target.h revision 117395
1/* Data structure definitions for a generic GCC target. 2 Copyright (C) 2001, 2002 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 47struct gcc_target 48{ 49 /* Functions that output assembler for the target. */ 50 struct asm_out 51 { 52 /* Opening and closing parentheses for asm expression grouping. */ 53 const char *open_paren, *close_paren; 54 55 /* Assembler instructions for creating various kinds of integer object. */ 56 const char *byte_op; 57 struct asm_int_op 58 { 59 const char *hi; 60 const char *si; 61 const char *di; 62 const char *ti; 63 } aligned_op, unaligned_op; 64 65 /* Try to output the assembler code for an integer object whose 66 value is given by X. SIZE is the size of the object in bytes and 67 ALIGNED_P indicates whether it is aligned. Return true if 68 successful. Only handles cases for which BYTE_OP, ALIGNED_OP 69 and UNALIGNED_OP are NULL. */ 70 bool (* integer) PARAMS ((rtx x, unsigned int size, int aligned_p)); 71 72 /* Output code that will globalize a label. */ 73 void (* globalize_label) PARAMS ((FILE *, const char *)); 74 75 /* Emit an assembler directive to set visibility for the symbol 76 associated with the tree decl. */ 77 void (* visibility) PARAMS ((tree, int)); 78 79 /* Output the assembler code for entry to a function. */ 80 void (* function_prologue) PARAMS ((FILE *, HOST_WIDE_INT)); 81 82 /* Output the assembler code for end of prologue. */ 83 void (* function_end_prologue) PARAMS ((FILE *)); 84 85 /* Output the assembler code for start of epilogue. */ 86 void (* function_begin_epilogue) PARAMS ((FILE *)); 87 88 /* Output the assembler code for function exit. */ 89 void (* function_epilogue) PARAMS ((FILE *, HOST_WIDE_INT)); 90 91 /* Switch to an arbitrary section NAME with attributes as 92 specified by FLAGS. */ 93 void (* named_section) PARAMS ((const char *, unsigned int)); 94 95 /* Switch to the section that holds the exception table. */ 96 void (* exception_section) PARAMS ((void)); 97 98 /* Switch to the section that holds the exception frames. */ 99 void (* eh_frame_section) PARAMS ((void)); 100 101 /* Select and switch to a section for EXP. It may be a DECL or a 102 constant for which TREE_CST_RTL is valid. RELOC is nonzero if 103 runtime relocations must be applied; bit 1 will be set if the 104 runtime relocations require non-local name resolution. ALIGN is 105 the required alignment of the data. */ 106 void (* select_section) PARAMS ((tree, int, unsigned HOST_WIDE_INT)); 107 108 /* Select and switch to a section for X with MODE. ALIGN is 109 the desired alignment of the data. */ 110 void (* select_rtx_section) PARAMS ((enum machine_mode, rtx, 111 unsigned HOST_WIDE_INT)); 112 113 /* Select a unique section name for DECL. RELOC is the same as 114 for SELECT_SECTION. */ 115 void (* unique_section) PARAMS ((tree, int)); 116 117 /* Output a constructor for a symbol with a given priority. */ 118 void (* constructor) PARAMS ((rtx, int)); 119 120 /* Output a destructor for a symbol with a given priority. */ 121 void (* destructor) PARAMS ((rtx, int)); 122 123 /* Output the assembler code for a thunk function. THUNK_DECL is the 124 declaration for the thunk function itself, FUNCTION is the decl for 125 the target function. DELTA is an immediate constant offset to be 126 added to THIS. If VCALL_OFFSET is nonzero, the word at 127 *(*this + vcall_offset) should be added to THIS. */ 128 void (* output_mi_thunk) PARAMS ((FILE *file, tree thunk_decl, 129 HOST_WIDE_INT delta, 130 HOST_WIDE_INT vcall_offset, 131 tree function_decl)); 132 133 /* Determine whether output_mi_thunk would succeed. */ 134 /* ??? Ideally, this hook would not exist, and success or failure 135 would be returned from output_mi_thunk directly. But there's 136 too much undo-able setup involved in invoking output_mi_thunk. 137 Could be fixed by making output_mi_thunk emit rtl instead of 138 text to the output file. */ 139 bool (* can_output_mi_thunk) PARAMS ((tree thunk_decl, 140 HOST_WIDE_INT delta, 141 HOST_WIDE_INT vcall_offset, 142 tree function_decl)); 143 } asm_out; 144 145 /* Functions relating to instruction scheduling. */ 146 struct sched 147 { 148 /* Given the current cost, COST, of an insn, INSN, calculate and 149 return a new cost based on its relationship to DEP_INSN through 150 the dependence LINK. The default is to make no adjustment. */ 151 int (* adjust_cost) PARAMS ((rtx insn, rtx link, rtx def_insn, int cost)); 152 153 /* Adjust the priority of an insn as you see fit. Returns the new 154 priority. */ 155 int (* adjust_priority) PARAMS ((rtx, int)); 156 157 /* Function which returns the maximum number of insns that can be 158 scheduled in the same machine cycle. This must be constant 159 over an entire compilation. The default is 1. */ 160 int (* issue_rate) PARAMS ((void)); 161 162 /* Calculate how much this insn affects how many more insns we 163 can emit this cycle. Default is they all cost the same. */ 164 int (* variable_issue) PARAMS ((FILE *, int, rtx, int)); 165 166 /* Initialize machine-dependent scheduling code. */ 167 void (* md_init) PARAMS ((FILE *, int, int)); 168 169 /* Finalize machine-dependent scheduling code. */ 170 void (* md_finish) PARAMS ((FILE *, int)); 171 172 /* Reorder insns in a machine-dependent fashion, in two different 173 places. Default does nothing. */ 174 int (* reorder) PARAMS ((FILE *, int, rtx *, int *, int)); 175 int (* reorder2) PARAMS ((FILE *, int, rtx *, int *, int)); 176 177 /* The following member value is a pointer to a function returning 178 nonzero if we should use DFA based scheduling. The default is 179 to use the old pipeline scheduler. */ 180 int (* use_dfa_pipeline_interface) PARAMS ((void)); 181 /* The values of all the following members are used only for the 182 DFA based scheduler: */ 183 /* The values of the following four members are pointers to 184 functions used to simplify the automaton descriptions. 185 dfa_pre_cycle_insn and dfa_post_cycle_insn give functions 186 returning insns which are used to change the pipeline hazard 187 recognizer state when the new simulated processor cycle 188 correspondingly starts and finishes. The function defined by 189 init_dfa_pre_cycle_insn and init_dfa_post_cycle_insn are used 190 to initialize the corresponding insns. The default values of 191 the memebers result in not changing the automaton state when 192 the new simulated processor cycle correspondingly starts and 193 finishes. */ 194 void (* init_dfa_pre_cycle_insn) PARAMS ((void)); 195 rtx (* dfa_pre_cycle_insn) PARAMS ((void)); 196 void (* init_dfa_post_cycle_insn) PARAMS ((void)); 197 rtx (* dfa_post_cycle_insn) PARAMS ((void)); 198 /* The following member value is a pointer to a function returning value 199 which defines how many insns in queue `ready' will we try for 200 multi-pass scheduling. if the member value is nonzero and the 201 function returns positive value, the DFA based scheduler will make 202 multi-pass scheduling for the first cycle. In other words, we will 203 try to choose ready insn which permits to start maximum number of 204 insns on the same cycle. */ 205 int (* first_cycle_multipass_dfa_lookahead) PARAMS ((void)); 206 /* The values of the following members are pointers to functions 207 used to improve the first cycle multipass scheduling by 208 inserting nop insns. dfa_scheduler_bubble gives a function 209 returning a nop insn with given index. The indexes start with 210 zero. The function should return NULL if there are no more nop 211 insns with indexes greater than given index. To initialize the 212 nop insn the function given by member 213 init_dfa_scheduler_bubbles is used. The default values of the 214 members result in not inserting nop insns during the multipass 215 scheduling. */ 216 void (* init_dfa_bubbles) PARAMS ((void)); 217 rtx (* dfa_bubble) PARAMS ((int)); 218 } sched; 219 220 /* Given two decls, merge their attributes and return the result. */ 221 tree (* merge_decl_attributes) PARAMS ((tree, tree)); 222 223 /* Given two types, merge their attributes and return the result. */ 224 tree (* merge_type_attributes) PARAMS ((tree, tree)); 225 226 /* Table of machine attributes and functions to handle them. 227 Ignored if NULL. */ 228 const struct attribute_spec *attribute_table; 229 230 /* Return zero if the attributes on TYPE1 and TYPE2 are incompatible, 231 one if they are compatible and two if they are nearly compatible 232 (which causes a warning to be generated). */ 233 int (* comp_type_attributes) PARAMS ((tree type1, tree type2)); 234 235 /* Assign default attributes to the newly defined TYPE. */ 236 void (* set_default_type_attributes) PARAMS ((tree type)); 237 238 /* Insert attributes on the newly created DECL. */ 239 void (* insert_attributes) PARAMS ((tree decl, tree *attributes)); 240 241 /* Return true if FNDECL (which has at least one machine attribute) 242 can be inlined despite its machine attributes, false otherwise. */ 243 bool (* function_attribute_inlinable_p) PARAMS ((tree fndecl)); 244 245 /* Return true if bitfields in RECORD_TYPE should follow the 246 Microsoft Visual C++ bitfield layout rules. */ 247 bool (* ms_bitfield_layout_p) PARAMS ((tree record_type)); 248 249 /* Set up target-specific built-in functions. */ 250 void (* init_builtins) PARAMS ((void)); 251 252 /* Expand a target-specific builtin. */ 253 rtx (* expand_builtin) PARAMS ((tree exp, rtx target, rtx subtarget, 254 enum machine_mode mode, int ignore)); 255 256 /* Given a decl, a section name, and whether the decl initializer 257 has relocs, choose attributes for the section. */ 258 /* ??? Should be merged with SELECT_SECTION and UNIQUE_SECTION. */ 259 unsigned int (* section_type_flags) PARAMS ((tree, const char *, int)); 260 261 /* True if new jumps cannot be created, to replace existing ones or 262 not, at the current point in the compilation. */ 263 bool (* cannot_modify_jumps_p) PARAMS ((void)); 264 265 /* True if the constant X cannot be placed in the constant pool. */ 266 bool (* cannot_force_const_mem) PARAMS ((rtx)); 267 268 /* True if EXP should be placed in a "small data" section. */ 269 bool (* in_small_data_p) PARAMS ((tree)); 270 271 /* True if EXP names an object for which name resolution must resolve 272 to the current module. */ 273 bool (* binds_local_p) PARAMS ((tree)); 274 275 /* Do something target-specific to record properties of the DECL into 276 the associated SYMBOL_REF. */ 277 void (* encode_section_info) PARAMS ((tree, int)); 278 279 /* Undo the effects of encode_section_info on the symbol string. */ 280 const char * (* strip_name_encoding) PARAMS ((const char *)); 281 282 /* Leave the boolean fields at the end. */ 283 284 /* True if arbitrary sections are supported. */ 285 bool have_named_sections; 286 287 /* True if "native" constructors and destructors are supported, 288 false if we're using collect2 for the job. */ 289 bool have_ctors_dtors; 290 291 /* True if thread-local storage is supported. */ 292 bool have_tls; 293 294 /* True if a small readonly data section is supported. */ 295 bool have_srodata_section; 296 297 /* True if EH frame info sections should be zero-terminated. */ 298 bool terminate_dw2_eh_frame_info; 299}; 300 301extern struct gcc_target targetm; 302