From e173ea00c2941af42ea4e2267446d6039a70da6e Mon Sep 17 00:00:00 2001 From: Joshua Oreman Date: Sat, 11 May 2019 07:27:10 +0800 Subject: Fix problem with ICF where diffs in EH frame info is ignored. PR gold/21066 * gc.h (gc_process_relocs): Track relocations in .eh_frame sections when ICF is enabled, even though the .eh_frame sections themselves are not foldable. * icf.cc (get_section_contents): Change arguments to permit operation on just part of a section. Include extra identity regions in the referring section's contents recursively. (match_sections): Lock object here instead of in get_section_contents so that get_section_contents can operate recursively. (Icf::add_ehframe_links): New method. (Icf::find_identical_sections): Pass .eh_frame sections to add_ehframe_links(). Increase default iteration count from 2 to 3 because handling exception info typically requires one extra iteration. * icf.h (Icf::extra_identity_list_): New data member with accessor. (is_section_foldable_candidate): Include .gcc_except_table sections. * options.h: Update documentation for new default ICF iteration count. * testsuite/Makefile.am (icf_test_pr21066): New test case. * testsuite/Makefile.in: Regenerate. * testsuite/icf_test_pr21066.cc: New source file. * testsuite/icf_test_pr21066.sh: New test script. --- gold/icf.h | 30 ++++++++++++++++++++++++++++++ 1 file changed, 30 insertions(+) (limited to 'gold/icf.h') diff --git a/gold/icf.h b/gold/icf.h index e99ac06..7f8e841 100644 --- a/gold/icf.h +++ b/gold/icf.h @@ -64,6 +64,19 @@ class Icf typedef Unordered_map Reloc_info_list; + // A region of some other section that should be considered part of + // a section for ICF purposes. This is used to avoid folding sections + // that have identical text and relocations but different .eh_frame + // information. + typedef struct + { + Section_id section; + section_offset_type offset; + section_size_type length; + } Extra_identity_info; + + typedef std::multimap Extra_identity_list; + Icf() : id_section_(), section_id_(), kept_section_id_(), fptr_section_id_(), @@ -137,6 +150,12 @@ class Icf reloc_info_list() { return this->reloc_info_list_; } + // Returns a map from section to region of a different section that should + // be considered part of the key section for ICF purposes. + Extra_identity_list& + extra_identity_list() + { return this->extra_identity_list_; } + // Returns a mapping of each section to a unique integer. Uniq_secn_id_map& section_to_int_map() @@ -144,6 +163,10 @@ class Icf private: + bool + add_ehframe_links(Relobj* object, unsigned int ehframe_shndx, + Reloc_info& ehframe_relocs); + // Maps integers to sections. std::vector id_section_; // Does the reverse. @@ -160,17 +183,24 @@ class Icf bool icf_ready_; // This list is populated by gc_process_relocs in gc.h. Reloc_info_list reloc_info_list_; + // Regions of other sections that should be considered part of + // each section for ICF purposes. + Extra_identity_list extra_identity_list_; }; // This function returns true if this section corresponds to a function that // should be considered by icf as a possible candidate for folding. Some // earlier gcc versions, like 4.0.3, put constructors and destructors in // .gnu.linkonce.t sections and hence should be included too. +// The mechanism used to safely fold functions referenced by .eh_frame +// requires folding .gcc_except_table sections as well; see "Notes regarding +// C++ exception handling" at the top of icf.cc for an explanation why. inline bool is_section_foldable_candidate(const std::string& section_name) { const char* section_name_cstr = section_name.c_str(); return (is_prefix_of(".text", section_name_cstr) + || is_prefix_of(".gcc_except_table", section_name_cstr) || is_prefix_of(".gnu.linkonce.t", section_name_cstr)); } -- cgit v1.1