From 4d78db49e6eee097365e31f9b5b47e5391243979 Mon Sep 17 00:00:00 2001 From: Vladimir Radosavljevic Date: Wed, 15 Mar 2017 16:46:26 -0700 Subject: [PATCH] Mips: Omit empty objects for merging processor-specific data. gold/ * mips.cc (Mips_relobj::merge_processor_specific_data_): New data member. (Mips_relobj::merge_processor_specific_data): New method. (Mips_relobj::do_read_symbols): Set merge_processor_specific_data_ to false, only if the input file is a binary or if object has no contents except the section name string table and an empty symbol table with the undefined symbol. (Target_mips::do_finalize_sections): Refactor. Skip empty object files for merging processor-specific data. --- gold/ChangeLog | 12 +++++++ gold/mips.cc | 97 +++++++++++++++++++++++++++++--------------------- 2 files changed, 69 insertions(+), 40 deletions(-) diff --git a/gold/ChangeLog b/gold/ChangeLog index 6532b9a68eb..d490468e489 100644 --- a/gold/ChangeLog +++ b/gold/ChangeLog @@ -1,3 +1,15 @@ +2017-03-15 Vladimir Radosavljevic + + * mips.cc (Mips_relobj::merge_processor_specific_data_): New data + member. + (Mips_relobj::merge_processor_specific_data): New method. + (Mips_relobj::do_read_symbols): Set merge_processor_specific_data_ + to false, only if the input file is a binary or if object has no + contents except the section name string table and an empty symbol + table with the undefined symbol. + (Target_mips::do_finalize_sections): Refactor. Skip empty object files + for merging processor-specific data. + 2017-03-15 Vladimir Radosavljevic * mips.cc (Target_mips::Relocate::calculated_value_): New data diff --git a/gold/mips.cc b/gold/mips.cc index 426817600eb..4cf3364bda3 100644 --- a/gold/mips.cc +++ b/gold/mips.cc @@ -1592,10 +1592,11 @@ class Mips_relobj : public Sized_relobj_file local_symbol_is_micromips_(), mips16_stub_sections_(), local_non_16bit_calls_(), local_16bit_calls_(), local_mips16_fn_stubs_(), local_mips16_call_stubs_(), gp_(0), has_reginfo_section_(false), - got_info_(NULL), section_is_mips16_fn_stub_(), - section_is_mips16_call_stub_(), section_is_mips16_call_fp_stub_(), - pdr_shndx_(-1U), attributes_section_data_(NULL), abiflags_(NULL), - gprmask_(0), cprmask1_(0), cprmask2_(0), cprmask3_(0), cprmask4_(0) + merge_processor_specific_data_(true), got_info_(NULL), + section_is_mips16_fn_stub_(), section_is_mips16_call_stub_(), + section_is_mips16_call_fp_stub_(), pdr_shndx_(-1U), + attributes_section_data_(NULL), abiflags_(NULL), gprmask_(0), + cprmask1_(0), cprmask2_(0), cprmask3_(0), cprmask4_(0) { this->is_pic_ = (ehdr.get_e_flags() & elfcpp::EF_MIPS_PIC) != 0; this->is_n32_ = elfcpp::abi_n32(ehdr.get_e_flags()); @@ -1836,6 +1837,11 @@ class Mips_relobj : public Sized_relobj_file has_reginfo_section() const { return this->has_reginfo_section_; } + // Return whether we want to merge processor-specific data. + bool + merge_processor_specific_data() const + { return this->merge_processor_specific_data_; } + // Return gprmask from the .reginfo section of this object. Valtype gprmask() const @@ -1926,6 +1932,8 @@ class Mips_relobj : public Sized_relobj_file bool is_n32_ : 1; // Whether the object contains a .reginfo section. bool has_reginfo_section_ : 1; + // Whether we merge processor-specific data of this object to output. + bool merge_processor_specific_data_ : 1; // The Mips_got_info for this object. Mips_got_info* got_info_; @@ -6818,6 +6826,16 @@ Mips_relobj::do_read_symbols(Read_symbols_data* sd) // Call parent class to read symbol information. this->base_read_symbols(sd); + // If this input file is a binary file, it has no processor + // specific data. + Input_file::Format format = this->input_file()->format(); + if (format != Input_file::FORMAT_ELF) + { + gold_assert(format == Input_file::FORMAT_BINARY); + this->merge_processor_specific_data_ = false; + return; + } + // Read processor-specific flags in ELF file header. const unsigned char* pehdr = this->get_view(elfcpp::file_header_offset, elfcpp::Elf_sizes::ehdr_size, @@ -6837,10 +6855,27 @@ Mips_relobj::do_read_symbols(Read_symbols_data* sd) const size_t shdr_size = elfcpp::Elf_sizes::shdr_size; const unsigned char* pshdrs = sd->section_headers->data(); const unsigned char* ps = pshdrs + shdr_size; + bool must_merge_processor_specific_data = false; for (unsigned int i = 1; i < this->shnum(); ++i, ps += shdr_size) { elfcpp::Shdr shdr(ps); + // Sometimes an object has no contents except the section name string + // table and an empty symbol table with the undefined symbol. We + // don't want to merge processor-specific data from such an object. + if (shdr.get_sh_type() == elfcpp::SHT_SYMTAB) + { + // Symbol table is not empty. + const typename elfcpp::Elf_types::Elf_WXword sym_size = + elfcpp::Elf_sizes::sym_size; + if (shdr.get_sh_size() > sym_size) + must_merge_processor_specific_data = true; + } + else if (shdr.get_sh_type() != elfcpp::SHT_STRTAB) + // If this is neither an empty symbol table nor a string table, + // be conservative. + must_merge_processor_specific_data = true; + if (shdr.get_sh_type() == elfcpp::SHT_MIPS_REGINFO) { this->has_reginfo_section_ = true; @@ -7013,6 +7048,10 @@ Mips_relobj::do_read_symbols(Read_symbols_data* sd) this->pdr_shndx_ = i; } } + + // This is rare. + if (!must_merge_processor_specific_data) + this->merge_processor_specific_data_ = false; } // Discard MIPS16 stub secions that are not needed. @@ -9600,6 +9639,8 @@ Target_mips::do_finalize_sections(Layout* layout, const Input_objects* input_objects, Symbol_table* symtab) { + const bool relocatable = parameters->options().relocatable(); + // Add +1 to MIPS16 and microMIPS init_ and _fini symbols so that DT_INIT and // DT_FINI have correct values. Mips_symbol* init = static_cast*>( @@ -9633,19 +9674,6 @@ Target_mips::do_finalize_sections(Layout* layout, if (this->got16_addends_.size() > 0) gold_error("Can't find matching LO16 reloc"); - // Check for any mips16 stub sections that we can discard. - if (!parameters->options().relocatable()) - { - for (Input_objects::Relobj_iterator p = input_objects->relobj_begin(); - p != input_objects->relobj_end(); - ++p) - { - Mips_relobj* object = - Mips_relobj::as_mips_relobj(*p); - object->discard_mips16_stub_sections(symtab); - } - } - Valtype gprmask = 0; Valtype cprmask1 = 0; Valtype cprmask2 = 0; @@ -9660,6 +9688,13 @@ Target_mips::do_finalize_sections(Layout* layout, Mips_relobj* relobj = Mips_relobj::as_mips_relobj(*p); + // Check for any mips16 stub sections that we can discard. + if (!relocatable) + relobj->discard_mips16_stub_sections(symtab); + + if (!relobj->merge_processor_specific_data()) + continue; + // Merge .reginfo contents of input objects. if (relobj->has_reginfo_section()) { @@ -9671,24 +9706,6 @@ Target_mips::do_finalize_sections(Layout* layout, cprmask4 |= relobj->cprmask4(); } - Input_file::Format format = relobj->input_file()->format(); - if (format != Input_file::FORMAT_ELF) - continue; - - // If all input sections will be discarded, don't use this object - // file for merging processor specific flags. - bool should_merge_processor_specific_flags = false; - - for (unsigned int i = 1; i < relobj->shnum(); ++i) - if (relobj->output_section(i) != NULL) - { - should_merge_processor_specific_flags = true; - break; - } - - if (!should_merge_processor_specific_flags) - continue; - // Merge processor specific flags. Mips_abiflags in_abiflags; @@ -9723,7 +9740,7 @@ Target_mips::do_finalize_sections(Layout* layout, elfcpp::SHF_ALLOC, abiflags_section, ORDER_INVALID, false); - if (!parameters->options().relocatable() && os != NULL) + if (!relocatable && os != NULL) { Output_segment* abiflags_segment = layout->make_output_segment(elfcpp::PT_MIPS_ABIFLAGS, elfcpp::PF_R); @@ -9744,7 +9761,7 @@ Target_mips::do_finalize_sections(Layout* layout, elfcpp::SHF_ALLOC, reginfo_section, ORDER_INVALID, false); - if (!parameters->options().relocatable() && os != NULL) + if (!relocatable && os != NULL) { Output_segment* reginfo_segment = layout->make_output_segment(elfcpp::PT_MIPS_REGINFO, @@ -9789,7 +9806,7 @@ Target_mips::do_finalize_sections(Layout* layout, false, false); } - if (!parameters->options().relocatable() && !parameters->doing_static_link()) + if (!relocatable && !parameters->doing_static_link()) // In case there is no .got section, create one. this->got_section(symtab, layout); @@ -9821,7 +9838,7 @@ Target_mips::do_finalize_sections(Layout* layout, symtab)); // Add NULL segment. - if (!parameters->options().relocatable()) + if (!relocatable) layout->make_output_segment(elfcpp::PT_NULL, 0); // Fill in some more dynamic tags. @@ -9833,7 +9850,7 @@ Target_mips::do_finalize_sections(Layout* layout, Output_data_dynamic* const odyn = layout->dynamic_data(); if (odyn != NULL - && !parameters->options().relocatable() + && !relocatable && !parameters->doing_static_link()) { unsigned int d_val; -- 2.30.2