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Fixup virtual member functions with linkage and no underlying symbol
This is from the problem report at https://sourceware.org/bugzilla/show_bug.cgi?id=19707. GCC 5.3.1, when invoked with -g -O2 emits some debug info where some virtual member functions with linkage name have no reference to any underlying symbol. When that binary is compared to its counterpart compiled with -g, the member function in question does have an underlying symbol and thus the comparison of the enclosing types yield a spurious change report like: method virtual void unity::scopes::ScopeBase::stop() didn't have any linkage name, and it now has: '_ZN5unity6scopes9ScopeBase4stopEv' This patch introduces a pass in the DWARF reader which fixes up virtual member function with linkage and no underlying symbol. If there is a symbol with a name equals to the linkage name, the virtual member function has its underlying symbol set to that symbol. This fixes the spurious change report. * src/abg-dwarf-reader.cc (die_function_decl_map_type): New typedef. (read_context::die_function_with_no_symbol_map_): New data member. (read_context::die_function_decl_with_no_symbol_map): New accessor. (read_context::fixup_functions_with_no_symbols): New member function. (finish_member_function_reading): Take a read_context. Schedule virtual member functions with linkage and no underlying symbol to be fixed up after all the debug info is read. (build_function_decl): After a virtual member function_decl has been updated, if it has its underlying symbol and was scheduled for fixup, then de-schedule it. (build_class_type_and_add_to_ir, build_ir_node_from_die): Adjust call to finish_member_function_reading. (read_corpus_from_elf): Move the pure ELF (symbol and other mundane information) information reading ... (read_debug_info_into_corpus): ... here. Make it happen *before* actual reading of DWARF information. We need symbol information to be present and fully set before we start reading debug info. This is so that we can know when a virtual member function doesn't need to be fixed up. Also, perform the fixup after the debug information was read. * tests/data/test-read-dwarf/test22-pr19097-libstdc++.so.6.0.17.so.abi: Adjust. Signed-off-by: Dodji Seketeli <dodji@redhat.com>
This commit is contained in:
Dodji Seketeli
parent
d78ad0e349
commit
2bbe75a08a
@ -92,6 +92,10 @@ typedef unordered_map<Dwarf_Off, type_base_sptr> die_type_map_type;
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/// corresponding class_decl.
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typedef unordered_map<Dwarf_Off, class_decl_sptr> die_class_map_type;
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/// Convenience typedef for a map which key the offset of a dwarf die
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/// and which value is the corresponding function_decl.
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typedef unordered_map<Dwarf_Off, function_decl_sptr> die_function_decl_map_type;
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/// Convenience typedef for a map which key is the offset of a dwarf
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/// die and which value is the corresponding function_type.
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typedef unordered_map<Dwarf_Off, function_type_sptr> die_function_type_map_type;
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@ -1929,6 +1933,7 @@ class read_context
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die_type_map_type alternate_die_type_map_;
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die_class_map_type die_wip_classes_map_;
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die_function_type_map_type die_wip_function_types_map_;
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die_function_decl_map_type die_function_with_no_symbol_map_;
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vector<Dwarf_Off> types_to_canonicalize_;
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vector<Dwarf_Off> alt_types_to_canonicalize_;
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string_classes_map decl_only_classes_map_;
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@ -2483,6 +2488,17 @@ public:
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die_wip_function_types_map()
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{return die_wip_function_types_map_;}
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/// Getter for a map that associates a die with a function decl
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/// which has a linkage name but no elf symbol yet.
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///
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/// This is to fixup function decls with linkage names, but with no
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/// link to their underlying elf symbol. There are some DIEs like
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/// that in DWARF sometimes, especially when the compiler optimizes
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/// stuff aggressively.
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die_function_decl_map_type&
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die_function_decl_with_no_symbol_map()
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{return die_function_with_no_symbol_map_;}
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/// Return true iff a given offset is for the DIE of a class that is
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/// being currently built.
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///
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@ -2648,6 +2664,53 @@ public:
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}
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}
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/// Some functions described by DWARF may have their linkage name
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/// set, but no link to their actual underlying elf symbol. When
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/// these are virtual member functions, comparing the enclosing type
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/// against another one which has its underlying symbol properly set
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/// might lead to spurious type changes.
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///
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/// If the corpus contains a symbol with the same name as the
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/// linkage name of the function, then set up the link between the
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/// function and its underlying symbol.
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///
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/// Note that for the moment, only virtual member functions are
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/// fixed up like this. This is because they really are the only
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/// fuctions of functions that can affect types (in spurious ways).
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void
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fixup_functions_with_no_symbols()
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{
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corpus_sptr corp = current_corpus();
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if (!corp)
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return;
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die_function_decl_map_type &fns_with_no_symbol =
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die_function_decl_with_no_symbol_map();
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if (do_log())
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cerr << fns_with_no_symbol.size()
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<< " functions to fixup, potentially\n";
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for (die_function_decl_map_type::iterator i = fns_with_no_symbol.begin();
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i != fns_with_no_symbol.end();
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++i)
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if (elf_symbol_sptr sym =
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corp->lookup_function_symbol(i->second->get_linkage_name()))
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{
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assert(is_member_function(i->second));
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assert(get_member_function_is_virtual(i->second));
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i->second->set_symbol(sym);
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if (do_log())
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cerr << "fixed up '"
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<< i->second->get_pretty_representation()
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<< "' with symbol '"
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<< sym->get_id_string()
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<< "'\n";
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}
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fns_with_no_symbol.clear();
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}
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/// Return a reference to the vector containing the offsets of the
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/// types that need late canonicalizing.
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///
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@ -4198,7 +4261,8 @@ build_function_decl(read_context& ctxt,
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static void
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finish_member_function_reading(Dwarf_Die* die,
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function_decl_sptr f,
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class_decl_sptr klass);
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class_decl_sptr klass,
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read_context& ctxt);
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/// Setter of the debug info root path for a dwarf reader context.
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///
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@ -6968,10 +7032,13 @@ build_enum_type(read_context& ctxt,
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/// @param f the function_decl that has just been built from @p die.
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///
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/// @param klass the class_decl that @p f belongs to.
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///
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/// @param ctxt the context used to read the ELF/DWARF information.
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static void
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finish_member_function_reading(Dwarf_Die* die,
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function_decl_sptr f,
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class_decl_sptr klass)
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class_decl_sptr klass,
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read_context& ctxt)
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{
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assert(klass);
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@ -7035,6 +7102,34 @@ finish_member_function_reading(Dwarf_Die* die,
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if (is_virtual)
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klass->sort_virtual_mem_fns();
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if (is_virtual && !f->get_linkage_name().empty() && !f->get_symbol())
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{
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// This is a virtual member function which has a linkage name
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// but has no underlying symbol set.
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//
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// The underlying elf symbol to set to this function can show up
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// later in the DWARF input or it can be that, because of some
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// compiler optimization, the relation between this function and
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// its underlying elf symbol is simply not emitted in the DWARF.
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//
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// Let's thus schedule this function for a later fixup pass
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// (performed by
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// read_context::fixup_functions_with_no_symbols()) that will
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// set its underlying symbol.
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//
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// Note that if the underying symbol is encountered later in the
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// DWARF input, then the part of build_function_decl() that
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// updates the function to set its underlying symbol will
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// de-schedule this function wrt fixup pass.
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Dwarf_Off die_offset = dwarf_dieoffset(die);
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die_function_decl_map_type &fns_with_no_symbol =
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ctxt.die_function_decl_with_no_symbol_map();
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die_function_decl_map_type::const_iterator i =
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fns_with_no_symbol.find(die_offset);
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if (i == fns_with_no_symbol.end())
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fns_with_no_symbol[die_offset] = f;
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}
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}
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/// Build a an IR node for class type from a DW_TAG_structure_type or
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@ -7285,7 +7380,7 @@ build_class_type_and_add_to_ir(read_context& ctxt,
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function_decl_sptr f = dynamic_pointer_cast<function_decl>(r);
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assert(f);
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finish_member_function_reading(&child, f, result);
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finish_member_function_reading(&child, f, result, ctxt);
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ctxt.associate_die_to_decl(dwarf_dieoffset(&child),
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is_in_alt_di, f);
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@ -8140,6 +8235,7 @@ build_function_decl(read_context& ctxt,
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// Check if a function symbol with this name is exported by the elf
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// binary.
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bool symbol_updated = false;
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Dwarf_Addr fn_addr;
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if (ctxt.get_function_address(die, fn_addr))
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{
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@ -8147,6 +8243,7 @@ build_function_decl(read_context& ctxt,
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if (sym->is_function() && sym->is_public())
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{
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result->set_symbol(sym);
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symbol_updated = true;
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// If the linkage name is not set or is wrong, set it to
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// the name of the underlying symbol.
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string linkage_name = result->get_linkage_name();
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@ -8156,10 +8253,20 @@ build_function_decl(read_context& ctxt,
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}
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}
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ctxt.associate_die_to_type(dwarf_dieoffset(die),
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is_in_alt_di,
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result->get_type());
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Dwarf_Off die_offset = dwarf_dieoffset(die);
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ctxt.associate_die_to_type(die_offset, is_in_alt_di, result->get_type());
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if (symbol_updated
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&& fn
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&& is_member_function(fn)
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&& get_member_function_is_virtual(fn)
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&& !result->get_linkage_name().empty())
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// This function is a virtual member function which has its
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// linkage name *and* and has its underlying symbol correctly set.
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// It thus doesn't need any fixup related to elf symbol. So
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// remove it from the set of virtual member functions with linkage
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// names and no elf symbol that need to be fixed up.
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ctxt.die_function_decl_with_no_symbol_map().erase(die_offset);
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return result;
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}
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@ -8184,12 +8291,30 @@ read_debug_info_into_corpus(read_context& ctxt)
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ctxt.env(corp->get_environment());
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}
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// First set some mundane properties of the corpus gathered from
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// ELF.
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ctxt.current_corpus()->set_path(ctxt.elf_path());
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ctxt.current_corpus()->set_origin(corpus::DWARF_ORIGIN);
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ctxt.current_corpus()->set_soname(ctxt.dt_soname());
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ctxt.current_corpus()->set_needed(ctxt.dt_needed());
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ctxt.current_corpus()->set_architecture_name(ctxt.elf_architecture());
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// Set symbols information to the corpus.
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ctxt.current_corpus()->set_fun_symbol_map(ctxt.fun_syms_sptr());
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ctxt.current_corpus()->set_undefined_fun_symbol_map
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(ctxt.undefined_fun_syms_sptr());
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ctxt.current_corpus()->set_var_symbol_map(ctxt.var_syms_sptr());
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ctxt.current_corpus()->set_undefined_var_symbol_map
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(ctxt.undefined_var_syms_sptr());
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// Get out now if no debug info is found.
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if (!ctxt.dwarf())
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return ctxt.current_corpus();
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uint8_t address_size = 0;
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size_t header_size = 0;
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// Set the set of exported declaration that are defined.
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ctxt.exported_decls_builder
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(ctxt.current_corpus()->get_exported_decls_builder().get());
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@ -8240,6 +8365,13 @@ read_debug_info_into_corpus(read_context& ctxt)
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if (ctxt.do_log())
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cerr << " DONE@" << ctxt.current_corpus()->get_path() <<"\n";
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if (ctxt.do_log())
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cerr << "fixing up functions with linkage name but "
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<< "no advertised underlying symbols ....";
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ctxt.fixup_functions_with_no_symbols();
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if (ctxt.do_log())
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cerr << " DONE@" << ctxt.current_corpus()->get_path() <<"\n";
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/// Now, look at the types that needs to be canonicalized after the
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/// translation has been constructed (which is just now) and
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/// canonicalize them.
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@ -8773,7 +8905,7 @@ build_ir_node_from_die(read_context& ctxt,
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class_decl_sptr klass(static_cast<class_decl*>(scope),
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sptr_utils::noop_deleter());
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assert(klass);
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finish_member_function_reading(die, fn, klass);
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finish_member_function_reading(die, fn, klass, ctxt);
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}
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if (fn)
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@ -9018,16 +9150,6 @@ read_corpus_from_elf(read_context& ctxt, status& status)
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// Read the variable and function descriptions from the debug info
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// we have, through the dwfl handle.
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corpus_sptr corp = read_debug_info_into_corpus(ctxt);
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corp->set_path(ctxt.elf_path());
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corp->set_origin(corpus::DWARF_ORIGIN);
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corp->set_soname(ctxt.dt_soname());
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corp->set_needed(ctxt.dt_needed());
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corp->set_architecture_name(ctxt.elf_architecture());
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corp->set_fun_symbol_map(ctxt.fun_syms_sptr());
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corp->set_undefined_fun_symbol_map(ctxt.undefined_fun_syms_sptr());
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corp->set_var_symbol_map(ctxt.var_syms_sptr());
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corp->set_undefined_var_symbol_map(ctxt.undefined_var_syms_sptr());
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status |= STATUS_OK;
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@ -45544,7 +45544,7 @@
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</function-decl>
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</member-function>
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<member-function access='protected' vtable-offset='10'>
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<function-decl name='uflow' mangled-name='_ZNSt15basic_streambufIwSt11char_traitsIwEE5uflowEv' filepath='/tmp/legendre/spack-stage/spack-stage-wfh0ig/gcc-4.7.4/x86_64-unknown-linux-gnu/libstdc++-v3/include/streambuf' line='697' column='1' visibility='default' binding='global' size-in-bits='64'>
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<function-decl name='uflow' mangled-name='_ZNSt15basic_streambufIwSt11char_traitsIwEE5uflowEv' filepath='/tmp/legendre/spack-stage/spack-stage-wfh0ig/gcc-4.7.4/x86_64-unknown-linux-gnu/libstdc++-v3/include/streambuf' line='697' column='1' visibility='default' binding='global' size-in-bits='64' elf-symbol-id='_ZNSt15basic_streambufIwSt11char_traitsIwEE5uflowEv@@GLIBCXX_3.4'>
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<parameter type-id='type-id-47' is-artificial='yes'/>
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<return type-id='type-id-52'/>
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</function-decl>
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@ -58775,7 +58775,7 @@
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</function-decl>
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</member-function>
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<member-function access='protected' vtable-offset='10'>
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<function-decl name='uflow' mangled-name='_ZNSt15basic_streambufIwSt11char_traitsIwEE5uflowEv' filepath='/tmp/legendre/spack-stage/spack-stage-wfh0ig/gcc-4.7.4/x86_64-unknown-linux-gnu/libstdc++-v3/include/streambuf' line='697' column='1' visibility='default' binding='global' size-in-bits='64'>
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<function-decl name='uflow' mangled-name='_ZNSt15basic_streambufIwSt11char_traitsIwEE5uflowEv' filepath='/tmp/legendre/spack-stage/spack-stage-wfh0ig/gcc-4.7.4/x86_64-unknown-linux-gnu/libstdc++-v3/include/streambuf' line='697' column='1' visibility='default' binding='global' size-in-bits='64' elf-symbol-id='_ZNSt15basic_streambufIwSt11char_traitsIwEE5uflowEv@@GLIBCXX_3.4'>
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<parameter type-id='type-id-47' is-artificial='yes'/>
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<return type-id='type-id-52'/>
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</function-decl>
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