* Function which returns the maximum number of insns that can be 172 scheduled in the same machine cycle. This must be constant 173 over an entire compilation. The default is 1. */ 174 int (* issue_rate) (void); 175 176 /* Calculate how much this insn affects how many more insns we 177 can emit this cycle. Default is they all cost the same. */ 178 int (* variable_issue) (FILE *, int, rtx, int); 179 180 /* Initialize machine-dependent scheduling code. */ 181 void (* md_init) (FILE *, int, int); 182 183 /* Finalize machine-dependent scheduling code. */ 184 void (* md_finish) (FILE *, int); 185 186 /* Reorder insns in a machine-dependent fashion, in two different 187 places. Default does nothing. */ 188 int (* reorder) (FILE *, int, rtx *, int *, int); 189 int (* reorder2) (FILE *, int, rtx *, int *, int); 190 191 /* The following member value is a pointer to a function called 192 after evaluation forward dependencies of insns in chain given 193 by two parameter values (head and tail correspondingly). */ 194 void (* dependencies_evaluation_hook) (rtx, rtx); 195 196 /* The following member value is a pointer to a function returning 197 nonzero if we should use DFA based scheduling. The default is 198 to use the old pipeline scheduler. */ 199 int (* use_dfa_pipeline_interface) (void); 200 /* The values of all the following members are used only for the 201 DFA based scheduler: */ 202 /* The values of the following four members are pointers to 203 functions used to simplify the automaton descriptions. 204 dfa_pre_cycle_insn and dfa_post_cycle_insn give functions 205 returning insns which are used to change the pipeline hazard 206 recognizer state when the new simulated processor cycle 207 correspondingly starts and finishes. The function defined by 208 init_dfa_pre_cycle_insn and init_dfa_post_cycle_insn are used 209 to initialize the corresponding insns. The default values of 210 the members result in not changing the automaton state when 211 the new simulated processor cycle correspondingly starts and 212 finishes. */ 213 void (* init_dfa_pre_cycle_insn) (void); 214 rtx (* dfa_pre_cycle_insn) (void); 215 void (* init_dfa_post_cycle_insn) (void); 216 rtx (* dfa_post_cycle_insn) (void); 217 /* The following member value is a pointer to a function returning value 218 which defines how many insns in queue `ready' will we try for 219 multi-pass scheduling. if the member value is nonzero and the 220 function returns positive value, the DFA based scheduler will make 221 multi-pass scheduling for the first cycle. In other words, we will 222 try to choose ready insn which permits to start maximum number of 223 insns on the same cycle. */ 224 int (* first_cycle_multipass_dfa_lookahead) (void); 225 /* The following member value is pointer to a function controlling 226 what insns from the ready insn queue will be considered for the 227 multipass insn scheduling. If the hook returns zero for insn 228 passed as the parameter, the insn will be not chosen to be 229 issued. */ 230 int (* first_cycle_multipass_dfa_lookahead_guard) (rtx); 231 /* The following member value is pointer to a function called by 232 the insn scheduler before issuing insn passed as the third 233 parameter on given cycle. If the hook returns nonzero, the 234 insn is not issued on given processors cycle. Instead of that, 235 the processor cycle is advanced. If the value passed through 236 the last parameter is zero, the insn ready queue is not sorted 237 on the new cycle start as usually. The first parameter passes 238 file for debugging output. The second one passes the scheduler 239 verbose level of the debugging output. The forth and the fifth 240 parameter values are correspondingly processor cycle on which 241 the previous insn has been issued and the current processor 242 cycle. */ 243 int (* dfa_new_cycle) (FILE *, int, rtx, int, int, int *); 244 /* The values of the following members are pointers to functions 245 used to improve the first cycle multipass scheduling by 246 inserting nop insns. dfa_scheduler_bubble gives a function 247 returning a nop insn with given index. The indexes start with 248 zero. The function should return NULL if there are no more nop 249 insns with indexes greater than given index. To initialize the 250 nop insn the function given by member 251 init_dfa_scheduler_bubbles is used. The default values of the 252 members result in not inserting nop insns during the multipass 253 scheduling. */ 254 void (* init_dfa_bubbles) (void); 255 rtx (* dfa_bubble) (int); 256 /* The following member value is a pointer to a function called 257 by the insn scheduler. It should return true if there exists a 258 dependence which is considered costly by the target, between 259 the insn passed as the first parameter, and the insn passed as 260 the second parameter. The third parameter is the INSN_DEPEND 261 link that represents the dependence between the two insns. The 262 fourth argument is the cost of the dependence as estimated by 263 the scheduler. The last argument is the distance in cycles 264 between the already scheduled insn (first parameter) and the 265 the second insn (second parameter). */ 266 bool (* is_costly_dependence) (rtx, rtx, rtx, int, int); 267 } sched; 268 269 /* Given two decls, merge their attributes and return the result. */ 270 tree (* merge_decl_attributes) (tree, tree); 271 272 /* Given two types, merge their attributes and return the result. */ 273 tree (* merge_type_attributes) (tree, tree); 274 275 /* Table of machine attributes and functions to handle them. 276 Ignored if NULL. */ 277 const struct attribute_spec *attribute_table; 278 279 /* Return zero if the attributes on TYPE1 and TYPE2 are incompatible, 280 one if they are compatible and two if they are nearly compatible 281 (which causes a warning to be generated). */ 282 int (* comp_type_attributes) (tree type1, tree type2); 283 284 /* Assign default attributes to the newly defined TYPE. */ 285 void (* set_default_type_attributes) (tree type); 286 287 /* Insert attributes on the newly created DECL. */ 288 void (* insert_attributes) (tree decl, tree *attributes); 289 290 /* Return true if FNDECL (which has at least one machine attribute) 291 can be inlined despite its machine attributes, false otherwise. */ 292 bool (* function_attribute_inlinable_p) (tree fndecl); 293 294 /* Return true if bitfields in RECORD_TYPE should follow the 295 Microsoft Visual C++ bitfield layout rules. */ 296 bool (* ms_bitfield_layout_p) (tree record_type); 297 298 /* Set up target-specific built-in functions. */ 299 void (* init_builtins) (void); 300 301 /* Expand a target-specific builtin. */ 302 rtx (* expand_builtin) (tree exp, rtx target, rtx subtarget, 303 enum machine_mode mode, int ignore); 304 305 /* Make any adjustments to libfunc names needed for this target. */ 306 void (* init_libfuncs) (void); 307 308 /* Given a decl, a section name, and whether the decl initializer 309 has relocs, choose attributes for the section. */ 310 /* ??? Should be merged with SELECT_SECTION and UNIQUE_SECTION. */ 311 unsigned int (* section_type_flags) (tree, const char *, int); 312 313 /* True if new jumps cannot be created, to replace existing ones or 314 not, at the current point in the compilation. */ 315 bool (* cannot_modify_jumps_p) (void); 316 317 /* Return a register class for which branch target register 318 optimizations should be applied. */ 319 int (* branch_target_register_class) (void); 320 321 /* Return true if branch target register optimizations should include 322 callee-saved registers that are not already live during the current 323 function. AFTER_PE_GEN is true if prologues and epilogues have 324 already been generated. */ 325 bool (* branch_target_register_callee_saved) (bool after_pe_gen); 326 327 /* True if the constant X cannot be placed in the constant pool. */ 328 bool (* cannot_force_const_mem) (rtx); 329 330 /* True if the insn X cannot be duplicated. */ 331 bool (* cannot_copy_insn_p) (rtx); 332 333 /* Given an address RTX, undo the effects of LEGITIMIZE_ADDRESS. */ 334 rtx (* delegitimize_address) (rtx); 335 336 /* True if it is OK to do sibling call optimization for the specified 337 call expression EXP. DECL will be the called function, or NULL if 338 this is an indirect call. */ 339 bool (*function_ok_for_sibcall) (tree decl, tree exp); 340 341 /* True if EXP should be placed in a "small data" section. */ 342 bool (* in_small_data_p) (tree); 343 344 /* True if EXP names an object for which name resolution must resolve 345 to the current module. */ 346 bool (* binds_local_p) (tree); 347 348 /* Do something target-specific to record properties of the DECL into 349 the associated SYMBOL_REF. */ 350 void (* encode_section_info) (tree, rtx, int); 351 352 /* Undo the effects of encode_section_info on the symbol string. */ 353 const char * (* strip_name_encoding) (const char *); 354 355 /* True if MODE is valid for a pointer in __attribute__((mode("MODE"))). */ 356 bool (* valid_pointer_mode) (enum machine_mode mode); 357 358 /* True if a vector is opaque. */ 359 bool (* vector_opaque_p) (tree); 360 361 /* Compute a (partial) cost for rtx X. Return true if the complete 362 cost has been computed, and false if subexpressions should be 363 scanned. In either case, *TOTAL contains the cost result. */ 364 /* Note that CODE and OUTER_CODE ought to be RTX_CODE, but that's 365 not necessarily defined at this point. */ 366 bool (* rtx_costs) (rtx x, int code, int outer_code, int *total); 367 368 /* Compute the cost of X, used as an address. Never called with 369 invalid addresses. */ 370 int (* address_cost) (rtx x); 371 372 /* Given a register, this hook should return a parallel of registers 373 to represent where to find the register pieces. Define this hook 374 if the register and its mode are represented in Dwarf in 375 non-contiguous locations, or if the register should be 376 represented in more than one register in Dwarf. Otherwise, this 377 hook should return NULL_RTX. */ 378 rtx (* dwarf_register_span) (rtx); 379 380 /* Fetch the fixed register(s) which hold condition codes, for 381 targets where it makes sense to look for duplicate assignments to 382 the condition codes. This should return true if there is such a 383 register, false otherwise. The arguments should be set to the 384 fixed register numbers. Up to two condition code registers are 385 supported. If there is only one for this target, the int pointed 386 at by the second argument should be set to -1. */ 387 bool (* fixed_condition_code_regs) (unsigned int *, unsigned int *); 388 389 /* If two condition code modes are compatible, return a condition 390 code mode which is compatible with both, such that a comparison 391 done in the returned mode will work for both of the original 392 modes. If the condition code modes are not compatible, return 393 VOIDmode. */ 394 enum machine_mode (* cc_modes_compatible) (enum machine_mode, 395 enum machine_mode); 396 397 /* Do machine-dependent code transformations. Called just before 398 delayed-branch scheduling. */ 399 void (* machine_dependent_reorg) (void); 400 401 /* Create the __builtin_va_list type. */ 402 tree (* build_builtin_va_list) (void); 403 404 /* Validity-checking routines for PCH files, target-specific. 405 get_pch_validity returns a pointer to the data to be stored, 406 and stores the size in its argument. pch_valid_p gets the same 407 information back and returns NULL if the PCH is valid, 408 or an error message if not. 409 */ 410 void * (* get_pch_validity) (size_t *); 411 const char * (* pch_valid_p) (const void *, size_t); 412 413 /* Functions relating to calls - argument passing, returns, etc. */ 414 struct calls { 415 bool (*promote_function_args) (tree fntype); 416 bool (*promote_function_return) (tree fntype); 417 bool (*promote_prototypes) (tree fntype); 418 rtx (*struct_value_rtx) (tree fndecl, int incoming); 419 bool (*return_in_memory) (tree type, tree fndecl); 420 bool (*return_in_msb) (tree type); 421 rtx (*expand_builtin_saveregs) (void); 422 /* Returns pretend_argument_size. */ 423 void (*setup_incoming_varargs) (CUMULATIVE_ARGS *ca, enum machine_mode mode, 424 tree type, int *pretend_arg_size, 425 int second_time); 426 bool (*strict_argument_naming) (CUMULATIVE_ARGS *ca); 427 /* Returns true if we should use SETUP_INCOMING_VARARGS and/or 428 targetm.calls.strict_argument_naming(). */ 429 bool (*pretend_outgoing_varargs_named) (CUMULATIVE_ARGS *ca); 430 431 /* Given a complex type T, return true if a parameter of type T 432 should be passed as two scalars. */ 433 bool (* split_complex_arg) (tree type); 434 } calls; 435 436 /* Leave the boolean fields at the end. */ 437 438 /* True if arbitrary sections are supported. */ 439 bool have_named_sections; 440 441 /* True if "native" constructors and destructors are supported, 442 false if we're using collect2 for the job. */ 443 bool have_ctors_dtors; 444 445 /* True if thread-local storage is supported. */ 446 bool have_tls; 447 448 /* True if a small readonly data section is supported. */ 449 bool have_srodata_section; 450 451 /* True if EH frame info sections should be zero-terminated. */ 452 bool terminate_dw2_eh_frame_info; 453 454 /* True if #NO_APP should be emitted at the beginning of 455 assembly output. */ 456 bool file_start_app_off; 457 458 /* True if output_file_directive should be called for main_input_filename 459 at the beginning of assembly output. */ 460 bool file_start_file_directive; 461 462 /* Leave the boolean fields at the end. */ 463}; 464 465extern struct gcc_target targetm; 466