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authorIan Lance Taylor <iant@google.com>2007-09-19 06:02:29 +0000
committerIan Lance Taylor <iant@google.com>2007-09-19 06:02:29 +0000
commit86f2e683461018af5274634f0b119b39576b17e0 (patch)
tree7c396540d3d7b2a9c1804ab484dc4ce21513d1e0 /gold/resolve.cc
parent8ae3da9046f6ef7b39eaf19cc85ee05f5c002c07 (diff)
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Let special symbols override existing symbols rather than
reinitializing them.
Diffstat (limited to 'gold/resolve.cc')
-rw-r--r--gold/resolve.cc377
1 files changed, 241 insertions, 136 deletions
diff --git a/gold/resolve.cc b/gold/resolve.cc
index e5ca6e3..599aad4 100644
--- a/gold/resolve.cc
+++ b/gold/resolve.cc
@@ -51,6 +51,25 @@ Sized_symbol<size>::override(const elfcpp::Sym<size, big_endian>& sym,
this->symsize_ = sym.get_st_size();
}
+// The resolve functions build a little code for each symbol.
+// Bit 0: 0 for global, 1 for weak.
+// Bit 1: 0 for regular object, 1 for shared object
+// Bits 2-3: 0 for normal, 1 for undefined, 2 for common
+// This gives us values from 0 to 11.
+
+static const int global_or_weak_shift = 0;
+static const unsigned int global_flag = 0 << global_or_weak_shift;
+static const unsigned int weak_flag = 1 << global_or_weak_shift;
+
+static const int regular_or_dynamic_shift = 1;
+static const unsigned int regular_flag = 0 << regular_or_dynamic_shift;
+static const unsigned int dynamic_flag = 1 << regular_or_dynamic_shift;
+
+static const int def_undef_or_common_shift = 2;
+static const unsigned int def_flag = 0 << def_undef_or_common_shift;
+static const unsigned int undef_flag = 1 << def_undef_or_common_shift;
+static const unsigned int common_flag = 2 << def_undef_or_common_shift;
+
// Resolve a symbol. This is called the second and subsequent times
// we see a symbol. TO is the pre-existing symbol. SYM is the new
// symbol, seen in OBJECT. VERSION of the version of SYM.
@@ -71,121 +90,138 @@ Symbol_table::resolve(Sized_symbol<size>* to,
return;
}
- // Build a little code for each symbol.
- // Bit 0: 0 for global, 1 for weak.
- // Bit 1: 0 for regular object, 1 for shared object
- // Bits 2-3: 0 for normal, 1 for undefined, 2 for common
- // This gives us values from 0 to 11:
-
- enum
- {
- DEF = 0,
- WEAK_DEF = 1,
- DYN_DEF = 2,
- DYN_WEAK_DEF = 3,
- UNDEF = 4,
- WEAK_UNDEF = 5,
- DYN_UNDEF = 6,
- DYN_WEAK_UNDEF = 7,
- COMMON = 8,
- WEAK_COMMON = 9,
- DYN_COMMON = 10,
- DYN_WEAK_COMMON = 11
- };
+ if (!object->is_dynamic())
+ {
+ // Record that we've seen this symbol in a regular object.
+ to->set_in_reg();
+ }
+ else
+ {
+ // Record that we've seen this symbol in a dynamic object.
+ to->set_in_dyn();
+ }
- int tobits;
- switch (to->binding())
+ unsigned int frombits;
+ switch (sym.get_st_bind())
{
case elfcpp::STB_GLOBAL:
- tobits = 0;
+ frombits = global_flag;
break;
case elfcpp::STB_WEAK:
- tobits = 1;
+ frombits = weak_flag;
break;
case elfcpp::STB_LOCAL:
- // We should only see externally visible symbols in the symbol
- // table.
- gold_unreachable();
+ fprintf(stderr,
+ _("%s: %s: invalid STB_LOCAL symbol %s in external symbols\n"),
+ program_name, object->name().c_str(), to->name());
+ gold_exit(false);
default:
- // Any target which wants to handle STB_LOOS, etc., needs to
- // define a resolve method.
- gold_unreachable();
+ fprintf(stderr,
+ _("%s: %s: unsupported symbol binding %d for symbol %s\n"),
+ program_name, object->name().c_str(),
+ static_cast<int>(sym.get_st_bind()), to->name());
+ gold_exit(false);
}
- if (to->source() == Symbol::FROM_OBJECT
- && to->object()->is_dynamic())
- tobits |= (1 << 1);
+ if (!object->is_dynamic())
+ frombits |= regular_flag;
+ else
+ frombits |= dynamic_flag;
- switch (to->shndx())
+ switch (sym.get_st_shndx())
{
case elfcpp::SHN_UNDEF:
- tobits |= (1 << 2);
+ frombits |= undef_flag;
break;
case elfcpp::SHN_COMMON:
- tobits |= (2 << 2);
+ frombits |= common_flag;
break;
default:
- if (to->type() == elfcpp::STT_COMMON)
- tobits |= (2 << 2);
+ if (sym.get_st_type() == elfcpp::STT_COMMON)
+ frombits |= common_flag;
+ else
+ frombits |= def_flag;
break;
}
- int frombits;
- switch (sym.get_st_bind())
+ bool adjust_common_sizes;
+ if (Symbol_table::should_override(to, frombits, &adjust_common_sizes))
+ {
+ typename Sized_symbol<size>::Size_type tosize = to->symsize();
+
+ to->override(sym, object, version);
+
+ if (adjust_common_sizes && tosize > to->symsize())
+ to->set_symsize(tosize);
+ }
+ else
+ {
+ if (adjust_common_sizes && sym.get_st_size() > to->symsize())
+ to->set_symsize(sym.get_st_size());
+ }
+}
+
+// Handle the core of symbol resolution. This is called with the
+// existing symbol, TO, and a bitflag describing the new symbol. This
+// returns true if we should override the existing symbol with the new
+// one, and returns false otherwise. It sets *ADJUST_COMMON_SIZES to
+// true if we should set the symbol size to the maximum of the TO and
+// FROM sizes. It handles error conditions.
+
+bool
+Symbol_table::should_override(const Symbol* to, unsigned int frombits,
+ bool* adjust_common_sizes)
+{
+ *adjust_common_sizes = false;
+
+ unsigned int tobits;
+ switch (to->binding())
{
case elfcpp::STB_GLOBAL:
- frombits = 0;
+ tobits = global_flag;
break;
case elfcpp::STB_WEAK:
- frombits = 1;
+ tobits = weak_flag;
break;
case elfcpp::STB_LOCAL:
- fprintf(stderr,
- _("%s: %s: invalid STB_LOCAL symbol %s in external symbols\n"),
- program_name, object->name().c_str(), to->name());
- gold_exit(false);
+ // We should only see externally visible symbols in the symbol
+ // table.
+ gold_unreachable();
default:
- fprintf(stderr,
- _("%s: %s: unsupported symbol binding %d for symbol %s\n"),
- program_name, object->name().c_str(),
- static_cast<int>(sym.get_st_bind()), to->name());
- gold_exit(false);
+ // Any target which wants to handle STB_LOOS, etc., needs to
+ // define a resolve method.
+ gold_unreachable();
}
- if (!object->is_dynamic())
- {
- // Record that we've seen this symbol in a regular object.
- to->set_in_reg();
- }
+ if (to->source() == Symbol::FROM_OBJECT
+ && to->object()->is_dynamic())
+ tobits |= dynamic_flag;
else
- {
- frombits |= (1 << 1);
+ tobits |= regular_flag;
- // Record that we've seen this symbol in a dynamic object.
- to->set_in_dyn();
- }
-
- switch (sym.get_st_shndx())
+ switch (to->shndx())
{
case elfcpp::SHN_UNDEF:
- frombits |= (1 << 2);
+ tobits |= undef_flag;
break;
case elfcpp::SHN_COMMON:
- frombits |= (2 << 2);
+ tobits |= common_flag;
break;
default:
- if (sym.get_st_type() == elfcpp::STT_COMMON)
- frombits |= (2 << 2);
+ if (to->type() == elfcpp::STT_COMMON)
+ tobits |= common_flag;
+ else
+ tobits |= def_flag;
break;
}
@@ -199,14 +235,31 @@ Symbol_table::resolve(Sized_symbol<size>* to,
// but that is no easier to understand than this large switch
// statement.
+ // These are the values generated by the bit codes.
+ enum
+ {
+ DEF = global_flag | regular_flag | def_flag,
+ WEAK_DEF = weak_flag | regular_flag | def_flag,
+ DYN_DEF = global_flag | dynamic_flag | def_flag,
+ DYN_WEAK_DEF = weak_flag | dynamic_flag | def_flag,
+ UNDEF = global_flag | regular_flag | undef_flag,
+ WEAK_UNDEF = weak_flag | regular_flag | undef_flag,
+ DYN_UNDEF = global_flag | dynamic_flag | undef_flag,
+ DYN_WEAK_UNDEF = weak_flag | dynamic_flag | undef_flag,
+ COMMON = global_flag | regular_flag | common_flag,
+ WEAK_COMMON = weak_flag | regular_flag | common_flag,
+ DYN_COMMON = global_flag | dynamic_flag | common_flag,
+ DYN_WEAK_COMMON = weak_flag | dynamic_flag | common_flag
+ };
+
switch (tobits * 16 + frombits)
{
case DEF * 16 + DEF:
// Two definitions of the same symbol.
- fprintf(stderr, "%s: %s: multiple definition of %s\n",
- program_name, object->name().c_str(), to->name());
+ fprintf(stderr, "%s: multiple definition of %s\n",
+ program_name, to->name());
// FIXME: Report locations. Record that we have seen an error.
- return;
+ return false;
case WEAK_DEF * 16 + DEF:
// We've seen a weak definition, and now we see a strong
@@ -217,8 +270,7 @@ Symbol_table::resolve(Sized_symbol<size>* to,
// are currently compatible with the GNU linker. In the future
// we should add a target specific option to change this.
// FIXME.
- to->override(sym, object, version);
- return;
+ return true;
case DYN_DEF * 16 + DEF:
case DYN_WEAK_DEF * 16 + DEF:
@@ -226,8 +278,7 @@ Symbol_table::resolve(Sized_symbol<size>* to,
// definition in a regular object. The definition in the
// regular object overrides the definition in the dynamic
// object.
- to->override(sym, object, version);
- return;
+ return true;
case UNDEF * 16 + DEF:
case WEAK_UNDEF * 16 + DEF:
@@ -235,8 +286,7 @@ Symbol_table::resolve(Sized_symbol<size>* to,
case DYN_WEAK_UNDEF * 16 + DEF:
// We've seen an undefined reference, and now we see a
// definition. We use the definition.
- to->override(sym, object, version);
- return;
+ return true;
case COMMON * 16 + DEF:
case WEAK_COMMON * 16 + DEF:
@@ -245,56 +295,51 @@ Symbol_table::resolve(Sized_symbol<size>* to,
// We've seen a common symbol and now we see a definition. The
// definition overrides. FIXME: We should optionally issue, version a
// warning.
- to->override(sym, object, version);
- return;
+ return true;
case DEF * 16 + WEAK_DEF:
case WEAK_DEF * 16 + WEAK_DEF:
// We've seen a definition and now we see a weak definition. We
// ignore the new weak definition.
- return;
+ return false;
case DYN_DEF * 16 + WEAK_DEF:
case DYN_WEAK_DEF * 16 + WEAK_DEF:
// We've seen a dynamic definition and now we see a regular weak
// definition. The regular weak definition overrides.
- to->override(sym, object, version);
- return;
+ return true;
case UNDEF * 16 + WEAK_DEF:
case WEAK_UNDEF * 16 + WEAK_DEF:
case DYN_UNDEF * 16 + WEAK_DEF:
case DYN_WEAK_UNDEF * 16 + WEAK_DEF:
// A weak definition of a currently undefined symbol.
- to->override(sym, object, version);
- return;
+ return true;
case COMMON * 16 + WEAK_DEF:
case WEAK_COMMON * 16 + WEAK_DEF:
// A weak definition does not override a common definition.
- return;
+ return false;
case DYN_COMMON * 16 + WEAK_DEF:
case DYN_WEAK_COMMON * 16 + WEAK_DEF:
// A weak definition does override a definition in a dynamic
// object. FIXME: We should optionally issue a warning.
- to->override(sym, object, version);
- return;
+ return true;
case DEF * 16 + DYN_DEF:
case WEAK_DEF * 16 + DYN_DEF:
case DYN_DEF * 16 + DYN_DEF:
case DYN_WEAK_DEF * 16 + DYN_DEF:
// Ignore a dynamic definition if we already have a definition.
- return;
+ return false;
case UNDEF * 16 + DYN_DEF:
case WEAK_UNDEF * 16 + DYN_DEF:
case DYN_UNDEF * 16 + DYN_DEF:
case DYN_WEAK_UNDEF * 16 + DYN_DEF:
// Use a dynamic definition if we have a reference.
- to->override(sym, object, version);
- return;
+ return true;
case COMMON * 16 + DYN_DEF:
case WEAK_COMMON * 16 + DYN_DEF:
@@ -302,7 +347,7 @@ Symbol_table::resolve(Sized_symbol<size>* to,
case DYN_WEAK_COMMON * 16 + DYN_DEF:
// Ignore a dynamic definition if we already have a common
// definition.
- return;
+ return false;
case DEF * 16 + DYN_WEAK_DEF:
case WEAK_DEF * 16 + DYN_WEAK_DEF:
@@ -310,15 +355,14 @@ Symbol_table::resolve(Sized_symbol<size>* to,
case DYN_WEAK_DEF * 16 + DYN_WEAK_DEF:
// Ignore a weak dynamic definition if we already have a
// definition.
- return;
+ return false;
case UNDEF * 16 + DYN_WEAK_DEF:
case WEAK_UNDEF * 16 + DYN_WEAK_DEF:
case DYN_UNDEF * 16 + DYN_WEAK_DEF:
case DYN_WEAK_UNDEF * 16 + DYN_WEAK_DEF:
// Use a weak dynamic definition if we have a reference.
- to->override(sym, object, version);
- return;
+ return true;
case COMMON * 16 + DYN_WEAK_DEF:
case WEAK_COMMON * 16 + DYN_WEAK_DEF:
@@ -326,7 +370,7 @@ Symbol_table::resolve(Sized_symbol<size>* to,
case DYN_WEAK_COMMON * 16 + DYN_WEAK_DEF:
// Ignore a weak dynamic definition if we already have a common
// definition.
- return;
+ return false;
case DEF * 16 + UNDEF:
case WEAK_DEF * 16 + UNDEF:
@@ -334,21 +378,20 @@ Symbol_table::resolve(Sized_symbol<size>* to,
case DYN_WEAK_DEF * 16 + UNDEF:
case UNDEF * 16 + UNDEF:
// A new undefined reference tells us nothing.
- return;
+ return false;
case WEAK_UNDEF * 16 + UNDEF:
case DYN_UNDEF * 16 + UNDEF:
case DYN_WEAK_UNDEF * 16 + UNDEF:
// A strong undef overrides a dynamic or weak undef.
- to->override(sym, object, version);
- return;
+ return true;
case COMMON * 16 + UNDEF:
case WEAK_COMMON * 16 + UNDEF:
case DYN_COMMON * 16 + UNDEF:
case DYN_WEAK_COMMON * 16 + UNDEF:
// A new undefined reference tells us nothing.
- return;
+ return false;
case DEF * 16 + WEAK_UNDEF:
case WEAK_DEF * 16 + WEAK_UNDEF:
@@ -363,7 +406,7 @@ Symbol_table::resolve(Sized_symbol<size>* to,
case DYN_COMMON * 16 + WEAK_UNDEF:
case DYN_WEAK_COMMON * 16 + WEAK_UNDEF:
// A new weak undefined reference tells us nothing.
- return;
+ return false;
case DEF * 16 + DYN_UNDEF:
case WEAK_DEF * 16 + DYN_UNDEF:
@@ -378,7 +421,7 @@ Symbol_table::resolve(Sized_symbol<size>* to,
case DYN_COMMON * 16 + DYN_UNDEF:
case DYN_WEAK_COMMON * 16 + DYN_UNDEF:
// A new dynamic undefined reference tells us nothing.
- return;
+ return false;
case DEF * 16 + DYN_WEAK_UNDEF:
case WEAK_DEF * 16 + DYN_WEAK_UNDEF:
@@ -393,50 +436,41 @@ Symbol_table::resolve(Sized_symbol<size>* to,
case DYN_COMMON * 16 + DYN_WEAK_UNDEF:
case DYN_WEAK_COMMON * 16 + DYN_WEAK_UNDEF:
// A new weak dynamic undefined reference tells us nothing.
- return;
+ return false;
case DEF * 16 + COMMON:
// A common symbol does not override a definition.
- return;
+ return false;
case WEAK_DEF * 16 + COMMON:
case DYN_DEF * 16 + COMMON:
case DYN_WEAK_DEF * 16 + COMMON:
// A common symbol does override a weak definition or a dynamic
// definition.
- to->override(sym, object, version);
- return;
+ return true;
case UNDEF * 16 + COMMON:
case WEAK_UNDEF * 16 + COMMON:
case DYN_UNDEF * 16 + COMMON:
case DYN_WEAK_UNDEF * 16 + COMMON:
// A common symbol is a definition for a reference.
- to->override(sym, object, version);
- return;
+ return true;
case COMMON * 16 + COMMON:
// Set the size to the maximum.
- if (sym.get_st_size() > to->symsize())
- to->set_symsize(sym.get_st_size());
- return;
+ *adjust_common_sizes = true;
+ return false;
case WEAK_COMMON * 16 + COMMON:
// I'm not sure just what a weak common symbol means, but
// presumably it can be overridden by a regular common symbol.
- to->override(sym, object, version);
- return;
+ return true;
case DYN_COMMON * 16 + COMMON:
case DYN_WEAK_COMMON * 16 + COMMON:
- {
- // Use the real common symbol, but adjust the size if necessary.
- typename Sized_symbol<size>::Size_type symsize = to->symsize();
- to->override(sym, object, version);
- if (to->symsize() < symsize)
- to->set_symsize(symsize);
- }
- return;
+ // Use the real common symbol, but adjust the size if necessary.
+ *adjust_common_sizes = true;
+ return true;
case DEF * 16 + WEAK_COMMON:
case WEAK_DEF * 16 + WEAK_COMMON:
@@ -444,15 +478,14 @@ Symbol_table::resolve(Sized_symbol<size>* to,
case DYN_WEAK_DEF * 16 + WEAK_COMMON:
// Whatever a weak common symbol is, it won't override a
// definition.
- return;
+ return false;
case UNDEF * 16 + WEAK_COMMON:
case WEAK_UNDEF * 16 + WEAK_COMMON:
case DYN_UNDEF * 16 + WEAK_COMMON:
case DYN_WEAK_UNDEF * 16 + WEAK_COMMON:
// A weak common symbol is better than an undefined symbol.
- to->override(sym, object, version);
- return;
+ return true;
case COMMON * 16 + WEAK_COMMON:
case WEAK_COMMON * 16 + WEAK_COMMON:
@@ -460,7 +493,7 @@ Symbol_table::resolve(Sized_symbol<size>* to,
case DYN_WEAK_COMMON * 16 + WEAK_COMMON:
// Ignore a weak common symbol in the presence of a real common
// symbol.
- return;
+ return false;
case DEF * 16 + DYN_COMMON:
case WEAK_DEF * 16 + DYN_COMMON:
@@ -468,54 +501,114 @@ Symbol_table::resolve(Sized_symbol<size>* to,
case DYN_WEAK_DEF * 16 + DYN_COMMON:
// Ignore a dynamic common symbol in the presence of a
// definition.
- return;
+ return false;
case UNDEF * 16 + DYN_COMMON:
case WEAK_UNDEF * 16 + DYN_COMMON:
case DYN_UNDEF * 16 + DYN_COMMON:
case DYN_WEAK_UNDEF * 16 + DYN_COMMON:
// A dynamic common symbol is a definition of sorts.
- to->override(sym, object, version);
- return;
+ return true;
case COMMON * 16 + DYN_COMMON:
case WEAK_COMMON * 16 + DYN_COMMON:
case DYN_COMMON * 16 + DYN_COMMON:
case DYN_WEAK_COMMON * 16 + DYN_COMMON:
// Set the size to the maximum.
- if (sym.get_st_size() > to->symsize())
- to->set_symsize(sym.get_st_size());
- return;
+ *adjust_common_sizes = true;
+ return false;
case DEF * 16 + DYN_WEAK_COMMON:
case WEAK_DEF * 16 + DYN_WEAK_COMMON:
case DYN_DEF * 16 + DYN_WEAK_COMMON:
case DYN_WEAK_DEF * 16 + DYN_WEAK_COMMON:
// A common symbol is ignored in the face of a definition.
- return;
+ return false;
case UNDEF * 16 + DYN_WEAK_COMMON:
case WEAK_UNDEF * 16 + DYN_WEAK_COMMON:
case DYN_UNDEF * 16 + DYN_WEAK_COMMON:
case DYN_WEAK_UNDEF * 16 + DYN_WEAK_COMMON:
// I guess a weak common symbol is better than a definition.
- to->override(sym, object, version);
- return;
+ return true;
case COMMON * 16 + DYN_WEAK_COMMON:
case WEAK_COMMON * 16 + DYN_WEAK_COMMON:
case DYN_COMMON * 16 + DYN_WEAK_COMMON:
case DYN_WEAK_COMMON * 16 + DYN_WEAK_COMMON:
// Set the size to the maximum.
- if (sym.get_st_size() > to->symsize())
- to->set_symsize(sym.get_st_size());
- return;
+ *adjust_common_sizes = true;
+ return false;
default:
gold_unreachable();
}
}
+// A special case of should_override which is only called for a strong
+// defined symbol from a regular object file. This is used when
+// defining special symbols.
+
+bool
+Symbol_table::should_override_with_special(const Symbol* to)
+{
+ bool adjust_common_sizes;
+ unsigned int frombits = global_flag | regular_flag | def_flag;
+ bool ret = Symbol_table::should_override(to, frombits, &adjust_common_sizes);
+ gold_assert(!adjust_common_sizes);
+ return ret;
+}
+
+// Override symbol base with a special symbol.
+
+void
+Symbol::override_base_with_special(const Symbol* from)
+{
+ this->source_ = from->source_;
+ switch (from->source_)
+ {
+ case FROM_OBJECT:
+ this->u_.from_object = from->u_.from_object;
+ break;
+ case IN_OUTPUT_DATA:
+ this->u_.in_output_data = from->u_.in_output_data;
+ break;
+ case IN_OUTPUT_SEGMENT:
+ this->u_.in_output_segment = from->u_.in_output_segment;
+ break;
+ case CONSTANT:
+ break;
+ default:
+ gold_unreachable();
+ break;
+ }
+
+ if (from->version_ != NULL && this->version_ != from->version_)
+ {
+ gold_assert(this->version_ == NULL);
+ this->version_ = from->version_;
+ }
+
+ this->type_ = from->type_;
+ this->binding_ = from->binding_;
+ this->visibility_ = from->visibility_;
+ this->nonvis_ = from->nonvis_;
+
+ // Special symbols are always considered to be regular symbols.
+ this->in_reg_ = true;
+}
+
+// Override a symbol with a special symbol.
+
+template<int size>
+void
+Sized_symbol<size>::override_with_special(const Sized_symbol<size>* from)
+{
+ this->override_base_with_special(from);
+ this->value_ = from->value_;
+ this->symsize_ = from->symsize_;
+}
+
// Instantiate the templates we need. We could use the configure
// script to restrict this to only the ones needed for implemented
// targets.
@@ -560,4 +653,16 @@ Symbol_table::resolve<64, true>(
const char* version);
#endif
+#if defined(HAVE_TARGET_32_LITTLE) || defined(HAVE_TARGET_32_BIG)
+template
+void
+Sized_symbol<32>::override_with_special(const Sized_symbol<32>*);
+#endif
+
+#if defined(HAVE_TARGET_64_LITTLE) || defined(HAVE_TARGET_64_BIG)
+template
+void
+Sized_symbol<64>::override_with_special(const Sized_symbol<64>*);
+#endif
+
} // End namespace gold.