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 expressions can refer to the dot symbol.  The dot symbol
  58   // is only available within a SECTIONS clause.
  59   bool is_dot_available;
  60   // The current value of the dot symbol.
  61   uint64_t dot_value;
  62   // The section in which the dot symbol is defined; this is NULL if
  63   // it is absolute.
  64   Output_section* dot_section;
  65   // Points to where the section of the result should be stored.
  66   Output_section** result_section_pointer;
  67 };
  68
  69 // Evaluate an expression.
  70
  71 uint64_t
  72 Expression::eval(const Symbol_table* symtab, const Layout* layout)
  73 {
  74   Output_section* dummy;
  75   return this->eval_maybe_dot(symtab, layout, false, 0, NULL, &dummy);
  76 }
  77
  78 // Evaluate an expression which may refer to the dot symbol.
  79
  80 uint64_t
  81 Expression::eval_with_dot(const Symbol_table* symtab, const Layout* layout,
  82                           uint64_t dot_value, Output_section* dot_section,
  83                           Output_section** result_section_pointer)
  84 {
  85   return this->eval_maybe_dot(symtab, layout, true, dot_value, dot_section,
  86                               result_section_pointer);
  87 }
  88
  89 // Evaluate an expression which may or may not refer to the dot
  90 // symbol.
  91
  92 uint64_t
  93 Expression::eval_maybe_dot(const Symbol_table* symtab, const Layout* layout,
  94                            bool is_dot_available, uint64_t dot_value,
  95                            Output_section* dot_section,
  96                            Output_section** result_section_pointer)
  97 {
  98   Expression_eval_info eei;
  99   eei.symtab = symtab;
 100   eei.layout = layout;
 101   eei.is_dot_available = is_dot_available;
 102   eei.dot_value = dot_value;
 103   eei.dot_section = dot_section;
 104
 105   // We assume the value is absolute, and only set this to a section
 106   // if we find a section relative reference.
 107   *result_section_pointer = NULL;
 108   eei.result_section_pointer = result_section_pointer;
 109
 110   return this->value(&eei);
 111 }
 112
 113 // A number.
 114
 115 class Integer_expression : public Expression
 116 {
 117  public:
 118   Integer_expression(uint64_t val)
 119     : val_(val)
 120   { }
 121
 122   uint64_t
 123   value(const Expression_eval_info*)
 124   { return this->val_; }
 125
 126   void
 127   print(FILE* f) const
 128   { fprintf(f, "0x%llx", static_cast<unsigned long long>(this->val_)); }
 129
 130  private:
 131   uint64_t val_;
 132 };
 133
 134 extern "C" Expression*
 135 script_exp_integer(uint64_t val)
 136 {
 137   return new Integer_expression(val);
 138 }
 139
 140 // An expression whose value is the value of a symbol.
 141
 142 class Symbol_expression : public Expression
 143 {
 144  public:
 145   Symbol_expression(const char* name, size_t length)
 146     : name_(name, length)
 147   { }
 148
 149   uint64_t
 150   value(const Expression_eval_info*);
 151
 152   void
 153   print(FILE* f) const
 154   { fprintf(f, "%s", this->name_.c_str()); }
 155
 156  private:
 157   std::string name_;
 158 };
 159
 160 uint64_t
 161 Symbol_expression::value(const Expression_eval_info* eei)
 162 {
 163   Symbol* sym = eei->symtab->lookup(this->name_.c_str());
 164   if (sym == NULL || !sym->is_defined())
 165     {
 166       gold_error(_("undefined symbol '%s' referenced in expression"),
 167                  this->name_.c_str());
 168       return 0;
 169     }
 170
 171   *eei->result_section_pointer = sym->output_section();
 172
 173   if (parameters->get_size() == 32)
 174     return eei->symtab->get_sized_symbol<32>(sym)->value();
 175   else if (parameters->get_size() == 64)
 176     return eei->symtab->get_sized_symbol<64>(sym)->value();
 177   else
 178     gold_unreachable();
 179 }
 180
 181 // An expression whose value is the value of the special symbol ".".
 182 // This is only valid within a SECTIONS clause.
 183
 184 class Dot_expression : public Expression
 185 {
 186  public:
 187   Dot_expression()
 188   { }
 189
 190   uint64_t
 191   value(const Expression_eval_info*);
 192
 193   void
 194   print(FILE* f) const
 195   { fprintf(f, "."); }
 196 };
 197
 198 uint64_t
 199 Dot_expression::value(const Expression_eval_info* eei)
 200 {
 201   if (!eei->is_dot_available)
 202     {
 203       gold_error(_("invalid reference to dot symbol outside of "
 204                    "SECTIONS clause"));
 205       return 0;
 206     }
 207   *eei->result_section_pointer = eei->dot_section;
 208   return eei->dot_value;
 209 }
 210
 211 // A string.  This is either the name of a symbol, or ".".
 212
 213 extern "C" Expression*
 214 script_exp_string(const char* name, size_t length)
 215 {
 216   if (length == 1 && name[0] == '.')
 217     return new Dot_expression();
 218   else
 219     return new Symbol_expression(name, length);
 220 }
 221
 222 // A unary expression.
 223
 224 class Unary_expression : public Expression
 225 {
 226  public:
 227   Unary_expression(Expression* arg)
 228     : arg_(arg)
 229   { }
 230
 231   ~Unary_expression()
 232   { delete this->arg_; }
 233
 234  protected:
 235   uint64_t
 236   arg_value(const Expression_eval_info* eei,
 237             Output_section** arg_section_pointer) const
 238   {
 239     return this->arg_->eval_maybe_dot(eei->symtab, eei->layout,
 240                                       eei->is_dot_available,
 241                                       eei->dot_value,
 242                                       eei->dot_section,
 243                                       arg_section_pointer);
 244   }
 245
 246   void
 247   arg_print(FILE* f) const
 248   { this->arg_->print(f); }
 249
 250  private:
 251   Expression* arg_;
 252 };
 253
 254 // Handle unary operators.  We use a preprocessor macro as a hack to
 255 // capture the C operator.
 256
 257 #define UNARY_EXPRESSION(NAME, OPERATOR)                                \
 258   class Unary_ ## NAME : public Unary_expression                        \
 259   {                                                                     \
 260   public:                                                               \
 261     Unary_ ## NAME(Expression* arg)                                     \
 262       : Unary_expression(arg)                                           \
 263     { }                                                                 \
 264                                                                         \
 265     uint64_t                                                            \
 266     value(const Expression_eval_info* eei)                              \
 267     {                                                                   \
 268       Output_section* arg_section;                                      \
 269       uint64_t ret = OPERATOR this->arg_value(eei, &arg_section);       \
 270       if (arg_section != NULL && parameters->output_is_object())        \
 271         gold_warning(_("unary " #NAME " applied to section "            \
 272                        "relative value"));                              \
 273       return ret;                                                       \
 274     }                                                                   \
 275                                                                         \
 276     void                                                                \
 277     print(FILE* f) const                                                \
 278     {                                                                   \
 279       fprintf(f, "(%s ", #OPERATOR);                                    \
 280       this->arg_print(f);                                               \
 281       fprintf(f, ")");                                                  \
 282     }                                                                   \
 283   };                                                                    \
 284                                                                         \
 285   extern "C" Expression*                                                \
 286   script_exp_unary_ ## NAME(Expression* arg)                            \
 287   {                                                                     \
 288       return new Unary_ ## NAME(arg);                                   \
 289   }
 290
 291 UNARY_EXPRESSION(minus, -)
 292 UNARY_EXPRESSION(logical_not, !)
 293 UNARY_EXPRESSION(bitwise_not, ~)
 294
 295 // A binary expression.
 296
 297 class Binary_expression : public Expression
 298 {
 299  public:
 300   Binary_expression(Expression* left, Expression* right)
 301     : left_(left), right_(right)
 302   { }
 303
 304   ~Binary_expression()
 305   {
 306     delete this->left_;
 307     delete this->right_;
 308   }
 309
 310  protected:
 311   uint64_t
 312   left_value(const Expression_eval_info* eei,
 313              Output_section** section_pointer) const
 314   {
 315     return this->left_->eval_maybe_dot(eei->symtab, eei->layout,
 316                                        eei->is_dot_available,
 317                                        eei->dot_value,
 318                                        eei->dot_section,
 319                                        section_pointer);
 320   }
 321
 322   uint64_t
 323   right_value(const Expression_eval_info* eei,
 324               Output_section** section_pointer) const
 325   {
 326     return this->right_->eval_maybe_dot(eei->symtab, eei->layout,
 327                                         eei->is_dot_available,
 328                                         eei->dot_value,
 329                                         eei->dot_section,
 330                                         section_pointer);
 331   }
 332
 333   void
 334   left_print(FILE* f) const
 335   { this->left_->print(f); }
 336
 337   void
 338   right_print(FILE* f) const
 339   { this->right_->print(f); }
 340
 341   // This is a call to function FUNCTION_NAME.  Print it.  This is for
 342   // debugging.
 343   void
 344   print_function(FILE* f, const char *function_name) const
 345   {
 346     fprintf(f, "%s(", function_name);
 347     this->left_print(f);
 348     fprintf(f, ", ");
 349     this->right_print(f);
 350     fprintf(f, ")");
 351   }
 352
 353  private:
 354   Expression* left_;
 355   Expression* right_;
 356 };
 357
 358 // Handle binary operators.  We use a preprocessor macro as a hack to
 359 // capture the C operator.  KEEP_LEFT means that if the left operand
 360 // is section relative and the right operand is not, the result uses
 361 // the same section as the left operand.  KEEP_RIGHT is the same with
 362 // left and right swapped.  IS_DIV means that we need to give an error
 363 // if the right operand is zero.  WARN means that we should warn if
 364 // used on section relative values in a relocatable link.  We always
 365 // warn if used on values in different sections in a relocatable link.
 366
 367 #define BINARY_EXPRESSION(NAME, OPERATOR, KEEP_LEFT, KEEP_RIGHT, IS_DIV, WARN) \
 368   class Binary_ ## NAME : public Binary_expression                      \
 369   {                                                                     \
 370   public:                                                               \
 371     Binary_ ## NAME(Expression* left, Expression* right)                \
 372       : Binary_expression(left, right)                                  \
 373     { }                                                                 \
 374                                                                         \
 375     uint64_t                                                            \
 376     value(const Expression_eval_info* eei)                              \
 377     {                                                                   \
 378       Output_section* left_section;                                     \
 379       uint64_t left = this->left_value(eei, &left_section);             \
 380       Output_section* right_section;                                    \
 381       uint64_t right = this->right_value(eei, &right_section);          \
 382       if (KEEP_RIGHT && left_section == NULL && right_section != NULL)  \
 383         *eei->result_section_pointer = right_section;                   \
 384       else if (KEEP_LEFT                                                \
 385                && left_section != NULL                                  \
 386                && right_section == NULL)                                \
 387         *eei->result_section_pointer = left_section;                    \
 388       else if ((WARN || left_section != right_section)                  \
 389                && (left_section != NULL || right_section != NULL)       \
 390                && parameters->output_is_object())                       \
 391         gold_warning(_("binary " #NAME " applied to section "           \
 392                        "relative value"));                              \
 393       if (IS_DIV && right == 0)                                         \
 394         {                                                               \
 395           gold_error(_(#NAME " by zero"));                              \
 396           return 0;                                                     \
 397         }                                                               \
 398       return left OPERATOR right;                                       \
 399     }                                                                   \
 400                                                                         \
 401     void                                                                \
 402     print(FILE* f) const                                                \
 403     {                                                                   \
 404       fprintf(f, "(");                                                  \
 405       this->left_print(f);                                              \
 406       fprintf(f, " %s ", #OPERATOR);                                    \
 407       this->right_print(f);                                             \
 408       fprintf(f, ")");                                                  \
 409     }                                                                   \
 410   };                                                                    \
 411                                                                         \
 412   extern "C" Expression*                                                \
 413   script_exp_binary_ ## NAME(Expression* left, Expression* right)       \
 414   {                                                                     \
 415     return new Binary_ ## NAME(left, right);                            \
 416   }
 417
 418 BINARY_EXPRESSION(mult, *, false, false, false, true)
 419 BINARY_EXPRESSION(div, /, false, false, true, true)
 420 BINARY_EXPRESSION(mod, %, false, false, true, true)
 421 BINARY_EXPRESSION(add, +, true, true, false, true)
 422 BINARY_EXPRESSION(sub, -, true, false, false, false)
 423 BINARY_EXPRESSION(lshift, <<, false, false, false, true)
 424 BINARY_EXPRESSION(rshift, >>, false, false, false, true)
 425 BINARY_EXPRESSION(eq, ==, false, false, false, false)
 426 BINARY_EXPRESSION(ne, !=, false, false, false, false)
 427 BINARY_EXPRESSION(le, <=, false, false, false, false)
 428 BINARY_EXPRESSION(ge, >=, false, false, false, false)
 429 BINARY_EXPRESSION(lt, <, false, false, false, false)
 430 BINARY_EXPRESSION(gt, >, false, false, false, false)
 431 BINARY_EXPRESSION(bitwise_and, &, true, true, false, true)
 432 BINARY_EXPRESSION(bitwise_xor, ^, true, true, false, true)
 433 BINARY_EXPRESSION(bitwise_or, |, true, true, false, true)
 434 BINARY_EXPRESSION(logical_and, &&, false, false, false, true)
 435 BINARY_EXPRESSION(logical_or, ||, false, false, false, true)
 436
 437 // A trinary expression.
 438
 439 class Trinary_expression : public Expression
 440 {
 441  public:
 442   Trinary_expression(Expression* arg1, Expression* arg2, Expression* arg3)
 443     : arg1_(arg1), arg2_(arg2), arg3_(arg3)
 444   { }
 445
 446   ~Trinary_expression()
 447   {
 448     delete this->arg1_;
 449     delete this->arg2_;
 450     delete this->arg3_;
 451   }
 452
 453  protected:
 454   uint64_t
 455   arg1_value(const Expression_eval_info* eei,
 456              Output_section** section_pointer) const
 457   {
 458     return this->arg1_->eval_maybe_dot(eei->symtab, eei->layout,
 459                                        eei->is_dot_available,
 460                                        eei->dot_value,
 461                                        eei->dot_section,
 462                                        section_pointer);
 463   }
 464
 465   uint64_t
 466   arg2_value(const Expression_eval_info* eei,
 467              Output_section** section_pointer) const
 468   {
 469     return this->arg1_->eval_maybe_dot(eei->symtab, eei->layout,
 470                                        eei->is_dot_available,
 471                                        eei->dot_value,
 472                                        eei->dot_section,
 473                                        section_pointer);
 474   }
 475
 476   uint64_t
 477   arg3_value(const Expression_eval_info* eei,
 478              Output_section** section_pointer) const
 479   {
 480     return this->arg1_->eval_maybe_dot(eei->symtab, eei->layout,
 481                                        eei->is_dot_available,
 482                                        eei->dot_value,
 483                                        eei->dot_section,
 484                                        section_pointer);
 485   }
 486
 487   void
 488   arg1_print(FILE* f) const
 489   { this->arg1_->print(f); }
 490
 491   void
 492   arg2_print(FILE* f) const
 493   { this->arg2_->print(f); }
 494
 495   void
 496   arg3_print(FILE* f) const
 497   { this->arg3_->print(f); }
 498
 499  private:
 500   Expression* arg1_;
 501   Expression* arg2_;
 502   Expression* arg3_;
 503 };
 504
 505 // The conditional operator.
 506
 507 class Trinary_cond : public Trinary_expression
 508 {
 509  public:
 510   Trinary_cond(Expression* arg1, Expression* arg2, Expression* arg3)
 511     : Trinary_expression(arg1, arg2, arg3)
 512   { }
 513
 514   uint64_t
 515   value(const Expression_eval_info* eei)
 516   {
 517     Output_section* arg1_section;
 518     uint64_t arg1 = this->arg1_value(eei, &arg1_section);
 519     return (arg1
 520             ? this->arg2_value(eei, eei->result_section_pointer)
 521             : this->arg3_value(eei, eei->result_section_pointer));
 522   }
 523
 524   void
 525   print(FILE* f) const
 526   {
 527     fprintf(f, "(");
 528     this->arg1_print(f);
 529     fprintf(f, " ? ");
 530     this->arg2_print(f);
 531     fprintf(f, " : ");
 532     this->arg3_print(f);
 533     fprintf(f, ")");
 534   }
 535 };
 536
 537 extern "C" Expression*
 538 script_exp_trinary_cond(Expression* arg1, Expression* arg2, Expression* arg3)
 539 {
 540   return new Trinary_cond(arg1, arg2, arg3);
 541 }
 542
 543 // Max function.
 544
 545 class Max_expression : public Binary_expression
 546 {
 547  public:
 548   Max_expression(Expression* left, Expression* right)
 549     : Binary_expression(left, right)
 550   { }
 551
 552   uint64_t
 553   value(const Expression_eval_info* eei)
 554   {
 555     Output_section* left_section;
 556     uint64_t left = this->left_value(eei, &left_section);
 557     Output_section* right_section;
 558     uint64_t right = this->right_value(eei, &right_section);
 559     if (left_section == right_section)
 560       *eei->result_section_pointer = left_section;
 561     else if ((left_section != NULL || right_section != NULL)
 562              && parameters->output_is_object())
 563       gold_warning(_("max applied to section relative value"));
 564     return std::max(left, right);
 565   }
 566
 567   void
 568   print(FILE* f) const
 569   { this->print_function(f, "MAX"); }
 570 };
 571
 572 extern "C" Expression*
 573 script_exp_function_max(Expression* left, Expression* right)
 574 {
 575   return new Max_expression(left, right);
 576 }
 577
 578 // Min function.
 579
 580 class Min_expression : public Binary_expression
 581 {
 582  public:
 583   Min_expression(Expression* left, Expression* right)
 584     : Binary_expression(left, right)
 585   { }
 586
 587   uint64_t
 588   value(const Expression_eval_info* eei)
 589   {
 590     Output_section* left_section;
 591     uint64_t left = this->left_value(eei, &left_section);
 592     Output_section* right_section;
 593     uint64_t right = this->right_value(eei, &right_section);
 594     if (left_section == right_section)
 595       *eei->result_section_pointer = left_section;
 596     else if ((left_section != NULL || right_section != NULL)
 597              && parameters->output_is_object())
 598       gold_warning(_("min applied to section relative value"));
 599     return std::min(left, right);
 600   }
 601
 602   void
 603   print(FILE* f) const
 604   { this->print_function(f, "MIN"); }
 605 };
 606
 607 extern "C" Expression*
 608 script_exp_function_min(Expression* left, Expression* right)
 609 {
 610   return new Min_expression(left, right);
 611 }
 612
 613 // Align function.
 614
 615 class Align_expression : public Binary_expression
 616 {
 617  public:
 618   Align_expression(Expression* left, Expression* right)
 619     : Binary_expression(left, right)
 620   { }
 621
 622   uint64_t
 623   value(const Expression_eval_info* eei)
 624   {
 625     Output_section* align_section;
 626     uint64_t align = this->right_value(eei, &align_section);
 627     if (align_section != NULL
 628         && parameters->output_is_object())
 629       gold_warning(_("aligning to section relative value"));
 630
 631     uint64_t value = this->left_value(eei, eei->result_section_pointer);
 632     if (align <= 1)
 633       return value;
 634     return ((value + align - 1) / align) * align;
 635   }
 636
 637   void
 638   print(FILE* f) const
 639   { this->print_function(f, "ALIGN"); }
 640 };
 641
 642 extern "C" Expression*
 643 script_exp_function_align(Expression* left, Expression* right)
 644 {
 645   return new Align_expression(left, right);
 646 }
 647
 648 // Assert function.
 649
 650 class Assert_expression : public Unary_expression
 651 {
 652  public:
 653   Assert_expression(Expression* arg, const char* message, size_t length)
 654     : Unary_expression(arg), message_(message, length)
 655   { }
 656
 657   uint64_t
 658   value(const Expression_eval_info* eei)
 659   {
 660     uint64_t value = this->arg_value(eei, eei->result_section_pointer);
 661     if (!value)
 662       gold_error("%s", this->message_.c_str());
 663     return value;
 664   }
 665
 666   void
 667   print(FILE* f) const
 668   {
 669     fprintf(f, "ASSERT(");
 670     this->arg_print(f);
 671     fprintf(f, ", %s)", this->message_.c_str());
 672   }
 673
 674  private:
 675   std::string message_;
 676 };
 677
 678 extern "C" Expression*
 679 script_exp_function_assert(Expression* expr, const char* message,
 680                            size_t length)
 681 {
 682   return new Assert_expression(expr, message, length);
 683 }
 684
 685 // Addr function.
 686
 687 class Addr_expression : public Expression
 688 {
 689  public:
 690   Addr_expression(const char* section_name, size_t section_name_len)
 691     : section_name_(section_name, section_name_len)
 692   { }
 693
 694   uint64_t
 695   value(const Expression_eval_info*);
 696
 697   void
 698   print(FILE* f) const
 699   { fprintf(f, "ADDR(%s)", this->section_name_.c_str()); }
 700
 701  private:
 702   std::string section_name_;
 703 };
 704
 705 uint64_t
 706 Addr_expression::value(const Expression_eval_info* eei)
 707 {
 708   const char* section_name = this->section_name_.c_str();
 709   Output_section* os = eei->layout->find_output_section(section_name);
 710   if (os == NULL)
 711     {
 712       gold_error("ADDR called on nonexistent output section '%s'",
 713                  section_name);
 714       return 0;
 715     }
 716
 717   *eei->result_section_pointer = os;
 718
 719   return os->address();
 720 }
 721
 722 extern "C" Expression*
 723 script_exp_function_addr(const char* section_name, size_t section_name_len)
 724 {
 725   return new Addr_expression(section_name, section_name_len);
 726 }
 727
 728 // CONSTANT.  It would be nice if we could simply evaluate this
 729 // immediately and return an Integer_expression, but unfortunately we
 730 // don't know the target.
 731
 732 class Constant_expression : public Expression
 733 {
 734  public:
 735   Constant_expression(const char* name, size_t length);
 736
 737   uint64_t
 738   value(const Expression_eval_info*);
 739
 740   void
 741   print(FILE* f) const;
 742
 743  private:
 744   enum Constant_function
 745   {
 746     CONSTANT_MAXPAGESIZE,
 747     CONSTANT_COMMONPAGESIZE
 748   };
 749
 750   Constant_function function_;
 751 };
 752
 753 Constant_expression::Constant_expression(const char* name, size_t length)
 754 {
 755   if (length == 11 && strncmp(name, "MAXPAGESIZE", length) == 0)
 756     this->function_ = CONSTANT_MAXPAGESIZE;
 757   else if (length == 14 && strncmp(name, "COMMONPAGESIZE", length) == 0)
 758     this->function_ = CONSTANT_COMMONPAGESIZE;
 759   else
 760     {
 761       std::string s(name, length);
 762       gold_error(_("unknown constant %s"), s.c_str());
 763       this->function_ = CONSTANT_MAXPAGESIZE;
 764     }
 765 }
 766
 767 uint64_t
 768 Constant_expression::value(const Expression_eval_info*)
 769 {
 770   switch (this->function_)
 771     {
 772     case CONSTANT_MAXPAGESIZE:
 773       return parameters->target()->abi_pagesize();
 774     case CONSTANT_COMMONPAGESIZE:
 775       return parameters->target()->common_pagesize();
 776     default:
 777       gold_unreachable();
 778     }
 779 }
 780
 781 void
 782 Constant_expression::print(FILE* f) const
 783 {
 784   const char* name;
 785   switch (this->function_)
 786     {
 787     case CONSTANT_MAXPAGESIZE:
 788       name = "MAXPAGESIZE";
 789       break;
 790     case CONSTANT_COMMONPAGESIZE:
 791       name = "COMMONPAGESIZE";
 792       break;
 793     default:
 794       gold_unreachable();
 795     }
 796   fprintf(f, "CONSTANT(%s)", name);
 797 }
 798
 799 extern "C" Expression*
 800 script_exp_function_constant(const char* name, size_t length)
 801 {
 802   return new Constant_expression(name, length);
 803 }
 804
 805 // DATA_SEGMENT_ALIGN.  FIXME: we don't implement this; we always fall
 806 // back to the general case.
 807
 808 extern "C" Expression*
 809 script_exp_function_data_segment_align(Expression* left, Expression*)
 810 {
 811   Expression* e1 = script_exp_function_align(script_exp_string(".", 1), left);
 812   Expression* e2 = script_exp_binary_sub(left, script_exp_integer(1));
 813   Expression* e3 = script_exp_binary_bitwise_and(script_exp_string(".", 1),
 814                                                  e2);
 815   return script_exp_binary_add(e1, e3);
 816 }
 817
 818 // DATA_SEGMENT_RELRO.  FIXME: This is not implemented.
 819
 820 extern "C" Expression*
 821 script_exp_function_data_segment_relro_end(Expression*, Expression* right)
 822 {
 823   return right;
 824 }
 825
 826 // DATA_SEGMENT_END.  FIXME: This is not implemented.
 827
 828 extern "C" Expression*
 829 script_exp_function_data_segment_end(Expression* val)
 830 {
 831   return val;
 832 }
 833
 834 // SIZEOF_HEADERS.
 835
 836 class Sizeof_headers_expression : public Expression
 837 {
 838  public:
 839   Sizeof_headers_expression()
 840   { }
 841
 842   uint64_t
 843   value(const Expression_eval_info*);
 844
 845   void
 846   print(FILE* f) const
 847   { fprintf(f, "SIZEOF_HEADERS"); }
 848 };
 849
 850 uint64_t
 851 Sizeof_headers_expression::value(const Expression_eval_info* eei)
 852 {
 853   unsigned int ehdr_size;
 854   unsigned int phdr_size;
 855   if (parameters->get_size() == 32)
 856     {
 857       ehdr_size = elfcpp::Elf_sizes<32>::ehdr_size;
 858       phdr_size = elfcpp::Elf_sizes<32>::phdr_size;
 859     }
 860   else if (parameters->get_size() == 64)
 861     {
 862       ehdr_size = elfcpp::Elf_sizes<64>::ehdr_size;
 863       phdr_size = elfcpp::Elf_sizes<64>::phdr_size;
 864     }
 865   else
 866     gold_unreachable();
 867
 868   return ehdr_size + phdr_size * eei->layout->expected_segment_count();
 869 }
 870
 871 extern "C" Expression*
 872 script_exp_function_sizeof_headers()
 873 {
 874   return new Sizeof_headers_expression();
 875 }
 876
 877 // Functions.
 878
 879 extern "C" Expression*
 880 script_exp_function_defined(const char*, size_t)
 881 {
 882   gold_fatal(_("DEFINED not implemented"));
 883 }
 884
 885 extern "C" Expression*
 886 script_exp_function_alignof(const char*, size_t)
 887 {
 888   gold_fatal(_("ALIGNOF not implemented"));
 889 }
 890
 891 extern "C" Expression*
 892 script_exp_function_sizeof(const char*, size_t)
 893 {
 894   gold_fatal(_("SIZEOF not implemented"));
 895 }
 896
 897 extern "C" Expression*
 898 script_exp_function_loadaddr(const char*, size_t)
 899 {
 900   gold_fatal(_("LOADADDR not implemented"));
 901 }
 902
 903 extern "C" Expression*
 904 script_exp_function_origin(const char*, size_t)
 905 {
 906   gold_fatal(_("ORIGIN not implemented"));
 907 }
 908
 909 extern "C" Expression*
 910 script_exp_function_length(const char*, size_t)
 911 {
 912   gold_fatal(_("LENGTH not implemented"));
 913 }
 914
 915 extern "C" Expression*
 916 script_exp_function_absolute(Expression*)
 917 {
 918   gold_fatal(_("ABSOLUTE not implemented"));
 919 }
 920
 921 extern "C" Expression*
 922 script_exp_function_segment_start(const char*, size_t, Expression*)
 923 {
 924   gold_fatal(_("SEGMENT_START not implemented"));
 925 }
 926
 927 } // End namespace gold.