expression.h

   1 #ifndef EXPRESSION_H
   2 #define EXPRESSION_H
   3 /*
   4  * sparse/expression.h
   5  *
   6  * Copyright (C) 2003 Transmeta Corp.
   7  *               2003 Linus Torvalds
   8  *
   9  * Permission is hereby granted, free of charge, to any person obtaining a copy
  10  * of this software and associated documentation files (the "Software"), to deal
  11  * in the Software without restriction, including without limitation the rights
  12  * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  13  * copies of the Software, and to permit persons to whom the Software is
  14  * furnished to do so, subject to the following conditions:
  15  *
  16  * The above copyright notice and this permission notice shall be included in
  17  * all copies or substantial portions of the Software.
  18  *
  19  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  20  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  21  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  22  * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  23  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  24  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
  25  * THE SOFTWARE.
  26  *
  27  * Declarations and helper functions for expression parsing.
  28  */
  29
  30 #include "allocate.h"
  31 #include "lib.h"
  32 #include "symbol.h"
  33
  34 struct expression_list;
  35
  36 enum expression_type {
  37         EXPR_VALUE = 1,
  38         EXPR_STRING,
  39         EXPR_SYMBOL,
  40         EXPR_TYPE,
  41         EXPR_BINOP,
  42         EXPR_ASSIGNMENT,
  43         EXPR_LOGICAL,
  44         EXPR_DEREF,
  45         EXPR_PREOP,
  46         EXPR_POSTOP,
  47         EXPR_CAST,
  48         EXPR_FORCE_CAST,
  49         EXPR_IMPLIED_CAST,
  50         EXPR_SIZEOF,
  51         EXPR_ALIGNOF,
  52         EXPR_PTRSIZEOF,
  53         EXPR_CONDITIONAL,
  54         EXPR_SELECT,            // a "safe" conditional expression
  55         EXPR_STATEMENT,
  56         EXPR_CALL,
  57         EXPR_COMMA,
  58         EXPR_COMPARE,
  59         EXPR_LABEL,
  60         EXPR_INITIALIZER,       // initializer list
  61         EXPR_IDENTIFIER,        // identifier in initializer
  62         EXPR_INDEX,             // index in initializer
  63         EXPR_POS,               // position in initializer
  64         EXPR_FVALUE,
  65         EXPR_SLICE,
  66         EXPR_OFFSETOF,
  67         EXPR_GENERIC,
  68 };
  69
  70
  71 /*
  72  * Flags for tracking the promotion of constness related attributes
  73  * from subexpressions to their parents.
  74  *
  75  * The flags are not independent as one might imply another.
  76  * The implications are as follows:
  77  * - CEF_INT, CEF_ENUM and
  78  *   CEF_CHAR imply CEF_ICE.
  79  *
  80  * Use the CEF_*_SET_MASK and CEF_*_CLEAR_MASK
  81  * helper macros defined below to set or clear one of these flags.
  82  */
  83 enum constexpr_flag {
  84         CEF_NONE = 0,
  85         /*
  86          * A constant in the sense of [6.4.4]:
  87          * - Integer constant [6.4.4.1]
  88          * - Floating point constant [6.4.4.2]
  89          * - Enumeration constant [6.4.4.3]
  90          * - Character constant [6.4.4.4]
  91          */
  92         CEF_INT = (1 << 0),
  93         CEF_FLOAT = (1 << 1),
  94         CEF_ENUM = (1 << 2),
  95         CEF_CHAR = (1 << 3),
  96
  97         /*
  98          * A constant expression in the sense of [6.6]:
  99          * - integer constant expression [6.6(6)]
 100          * - arithmetic constant expression [6.6(8)]
 101          * - address constant [6.6(9)]
 102          */
 103         CEF_ICE = (1 << 4),
 104         CEF_ACE = (1 << 5),
 105         CEF_ADDR = (1 << 6),
 106
 107         /* integer constant expression => arithmetic constant expression */
 108         CEF_SET_ICE = (CEF_ICE | CEF_ACE),
 109
 110         /* integer constant => integer constant expression */
 111         CEF_SET_INT = (CEF_INT | CEF_SET_ICE),
 112
 113         /* floating point constant => arithmetic constant expression */
 114         CEF_SET_FLOAT = (CEF_FLOAT | CEF_ACE),
 115
 116         /* enumeration constant => integer constant expression */
 117         CEF_SET_ENUM = (CEF_ENUM | CEF_SET_ICE),
 118
 119         /* character constant => integer constant expression */
 120         CEF_SET_CHAR = (CEF_CHAR | CEF_SET_ICE),
 121
 122         /*
 123          * Remove any "Constant" [6.4.4] flag, but retain the "constant
 124          * expression" [6.6] flags.
 125          */
 126         CEF_CONST_MASK = (CEF_INT | CEF_FLOAT | CEF_CHAR),
 127
 128         /*
 129          * not an integer constant expression => neither of integer,
 130          * enumeration and character constant
 131          */
 132         CEF_CLR_ICE = (CEF_ICE | CEF_INT | CEF_ENUM | CEF_CHAR),
 133 };
 134
 135 enum {
 136         Handled = 1 << 0,
 137         Tmp     = 1 << 1,
 138         Fake    = 1 << 2,
 139 }; /* for expr->smatch_flags */
 140
 141 enum {
 142         Taint_comma = 1,
 143 }; /* for expr->taint */
 144
 145 struct asm_operand {
 146         struct ident *name;
 147         struct expression *constraint;
 148         struct expression *expr;
 149         unsigned int is_assign:1;
 150         unsigned int is_modify:1;
 151         unsigned int is_earlyclobber:1;
 152         unsigned int is_commutative:1;
 153         unsigned int is_register:1;
 154         unsigned int is_memory:1;
 155 };
 156
 157 struct type_expression {
 158         struct symbol *type;
 159         struct expression *expr;
 160         struct type_expression *next;
 161 };
 162
 163 DECLARE_ALLOCATOR(type_expression);
 164
 165 struct expression {
 166         enum expression_type type:8;
 167         unsigned flags:8;
 168         unsigned smatch_flags:16;
 169         unsigned zero_init:1;
 170         int op;
 171         struct position pos;
 172         struct symbol *ctype;
 173         unsigned long parent;
 174         union {
 175                 // EXPR_VALUE
 176                 struct {
 177                         unsigned long long value;
 178                         unsigned taint;
 179                 };
 180
 181                 // EXPR_FVALUE
 182                 long double fvalue;
 183
 184                 // EXPR_STRING
 185                 struct {
 186                         int wide;
 187                         struct string *string;
 188                 };
 189
 190                 // EXPR_UNOP, EXPR_PREOP and EXPR_POSTOP
 191                 struct /* unop */ {
 192                         struct expression *unop;
 193                         unsigned long op_value;
 194                 };
 195
 196                 // EXPR_SYMBOL, EXPR_TYPE
 197                 struct /* symbol_arg */ {
 198                         struct symbol *symbol;
 199                         struct ident *symbol_name;
 200                 };
 201
 202                 // EXPR_STATEMENT
 203                 struct statement *statement;
 204
 205                 // EXPR_BINOP, EXPR_COMMA, EXPR_COMPARE, EXPR_LOGICAL and EXPR_ASSIGNMENT
 206                 struct /* binop_arg */ {
 207                         struct expression *left, *right;
 208                 };
 209                 // EXPR_DEREF
 210                 struct /* deref_arg */ {
 211                         struct expression *deref;
 212                         struct ident *member;
 213                         int member_offset;
 214                 };
 215                 // EXPR_SLICE
 216                 struct /* slice */ {
 217                         struct expression *base;
 218                         unsigned r_bitpos, r_nrbits;
 219                 };
 220                 // EXPR_CAST, EXPR_FORCE_CAST, EXPR_IMPLIED_CAST,
 221                 // EXPR_SIZEOF, EXPR_ALIGNOF and EXPR_PTRSIZEOF
 222                 struct /* cast_arg */ {
 223                         struct symbol *cast_type;
 224                         struct expression *cast_expression;
 225                 };
 226                 // EXPR_CONDITIONAL
 227                 // EXPR_SELECT
 228                 struct /* conditional_expr */ {
 229                         struct expression *conditional, *cond_true, *cond_false;
 230                 };
 231                 // EXPR_CALL
 232                 struct /* call_expr */ {
 233                         struct expression *fn;
 234                         struct expression_list *args;
 235                 };
 236                 // EXPR_LABEL
 237                 struct /* label_expr */ {
 238                         struct symbol *label_symbol;
 239                 };
 240                 // EXPR_INITIALIZER
 241                 struct expression_list *expr_list;
 242                 // EXPR_IDENTIFIER
 243                 struct /* ident_expr */ {
 244                         int offset;
 245                         struct ident *expr_ident;
 246                         struct symbol *field;
 247                         struct expression *ident_expression;
 248                 };
 249                 // EXPR_INDEX
 250                 struct /* index_expr */ {
 251                         unsigned int idx_from, idx_to;
 252                         struct expression *idx_expression;
 253                 };
 254                 // EXPR_POS
 255                 struct /* initpos_expr */ {
 256                         unsigned int init_offset, init_nr;
 257                         struct expression *init_expr;
 258                 };
 259                 // EXPR_OFFSETOF
 260                 struct {
 261                         struct symbol *in;
 262                         struct expression *down;
 263                         union {
 264                                 struct ident *ident;
 265                                 struct expression *index;
 266                         };
 267                 };
 268                 // EXPR_GENERIC
 269                 struct {
 270                         struct expression *control;
 271                         struct expression *def;
 272                         struct type_expression *map;
 273                 };
 274         };
 275 };
 276
 277 ///
 278 // Constant expression values
 279 // --------------------------
 280
 281 ///
 282 // test if an expression evaluates to the constant ``0``.
 283 // @return: ``1`` if @expr evaluate to ``0``,
 284 //      ``0`` otherwise.
 285 int is_zero_constant(struct expression *expr);
 286
 287 ///
 288 // test the compile time truth value of an expression
 289 // @return:
 290 //      * ``-1`` if @expr is not constant,
 291 //      * ``0`` or ``1`` depending on the truth value of @expr.
 292 int expr_truth_value(struct expression *expr);
 293
 294 long long get_expression_value(struct expression *);
 295 long long const_expression_value(struct expression *);
 296 long long get_expression_value_silent(struct expression *expr);
 297
 298 /* Expression parsing */
 299 struct token *parse_expression(struct token *token, struct expression **tree);
 300 struct token *conditional_expression(struct token *token, struct expression **tree);
 301 struct token *primary_expression(struct token *token, struct expression **tree);
 302 struct token *parens_expression(struct token *token, struct expression **expr, const char *where);
 303 struct token *string_expression(struct token *token, struct expression **expr, const char *where);
 304 struct token *assignment_expression(struct token *token, struct expression **tree);
 305
 306 extern void evaluate_symbol_list(struct symbol_list *list);
 307 extern struct symbol *evaluate_statement(struct statement *stmt);
 308 extern struct symbol *evaluate_expression(struct expression *);
 309 struct symbol *find_identifier(struct ident *ident, struct symbol_list *_list, int *offset);
 310
 311 extern int expand_symbol(struct symbol *);
 312
 313 static inline struct expression *alloc_expression(struct position pos, int type)
 314 {
 315         struct expression *expr = __alloc_expression(0);
 316         expr->type = type;
 317         expr->pos = pos;
 318         expr->flags = CEF_NONE;
 319         return expr;
 320 }
 321
 322 static inline struct expression *alloc_const_expression(struct position pos, int value)
 323 {
 324         struct expression *expr = __alloc_expression(0);
 325         expr->type = EXPR_VALUE;
 326         expr->pos = pos;
 327         expr->value = value;
 328         expr->ctype = &int_ctype;
 329         expr->flags = CEF_SET_INT;
 330         return expr;
 331 }
 332
 333 /* Type name parsing */
 334 struct token *typename(struct token *, struct symbol **, int *);
 335
 336 static inline int lookup_type(struct token *token)
 337 {
 338         if (token->pos.type == TOKEN_IDENT) {
 339                 struct symbol *sym = lookup_symbol(token->ident, NS_SYMBOL | NS_TYPEDEF);
 340                 return sym && (sym->namespace & NS_TYPEDEF);
 341         }
 342         return 0;
 343 }
 344
 345 /* Statement parsing */
 346 struct statement *alloc_statement(struct position pos, int type);
 347 struct token *initializer(struct expression **tree, struct token *token);
 348 struct token *compound_statement(struct token *, struct statement *);
 349
 350 /* The preprocessor calls this 'constant_expression()' */
 351 #define constant_expression(token,tree) conditional_expression(token, tree)
 352
 353 /* Cast folding of constant values.. */
 354 void cast_value(struct expression *expr, struct symbol *newtype,
 355         struct expression *old, struct symbol *oldtype);
 356
 357 #endif