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