From 9f3f9d19c7edc99a1450ee15d7cde67a67eb445d Mon Sep 17 00:00:00 2001 From: Alexander Yermolovich Date: Mon, 31 Jan 2022 11:06:06 -0800 Subject: [PATCH] [BOLT][DWARF] Handle shared abbrev section We can have a scenario where multiple CUs share an abbrev table. We modify or don't modify one CU, which leads to other CUs having invalid abbrev section. Example that caused it. All of CUs shared the same abbrev table. First CU just had compile_unit and sub_program. It was not modified. Next CU had DW_TAG_lexical_block with DW_AT_low_pc/DW_AT_high_pc converted to DW_AT_low_pc/DW_AT_ranges. We used unmodified abbrev section for first and subsequent CUs. So when parsing subsequent CUs debug info was corrupted. In this patch we will now duplicate all sections that are modified and are different. This also means that if .debug_types is present and it shares Abbrev table, and they usually are, we now can have two Abbrev tables. One for CU that was modified, and unmodified one for TU. Reviewed By: maksfb Differential Revision: https://reviews.llvm.org/D118517 --- bolt/include/bolt/Core/DebugData.h | 13 ++-- bolt/lib/Core/DebugData.cpp | 77 +++++++++++------- bolt/test/X86/shared-abbrev.s | 121 +++++++++++++++++++++++++++++ 3 files changed, 178 insertions(+), 33 deletions(-) create mode 100644 bolt/test/X86/shared-abbrev.s diff --git a/bolt/include/bolt/Core/DebugData.h b/bolt/include/bolt/Core/DebugData.h index 91041c5a50f9..2ea10cbc234b 100644 --- a/bolt/include/bolt/Core/DebugData.h +++ b/bolt/include/bolt/Core/DebugData.h @@ -715,8 +715,11 @@ class DebugAbbrevWriter { std::unique_ptr Buffer; std::unique_ptr Stream; }; - /// Map original unit abbrev offset to abbreviations data. - std::map UnitsAbbrevData; + /// Map original unit to abbreviations data. + std::unordered_map UnitsAbbrevData; + + /// Map from Hash Signature to AbbrevData. + llvm::StringMap> AbbrevDataCache; /// Attributes substitution (patch) information. struct PatchInfo { @@ -783,10 +786,8 @@ public: /// Return an offset in the finalized abbrev section corresponding to CU/TU. uint64_t getAbbreviationsOffsetForUnit(const DWARFUnit &Unit) { assert(!DWOId && "offsets are tracked for non-DWO units only"); - assert(UnitsAbbrevData.find(Unit.getAbbreviationsOffset()) != - UnitsAbbrevData.end() && - "no abbrev data found for unit"); - return UnitsAbbrevData[Unit.getAbbreviationsOffset()].Offset; + assert(UnitsAbbrevData.count(&Unit) && "no abbrev data found for unit"); + return UnitsAbbrevData[&Unit]->Offset; } }; diff --git a/bolt/lib/Core/DebugData.cpp b/bolt/lib/Core/DebugData.cpp index 0f893a618411..2979a6bbb9b7 100644 --- a/bolt/lib/Core/DebugData.cpp +++ b/bolt/lib/Core/DebugData.cpp @@ -18,6 +18,7 @@ #include "llvm/Support/CommandLine.h" #include "llvm/Support/EndianStream.h" #include "llvm/Support/LEB128.h" +#include "llvm/Support/SHA1.h" #include #include #include @@ -694,20 +695,30 @@ void DebugAbbrevWriter::addUnitAbbreviations(DWARFUnit &Unit) { if (!Abbrevs) return; - // Multiple units may share the same abbreviations. Only add abbreviations - // for the first unit and reuse them. - const uint64_t AbbrevOffset = Unit.getAbbreviationsOffset(); - if (UnitsAbbrevData.find(AbbrevOffset) != UnitsAbbrevData.end()) - return; - - AbbrevData &UnitData = UnitsAbbrevData[AbbrevOffset]; - UnitData.Buffer = std::make_unique(); - UnitData.Stream = std::make_unique(*UnitData.Buffer); - const PatchesTy &UnitPatches = Patches[&Unit]; + // We are duplicating abbrev sections, to handle the case where for one CU we + // modify it, but for another we don't. + auto UnitDataPtr = std::make_unique(); + AbbrevData &UnitData = *UnitDataPtr.get(); + UnitData.Buffer = std::make_unique(); + UnitData.Stream = std::make_unique(*UnitData.Buffer); raw_svector_ostream &OS = *UnitData.Stream.get(); + // Returns true if AbbrevData is re-used, false otherwise. + auto hashAndAddAbbrev = [&](StringRef AbbrevData) -> bool { + llvm::SHA1 Hasher; + Hasher.update(AbbrevData); + StringRef Key = Hasher.final(); + auto Iter = AbbrevDataCache.find(Key); + if (Iter != AbbrevDataCache.end()) { + UnitsAbbrevData[&Unit] = Iter->second.get(); + return true; + } + AbbrevDataCache[Key] = std::move(UnitDataPtr); + UnitsAbbrevData[&Unit] = &UnitData; + return false; + }; // Take a fast path if there are no patches to apply. Simply copy the original // contents. if (UnitPatches.empty()) { @@ -756,9 +767,10 @@ void DebugAbbrevWriter::addUnitAbbreviations(DWARFUnit &Unit) { AbbrevContents = AbbrevSectionContents; } - OS.reserveExtraSpace(AbbrevContents.size()); - OS << AbbrevContents; - + if (!hashAndAddAbbrev(AbbrevContents)) { + OS.reserveExtraSpace(AbbrevContents.size()); + OS << AbbrevContents; + } return; } @@ -798,9 +810,13 @@ void DebugAbbrevWriter::addUnitAbbreviations(DWARFUnit &Unit) { encodeULEB128(0, OS); } encodeULEB128(0, OS); + + hashAndAddAbbrev(OS.str()); } std::unique_ptr DebugAbbrevWriter::finalize() { + // Used to create determinism for writing out abbrevs. + std::vector Abbrevs; if (DWOId) { // We expect abbrev_offset to always be zero for DWO units as there // should be one CU per DWO, and TUs should share the same abbreviation @@ -818,33 +834,40 @@ std::unique_ptr DebugAbbrevWriter::finalize() { } } + DWARFUnit *Unit = Context.getDWOCompileUnitForHash(*DWOId); // Issue abbreviations for the DWO CU only. - addUnitAbbreviations(*Context.getDWOCompileUnitForHash(*DWOId)); + addUnitAbbreviations(*Unit); + AbbrevData *Abbrev = UnitsAbbrevData[Unit]; + Abbrevs.push_back(Abbrev); } else { + Abbrevs.reserve(Context.getNumCompileUnits() + Context.getNumTypeUnits()); + std::unordered_set ProcessedAbbrevs; // Add abbreviations from compile and type non-DWO units. - for (const std::unique_ptr &Unit : Context.normal_units()) + for (const std::unique_ptr &Unit : Context.normal_units()) { addUnitAbbreviations(*Unit); + AbbrevData *Abbrev = UnitsAbbrevData[Unit.get()]; + if (!ProcessedAbbrevs.insert(Abbrev).second) + continue; + Abbrevs.push_back(Abbrev); + } } DebugBufferVector ReturnBuffer; - // Pre-calculate the total size of abbrev section. uint64_t Size = 0; - for (const auto &KV : UnitsAbbrevData) { - const AbbrevData &UnitData = KV.second; - Size += UnitData.Buffer->size(); - } + for (const AbbrevData *UnitData : Abbrevs) + Size += UnitData->Buffer->size(); + ReturnBuffer.reserve(Size); uint64_t Pos = 0; - for (auto &KV : UnitsAbbrevData) { - AbbrevData &UnitData = KV.second; - ReturnBuffer.append(*UnitData.Buffer); - UnitData.Offset = Pos; - Pos += UnitData.Buffer->size(); + for (AbbrevData *UnitData : Abbrevs) { + ReturnBuffer.append(*UnitData->Buffer); + UnitData->Offset = Pos; + Pos += UnitData->Buffer->size(); - UnitData.Buffer.reset(); - UnitData.Stream.reset(); + UnitData->Buffer.reset(); + UnitData->Stream.reset(); } return std::make_unique(ReturnBuffer); diff --git a/bolt/test/X86/shared-abbrev.s b/bolt/test/X86/shared-abbrev.s new file mode 100644 index 000000000000..0975a005a400 --- /dev/null +++ b/bolt/test/X86/shared-abbrev.s @@ -0,0 +1,121 @@ +# RUN: rm -rf %t +# RUN: mkdir %t +# RUN: llvm-mc -filetype=obj -triple=x86_64 -dwarf-version=4 %s -o %t/shared-abbrev.o +# RUN: %clang %cflags %t/shared-abbrev.o -o %t/shared-abbrev.exe +# RUN: llvm-bolt %t/shared-abbrev.exe -o %t/shared-abbrev.exe.bolt -update-debug-sections +# RUN: llvm-dwarfdump --debug-info %t/shared-abbrev.exe.bolt | FileCheck %s + +# CHECK: 0x00000000: +# CHECK-SAME: abbr_offset = 0x0000 +# CHECK-EMPTY: +# CHECK-NEXT: DW_TAG_compile_unit +# CHECK-NEXT: DW_AT_stmt_list +# CHECK-NEXT: DW_AT_low_pc +# CHECK-NEXT: DW_AT_ranges +# CHECK: 0x0000001d: +# CHECK-SAME: abbr_offset = 0x0017 +# CHECK-EMPTY: +# CHECK: DW_TAG_compile_unit +# CHECK-NEXT: DW_AT_stmt_list +# CHECK-NEXT: DW_AT_low_pc +# CHECK-NEXT: DW_AT_ranges +# CHECK: 0x0000003a: +# CHECK-SAME: abbr_offset = 0x0000 +# CHECK-EMPTY: +# CHECK-NEXT: DW_TAG_compile_unit +# CHECK-NEXT: DW_AT_stmt_list +# CHECK-NEXT: DW_AT_low_pc +# CHECK-NEXT: DW_AT_ranges + + .text + .file "main.cpp" + .globl main # -- Begin function main + .p2align 4, 0x90 + .type main,@function +main: # @main +.Lfunc_begin0: + .file 1 "test" "main.cpp" + .loc 1 1 0 # main.cpp:1:0 + .cfi_startproc + .cfi_def_cfa %rsp, 8 + retq +.Ltmp1: +.Lfunc_end0: + .size main, .Lfunc_end0-main + .cfi_endproc + # -- End function + .section .debug_abbrev,"",@progbits + .byte 1 # Abbreviation Code + .byte 17 # DW_TAG_compile_unit + .byte 0 # DW_CHILDREN_no + .byte 16 # DW_AT_stmt_list + .byte 23 # DW_FORM_sec_offset + .byte 17 # DW_AT_low_pc + .byte 1 # DW_FORM_addr + .byte 18 # DW_AT_high_pc + .byte 7 # DW_FORM_data8 + .byte 0 # EOM(1) + .byte 0 # EOM(2) + .byte 2 # Abbreviation Code + .byte 17 # DW_TAG_compile_unit + .byte 0 # DW_CHILDREN_no + .byte 16 # DW_AT_stmt_list + .byte 23 # DW_FORM_sec_offset + .byte 17 # DW_AT_low_pc + .byte 1 # DW_FORM_addr + .byte 85 # DW_AT_ranges + .byte 23 # DW_FORM_sec_offset + .byte 0 # EOM(1) + .byte 0 # EOM(2) + .byte 0 # EOM(3) + .section .debug_info,"",@progbits +.Lcu_begin0: + .long .Ldebug_info_end0-.Ldebug_info_start0 # Length of Unit +.Ldebug_info_start0: + .short 4 # DWARF version number + .long .debug_abbrev # Offset Into Abbrev. Section + .byte 8 # Address Size (in bytes) + .byte 2 # Abbrev [2] DW_TAG_compile_unit + .long .Lline_table_start0 # DW_AT_stmt_list + .quad 0 # DW_AT_low_pc + .byte 0 # End Of Children Mark + .long .Ldebug_ranges0 # DW_AT_ranges --- end manual -- +.Ldebug_info_end0: + + # Second CU table. + .long .Ldebug_info_end1-.Ldebug_info_start1 # Length of Unit +.Ldebug_info_start1: + .short 4 # DWARF version number + .long .debug_abbrev # Offset Into Abbrev. Section + .byte 8 # Address Size (in bytes) + .byte 1 # Abbrev [1] DW_TAG_compile_unit + .long .Lline_table_start0 # DW_AT_stmt_list + .quad .Lfunc_begin0 # DW_AT_low_pc + .quad .Lfunc_end0-.Lfunc_begin0 # DW_AT_high_pc + .byte 0 # End Of Children Mark +.Ldebug_info_end1: + + # Third CU table. + .long .Ldebug_info_end2-.Ldebug_info_start2 # Length of Unit +.Ldebug_info_start2: + .short 4 # DWARF version number + .long .debug_abbrev # Offset Into Abbrev. Section + .byte 8 # Address Size (in bytes) + .byte 2 # Abbrev [2] DW_TAG_compile_unit + .long .Lline_table_start0 # DW_AT_stmt_list + .quad 0 # DW_AT_low_pc + .byte 0 # End Of Children Mark + .long .Ldebug_ranges0 # DW_AT_ranges --- end manual -- +.Ldebug_info_end2: + .section .debug_ranges,"",@progbits +.Ldebug_ranges0: + .quad .Lfunc_begin0 + .quad .Lfunc_end0 + .quad .Lfunc_begin0 + .quad .Lfunc_end0 + .quad 0 + .quad 0 + .section ".note.GNU-stack","",@progbits + .addrsig + .section .debug_line,"",@progbits +.Lline_table_start0: