gold/expression.cc

   1 // expression.cc -- expressions in linker scripts for gold
   2
   3 // Copyright 2006, 2007, 2008 Free Software Foundation, Inc.
   4 // Written by Ian Lance Taylor <iant@google.com>.
   5
   6 // This file is part of gold.
   7
   8 // This program is free software; you can redistribute it and/or modify
   9 // it under the terms of the GNU General Public License as published by
  10 // the Free Software Foundation; either version 3 of the License, or
  11 // (at your option) any later version.
  12
  13 // This program is distributed in the hope that it will be useful,
  14 // but WITHOUT ANY WARRANTY; without even the implied warranty of
  15 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16 // GNU General Public License for more details.
  17
  18 // You should have received a copy of the GNU General Public License
  19 // along with this program; if not, write to the Free Software
  20 // Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,
  21 // MA 02110-1301, USA.
  22
  23 #include "gold.h"
  24
  25 #include <string>
  26
  27 #include "elfcpp.h"
  28 #include "parameters.h"
  29 #include "symtab.h"
  30 #include "layout.h"
  31 #include "output.h"
  32 #include "script.h"
  33 #include "script-c.h"
  34
  35 namespace gold
  36 {
  37
  38 // This file holds the code which handles linker expressions.
  39
  40 // The dot symbol, which linker scripts refer to simply as ".",
  41 // requires special treatment.  The dot symbol is set several times,
  42 // section addresses will refer to it, output sections will change it,
  43 // and it can be set based on the value of other symbols.  We simplify
  44 // the handling by prohibiting setting the dot symbol to the value of
  45 // a non-absolute symbol.
  46
  47 // When evaluating the value of an expression, we pass in a pointer to
  48 // this struct, so that the expression evaluation can find the
  49 // information it needs.
  50
  51 struct Expression::Expression_eval_info
  52 {
  53   // The symbol table.
  54   const Symbol_table* symtab;
  55   // The layout--we use this to get section information.
  56   const Layout* layout;
  57   // Whether to check assertions.
  58   bool check_assertions;
  59   // Whether expressions can refer to the dot symbol.  The dot symbol
  60   // is only available within a SECTIONS clause.
  61   bool is_dot_available;
  62   // The current value of the dot symbol.
  63   uint64_t dot_value;
  64   // The section in which the dot symbol is defined; this is NULL if
  65   // it is absolute.
  66   Output_section* dot_section;
  67   // Points to where the section of the result should be stored.
  68   Output_section** result_section_pointer;
  69   // Pointer to where the alignment of the result should be stored.
  70   uint64_t* result_alignment_pointer;
  71 };
  72
  73 // Evaluate an expression.
  74
  75 uint64_t
  76 Expression::eval(const Symbol_table* symtab, const Layout* layout,
  77                  bool check_assertions)
  78 {
  79   return this->eval_maybe_dot(symtab, layout, check_assertions,
  80                               false, 0, NULL, NULL, NULL);
  81 }
  82
  83 // Evaluate an expression which may refer to the dot symbol.
  84
  85 uint64_t
  86 Expression::eval_with_dot(const Symbol_table* symtab, const Layout* layout,
  87                           bool check_assertions, uint64_t dot_value,
  88                           Output_section* dot_section,
  89                           Output_section** result_section_pointer,
  90                           uint64_t* result_alignment_pointer)
  91 {
  92   return this->eval_maybe_dot(symtab, layout, check_assertions, true,
  93                               dot_value, dot_section, result_section_pointer,
  94                               result_alignment_pointer);
  95 }
  96
  97 // Evaluate an expression which may or may not refer to the dot
  98 // symbol.
  99
 100 uint64_t
 101 Expression::eval_maybe_dot(const Symbol_table* symtab, const Layout* layout,
 102                            bool check_assertions, bool is_dot_available,
 103                            uint64_t dot_value, Output_section* dot_section,
 104                            Output_section** result_section_pointer,
 105                            uint64_t* result_alignment_pointer)
 106 {
 107   Expression_eval_info eei;
 108   eei.symtab = symtab;
 109   eei.layout = layout;
 110   eei.check_assertions = check_assertions;
 111   eei.is_dot_available = is_dot_available;
 112   eei.dot_value = dot_value;
 113   eei.dot_section = dot_section;
 114
 115   // We assume the value is absolute, and only set this to a section
 116   // if we find a section relative reference.
 117   if (result_section_pointer != NULL)
 118     *result_section_pointer = NULL;
 119   eei.result_section_pointer = result_section_pointer;
 120
 121   eei.result_alignment_pointer = result_alignment_pointer;
 122
 123   return this->value(&eei);
 124 }
 125
 126 // A number.
 127
 128 class Integer_expression : public Expression
 129 {
 130  public:
 131   Integer_expression(uint64_t val)
 132     : val_(val)
 133   { }
 134
 135   uint64_t
 136   value(const Expression_eval_info*)
 137   { return this->val_; }
 138
 139   void
 140   print(FILE* f) const
 141   { fprintf(f, "0x%llx", static_cast<unsigned long long>(this->val_)); }
 142
 143  private:
 144   uint64_t val_;
 145 };
 146
 147 extern "C" Expression*
 148 script_exp_integer(uint64_t val)
 149 {
 150   return new Integer_expression(val);
 151 }
 152
 153 // An expression whose value is the value of a symbol.
 154
 155 class Symbol_expression : public Expression
 156 {
 157  public:
 158   Symbol_expression(const char* name, size_t length)
 159     : name_(name, length)
 160   { }
 161
 162   uint64_t
 163   value(const Expression_eval_info*);
 164
 165   void
 166   print(FILE* f) const
 167   { fprintf(f, "%s", this->name_.c_str()); }
 168
 169  private:
 170   std::string name_;
 171 };
 172
 173 uint64_t
 174 Symbol_expression::value(const Expression_eval_info* eei)
 175 {
 176   Symbol* sym = eei->symtab->lookup(this->name_.c_str());
 177   if (sym == NULL || !sym->is_defined())
 178     {
 179       gold_error(_("undefined symbol '%s' referenced in expression"),
 180                  this->name_.c_str());
 181       return 0;
 182     }
 183
 184   if (eei->result_section_pointer != NULL)
 185     *eei->result_section_pointer = sym->output_section();
 186
 187   if (parameters->target().get_size() == 32)
 188     return eei->symtab->get_sized_symbol<32>(sym)->value();
 189   else if (parameters->target().get_size() == 64)
 190     return eei->symtab->get_sized_symbol<64>(sym)->value();
 191   else
 192     gold_unreachable();
 193 }
 194
 195 // An expression whose value is the value of the special symbol ".".
 196 // This is only valid within a SECTIONS clause.
 197
 198 class Dot_expression : public Expression
 199 {
 200  public:
 201   Dot_expression()
 202   { }
 203
 204   uint64_t
 205   value(const Expression_eval_info*);
 206
 207   void
 208   print(FILE* f) const
 209   { fprintf(f, "."); }
 210 };
 211
 212 uint64_t
 213 Dot_expression::value(const Expression_eval_info* eei)
 214 {
 215   if (!eei->is_dot_available)
 216     {
 217       gold_error(_("invalid reference to dot symbol outside of "
 218                    "SECTIONS clause"));
 219       return 0;
 220     }
 221   if (eei->result_section_pointer != NULL)
 222     *eei->result_section_pointer = eei->dot_section;
 223   return eei->dot_value;
 224 }
 225
 226 // A string.  This is either the name of a symbol, or ".".
 227
 228 extern "C" Expression*
 229 script_exp_string(const char* name, size_t length)
 230 {
 231   if (length == 1 && name[0] == '.')
 232     return new Dot_expression();
 233   else
 234     return new Symbol_expression(name, length);
 235 }
 236
 237 // A unary expression.
 238
 239 class Unary_expression : public Expression
 240 {
 241  public:
 242   Unary_expression(Expression* arg)
 243     : arg_(arg)
 244   { }
 245
 246   ~Unary_expression()
 247   { delete this->arg_; }
 248
 249  protected:
 250   uint64_t
 251   arg_value(const Expression_eval_info* eei,
 252             Output_section** arg_section_pointer) const
 253   {
 254     return this->arg_->eval_maybe_dot(eei->symtab, eei->layout,
 255                                       eei->check_assertions,
 256                                       eei->is_dot_available,
 257                                       eei->dot_value,
 258                                       eei->dot_section,
 259                                       arg_section_pointer,
 260                                       eei->result_alignment_pointer);
 261   }
 262
 263   void
 264   arg_print(FILE* f) const
 265   { this->arg_->print(f); }
 266
 267  private:
 268   Expression* arg_;
 269 };
 270
 271 // Handle unary operators.  We use a preprocessor macro as a hack to
 272 // capture the C operator.
 273
 274 #define UNARY_EXPRESSION(NAME, OPERATOR)                                \
 275   class Unary_ ## NAME : public Unary_expression                        \
 276   {                                                                     \
 277   public:                                                               \
 278     Unary_ ## NAME(Expression* arg)                                     \
 279       : Unary_expression(arg)                                           \
 280     { }                                                                 \
 281                                                                         \
 282     uint64_t                                                            \
 283     value(const Expression_eval_info* eei)                              \
 284     {                                                                   \
 285       Output_section* arg_section;                                      \
 286       uint64_t ret = OPERATOR this->arg_value(eei, &arg_section);       \
 287       if (arg_section != NULL && parameters->options().relocatable())   \
 288         gold_warning(_("unary " #NAME " applied to section "            \
 289                        "relative value"));                              \
 290       return ret;                                                       \
 291     }                                                                   \
 292                                                                         \
 293     void                                                                \
 294     print(FILE* f) const                                                \
 295     {                                                                   \
 296       fprintf(f, "(%s ", #OPERATOR);                                    \
 297       this->arg_print(f);                                               \
 298       fprintf(f, ")");                                                  \
 299     }                                                                   \
 300   };                                                                    \
 301                                                                         \
 302   extern "C" Expression*                                                \
 303   script_exp_unary_ ## NAME(Expression* arg)                            \
 304   {                                                                     \
 305       return new Unary_ ## NAME(arg);                                   \
 306   }
 307
 308 UNARY_EXPRESSION(minus, -)
 309 UNARY_EXPRESSION(logical_not, !)
 310 UNARY_EXPRESSION(bitwise_not, ~)
 311
 312 // A binary expression.
 313
 314 class Binary_expression : public Expression
 315 {
 316  public:
 317   Binary_expression(Expression* left, Expression* right)
 318     : left_(left), right_(right)
 319   { }
 320
 321   ~Binary_expression()
 322   {
 323     delete this->left_;
 324     delete this->right_;
 325   }
 326
 327  protected:
 328   uint64_t
 329   left_value(const Expression_eval_info* eei,
 330              Output_section** section_pointer,
 331              uint64_t* alignment_pointer) const
 332   {
 333     return this->left_->eval_maybe_dot(eei->symtab, eei->layout,
 334                                        eei->check_assertions,
 335                                        eei->is_dot_available,
 336                                        eei->dot_value,
 337                                        eei->dot_section,
 338                                        section_pointer,
 339                                        alignment_pointer);
 340   }
 341
 342   uint64_t
 343   right_value(const Expression_eval_info* eei,
 344               Output_section** section_pointer,
 345               uint64_t* alignment_pointer) const
 346   {
 347     return this->right_->eval_maybe_dot(eei->symtab, eei->layout,
 348                                         eei->check_assertions,
 349                                         eei->is_dot_available,
 350                                         eei->dot_value,
 351                                         eei->dot_section,
 352                                         section_pointer,
 353                                         alignment_pointer);
 354   }
 355
 356   void
 357   left_print(FILE* f) const
 358   { this->left_->print(f); }
 359
 360   void
 361   right_print(FILE* f) const
 362   { this->right_->print(f); }
 363
 364   // This is a call to function FUNCTION_NAME.  Print it.  This is for
 365   // debugging.
 366   void
 367   print_function(FILE* f, const char* function_name) const
 368   {
 369     fprintf(f, "%s(", function_name);
 370     this->left_print(f);
 371     fprintf(f, ", ");
 372     this->right_print(f);
 373     fprintf(f, ")");
 374   }
 375
 376  private:
 377   Expression* left_;
 378   Expression* right_;
 379 };
 380
 381 // Handle binary operators.  We use a preprocessor macro as a hack to
 382 // capture the C operator.  KEEP_LEFT means that if the left operand
 383 // is section relative and the right operand is not, the result uses
 384 // the same section as the left operand.  KEEP_RIGHT is the same with
 385 // left and right swapped.  IS_DIV means that we need to give an error
 386 // if the right operand is zero.  WARN means that we should warn if
 387 // used on section relative values in a relocatable link.  We always
 388 // warn if used on values in different sections in a relocatable link.
 389
 390 #define BINARY_EXPRESSION(NAME, OPERATOR, KEEP_LEFT, KEEP_RIGHT, IS_DIV, WARN) \
 391   class Binary_ ## NAME : public Binary_expression                      \
 392   {                                                                     \
 393   public:                                                               \
 394     Binary_ ## NAME(Expression* left, Expression* right)                \
 395       : Binary_expression(left, right)                                  \
 396     { }                                                                 \
 397                                                                         \
 398     uint64_t                                                            \
 399     value(const Expression_eval_info* eei)                              \
 400     {                                                                   \
 401       Output_section* left_section;                                     \
 402       uint64_t left_alignment;                                          \
 403       uint64_t left = this->left_value(eei, &left_section,              \
 404                                        &left_alignment);                \
 405       Output_section* right_section;                                    \
 406       uint64_t right_alignment;                                         \
 407       uint64_t right = this->right_value(eei, &right_section,           \
 408                                          &right_alignment);             \
 409       if (KEEP_RIGHT && left_section == NULL && right_section != NULL)  \
 410         {                                                               \
 411           if (eei->result_section_pointer != NULL)                      \
 412             *eei->result_section_pointer = right_section;               \
 413           if (eei->result_alignment_pointer != NULL)                    \
 414             *eei->result_alignment_pointer = right_alignment;           \
 415         }                                                               \
 416       else if (KEEP_LEFT                                                \
 417                && left_section != NULL                                  \
 418                && right_section == NULL)                                \
 419         {                                                               \
 420           if (eei->result_section_pointer != NULL)                      \
 421             *eei->result_section_pointer = left_section;                \
 422           if (eei->result_alignment_pointer != NULL)                    \
 423             *eei->result_alignment_pointer = right_alignment;           \
 424         }                                                               \
 425       else if ((WARN || left_section != right_section)                  \
 426                && (left_section != NULL || right_section != NULL)       \
 427                && parameters->options().relocatable())                  \
 428         gold_warning(_("binary " #NAME " applied to section "           \
 429                        "relative value"));                              \
 430       if (IS_DIV && right == 0)                                         \
 431         {                                                               \
 432           gold_error(_(#NAME " by zero"));                              \
 433           return 0;                                                     \
 434         }                                                               \
 435       return left OPERATOR right;                                       \
 436     }                                                                   \
 437                                                                         \
 438     void                                                                \
 439     print(FILE* f) const                                                \
 440     {                                                                   \
 441       fprintf(f, "(");                                                  \
 442       this->left_print(f);                                              \
 443       fprintf(f, " %s ", #OPERATOR);                                    \
 444       this->right_print(f);                                             \
 445       fprintf(f, ")");                                                  \
 446     }                                                                   \
 447   };                                                                    \
 448                                                                         \
 449   extern "C" Expression*                                                \
 450   script_exp_binary_ ## NAME(Expression* left, Expression* right)       \
 451   {                                                                     \
 452     return new Binary_ ## NAME(left, right);                            \
 453   }
 454
 455 BINARY_EXPRESSION(mult, *, false, false, false, true)
 456 BINARY_EXPRESSION(div, /, false, false, true, true)
 457 BINARY_EXPRESSION(mod, %, false, false, true, true)
 458 BINARY_EXPRESSION(add, +, true, true, false, true)
 459 BINARY_EXPRESSION(sub, -, true, false, false, false)
 460 BINARY_EXPRESSION(lshift, <<, false, false, false, true)
 461 BINARY_EXPRESSION(rshift, >>, false, false, false, true)
 462 BINARY_EXPRESSION(eq, ==, false, false, false, false)
 463 BINARY_EXPRESSION(ne, !=, false, false, false, false)
 464 BINARY_EXPRESSION(le, <=, false, false, false, false)
 465 BINARY_EXPRESSION(ge, >=, false, false, false, false)
 466 BINARY_EXPRESSION(lt, <, false, false, false, false)
 467 BINARY_EXPRESSION(gt, >, false, false, false, false)
 468 BINARY_EXPRESSION(bitwise_and, &, true, true, false, true)
 469 BINARY_EXPRESSION(bitwise_xor, ^, true, true, false, true)
 470 BINARY_EXPRESSION(bitwise_or, |, true, true, false, true)
 471 BINARY_EXPRESSION(logical_and, &&, false, false, false, true)
 472 BINARY_EXPRESSION(logical_or, ||, false, false, false, true)
 473
 474 // A trinary expression.
 475
 476 class Trinary_expression : public Expression
 477 {
 478  public:
 479   Trinary_expression(Expression* arg1, Expression* arg2, Expression* arg3)
 480     : arg1_(arg1), arg2_(arg2), arg3_(arg3)
 481   { }
 482
 483   ~Trinary_expression()
 484   {
 485     delete this->arg1_;
 486     delete this->arg2_;
 487     delete this->arg3_;
 488   }
 489
 490  protected:
 491   uint64_t
 492   arg1_value(const Expression_eval_info* eei,
 493              Output_section** section_pointer) const
 494   {
 495     return this->arg1_->eval_maybe_dot(eei->symtab, eei->layout,
 496                                        eei->check_assertions,
 497                                        eei->is_dot_available,
 498                                        eei->dot_value,
 499                                        eei->dot_section,
 500                                        section_pointer,
 501                                        NULL);
 502   }
 503
 504   uint64_t
 505   arg2_value(const Expression_eval_info* eei,
 506              Output_section** section_pointer,
 507              uint64_t* alignment_pointer) const
 508   {
 509     return this->arg1_->eval_maybe_dot(eei->symtab, eei->layout,
 510                                        eei->check_assertions,
 511                                        eei->is_dot_available,
 512                                        eei->dot_value,
 513                                        eei->dot_section,
 514                                        section_pointer,
 515                                        alignment_pointer);
 516   }
 517
 518   uint64_t
 519   arg3_value(const Expression_eval_info* eei,
 520              Output_section** section_pointer,
 521              uint64_t* alignment_pointer) const
 522   {
 523     return this->arg1_->eval_maybe_dot(eei->symtab, eei->layout,
 524                                        eei->check_assertions,
 525                                        eei->is_dot_available,
 526                                        eei->dot_value,
 527                                        eei->dot_section,
 528                                        section_pointer,
 529                                        alignment_pointer);
 530   }
 531
 532   void
 533   arg1_print(FILE* f) const
 534   { this->arg1_->print(f); }
 535
 536   void
 537   arg2_print(FILE* f) const
 538   { this->arg2_->print(f); }
 539
 540   void
 541   arg3_print(FILE* f) const
 542   { this->arg3_->print(f); }
 543
 544  private:
 545   Expression* arg1_;
 546   Expression* arg2_;
 547   Expression* arg3_;
 548 };
 549
 550 // The conditional operator.
 551
 552 class Trinary_cond : public Trinary_expression
 553 {
 554  public:
 555   Trinary_cond(Expression* arg1, Expression* arg2, Expression* arg3)
 556     : Trinary_expression(arg1, arg2, arg3)
 557   { }
 558
 559   uint64_t
 560   value(const Expression_eval_info* eei)
 561   {
 562     Output_section* arg1_section;
 563     uint64_t arg1 = this->arg1_value(eei, &arg1_section);
 564     return (arg1
 565             ? this->arg2_value(eei, eei->result_section_pointer,
 566                                eei->result_alignment_pointer)
 567             : this->arg3_value(eei, eei->result_section_pointer,
 568                                eei->result_alignment_pointer));
 569   }
 570
 571   void
 572   print(FILE* f) const
 573   {
 574     fprintf(f, "(");
 575     this->arg1_print(f);
 576     fprintf(f, " ? ");
 577     this->arg2_print(f);
 578     fprintf(f, " : ");
 579     this->arg3_print(f);
 580     fprintf(f, ")");
 581   }
 582 };
 583
 584 extern "C" Expression*
 585 script_exp_trinary_cond(Expression* arg1, Expression* arg2, Expression* arg3)
 586 {
 587   return new Trinary_cond(arg1, arg2, arg3);
 588 }
 589
 590 // Max function.
 591
 592 class Max_expression : public Binary_expression
 593 {
 594  public:
 595   Max_expression(Expression* left, Expression* right)
 596     : Binary_expression(left, right)
 597   { }
 598
 599   uint64_t
 600   value(const Expression_eval_info* eei)
 601   {
 602     Output_section* left_section;
 603     uint64_t left_alignment;
 604     uint64_t left = this->left_value(eei, &left_section, &left_alignment);
 605     Output_section* right_section;
 606     uint64_t right_alignment;
 607     uint64_t right = this->right_value(eei, &right_section, &right_alignment);
 608     if (left_section == right_section)
 609       {
 610         if (eei->result_section_pointer != NULL)
 611           *eei->result_section_pointer = left_section;
 612       }
 613     else if ((left_section != NULL || right_section != NULL)
 614              && parameters->options().relocatable())
 615       gold_warning(_("max applied to section relative value"));
 616     if (eei->result_alignment_pointer != NULL)
 617       {
 618         uint64_t ra = *eei->result_alignment_pointer;
 619         if (left > right)
 620           ra = std::max(ra, left_alignment);
 621         else if (right > left)
 622           ra = std::max(ra, right_alignment);
 623         else
 624           ra = std::max(ra, std::max(left_alignment, right_alignment));
 625         *eei->result_alignment_pointer = ra;
 626       }
 627     return std::max(left, right);
 628   }
 629
 630   void
 631   print(FILE* f) const
 632   { this->print_function(f, "MAX"); }
 633 };
 634
 635 extern "C" Expression*
 636 script_exp_function_max(Expression* left, Expression* right)
 637 {
 638   return new Max_expression(left, right);
 639 }
 640
 641 // Min function.
 642
 643 class Min_expression : public Binary_expression
 644 {
 645  public:
 646   Min_expression(Expression* left, Expression* right)
 647     : Binary_expression(left, right)
 648   { }
 649
 650   uint64_t
 651   value(const Expression_eval_info* eei)
 652   {
 653     Output_section* left_section;
 654     uint64_t left_alignment;
 655     uint64_t left = this->left_value(eei, &left_section, &left_alignment);
 656     Output_section* right_section;
 657     uint64_t right_alignment;
 658     uint64_t right = this->right_value(eei, &right_section, &right_alignment);
 659     if (left_section == right_section)
 660       {
 661         if (eei->result_section_pointer != NULL)
 662           *eei->result_section_pointer = left_section;
 663       }
 664     else if ((left_section != NULL || right_section != NULL)
 665              && parameters->options().relocatable())
 666       gold_warning(_("min applied to section relative value"));
 667     if (eei->result_alignment_pointer != NULL)
 668       {
 669         uint64_t ra = *eei->result_alignment_pointer;
 670         if (left < right)
 671           ra = std::max(ra, left_alignment);
 672         else if (right < left)
 673           ra = std::max(ra, right_alignment);
 674         else
 675           ra = std::max(ra, std::max(left_alignment, right_alignment));
 676         *eei->result_alignment_pointer = ra;
 677       }
 678     return std::min(left, right);
 679   }
 680
 681   void
 682   print(FILE* f) const
 683   { this->print_function(f, "MIN"); }
 684 };
 685
 686 extern "C" Expression*
 687 script_exp_function_min(Expression* left, Expression* right)
 688 {
 689   return new Min_expression(left, right);
 690 }
 691
 692 // Class Section_expression.  This is a parent class used for
 693 // functions which take the name of an output section.
 694
 695 class Section_expression : public Expression
 696 {
 697  public:
 698   Section_expression(const char* section_name, size_t section_name_len)
 699     : section_name_(section_name, section_name_len)
 700   { }
 701
 702   uint64_t
 703   value(const Expression_eval_info*);
 704
 705   void
 706   print(FILE* f) const
 707   { fprintf(f, "%s(%s)", this->function_name(), this->section_name_.c_str()); }
 708
 709  protected:
 710   // The child class must implement this.
 711   virtual uint64_t
 712   value_from_output_section(const Expression_eval_info*,
 713                             Output_section*) = 0;
 714
 715   // The child class must implement this.
 716   virtual uint64_t
 717   value_from_script_output_section(uint64_t address, uint64_t load_address,
 718                                    uint64_t addralign, uint64_t size) = 0;
 719
 720   // The child class must implement this.
 721   virtual const char*
 722   function_name() const = 0;
 723
 724  private:
 725   std::string section_name_;
 726 };
 727
 728 uint64_t
 729 Section_expression::value(const Expression_eval_info* eei)
 730 {
 731   const char* section_name = this->section_name_.c_str();
 732   Output_section* os = eei->layout->find_output_section(section_name);
 733   if (os != NULL)
 734     return this->value_from_output_section(eei, os);
 735
 736   uint64_t address;
 737   uint64_t load_address;
 738   uint64_t addralign;
 739   uint64_t size;
 740   const Script_options* ss = eei->layout->script_options();
 741   if (ss->saw_sections_clause())
 742     {
 743       if (ss->script_sections()->get_output_section_info(section_name,
 744                                                          &address,
 745                                                          &load_address,
 746                                                          &addralign,
 747                                                          &size))
 748         return this->value_from_script_output_section(address, load_address,
 749                                                       addralign, size);
 750     }
 751
 752   gold_error("%s called on nonexistent output section '%s'",
 753              this->function_name(), section_name);
 754   return 0;
 755 }
 756
 757 // ABSOLUTE function.
 758
 759 class Absolute_expression : public Unary_expression
 760 {
 761  public:
 762   Absolute_expression(Expression* arg)
 763     : Unary_expression(arg)
 764   { }
 765
 766   uint64_t
 767   value(const Expression_eval_info* eei)
 768   {
 769     uint64_t ret = this->arg_value(eei, NULL);
 770     // Force the value to be absolute.
 771     if (eei->result_section_pointer != NULL)
 772       *eei->result_section_pointer = NULL;
 773     return ret;
 774   }
 775
 776   void
 777   print(FILE* f) const
 778   {
 779     fprintf(f, "ABSOLUTE(");
 780     this->arg_print(f);
 781     fprintf(f, ")");
 782   }
 783 };
 784
 785 extern "C" Expression*
 786 script_exp_function_absolute(Expression* arg)
 787 {
 788   return new Absolute_expression(arg);
 789 }
 790
 791 // ALIGN function.
 792
 793 class Align_expression : public Binary_expression
 794 {
 795  public:
 796   Align_expression(Expression* left, Expression* right)
 797     : Binary_expression(left, right)
 798   { }
 799
 800   uint64_t
 801   value(const Expression_eval_info* eei)
 802   {
 803     Output_section* align_section;
 804     uint64_t align = this->right_value(eei, &align_section, NULL);
 805     if (align_section != NULL
 806         && parameters->options().relocatable())
 807       gold_warning(_("aligning to section relative value"));
 808
 809     if (eei->result_alignment_pointer != NULL
 810         && align > *eei->result_alignment_pointer)
 811       {
 812         uint64_t a = align;
 813         while ((a & (a - 1)) != 0)
 814           a &= a - 1;
 815         *eei->result_alignment_pointer = a;
 816       }
 817
 818     uint64_t value = this->left_value(eei, eei->result_section_pointer, NULL);
 819     if (align <= 1)
 820       return value;
 821     return ((value + align - 1) / align) * align;
 822   }
 823
 824   void
 825   print(FILE* f) const
 826   { this->print_function(f, "ALIGN"); }
 827 };
 828
 829 extern "C" Expression*
 830 script_exp_function_align(Expression* left, Expression* right)
 831 {
 832   return new Align_expression(left, right);
 833 }
 834
 835 // ASSERT function.
 836
 837 class Assert_expression : public Unary_expression
 838 {
 839  public:
 840   Assert_expression(Expression* arg, const char* message, size_t length)
 841     : Unary_expression(arg), message_(message, length)
 842   { }
 843
 844   uint64_t
 845   value(const Expression_eval_info* eei)
 846   {
 847     uint64_t value = this->arg_value(eei, eei->result_section_pointer);
 848     if (!value && eei->check_assertions)
 849       gold_error("%s", this->message_.c_str());
 850     return value;
 851   }
 852
 853   void
 854   print(FILE* f) const
 855   {
 856     fprintf(f, "ASSERT(");
 857     this->arg_print(f);
 858     fprintf(f, ", %s)", this->message_.c_str());
 859   }
 860
 861  private:
 862   std::string message_;
 863 };
 864
 865 extern "C" Expression*
 866 script_exp_function_assert(Expression* expr, const char* message,
 867                            size_t length)
 868 {
 869   return new Assert_expression(expr, message, length);
 870 }
 871
 872 // ADDR function.
 873
 874 class Addr_expression : public Section_expression
 875 {
 876  public:
 877   Addr_expression(const char* section_name, size_t section_name_len)
 878     : Section_expression(section_name, section_name_len)
 879   { }
 880
 881  protected:
 882   uint64_t
 883   value_from_output_section(const Expression_eval_info* eei,
 884                             Output_section* os)
 885   {
 886     if (eei->result_section_pointer != NULL)
 887       *eei->result_section_pointer = os;
 888     return os->address();
 889   }
 890
 891   uint64_t
 892   value_from_script_output_section(uint64_t address, uint64_t, uint64_t,
 893                                    uint64_t)
 894   { return address; }
 895
 896   const char*
 897   function_name() const
 898   { return "ADDR"; }
 899 };
 900
 901 extern "C" Expression*
 902 script_exp_function_addr(const char* section_name, size_t section_name_len)
 903 {
 904   return new Addr_expression(section_name, section_name_len);
 905 }
 906
 907 // ALIGNOF.
 908
 909 class Alignof_expression : public Section_expression
 910 {
 911  public:
 912   Alignof_expression(const char* section_name, size_t section_name_len)
 913     : Section_expression(section_name, section_name_len)
 914   { }
 915
 916  protected:
 917   uint64_t
 918   value_from_output_section(const Expression_eval_info*,
 919                             Output_section* os)
 920   { return os->addralign(); }
 921
 922   uint64_t
 923   value_from_script_output_section(uint64_t, uint64_t, uint64_t addralign,
 924                                    uint64_t)
 925   { return addralign; }
 926
 927   const char*
 928   function_name() const
 929   { return "ALIGNOF"; }
 930 };
 931
 932 extern "C" Expression*
 933 script_exp_function_alignof(const char* section_name, size_t section_name_len)
 934 {
 935   return new Alignof_expression(section_name, section_name_len);
 936 }
 937
 938 // CONSTANT.  It would be nice if we could simply evaluate this
 939 // immediately and return an Integer_expression, but unfortunately we
 940 // don't know the target.
 941
 942 class Constant_expression : public Expression
 943 {
 944  public:
 945   Constant_expression(const char* name, size_t length);
 946
 947   uint64_t
 948   value(const Expression_eval_info*);
 949
 950   void
 951   print(FILE* f) const;
 952
 953  private:
 954   enum Constant_function
 955   {
 956     CONSTANT_MAXPAGESIZE,
 957     CONSTANT_COMMONPAGESIZE
 958   };
 959
 960   Constant_function function_;
 961 };
 962
 963 Constant_expression::Constant_expression(const char* name, size_t length)
 964 {
 965   if (length == 11 && strncmp(name, "MAXPAGESIZE", length) == 0)
 966     this->function_ = CONSTANT_MAXPAGESIZE;
 967   else if (length == 14 && strncmp(name, "COMMONPAGESIZE", length) == 0)
 968     this->function_ = CONSTANT_COMMONPAGESIZE;
 969   else
 970     {
 971       std::string s(name, length);
 972       gold_error(_("unknown constant %s"), s.c_str());
 973       this->function_ = CONSTANT_MAXPAGESIZE;
 974     }
 975 }
 976
 977 uint64_t
 978 Constant_expression::value(const Expression_eval_info*)
 979 {
 980   switch (this->function_)
 981     {
 982     case CONSTANT_MAXPAGESIZE:
 983       return parameters->target().abi_pagesize();
 984     case CONSTANT_COMMONPAGESIZE:
 985       return parameters->target().common_pagesize();
 986     default:
 987       gold_unreachable();
 988     }
 989 }
 990
 991 void
 992 Constant_expression::print(FILE* f) const
 993 {
 994   const char* name;
 995   switch (this->function_)
 996     {
 997     case CONSTANT_MAXPAGESIZE:
 998       name = "MAXPAGESIZE";
 999       break;
1000     case CONSTANT_COMMONPAGESIZE:
1001       name = "COMMONPAGESIZE";
1002       break;
1003     default:
1004       gold_unreachable();
1005     }
1006   fprintf(f, "CONSTANT(%s)", name);
1007 }
1008
1009 extern "C" Expression*
1010 script_exp_function_constant(const char* name, size_t length)
1011 {
1012   return new Constant_expression(name, length);
1013 }
1014
1015 // DATA_SEGMENT_ALIGN.  FIXME: we don't implement this; we always fall
1016 // back to the general case.
1017
1018 extern "C" Expression*
1019 script_exp_function_data_segment_align(Expression* left, Expression*)
1020 {
1021   Expression* e1 = script_exp_function_align(script_exp_string(".", 1), left);
1022   Expression* e2 = script_exp_binary_sub(left, script_exp_integer(1));
1023   Expression* e3 = script_exp_binary_bitwise_and(script_exp_string(".", 1),
1024                                                  e2);
1025   return script_exp_binary_add(e1, e3);
1026 }
1027
1028 // DATA_SEGMENT_RELRO.  FIXME: This is not implemented.
1029
1030 extern "C" Expression*
1031 script_exp_function_data_segment_relro_end(Expression*, Expression* right)
1032 {
1033   return right;
1034 }
1035
1036 // DATA_SEGMENT_END.  FIXME: This is not implemented.
1037
1038 extern "C" Expression*
1039 script_exp_function_data_segment_end(Expression* val)
1040 {
1041   return val;
1042 }
1043
1044 // DEFINED function.
1045
1046 class Defined_expression : public Expression
1047 {
1048  public:
1049   Defined_expression(const char* symbol_name, size_t symbol_name_len)
1050     : symbol_name_(symbol_name, symbol_name_len)
1051   { }
1052
1053   uint64_t
1054   value(const Expression_eval_info* eei)
1055   {
1056     Symbol* sym = eei->symtab->lookup(this->symbol_name_.c_str());
1057     return sym != NULL && sym->is_defined();
1058   }
1059
1060   void
1061   print(FILE* f) const
1062   { fprintf(f, "DEFINED(%s)", this->symbol_name_.c_str()); }
1063
1064  private:
1065   std::string symbol_name_;
1066 };
1067
1068 extern "C" Expression*
1069 script_exp_function_defined(const char* symbol_name, size_t symbol_name_len)
1070 {
1071   return new Defined_expression(symbol_name, symbol_name_len);
1072 }
1073
1074 // LOADADDR function
1075
1076 class Loadaddr_expression : public Section_expression
1077 {
1078  public:
1079   Loadaddr_expression(const char* section_name, size_t section_name_len)
1080     : Section_expression(section_name, section_name_len)
1081   { }
1082
1083  protected:
1084   uint64_t
1085   value_from_output_section(const Expression_eval_info* eei,
1086                             Output_section* os)
1087   {
1088     if (os->has_load_address())
1089       return os->load_address();
1090     else
1091       {
1092         if (eei->result_section_pointer != NULL)
1093           *eei->result_section_pointer = os;
1094         return os->address();
1095       }
1096   }
1097
1098   uint64_t
1099   value_from_script_output_section(uint64_t, uint64_t load_address, uint64_t,
1100                                    uint64_t)
1101   { return load_address; }
1102
1103   const char*
1104   function_name() const
1105   { return "LOADADDR"; }
1106 };
1107
1108 extern "C" Expression*
1109 script_exp_function_loadaddr(const char* section_name, size_t section_name_len)
1110 {
1111   return new Loadaddr_expression(section_name, section_name_len);
1112 }
1113
1114 // SIZEOF function
1115
1116 class Sizeof_expression : public Section_expression
1117 {
1118  public:
1119   Sizeof_expression(const char* section_name, size_t section_name_len)
1120     : Section_expression(section_name, section_name_len)
1121   { }
1122
1123  protected:
1124   uint64_t
1125   value_from_output_section(const Expression_eval_info*,
1126                             Output_section* os)
1127   {
1128     // We can not use data_size here, as the size of the section may
1129     // not have been finalized.  Instead we get whatever the current
1130     // size is.  This will work correctly for backward references in
1131     // linker scripts.
1132     return os->current_data_size();
1133   }
1134
1135   uint64_t
1136   value_from_script_output_section(uint64_t, uint64_t, uint64_t,
1137                                    uint64_t size)
1138   { return size; }
1139
1140   const char*
1141   function_name() const
1142   { return "SIZEOF"; }
1143 };
1144
1145 extern "C" Expression*
1146 script_exp_function_sizeof(const char* section_name, size_t section_name_len)
1147 {
1148   return new Sizeof_expression(section_name, section_name_len);
1149 }
1150
1151 // SIZEOF_HEADERS.
1152
1153 class Sizeof_headers_expression : public Expression
1154 {
1155  public:
1156   Sizeof_headers_expression()
1157   { }
1158
1159   uint64_t
1160   value(const Expression_eval_info*);
1161
1162   void
1163   print(FILE* f) const
1164   { fprintf(f, "SIZEOF_HEADERS"); }
1165 };
1166
1167 uint64_t
1168 Sizeof_headers_expression::value(const Expression_eval_info* eei)
1169 {
1170   unsigned int ehdr_size;
1171   unsigned int phdr_size;
1172   if (parameters->target().get_size() == 32)
1173     {
1174       ehdr_size = elfcpp::Elf_sizes<32>::ehdr_size;
1175       phdr_size = elfcpp::Elf_sizes<32>::phdr_size;
1176     }
1177   else if (parameters->target().get_size() == 64)
1178     {
1179       ehdr_size = elfcpp::Elf_sizes<64>::ehdr_size;
1180       phdr_size = elfcpp::Elf_sizes<64>::phdr_size;
1181     }
1182   else
1183     gold_unreachable();
1184
1185   return ehdr_size + phdr_size * eei->layout->expected_segment_count();
1186 }
1187
1188 extern "C" Expression*
1189 script_exp_function_sizeof_headers()
1190 {
1191   return new Sizeof_headers_expression();
1192 }
1193
1194 // SEGMENT_START.
1195
1196 class Segment_start_expression : public Unary_expression
1197 {
1198  public:
1199   Segment_start_expression(const char* segment_name, size_t segment_name_len,
1200                            Expression* default_value)
1201     : Unary_expression(default_value),
1202       segment_name_(segment_name, segment_name_len)
1203   { }
1204
1205   uint64_t
1206   value(const Expression_eval_info*);
1207
1208   void
1209   print(FILE* f) const
1210   {
1211     fprintf(f, "SEGMENT_START(\"%s\", ", this->segment_name_.c_str());
1212     this->arg_print(f);
1213     fprintf(f, ")");
1214   }
1215
1216  private:
1217   std::string segment_name_;
1218 };
1219
1220 uint64_t
1221 Segment_start_expression::value(const Expression_eval_info* eei)
1222 {
1223   // Check for command line overrides.
1224   if (parameters->options().user_set_Ttext()
1225       && this->segment_name_ == ".text")
1226     return parameters->options().Ttext();
1227   else if (parameters->options().user_set_Tdata()
1228            && this->segment_name_ == ".data")
1229     return parameters->options().Tdata();
1230   else if (parameters->options().user_set_Tbss()
1231            && this->segment_name_ == ".bss")
1232     return parameters->options().Tbss();
1233   else
1234     {
1235       uint64_t ret = this->arg_value(eei, NULL);
1236       // Force the value to be absolute.
1237       if (eei->result_section_pointer != NULL)
1238         *eei->result_section_pointer = NULL;
1239       return ret;
1240     }
1241 }
1242
1243 extern "C" Expression*
1244 script_exp_function_segment_start(const char* segment_name,
1245                                   size_t segment_name_len,
1246                                   Expression* default_value)
1247 {
1248   return new Segment_start_expression(segment_name, segment_name_len,
1249                                       default_value);
1250 }
1251
1252 } // End namespace gold.