Automatic date update in version.in
[external/binutils.git] / gold / expression.cc
1 // expression.cc -- expressions in linker scripts for gold
2
3 // Copyright (C) 2006-2019 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   // Pointer to where the type of the symbol on the RHS should be stored.
72   elfcpp::STT* type_pointer;
73   // Pointer to where the visibility of the symbol on the RHS should be stored.
74   elfcpp::STV* vis_pointer;
75   // Pointer to where the rest of the symbol's st_other field should be stored.
76   unsigned char* nonvis_pointer;
77   // Whether the value is valid.  In Symbol_assignment::set_if_absolute, we
78   // may be trying to evaluate the address of a section whose address is not
79   // yet finalized, and we need to fail the evaluation gracefully.
80   bool *is_valid_pointer;
81 };
82
83 // Evaluate an expression.
84
85 uint64_t
86 Expression::eval(const Symbol_table* symtab, const Layout* layout,
87                  bool check_assertions)
88 {
89   return this->eval_maybe_dot(symtab, layout, check_assertions, false, 0,
90                               NULL, NULL, NULL, NULL, NULL, NULL, false, NULL);
91 }
92
93 // Evaluate an expression which may refer to the dot symbol.
94
95 uint64_t
96 Expression::eval_with_dot(const Symbol_table* symtab, const Layout* layout,
97                           bool check_assertions, uint64_t dot_value,
98                           Output_section* dot_section,
99                           Output_section** result_section_pointer,
100                           uint64_t* result_alignment_pointer,
101                           bool is_section_dot_assignment)
102 {
103   return this->eval_maybe_dot(symtab, layout, check_assertions, true,
104                               dot_value, dot_section, result_section_pointer,
105                               result_alignment_pointer, NULL, NULL, NULL,
106                               is_section_dot_assignment, NULL);
107 }
108
109 // Evaluate an expression which may or may not refer to the dot
110 // symbol.
111
112 uint64_t
113 Expression::eval_maybe_dot(const Symbol_table* symtab, const Layout* layout,
114                            bool check_assertions, bool is_dot_available,
115                            uint64_t dot_value, Output_section* dot_section,
116                            Output_section** result_section_pointer,
117                            uint64_t* result_alignment_pointer,
118                            elfcpp::STT* type_pointer,
119                            elfcpp::STV* vis_pointer,
120                            unsigned char* nonvis_pointer,
121                            bool is_section_dot_assignment,
122                            bool* is_valid_pointer)
123 {
124   Expression_eval_info eei;
125   eei.symtab = symtab;
126   eei.layout = layout;
127   eei.check_assertions = check_assertions;
128   eei.is_dot_available = is_dot_available;
129   eei.dot_value = dot_value;
130   eei.dot_section = dot_section;
131
132   // We assume the value is absolute, and only set this to a section
133   // if we find a section-relative reference.
134   if (result_section_pointer != NULL)
135     *result_section_pointer = NULL;
136   eei.result_section_pointer = result_section_pointer;
137
138   // For symbol=symbol assignments, we need to track the type, visibility,
139   // and remaining st_other bits.
140   eei.type_pointer = type_pointer;
141   eei.vis_pointer = vis_pointer;
142   eei.nonvis_pointer = nonvis_pointer;
143
144   eei.result_alignment_pointer = result_alignment_pointer;
145
146   // Assume the value is valid until we try to evaluate an expression
147   // that can't be evaluated yet.
148   bool is_valid = true;
149   eei.is_valid_pointer = &is_valid;
150
151   uint64_t val = this->value(&eei);
152
153   if (is_valid_pointer != NULL)
154     *is_valid_pointer = is_valid;
155   else
156     gold_assert(is_valid);
157
158   // If this is an assignment to dot within a section, and the value
159   // is absolute, treat it as a section-relative offset.
160   if (is_section_dot_assignment && *result_section_pointer == NULL)
161     {
162       gold_assert(dot_section != NULL);
163       val += dot_section->address();
164       *result_section_pointer = dot_section;
165     }
166   return val;
167 }
168
169 // A number.
170
171 class Integer_expression : public Expression
172 {
173  public:
174   Integer_expression(uint64_t val)
175     : val_(val)
176   { }
177
178   uint64_t
179   value(const Expression_eval_info*)
180   { return this->val_; }
181
182   void
183   print(FILE* f) const
184   { fprintf(f, "0x%llx", static_cast<unsigned long long>(this->val_)); }
185
186  private:
187   uint64_t val_;
188 };
189
190 extern "C" Expression*
191 script_exp_integer(uint64_t val)
192 {
193   return new Integer_expression(val);
194 }
195
196 // An expression whose value is the value of a symbol.
197
198 class Symbol_expression : public Expression
199 {
200  public:
201   Symbol_expression(const char* name, size_t length)
202     : name_(name, length)
203   { }
204
205   uint64_t
206   value(const Expression_eval_info*);
207
208   void
209   set_expr_sym_in_real_elf(Symbol_table* symtab) const
210   {
211     Symbol* sym = symtab->lookup(this->name_.c_str());
212     if (sym != NULL)
213       sym->set_in_real_elf();
214   }
215
216   void
217   print(FILE* f) const
218   { fprintf(f, "%s", this->name_.c_str()); }
219
220  private:
221   std::string name_;
222 };
223
224 uint64_t
225 Symbol_expression::value(const Expression_eval_info* eei)
226 {
227   Symbol* sym = eei->symtab->lookup(this->name_.c_str());
228   if (sym == NULL || !sym->is_defined())
229     {
230       gold_error(_("undefined symbol '%s' referenced in expression"),
231                  this->name_.c_str());
232       return 0;
233     }
234
235   if (eei->result_section_pointer != NULL)
236     *eei->result_section_pointer = sym->output_section();
237   if (eei->type_pointer != NULL)
238     *eei->type_pointer = sym->type();
239   if (eei->vis_pointer != NULL)
240     *eei->vis_pointer = sym->visibility();
241   if (eei->nonvis_pointer != NULL)
242     *eei->nonvis_pointer = sym->nonvis();
243
244   if (parameters->target().get_size() == 32)
245     return eei->symtab->get_sized_symbol<32>(sym)->value();
246   else if (parameters->target().get_size() == 64)
247     return eei->symtab->get_sized_symbol<64>(sym)->value();
248   else
249     gold_unreachable();
250 }
251
252 // An expression whose value is the value of the special symbol ".".
253 // This is only valid within a SECTIONS clause.
254
255 class Dot_expression : public Expression
256 {
257  public:
258   Dot_expression()
259   { }
260
261   uint64_t
262   value(const Expression_eval_info*);
263
264   void
265   print(FILE* f) const
266   { fprintf(f, "."); }
267 };
268
269 uint64_t
270 Dot_expression::value(const Expression_eval_info* eei)
271 {
272   if (!eei->is_dot_available)
273     {
274       gold_error(_("invalid reference to dot symbol outside of "
275                    "SECTIONS clause"));
276       return 0;
277     }
278   if (eei->result_section_pointer != NULL)
279     *eei->result_section_pointer = eei->dot_section;
280   return eei->dot_value;
281 }
282
283 // A string.  This is either the name of a symbol, or ".".
284
285 extern "C" Expression*
286 script_exp_string(const char* name, size_t length)
287 {
288   if (length == 1 && name[0] == '.')
289     return new Dot_expression();
290   else
291     return new Symbol_expression(name, length);
292 }
293
294 // A unary expression.
295
296 class Unary_expression : public Expression
297 {
298  public:
299   Unary_expression(Expression* arg)
300     : arg_(arg)
301   { }
302
303   ~Unary_expression()
304   { delete this->arg_; }
305
306  protected:
307   uint64_t
308   arg_value(const Expression_eval_info* eei,
309             Output_section** arg_section_pointer) const
310   {
311     return this->arg_->eval_maybe_dot(eei->symtab, eei->layout,
312                                       eei->check_assertions,
313                                       eei->is_dot_available,
314                                       eei->dot_value,
315                                       eei->dot_section,
316                                       arg_section_pointer,
317                                       eei->result_alignment_pointer,
318                                       NULL,
319                                       NULL,
320                                       NULL,
321                                       false,
322                                       eei->is_valid_pointer);
323   }
324
325   void
326   arg_print(FILE* f) const
327   { this->arg_->print(f); }
328
329   void
330   set_expr_sym_in_real_elf(Symbol_table* symtab) const
331   { return this->arg_->set_expr_sym_in_real_elf(symtab); }
332
333  private:
334   Expression* arg_;
335 };
336
337 // Handle unary operators.  We use a preprocessor macro as a hack to
338 // capture the C operator.
339
340 #define UNARY_EXPRESSION(NAME, OPERATOR)                                \
341   class Unary_ ## NAME : public Unary_expression                        \
342   {                                                                     \
343   public:                                                               \
344     Unary_ ## NAME(Expression* arg)                                     \
345       : Unary_expression(arg)                                           \
346     { }                                                                 \
347                                                                         \
348     uint64_t                                                            \
349     value(const Expression_eval_info* eei)                              \
350     {                                                                   \
351       Output_section* arg_section;                                      \
352       uint64_t ret = OPERATOR this->arg_value(eei, &arg_section);       \
353       if (arg_section != NULL && parameters->options().relocatable())   \
354         gold_warning(_("unary " #NAME " applied to section "            \
355                        "relative value"));                              \
356       return ret;                                                       \
357     }                                                                   \
358                                                                         \
359     void                                                                \
360     print(FILE* f) const                                                \
361     {                                                                   \
362       fprintf(f, "(%s ", #OPERATOR);                                    \
363       this->arg_print(f);                                               \
364       fprintf(f, ")");                                                  \
365     }                                                                   \
366   };                                                                    \
367                                                                         \
368   extern "C" Expression*                                                \
369   script_exp_unary_ ## NAME(Expression* arg)                            \
370   {                                                                     \
371       return new Unary_ ## NAME(arg);                                   \
372   }
373
374 UNARY_EXPRESSION(minus, -)
375 UNARY_EXPRESSION(logical_not, !)
376 UNARY_EXPRESSION(bitwise_not, ~)
377
378 // A binary expression.
379
380 class Binary_expression : public Expression
381 {
382  public:
383   Binary_expression(Expression* left, Expression* right)
384     : left_(left), right_(right)
385   { }
386
387   ~Binary_expression()
388   {
389     delete this->left_;
390     delete this->right_;
391   }
392
393  protected:
394   uint64_t
395   left_value(const Expression_eval_info* eei,
396              Output_section** section_pointer,
397              uint64_t* alignment_pointer) const
398   {
399     return this->left_->eval_maybe_dot(eei->symtab, eei->layout,
400                                        eei->check_assertions,
401                                        eei->is_dot_available,
402                                        eei->dot_value,
403                                        eei->dot_section,
404                                        section_pointer,
405                                        alignment_pointer,
406                                        NULL,
407                                        NULL,
408                                        NULL,
409                                        false,
410                                        eei->is_valid_pointer);
411   }
412
413   uint64_t
414   right_value(const Expression_eval_info* eei,
415               Output_section** section_pointer,
416               uint64_t* alignment_pointer) const
417   {
418     return this->right_->eval_maybe_dot(eei->symtab, eei->layout,
419                                         eei->check_assertions,
420                                         eei->is_dot_available,
421                                         eei->dot_value,
422                                         eei->dot_section,
423                                         section_pointer,
424                                         alignment_pointer,
425                                         NULL,
426                                         NULL,
427                                         NULL,
428                                         false,
429                                         eei->is_valid_pointer);
430   }
431
432   void
433   left_print(FILE* f) const
434   { this->left_->print(f); }
435
436   void
437   right_print(FILE* f) const
438   { this->right_->print(f); }
439
440   // This is a call to function FUNCTION_NAME.  Print it.  This is for
441   // debugging.
442   void
443   print_function(FILE* f, const char* function_name) const
444   {
445     fprintf(f, "%s(", function_name);
446     this->left_print(f);
447     fprintf(f, ", ");
448     this->right_print(f);
449     fprintf(f, ")");
450   }
451
452   void
453   set_expr_sym_in_real_elf(Symbol_table* symtab) const
454   {
455     this->left_->set_expr_sym_in_real_elf(symtab);
456     this->right_->set_expr_sym_in_real_elf(symtab);
457   }
458
459  private:
460   Expression* left_;
461   Expression* right_;
462 };
463
464 // Handle binary operators.  We use a preprocessor macro as a hack to
465 // capture the C operator.  KEEP_LEFT means that if the left operand
466 // is section relative and the right operand is not, the result uses
467 // the same section as the left operand.  KEEP_RIGHT is the same with
468 // left and right swapped.  IS_DIV means that we need to give an error
469 // if the right operand is zero.  WARN means that we should warn if
470 // used on section relative values in a relocatable link.  We always
471 // warn if used on values in different sections in a relocatable link.
472
473 #define BINARY_EXPRESSION(NAME, OPERATOR, KEEP_LEFT, KEEP_RIGHT, IS_DIV, WARN) \
474   class Binary_ ## NAME : public Binary_expression                      \
475   {                                                                     \
476   public:                                                               \
477     Binary_ ## NAME(Expression* left, Expression* right)                \
478       : Binary_expression(left, right)                                  \
479     { }                                                                 \
480                                                                         \
481     uint64_t                                                            \
482     value(const Expression_eval_info* eei)                              \
483     {                                                                   \
484       Output_section* left_section;                                     \
485       uint64_t left_alignment = 0;                                      \
486       uint64_t left = this->left_value(eei, &left_section,              \
487                                        &left_alignment);                \
488       Output_section* right_section;                                    \
489       uint64_t right_alignment = 0;                                     \
490       uint64_t right = this->right_value(eei, &right_section,           \
491                                          &right_alignment);             \
492       if (KEEP_RIGHT && left_section == NULL && right_section != NULL)  \
493         {                                                               \
494           if (eei->result_section_pointer != NULL)                      \
495             *eei->result_section_pointer = right_section;               \
496           if (eei->result_alignment_pointer != NULL                     \
497               && right_alignment > *eei->result_alignment_pointer)      \
498             *eei->result_alignment_pointer = right_alignment;           \
499         }                                                               \
500       else if (KEEP_LEFT                                                \
501                && left_section != NULL                                  \
502                && right_section == NULL)                                \
503         {                                                               \
504           if (eei->result_section_pointer != NULL)                      \
505             *eei->result_section_pointer = left_section;                \
506           if (eei->result_alignment_pointer != NULL                     \
507               && left_alignment > *eei->result_alignment_pointer)       \
508             *eei->result_alignment_pointer = left_alignment;            \
509         }                                                               \
510       else if ((WARN || left_section != right_section)                  \
511                && (left_section != NULL || right_section != NULL)       \
512                && parameters->options().relocatable())                  \
513         gold_warning(_("binary " #NAME " applied to section "           \
514                        "relative value"));                              \
515       if (IS_DIV && right == 0)                                         \
516         {                                                               \
517           gold_error(_(#NAME " by zero"));                              \
518           return 0;                                                     \
519         }                                                               \
520       return left OPERATOR right;                                       \
521     }                                                                   \
522                                                                         \
523     void                                                                \
524     print(FILE* f) const                                                \
525     {                                                                   \
526       fprintf(f, "(");                                                  \
527       this->left_print(f);                                              \
528       fprintf(f, " %s ", #OPERATOR);                                    \
529       this->right_print(f);                                             \
530       fprintf(f, ")");                                                  \
531     }                                                                   \
532   };                                                                    \
533                                                                         \
534   extern "C" Expression*                                                \
535   script_exp_binary_ ## NAME(Expression* left, Expression* right)       \
536   {                                                                     \
537     return new Binary_ ## NAME(left, right);                            \
538   }
539
540 BINARY_EXPRESSION(mult, *, false, false, false, true)
541 BINARY_EXPRESSION(div, /, false, false, true, true)
542 BINARY_EXPRESSION(mod, %, false, false, true, true)
543 BINARY_EXPRESSION(add, +, true, true, false, true)
544 BINARY_EXPRESSION(sub, -, true, false, false, false)
545 BINARY_EXPRESSION(lshift, <<, false, false, false, true)
546 BINARY_EXPRESSION(rshift, >>, false, false, false, true)
547 BINARY_EXPRESSION(eq, ==, false, false, false, false)
548 BINARY_EXPRESSION(ne, !=, false, false, false, false)
549 BINARY_EXPRESSION(le, <=, false, false, false, false)
550 BINARY_EXPRESSION(ge, >=, false, false, false, false)
551 BINARY_EXPRESSION(lt, <, false, false, false, false)
552 BINARY_EXPRESSION(gt, >, false, false, false, false)
553 BINARY_EXPRESSION(bitwise_and, &, true, true, false, true)
554 BINARY_EXPRESSION(bitwise_xor, ^, true, true, false, true)
555 BINARY_EXPRESSION(bitwise_or, |, true, true, false, true)
556 BINARY_EXPRESSION(logical_and, &&, false, false, false, true)
557 BINARY_EXPRESSION(logical_or, ||, false, false, false, true)
558
559 // A trinary expression.
560
561 class Trinary_expression : public Expression
562 {
563  public:
564   Trinary_expression(Expression* arg1, Expression* arg2, Expression* arg3)
565     : arg1_(arg1), arg2_(arg2), arg3_(arg3)
566   { }
567
568   ~Trinary_expression()
569   {
570     delete this->arg1_;
571     delete this->arg2_;
572     delete this->arg3_;
573   }
574
575  protected:
576   uint64_t
577   arg1_value(const Expression_eval_info* eei,
578              Output_section** section_pointer) const
579   {
580     return this->arg1_->eval_maybe_dot(eei->symtab, eei->layout,
581                                        eei->check_assertions,
582                                        eei->is_dot_available,
583                                        eei->dot_value,
584                                        eei->dot_section,
585                                        section_pointer,
586                                        NULL,
587                                        NULL,
588                                        NULL,
589                                        NULL,
590                                        false,
591                                        eei->is_valid_pointer);
592   }
593
594   uint64_t
595   arg2_value(const Expression_eval_info* eei,
596              Output_section** section_pointer,
597              uint64_t* alignment_pointer) const
598   {
599     return this->arg1_->eval_maybe_dot(eei->symtab, eei->layout,
600                                        eei->check_assertions,
601                                        eei->is_dot_available,
602                                        eei->dot_value,
603                                        eei->dot_section,
604                                        section_pointer,
605                                        alignment_pointer,
606                                        NULL,
607                                        NULL,
608                                        NULL,
609                                        false,
610                                        eei->is_valid_pointer);
611   }
612
613   uint64_t
614   arg3_value(const Expression_eval_info* eei,
615              Output_section** section_pointer,
616              uint64_t* alignment_pointer) const
617   {
618     return this->arg1_->eval_maybe_dot(eei->symtab, eei->layout,
619                                        eei->check_assertions,
620                                        eei->is_dot_available,
621                                        eei->dot_value,
622                                        eei->dot_section,
623                                        section_pointer,
624                                        alignment_pointer,
625                                        NULL,
626                                        NULL,
627                                        NULL,
628                                        false,
629                                        eei->is_valid_pointer);
630   }
631
632   void
633   arg1_print(FILE* f) const
634   { this->arg1_->print(f); }
635
636   void
637   arg2_print(FILE* f) const
638   { this->arg2_->print(f); }
639
640   void
641   arg3_print(FILE* f) const
642   { this->arg3_->print(f); }
643
644   void
645   set_expr_sym_in_real_elf(Symbol_table* symtab) const
646   {
647     this->arg1_->set_expr_sym_in_real_elf(symtab);
648     this->arg2_->set_expr_sym_in_real_elf(symtab);
649     this->arg3_->set_expr_sym_in_real_elf(symtab);
650   }
651
652  private:
653   Expression* arg1_;
654   Expression* arg2_;
655   Expression* arg3_;
656 };
657
658 // The conditional operator.
659
660 class Trinary_cond : public Trinary_expression
661 {
662  public:
663   Trinary_cond(Expression* arg1, Expression* arg2, Expression* arg3)
664     : Trinary_expression(arg1, arg2, arg3)
665   { }
666
667   uint64_t
668   value(const Expression_eval_info* eei)
669   {
670     Output_section* arg1_section;
671     uint64_t arg1 = this->arg1_value(eei, &arg1_section);
672     return (arg1
673             ? this->arg2_value(eei, eei->result_section_pointer,
674                                eei->result_alignment_pointer)
675             : this->arg3_value(eei, eei->result_section_pointer,
676                                eei->result_alignment_pointer));
677   }
678
679   void
680   print(FILE* f) const
681   {
682     fprintf(f, "(");
683     this->arg1_print(f);
684     fprintf(f, " ? ");
685     this->arg2_print(f);
686     fprintf(f, " : ");
687     this->arg3_print(f);
688     fprintf(f, ")");
689   }
690 };
691
692 extern "C" Expression*
693 script_exp_trinary_cond(Expression* arg1, Expression* arg2, Expression* arg3)
694 {
695   return new Trinary_cond(arg1, arg2, arg3);
696 }
697
698 // Max function.
699
700 class Max_expression : public Binary_expression
701 {
702  public:
703   Max_expression(Expression* left, Expression* right)
704     : Binary_expression(left, right)
705   { }
706
707   uint64_t
708   value(const Expression_eval_info* eei)
709   {
710     Output_section* left_section;
711     uint64_t left_alignment;
712     uint64_t left = this->left_value(eei, &left_section, &left_alignment);
713     Output_section* right_section;
714     uint64_t right_alignment;
715     uint64_t right = this->right_value(eei, &right_section, &right_alignment);
716     if (left_section == right_section)
717       {
718         if (eei->result_section_pointer != NULL)
719           *eei->result_section_pointer = left_section;
720       }
721     else if ((left_section != NULL || right_section != NULL)
722              && parameters->options().relocatable())
723       gold_warning(_("max applied to section relative value"));
724     if (eei->result_alignment_pointer != NULL)
725       {
726         uint64_t ra = *eei->result_alignment_pointer;
727         if (left > right)
728           ra = std::max(ra, left_alignment);
729         else if (right > left)
730           ra = std::max(ra, right_alignment);
731         else
732           ra = std::max(ra, std::max(left_alignment, right_alignment));
733         *eei->result_alignment_pointer = ra;
734       }
735     return std::max(left, right);
736   }
737
738   void
739   print(FILE* f) const
740   { this->print_function(f, "MAX"); }
741 };
742
743 extern "C" Expression*
744 script_exp_function_max(Expression* left, Expression* right)
745 {
746   return new Max_expression(left, right);
747 }
748
749 // Min function.
750
751 class Min_expression : public Binary_expression
752 {
753  public:
754   Min_expression(Expression* left, Expression* right)
755     : Binary_expression(left, right)
756   { }
757
758   uint64_t
759   value(const Expression_eval_info* eei)
760   {
761     Output_section* left_section;
762     uint64_t left_alignment;
763     uint64_t left = this->left_value(eei, &left_section, &left_alignment);
764     Output_section* right_section;
765     uint64_t right_alignment;
766     uint64_t right = this->right_value(eei, &right_section, &right_alignment);
767     if (left_section == right_section)
768       {
769         if (eei->result_section_pointer != NULL)
770           *eei->result_section_pointer = left_section;
771       }
772     else if ((left_section != NULL || right_section != NULL)
773              && parameters->options().relocatable())
774       gold_warning(_("min applied to section relative value"));
775     if (eei->result_alignment_pointer != NULL)
776       {
777         uint64_t ra = *eei->result_alignment_pointer;
778         if (left < right)
779           ra = std::max(ra, left_alignment);
780         else if (right < left)
781           ra = std::max(ra, right_alignment);
782         else
783           ra = std::max(ra, std::max(left_alignment, right_alignment));
784         *eei->result_alignment_pointer = ra;
785       }
786     return std::min(left, right);
787   }
788
789   void
790   print(FILE* f) const
791   { this->print_function(f, "MIN"); }
792 };
793
794 extern "C" Expression*
795 script_exp_function_min(Expression* left, Expression* right)
796 {
797   return new Min_expression(left, right);
798 }
799
800 // Class Section_expression.  This is a parent class used for
801 // functions which take the name of an output section.
802
803 class Section_expression : public Expression
804 {
805  public:
806   Section_expression(const char* section_name, size_t section_name_len)
807     : section_name_(section_name, section_name_len)
808   { }
809
810   uint64_t
811   value(const Expression_eval_info*);
812
813   void
814   print(FILE* f) const
815   { fprintf(f, "%s(%s)", this->function_name(), this->section_name_.c_str()); }
816
817  protected:
818   // The child class must implement this.
819   virtual uint64_t
820   value_from_output_section(const Expression_eval_info*,
821                             Output_section*) = 0;
822
823   // The child class must implement this.
824   virtual uint64_t
825   value_from_script_output_section(uint64_t address, uint64_t load_address,
826                                    uint64_t addralign, uint64_t size) = 0;
827
828   // The child class must implement this.
829   virtual const char*
830   function_name() const = 0;
831
832  private:
833   std::string section_name_;
834 };
835
836 uint64_t
837 Section_expression::value(const Expression_eval_info* eei)
838 {
839   const char* section_name = this->section_name_.c_str();
840   Output_section* os = eei->layout->find_output_section(section_name);
841   if (os != NULL)
842     return this->value_from_output_section(eei, os);
843
844   uint64_t address;
845   uint64_t load_address;
846   uint64_t addralign;
847   uint64_t size;
848   const Script_options* ss = eei->layout->script_options();
849   if (ss->saw_sections_clause())
850     {
851       if (ss->script_sections()->get_output_section_info(section_name,
852                                                          &address,
853                                                          &load_address,
854                                                          &addralign,
855                                                          &size))
856         return this->value_from_script_output_section(address, load_address,
857                                                       addralign, size);
858     }
859
860   gold_error("%s called on nonexistent output section '%s'",
861              this->function_name(), section_name);
862   return 0;
863 }
864
865 // ABSOLUTE function.
866
867 class Absolute_expression : public Unary_expression
868 {
869  public:
870   Absolute_expression(Expression* arg)
871     : Unary_expression(arg)
872   { }
873
874   uint64_t
875   value(const Expression_eval_info* eei)
876   {
877     uint64_t ret = this->arg_value(eei, NULL);
878     // Force the value to be absolute.
879     if (eei->result_section_pointer != NULL)
880       *eei->result_section_pointer = NULL;
881     return ret;
882   }
883
884   void
885   print(FILE* f) const
886   {
887     fprintf(f, "ABSOLUTE(");
888     this->arg_print(f);
889     fprintf(f, ")");
890   }
891 };
892
893 extern "C" Expression*
894 script_exp_function_absolute(Expression* arg)
895 {
896   return new Absolute_expression(arg);
897 }
898
899 // ALIGN function.
900
901 class Align_expression : public Binary_expression
902 {
903  public:
904   Align_expression(Expression* left, Expression* right)
905     : Binary_expression(left, right)
906   { }
907
908   uint64_t
909   value(const Expression_eval_info* eei)
910   {
911     Output_section* align_section;
912     uint64_t align = this->right_value(eei, &align_section, NULL);
913     if (align_section != NULL
914         && parameters->options().relocatable())
915       gold_warning(_("aligning to section relative value"));
916
917     if (eei->result_alignment_pointer != NULL
918         && align > *eei->result_alignment_pointer)
919       {
920         uint64_t a = align;
921         while ((a & (a - 1)) != 0)
922           a &= a - 1;
923         *eei->result_alignment_pointer = a;
924       }
925
926     uint64_t value = this->left_value(eei, eei->result_section_pointer, NULL);
927     if (align <= 1)
928       return value;
929     return ((value + align - 1) / align) * align;
930   }
931
932   void
933   print(FILE* f) const
934   { this->print_function(f, "ALIGN"); }
935 };
936
937 extern "C" Expression*
938 script_exp_function_align(Expression* left, Expression* right)
939 {
940   return new Align_expression(left, right);
941 }
942
943 // ASSERT function.
944
945 class Assert_expression : public Unary_expression
946 {
947  public:
948   Assert_expression(Expression* arg, const char* message, size_t length)
949     : Unary_expression(arg), message_(message, length)
950   { }
951
952   uint64_t
953   value(const Expression_eval_info* eei)
954   {
955     uint64_t value = this->arg_value(eei, eei->result_section_pointer);
956     if (!value && eei->check_assertions)
957       gold_error("%s", this->message_.c_str());
958     return value;
959   }
960
961   void
962   print(FILE* f) const
963   {
964     fprintf(f, "ASSERT(");
965     this->arg_print(f);
966     fprintf(f, ", %s)", this->message_.c_str());
967   }
968
969  private:
970   std::string message_;
971 };
972
973 extern "C" Expression*
974 script_exp_function_assert(Expression* expr, const char* message,
975                            size_t length)
976 {
977   return new Assert_expression(expr, message, length);
978 }
979
980 // ADDR function.
981
982 class Addr_expression : public Section_expression
983 {
984  public:
985   Addr_expression(const char* section_name, size_t section_name_len)
986     : Section_expression(section_name, section_name_len)
987   { }
988
989  protected:
990   uint64_t
991   value_from_output_section(const Expression_eval_info* eei,
992                             Output_section* os)
993   {
994     if (eei->result_section_pointer != NULL)
995       *eei->result_section_pointer = os;
996     if (os->is_address_valid())
997       return os->address();
998     *eei->is_valid_pointer = false;
999     return 0;
1000   }
1001
1002   uint64_t
1003   value_from_script_output_section(uint64_t address, uint64_t, uint64_t,
1004                                    uint64_t)
1005   { return address; }
1006
1007   const char*
1008   function_name() const
1009   { return "ADDR"; }
1010 };
1011
1012 extern "C" Expression*
1013 script_exp_function_addr(const char* section_name, size_t section_name_len)
1014 {
1015   return new Addr_expression(section_name, section_name_len);
1016 }
1017
1018 // ALIGNOF.
1019
1020 class Alignof_expression : public Section_expression
1021 {
1022  public:
1023   Alignof_expression(const char* section_name, size_t section_name_len)
1024     : Section_expression(section_name, section_name_len)
1025   { }
1026
1027  protected:
1028   uint64_t
1029   value_from_output_section(const Expression_eval_info*,
1030                             Output_section* os)
1031   { return os->addralign(); }
1032
1033   uint64_t
1034   value_from_script_output_section(uint64_t, uint64_t, uint64_t addralign,
1035                                    uint64_t)
1036   { return addralign; }
1037
1038   const char*
1039   function_name() const
1040   { return "ALIGNOF"; }
1041 };
1042
1043 extern "C" Expression*
1044 script_exp_function_alignof(const char* section_name, size_t section_name_len)
1045 {
1046   return new Alignof_expression(section_name, section_name_len);
1047 }
1048
1049 // CONSTANT.  It would be nice if we could simply evaluate this
1050 // immediately and return an Integer_expression, but unfortunately we
1051 // don't know the target.
1052
1053 class Constant_expression : public Expression
1054 {
1055  public:
1056   Constant_expression(const char* name, size_t length);
1057
1058   uint64_t
1059   value(const Expression_eval_info*);
1060
1061   void
1062   print(FILE* f) const;
1063
1064  private:
1065   enum Constant_function
1066   {
1067     CONSTANT_MAXPAGESIZE,
1068     CONSTANT_COMMONPAGESIZE
1069   };
1070
1071   Constant_function function_;
1072 };
1073
1074 Constant_expression::Constant_expression(const char* name, size_t length)
1075 {
1076   if (length == 11 && strncmp(name, "MAXPAGESIZE", length) == 0)
1077     this->function_ = CONSTANT_MAXPAGESIZE;
1078   else if (length == 14 && strncmp(name, "COMMONPAGESIZE", length) == 0)
1079     this->function_ = CONSTANT_COMMONPAGESIZE;
1080   else
1081     {
1082       std::string s(name, length);
1083       gold_error(_("unknown constant %s"), s.c_str());
1084       this->function_ = CONSTANT_MAXPAGESIZE;
1085     }
1086 }
1087
1088 uint64_t
1089 Constant_expression::value(const Expression_eval_info*)
1090 {
1091   switch (this->function_)
1092     {
1093     case CONSTANT_MAXPAGESIZE:
1094       return parameters->target().abi_pagesize();
1095     case CONSTANT_COMMONPAGESIZE:
1096       return parameters->target().common_pagesize();
1097     default:
1098       gold_unreachable();
1099     }
1100 }
1101
1102 void
1103 Constant_expression::print(FILE* f) const
1104 {
1105   const char* name;
1106   switch (this->function_)
1107     {
1108     case CONSTANT_MAXPAGESIZE:
1109       name = "MAXPAGESIZE";
1110       break;
1111     case CONSTANT_COMMONPAGESIZE:
1112       name = "COMMONPAGESIZE";
1113       break;
1114     default:
1115       gold_unreachable();
1116     }
1117   fprintf(f, "CONSTANT(%s)", name);
1118 }
1119   
1120 extern "C" Expression*
1121 script_exp_function_constant(const char* name, size_t length)
1122 {
1123   return new Constant_expression(name, length);
1124 }
1125
1126 // DATA_SEGMENT_ALIGN.  FIXME: we don't implement this; we always fall
1127 // back to the general case.
1128
1129 extern "C" Expression*
1130 script_exp_function_data_segment_align(Expression* left, Expression*)
1131 {
1132   Expression* e1 = script_exp_function_align(script_exp_string(".", 1), left);
1133   Expression* e2 = script_exp_binary_sub(left, script_exp_integer(1));
1134   Expression* e3 = script_exp_binary_bitwise_and(script_exp_string(".", 1),
1135                                                  e2);
1136   return script_exp_binary_add(e1, e3);
1137 }
1138
1139 // DATA_SEGMENT_RELRO.  FIXME: This is not implemented.
1140
1141 extern "C" Expression*
1142 script_exp_function_data_segment_relro_end(Expression*, Expression* right)
1143 {
1144   return right;
1145 }
1146
1147 // DATA_SEGMENT_END.  FIXME: This is not implemented.
1148
1149 extern "C" Expression*
1150 script_exp_function_data_segment_end(Expression* val)
1151 {
1152   return val;
1153 }
1154
1155 // DEFINED function.
1156
1157 class Defined_expression : public Expression
1158 {
1159  public:
1160   Defined_expression(const char* symbol_name, size_t symbol_name_len)
1161     : symbol_name_(symbol_name, symbol_name_len)
1162   { }
1163
1164   uint64_t
1165   value(const Expression_eval_info* eei)
1166   {
1167     Symbol* sym = eei->symtab->lookup(this->symbol_name_.c_str());
1168     return sym != NULL && sym->is_defined();
1169   }
1170
1171   void
1172   print(FILE* f) const
1173   { fprintf(f, "DEFINED(%s)", this->symbol_name_.c_str()); }
1174
1175  private:
1176   std::string symbol_name_;
1177 };
1178
1179 extern "C" Expression*
1180 script_exp_function_defined(const char* symbol_name, size_t symbol_name_len)
1181 {
1182   return new Defined_expression(symbol_name, symbol_name_len);
1183 }
1184
1185 // LOADADDR function
1186
1187 class Loadaddr_expression : public Section_expression
1188 {
1189  public:
1190   Loadaddr_expression(const char* section_name, size_t section_name_len)
1191     : Section_expression(section_name, section_name_len)
1192   { }
1193
1194  protected:
1195   uint64_t
1196   value_from_output_section(const Expression_eval_info* eei,
1197                             Output_section* os)
1198   {
1199     if (os->has_load_address())
1200       return os->load_address();
1201     else
1202       {
1203         if (eei->result_section_pointer != NULL)
1204           *eei->result_section_pointer = os;
1205         return os->address();
1206       }
1207   }
1208
1209   uint64_t
1210   value_from_script_output_section(uint64_t, uint64_t load_address, uint64_t,
1211                                    uint64_t)
1212   { return load_address; }
1213
1214   const char*
1215   function_name() const
1216   { return "LOADADDR"; }
1217 };
1218
1219 extern "C" Expression*
1220 script_exp_function_loadaddr(const char* section_name, size_t section_name_len)
1221 {
1222   return new Loadaddr_expression(section_name, section_name_len);
1223 }
1224
1225 // SIZEOF function
1226
1227 class Sizeof_expression : public Section_expression
1228 {
1229  public:
1230   Sizeof_expression(const char* section_name, size_t section_name_len)
1231     : Section_expression(section_name, section_name_len)
1232   { }
1233
1234  protected:
1235   uint64_t
1236   value_from_output_section(const Expression_eval_info*,
1237                             Output_section* os)
1238   {
1239     // We can not use data_size here, as the size of the section may
1240     // not have been finalized.  Instead we get whatever the current
1241     // size is.  This will work correctly for backward references in
1242     // linker scripts.
1243     return os->current_data_size();
1244   }
1245
1246   uint64_t
1247   value_from_script_output_section(uint64_t, uint64_t, uint64_t,
1248                                    uint64_t size)
1249   { return size; }
1250
1251   const char*
1252   function_name() const
1253   { return "SIZEOF"; }
1254 };
1255
1256 extern "C" Expression*
1257 script_exp_function_sizeof(const char* section_name, size_t section_name_len)
1258 {
1259   return new Sizeof_expression(section_name, section_name_len);
1260 }
1261
1262 // SIZEOF_HEADERS.
1263
1264 class Sizeof_headers_expression : public Expression
1265 {
1266  public:
1267   Sizeof_headers_expression()
1268   { }
1269
1270   uint64_t
1271   value(const Expression_eval_info*);
1272
1273   void
1274   print(FILE* f) const
1275   { fprintf(f, "SIZEOF_HEADERS"); }
1276 };
1277
1278 uint64_t
1279 Sizeof_headers_expression::value(const Expression_eval_info* eei)
1280 {
1281   unsigned int ehdr_size;
1282   unsigned int phdr_size;
1283   if (parameters->target().get_size() == 32)
1284     {
1285       ehdr_size = elfcpp::Elf_sizes<32>::ehdr_size;
1286       phdr_size = elfcpp::Elf_sizes<32>::phdr_size;
1287     }
1288   else if (parameters->target().get_size() == 64)
1289     {
1290       ehdr_size = elfcpp::Elf_sizes<64>::ehdr_size;
1291       phdr_size = elfcpp::Elf_sizes<64>::phdr_size;
1292     }
1293   else
1294     gold_unreachable();
1295
1296   return ehdr_size + phdr_size * eei->layout->expected_segment_count();
1297 }
1298
1299 extern "C" Expression*
1300 script_exp_function_sizeof_headers()
1301 {
1302   return new Sizeof_headers_expression();
1303 }
1304
1305 // SEGMENT_START.
1306
1307 class Segment_start_expression : public Unary_expression
1308 {
1309  public:
1310   Segment_start_expression(const char* segment_name, size_t segment_name_len,
1311                            Expression* default_value)
1312     : Unary_expression(default_value),
1313       segment_name_(segment_name, segment_name_len)
1314   { }
1315
1316   uint64_t
1317   value(const Expression_eval_info*);
1318
1319   void
1320   print(FILE* f) const
1321   {
1322     fprintf(f, "SEGMENT_START(\"%s\", ", this->segment_name_.c_str());
1323     this->arg_print(f);
1324     fprintf(f, ")");
1325   }
1326
1327  private:
1328   std::string segment_name_;
1329 };
1330
1331 uint64_t
1332 Segment_start_expression::value(const Expression_eval_info* eei)
1333 {
1334   // Check for command line overrides.
1335   if (parameters->options().user_set_Ttext()
1336       && this->segment_name_ == ".text")
1337     return parameters->options().Ttext();
1338   else if (parameters->options().user_set_Tdata()
1339            && this->segment_name_ == ".data")
1340     return parameters->options().Tdata();
1341   else if (parameters->options().user_set_Tbss()
1342            && this->segment_name_ == ".bss")
1343     return parameters->options().Tbss();
1344   else
1345     {
1346       uint64_t ret = this->arg_value(eei, NULL);
1347       // Force the value to be absolute.
1348       if (eei->result_section_pointer != NULL)
1349         *eei->result_section_pointer = NULL;
1350       return ret;
1351     }
1352 }
1353
1354 extern "C" Expression*
1355 script_exp_function_segment_start(const char* segment_name,
1356                                   size_t segment_name_len,
1357                                   Expression* default_value)
1358 {
1359   return new Segment_start_expression(segment_name, segment_name_len,
1360                                       default_value);
1361 }
1362
1363 } // End namespace gold.