Support assignments and expressions in linker scripts.

1 files changed, 508 insertions, 0 deletions

diff --git a/gold/expression.cc b/gold/expression.cc
new file mode 100644
index 0000000..3933280
--- /dev/null
+++ b/gold/expression.cc
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+// expression.cc -- expressions in linker scripts for gold
+
+// Copyright 2006, 2007, 2008 Free Software Foundation, Inc.
+// Written by Ian Lance Taylor <iant@google.com>.
+
+// This file is part of gold.
+
+// This program is free software; you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation; either version 3 of the License, or
+// (at your option) any later version.
+
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License
+// along with this program; if not, write to the Free Software
+// Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,
+// MA 02110-1301, USA.
+
+#include "gold.h"
+
+#include <string>
+
+#include "parameters.h"
+#include "symtab.h"
+#include "layout.h"
+#include "script.h"
+#include "script-c.h"
+
+namespace gold
+{
+
+// This file holds the code which handles linker expressions.
+
+// When evaluating the value of an expression, we pass in a pointer to
+// this struct, so that the expression evaluation can find the
+// information it needs.
+
+struct Expression::Expression_eval_info
+{
+  const Symbol_table* symtab;
+  const Layout* layout;
+};
+
+// Evaluate an expression.
+
+uint64_t
+Expression::eval(const Symbol_table* symtab, const Layout* layout)
+{
+  Expression_eval_info eei;
+  eei.symtab = symtab;
+  eei.layout = layout;
+  return this->value(&eei);
+}
+
+// A number.
+
+class Integer_expression : public Expression
+{
+ public:
+  Integer_expression(uint64_t val)
+    : val_(val)
+  { }
+
+  uint64_t
+  value(const Expression_eval_info*)
+  { return this->val_; }
+
+ private:
+  uint64_t val_;
+};
+
+extern "C" Expression*
+script_exp_integer(uint64_t val)
+{
+  return new Integer_expression(val);
+}
+
+// An expression whose value is the value of a symbol.
+
+class Symbol_expression : public Expression
+{
+ public:
+  Symbol_expression(const char* name, size_t length)
+    : name_(name, length)
+  { }
+
+  uint64_t
+  value(const Expression_eval_info*);
+
+ private:
+  std::string name_;
+};
+
+uint64_t
+Symbol_expression::value(const Expression_eval_info* eei)
+{
+  Symbol* sym = eei->symtab->lookup(this->name_.c_str());
+  if (sym == NULL || !sym->is_defined())
+    {
+      gold_error(_("undefined symbol '%s' referenced in expression"),
+		 this->name_.c_str());
+      return 0;
+    }
+
+  if (parameters->get_size() == 32)
+    return eei->symtab->get_sized_symbol<32>(sym)->value();
+  else if (parameters->get_size() == 64)
+    return eei->symtab->get_sized_symbol<64>(sym)->value();
+  else
+    gold_unreachable();
+}
+
+// An expression whose value is the value of the special symbol ".".
+// This is only valid within a SECTIONS clause.
+
+class Dot_expression : public Expression
+{
+ public:
+  Dot_expression()
+  { }
+
+  uint64_t
+  value(const Expression_eval_info*);
+};
+
+uint64_t
+Dot_expression::value(const Expression_eval_info*)
+{
+  gold_error("dot symbol unimplemented");
+  return 0;
+}
+
+// A string.  This is either the name of a symbol, or ".".
+
+extern "C" Expression*
+script_exp_string(const char* name, size_t length)
+{
+  if (length == 1 && name[0] == '.')
+    return new Dot_expression();
+  else
+    return new Symbol_expression(name, length);
+}
+
+// A unary expression.
+
+class Unary_expression : public Expression
+{
+ public:
+  Unary_expression(Expression* arg)
+    : arg_(arg)
+  { }
+
+  ~Unary_expression()
+  { delete this->arg_; }
+
+ protected:
+  uint64_t
+  arg_value(const Expression_eval_info* eei) const
+  { return this->arg_->value(eei); }
+
+ private:
+  Expression* arg_;
+};
+
+// Handle unary operators.  We use a preprocessor macro as a hack to
+// capture the C operator.
+
+#define UNARY_EXPRESSION(NAME, OPERATOR)			\
+  class Unary_ ## NAME : public Unary_expression		\
+  {								\
+   public:							\
+    Unary_ ## NAME(Expression* arg)				\
+      : Unary_expression(arg)					\
+    { }								\
+    								\
+    uint64_t							\
+    value(const Expression_eval_info* eei)			\
+    { return OPERATOR this->arg_value(eei); }			\
+  };								\
+  								\
+  extern "C" Expression*					\
+  script_exp_unary_ ## NAME(Expression* arg)			\
+  {								\
+    return new Unary_ ## NAME(arg);				\
+  }
+
+UNARY_EXPRESSION(minus, -)
+UNARY_EXPRESSION(logical_not, !)
+UNARY_EXPRESSION(bitwise_not, ~)
+
+// A binary expression.
+
+class Binary_expression : public Expression
+{
+ public:
+  Binary_expression(Expression* left, Expression* right)
+    : left_(left), right_(right)
+  { }
+
+  ~Binary_expression()
+  {
+    delete this->left_;
+    delete this->right_;
+  }
+
+ protected:
+  uint64_t
+  left_value(const Expression_eval_info* eei) const
+  { return this->left_->value(eei); }
+
+  uint64_t
+  right_value(const Expression_eval_info* eei) const
+  { return this->right_->value(eei); }
+
+ private:
+  Expression* left_;
+  Expression* right_;
+};
+
+// Handle binary operators.  We use a preprocessor macro as a hack to
+// capture the C operator.
+
+#define BINARY_EXPRESSION(NAME, OPERATOR)				\
+  class Binary_ ## NAME : public Binary_expression			\
+  {									\
+  public:								\
+    Binary_ ## NAME(Expression* left, Expression* right)		\
+      : Binary_expression(left, right)					\
+    { }									\
+									\
+    uint64_t								\
+    value(const Expression_eval_info* eei)				\
+    {									\
+      return (this->left_value(eei)					\
+	      OPERATOR this->right_value(eei));				\
+    }									\
+  };									\
+									\
+  extern "C" Expression*						\
+  script_exp_binary_ ## NAME(Expression* left, Expression* right)	\
+  {									\
+    return new Binary_ ## NAME(left, right);				\
+  }
+
+BINARY_EXPRESSION(mult, *)
+BINARY_EXPRESSION(div, /)
+BINARY_EXPRESSION(mod, %)
+BINARY_EXPRESSION(add, +)
+BINARY_EXPRESSION(sub, -)
+BINARY_EXPRESSION(lshift, <<)
+BINARY_EXPRESSION(rshift, >>)
+BINARY_EXPRESSION(eq, ==)
+BINARY_EXPRESSION(ne, !=)
+BINARY_EXPRESSION(le, <=)
+BINARY_EXPRESSION(ge, >=)
+BINARY_EXPRESSION(lt, <)
+BINARY_EXPRESSION(gt, >)
+BINARY_EXPRESSION(bitwise_and, &)
+BINARY_EXPRESSION(bitwise_xor, ^)
+BINARY_EXPRESSION(bitwise_or, |)
+BINARY_EXPRESSION(logical_and, &&)
+BINARY_EXPRESSION(logical_or, ||)
+
+// A trinary expression.
+
+class Trinary_expression : public Expression
+{
+ public:
+  Trinary_expression(Expression* arg1, Expression* arg2, Expression* arg3)
+    : arg1_(arg1), arg2_(arg2), arg3_(arg3)
+  { }
+
+  ~Trinary_expression()
+  {
+    delete this->arg1_;
+    delete this->arg2_;
+    delete this->arg3_;
+  }
+
+ protected:
+  uint64_t
+  arg1_value(const Expression_eval_info* eei) const
+  { return this->arg1_->value(eei); }
+
+  uint64_t
+  arg2_value(const Expression_eval_info* eei) const
+  { return this->arg2_->value(eei); }
+
+  uint64_t
+  arg3_value(const Expression_eval_info* eei) const
+  { return this->arg3_->value(eei); }
+
+ private:
+  Expression* arg1_;
+  Expression* arg2_;
+  Expression* arg3_;
+};
+
+// The conditional operator.
+
+class Trinary_cond : public Trinary_expression
+{
+ public:
+  Trinary_cond(Expression* arg1, Expression* arg2, Expression* arg3)
+    : Trinary_expression(arg1, arg2, arg3)
+  { }
+
+  uint64_t
+  value(const Expression_eval_info* eei)
+  {
+    return (this->arg1_value(eei)
+	    ? this->arg2_value(eei)
+	    : this->arg3_value(eei));
+  }
+};
+
+extern "C" Expression*
+script_exp_trinary_cond(Expression* arg1, Expression* arg2, Expression* arg3)
+{
+  return new Trinary_cond(arg1, arg2, arg3);
+}
+
+// Max function.
+
+class Max_expression : public Binary_expression
+{
+ public:
+  Max_expression(Expression* left, Expression* right)
+    : Binary_expression(left, right)
+  { }
+
+  uint64_t
+  value(const Expression_eval_info* eei)
+  { return std::max(this->left_value(eei), this->right_value(eei)); }
+};
+
+extern "C" Expression*
+script_exp_function_max(Expression* left, Expression* right)
+{
+  return new Max_expression(left, right);
+}
+
+// Min function.
+
+class Min_expression : public Binary_expression
+{
+ public:
+  Min_expression(Expression* left, Expression* right)
+    : Binary_expression(left, right)
+  { }
+
+  uint64_t
+  value(const Expression_eval_info* eei)
+  { return std::min(this->left_value(eei), this->right_value(eei)); }
+};
+
+extern "C" Expression*
+script_exp_function_min(Expression* left, Expression* right)
+{
+  return new Min_expression(left, right);
+}
+
+// Align function.
+
+class Align_expression : public Binary_expression
+{
+ public:
+  Align_expression(Expression* left, Expression* right)
+    : Binary_expression(left, right)
+  { }
+
+  uint64_t
+  value(const Expression_eval_info* eei)
+  {
+    uint64_t align = this->right_value(eei);
+    uint64_t value = this->left_value(eei);
+    if (align <= 1)
+      return value;
+    return ((value + align - 1) / align) * align;
+  }
+};
+
+extern "C" Expression*
+script_exp_function_align(Expression* left, Expression* right)
+{
+  return new Align_expression(left, right);
+}
+
+// Assert function.
+
+class Assert_expression : public Unary_expression
+{
+ public:
+  Assert_expression(Expression* arg, const char* message, size_t length)
+    : Unary_expression(arg), message_(message, length)
+  { }
+
+  uint64_t
+  value(const Expression_eval_info* eei)
+  {
+    uint64_t value = this->arg_value(eei);
+    if (!value)
+      gold_error("%s", this->message_.c_str());
+    return value;
+  }
+
+ private:
+  std::string message_;
+};
+
+extern "C" Expression*
+script_exp_function_assert(Expression* expr, const char* message,
+			   size_t length)
+{
+  return new Assert_expression(expr, message, length);
+}
+
+// Functions.
+
+extern "C" Expression*
+script_exp_function_defined(const char*, size_t)
+{
+  gold_fatal(_("DEFINED not implemented"));
+}
+
+extern "C" Expression*
+script_exp_function_sizeof_headers()
+{
+  gold_fatal(_("SIZEOF_HEADERS not implemented"));
+}
+
+extern "C" Expression*
+script_exp_function_alignof(const char*, size_t)
+{
+  gold_fatal(_("ALIGNOF not implemented"));
+}
+
+extern "C" Expression*
+script_exp_function_sizeof(const char*, size_t)
+{
+  gold_fatal(_("SIZEOF not implemented"));
+}
+
+extern "C" Expression*
+script_exp_function_addr(const char*, size_t)
+{
+  gold_fatal(_("ADDR not implemented"));
+}
+
+extern "C" Expression*
+script_exp_function_loadaddr(const char*, size_t)
+{
+  gold_fatal(_("LOADADDR not implemented"));
+}
+
+extern "C" Expression*
+script_exp_function_origin(const char*, size_t)
+{
+  gold_fatal(_("ORIGIN not implemented"));
+}
+
+extern "C" Expression*
+script_exp_function_length(const char*, size_t)
+{
+  gold_fatal(_("LENGTH not implemented"));
+}
+
+extern "C" Expression*
+script_exp_function_constant(const char*, size_t)
+{
+  gold_fatal(_("CONSTANT not implemented"));
+}
+
+extern "C" Expression*
+script_exp_function_absolute(Expression*)
+{
+  gold_fatal(_("ABSOLUTE not implemented"));
+}
+
+extern "C" Expression*
+script_exp_function_data_segment_align(Expression*, Expression*)
+{
+  gold_fatal(_("DATA_SEGMENT_ALIGN not implemented"));
+}
+
+extern "C" Expression*
+script_exp_function_data_segment_relro_end(Expression*, Expression*)
+{
+  gold_fatal(_("DATA_SEGMENT_RELRO_END not implemented"));
+}
+
+extern "C" Expression*
+script_exp_function_data_segment_end(Expression*)
+{
+  gold_fatal(_("DATA_SEGMENT_END not implemented"));
+}
+
+extern "C" Expression*
+script_exp_function_segment_start(const char*, size_t, Expression*)
+{
+  gold_fatal(_("SEGMENT_START not implemented"));
+}
+
+} // End namespace gold.