target.h revision 90075
1/* Data structure definitions for a generic GCC target. 2 Copyright (C) 2001 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 the assembler code for entry to a function. */ 73 void (* function_prologue) PARAMS ((FILE *, HOST_WIDE_INT)); 74 75 /* Output the assembler code for end of prologue. */ 76 void (* function_end_prologue) PARAMS ((FILE *)); 77 78 /* Output the assembler code for start of epilogue. */ 79 void (* function_begin_epilogue) PARAMS ((FILE *)); 80 81 /* Output the assembler code for function exit. */ 82 void (* function_epilogue) PARAMS ((FILE *, HOST_WIDE_INT)); 83 84 /* Switch to an arbitrary section NAME with attributes as 85 specified by FLAGS. */ 86 void (* named_section) PARAMS ((const char *, unsigned int)); 87 88 /* Switch to the section that holds the exception table. */ 89 void (* exception_section) PARAMS ((void)); 90 91 /* Switch to the section that holds the exception frames. */ 92 void (* eh_frame_section) PARAMS ((void)); 93 94 /* Output a constructor for a symbol with a given priority. */ 95 void (* constructor) PARAMS ((rtx, int)); 96 97 /* Output a destructor for a symbol with a given priority. */ 98 void (* destructor) PARAMS ((rtx, int)); 99 } asm_out; 100 101 /* Functions relating to instruction scheduling. */ 102 struct sched 103 { 104 /* Given the current cost, COST, of an insn, INSN, calculate and 105 return a new cost based on its relationship to DEP_INSN through 106 the dependence LINK. The default is to make no adjustment. */ 107 int (* adjust_cost) PARAMS ((rtx insn, rtx link, rtx def_insn, int cost)); 108 109 /* Adjust the priority of an insn as you see fit. Returns the new 110 priority. */ 111 int (* adjust_priority) PARAMS ((rtx, int)); 112 113 /* Function which returns the maximum number of insns that can be 114 scheduled in the same machine cycle. This must be constant 115 over an entire compilation. The default is 1. */ 116 int (* issue_rate) PARAMS ((void)); 117 118 /* Calculate how much this insn affects how many more insns we 119 can emit this cycle. Default is they all cost the same. */ 120 int (* variable_issue) PARAMS ((FILE *, int, rtx, int)); 121 122 /* Initialize machine-dependent scheduling code. */ 123 void (* md_init) PARAMS ((FILE *, int, int)); 124 125 /* Finalize machine-dependent scheduling code. */ 126 void (* md_finish) PARAMS ((FILE *, int)); 127 128 /* Reorder insns in a machine-dependent fashion, in two different 129 places. Default does nothing. */ 130 int (* reorder) PARAMS ((FILE *, int, rtx *, int *, int)); 131 int (* reorder2) PARAMS ((FILE *, int, rtx *, int *, int)); 132 133 /* cycle_display is a pointer to a function which can emit 134 data into the assembly stream about the current cycle. 135 Arguments are CLOCK, the data to emit, and LAST, the last 136 insn in the new chain we're building. Returns a new LAST. 137 The default is to do nothing. */ 138 rtx (* cycle_display) PARAMS ((int clock, rtx last)); 139 } sched; 140 141 /* Given two decls, merge their attributes and return the result. */ 142 tree (* merge_decl_attributes) PARAMS ((tree, tree)); 143 144 /* Given two types, merge their attributes and return the result. */ 145 tree (* merge_type_attributes) PARAMS ((tree, tree)); 146 147 /* Table of machine attributes and functions to handle them. */ 148 const struct attribute_spec *attribute_table; 149 150 /* Return zero if the attributes on TYPE1 and TYPE2 are incompatible, 151 one if they are compatible and two if they are nearly compatible 152 (which causes a warning to be generated). */ 153 int (* comp_type_attributes) PARAMS ((tree type1, tree type2)); 154 155 /* Assign default attributes to the newly defined TYPE. */ 156 void (* set_default_type_attributes) PARAMS ((tree type)); 157 158 /* Insert attributes on the newly created DECL. */ 159 void (* insert_attributes) PARAMS ((tree decl, tree *attributes)); 160 161 /* Return true if FNDECL (which has at least one machine attribute) 162 can be inlined despite its machine attributes, false otherwise. */ 163 bool (* function_attribute_inlinable_p) PARAMS ((tree fndecl)); 164 165 /* Set up target-specific built-in functions. */ 166 void (* init_builtins) PARAMS ((void)); 167 168 /* Expand a target-specific builtin. */ 169 rtx (* expand_builtin) PARAMS ((tree exp, rtx target, rtx subtarget, 170 enum machine_mode mode, int ignore)); 171 172 /* Given a decl, a section name, and whether the decl initializer 173 has relocs, choose attributes for the section. */ 174 /* ??? Should be merged with SELECT_SECTION and UNIQUE_SECTION. */ 175 unsigned int (* section_type_flags) PARAMS ((tree, const char *, int)); 176 177 /* True if arbitrary sections are supported. */ 178 bool have_named_sections; 179 180 /* True if "native" constructors and destructors are supported, 181 false if we're using collect2 for the job. */ 182 bool have_ctors_dtors; 183}; 184 185extern struct gcc_target targetm; 186