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[DWARF] Don't process .debug_info relocations for DWO Context

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When we build with split dwarf in single mode the .o files that contain both "normal" debug sections and dwo sections, along with relocaiton sections for "normal" debug sections.
When we create DWARF context in DWARFObjInMemory we process relocations and store them in the map for .debug_info, etc section.
For DWO Context we also do it for non dwo dwarf sections. Which I believe is not necessary. This leads to a lot of memory being wasted. We observed 70GB extra memory being used.

I went with context sensitive approach, flag is passed in. I am not sure if it's always safe not to process relocations for regular debug sections if Obj contains .dwo sections.
If it is alternatvie might be just to scan, in constructor, sections and if there are .dwo sections not to process regular debug ones.

Reviewed By: dblaikie

Differential Revision: https://reviews.llvm.org/D106624
This commit is contained in:
Alexander Yermolovich 2021-08-02 10:41:35 -07:00
parent ce1c59dea6
commit 5a865b0b1e
8 changed files with 95 additions and 27 deletions
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7
llvm/include/llvm/DebugInfo/DWARF/DWARFContext.h
View file

@ -387,9 +387,12 @@ public:
function_ref<void(Error)> getWarningHandler() { return WarningHandler; }
enum class ProcessDebugRelocations { Process, Ignore };
static std::unique_ptr<DWARFContext>
create(const object::ObjectFile &Obj, const LoadedObjectInfo *L = nullptr,
std::string DWPName = "",
create(const object::ObjectFile &Obj,
ProcessDebugRelocations RelocAction = ProcessDebugRelocations::Process,
const LoadedObjectInfo *L = nullptr, std::string DWPName = "",
std::function<void(Error)> RecoverableErrorHandler =
WithColor::defaultErrorHandler,
std::function<void(Error)> WarningHandler =

31
llvm/lib/DebugInfo/DWARF/DWARFContext.cpp
View file

@ -1411,7 +1411,8 @@ DWARFContext::getDWOContext(StringRef AbsolutePath) {
auto S = std::make_shared<DWOFile>();
S->File = std::move(Obj.get());
S->Context = DWARFContext::create(*S->File.getBinary());
S->Context = DWARFContext::create(*S->File.getBinary(),
ProcessDebugRelocations::Ignore);
*Entry = S;
auto *Ctxt = S->Context.get();
return std::shared_ptr<DWARFContext>(std::move(S), Ctxt);
@ -1652,7 +1653,9 @@ public:
}
}
DWARFObjInMemory(const object::ObjectFile &Obj, const LoadedObjectInfo *L,
function_ref<void(Error)> HandleError, function_ref<void(Error)> HandleWarning )
function_ref<void(Error)> HandleError,
function_ref<void(Error)> HandleWarning,
DWARFContext::ProcessDebugRelocations RelocAction)
: IsLittleEndian(Obj.isLittleEndian()),
AddressSize(Obj.getBytesInAddress()), FileName(Obj.getFileName()),
Obj(&Obj) {
@ -1735,7 +1738,12 @@ public:
S.Data = Data;
}
if (RelocatedSection == Obj.section_end())
if (RelocatedSection != Obj.section_end() && Name.contains(".dwo"))
HandleWarning(
createError("Unexpected relocations for dwo section " + Name));
if (RelocatedSection == Obj.section_end() ||
(RelocAction == DWARFContext::ProcessDebugRelocations::Ignore))
continue;
StringRef RelSecName;
@ -1772,18 +1780,10 @@ public:
if (RelSecName == "debug_info")
Map = &static_cast<DWARFSectionMap &>(InfoSections[*RelocatedSection])
.Relocs;
else if (RelSecName == "debug_info.dwo")
Map = &static_cast<DWARFSectionMap &>(
InfoDWOSections[*RelocatedSection])
.Relocs;
else if (RelSecName == "debug_types")
Map =
&static_cast<DWARFSectionMap &>(TypesSections[*RelocatedSection])
.Relocs;
else if (RelSecName == "debug_types.dwo")
Map = &static_cast<DWARFSectionMap &>(
TypesDWOSections[*RelocatedSection])
.Relocs;
else
continue;
}
@ -1966,12 +1966,13 @@ public:
} // namespace
std::unique_ptr<DWARFContext>
DWARFContext::create(const object::ObjectFile &Obj, const LoadedObjectInfo *L,
std::string DWPName,
DWARFContext::create(const object::ObjectFile &Obj,
ProcessDebugRelocations RelocAction,
const LoadedObjectInfo *L, std::string DWPName,
std::function<void(Error)> RecoverableErrorHandler,
std::function<void(Error)> WarningHandler) {
auto DObj =
std::make_unique<DWARFObjInMemory>(Obj, L, RecoverableErrorHandler, WarningHandler);
auto DObj = std::make_unique<DWARFObjInMemory>(
Obj, L, RecoverableErrorHandler, WarningHandler, RelocAction);
return std::make_unique<DWARFContext>(std::move(DObj), std::move(DWPName),
RecoverableErrorHandler,
WarningHandler);

4
llvm/lib/DebugInfo/Symbolize/Symbolize.cpp
View file

@ -600,7 +600,9 @@ LLVMSymbolizer::getOrCreateModuleInfo(const std::string &ModuleName) {
}
}
if (!Context)
Context = DWARFContext::create(*Objects.second, nullptr, Opts.DWPName);
Context = DWARFContext::create(
*Objects.second, DWARFContext::ProcessDebugRelocations::Process,
nullptr, Opts.DWPName);
return createModuleInfo(Objects.first, std::move(Context), ModuleName);
}

57
llvm/test/DebugInfo/X86/dwarfdump-rela-dwo.s Normal file
View file

@ -0,0 +1,57 @@
# Test objective to verify warning is printed if DWO secton has relocations.
#
# RUN: llvm-mc -triple x86_64-unknown-linux %s -filetype=obj -o %t.o
# RUN: llvm-dwarfdump --debug-info %t.o | FileCheck %s
# RUN: llvm-dwarfdump --debug-info %t.o 2> %t.txt
# RUN: cat %t.txt | FileCheck %s --check-prefix=PART2
.section .debug_str.dwo,"MSe",@progbits,1
.dwo_producer:
.asciz "Handmade DWO producer"
.dwo_CU_5:
.asciz "V5_dwo_compile_unit"
.section .debug_str_offsets.dwo,"e",@progbits
.long Lstr_offsets_end-Lstr_offsets_start # Length of String Offsets Set
Lstr_offsets_start:
.short 5
.short 0
.long .dwo_producer-.debug_str.dwo
.long .dwo_CU_5-.debug_str.dwo
Lstr_offsets_end:
# And a .dwo copy for the .dwo sections.
.section .debug_abbrev.dwo,"e",@progbits
.byte 0x01 # Abbrev code
.byte 0x11 # DW_TAG_compile_unit
.byte 0x00 # DW_CHILDREN_no
.byte 0x25 # DW_AT_producer
.byte 0x0e # DW_FORM_strp
.byte 0x03 # DW_AT_name
.byte 0x25 # DW_FORM_strx1
.byte 0x00 # EOM(1)
.byte 0x00 # EOM(2)
.section .debug_info.dwo,"e",@progbits
# CHECK-LABEL: .debug_info.dwo
# DWARF v5 split CU header.
.long CU_split_5_end-CU_split_5_version # Length of Unit
CU_split_5_version:
.short 5 # DWARF version number
.byte 5 # DWARF Unit Type
.byte 8 # Address Size (in bytes)
.long 0 # Offset Into Abbrev. Section
.quad 0x5a # DWO ID
# The split compile-unit DIE, with DW_AT_producer, DW_AT_name, DW_AT_stmt_list.
.byte 1
.long .dwo_producer
.byte 1
.byte 0 # NULL
CU_split_5_end:
# CHECK: 0x00000000: Compile Unit: length = 0x00000017, format = DWARF32, version = 0x0005, unit_type = DW_UT_split_compile, abbr_offset = 0x0000, addr_size = 0x08, DWO_id = 0x000000000000005a (next unit at 0x0000001b)
# CHECK: 0x00000014: DW_TAG_compile_unit
# CHECK-NEXT: DW_AT_producer ("Handmade DWO producer")
# CHECK-NEXT: DW_AT_name ("V5_dwo_compile_unit")
# PART2: warning: Unexpected relocations for dwo section rela.debug_info.dwo

10
llvm/tools/llvm-dwarfdump/llvm-dwarfdump.cpp
View file

@ -536,8 +536,9 @@ static bool handleBuffer(StringRef Filename, MemoryBufferRef Buffer,
};
if (auto *Obj = dyn_cast<ObjectFile>(BinOrErr->get())) {
if (filterArch(*Obj)) {
std::unique_ptr<DWARFContext> DICtx =
DWARFContext::create(*Obj, nullptr, "", RecoverableErrorHandler);
std::unique_ptr<DWARFContext> DICtx = DWARFContext::create(
*Obj, DWARFContext::ProcessDebugRelocations::Process, nullptr, "",
RecoverableErrorHandler);
if (!HandleObj(*Obj, *DICtx, Filename, OS))
Result = false;
}
@ -548,8 +549,9 @@ static bool handleBuffer(StringRef Filename, MemoryBufferRef Buffer,
if (auto MachOOrErr = ObjForArch.getAsObjectFile()) {
auto &Obj = **MachOOrErr;
if (filterArch(Obj)) {
std::unique_ptr<DWARFContext> DICtx =
DWARFContext::create(Obj, nullptr, "", RecoverableErrorHandler);
std::unique_ptr<DWARFContext> DICtx = DWARFContext::create(
Obj, DWARFContext::ProcessDebugRelocations::Process, nullptr, "",
RecoverableErrorHandler);
if (!HandleObj(Obj, *DICtx, ObjName, OS))
Result = false;
}

3
llvm/tools/llvm-readobj/DwarfCFIEHPrinter.h
View file

@ -185,7 +185,8 @@ void PrinterContext<ELFT>::printEHFrame(const Elf_Shdr *EHFrameShdr) const {
reportError(DataOrErr.takeError(), ObjF.getFileName());
// Construct DWARFDataExtractor to handle relocations ("PC Begin" fields).
std::unique_ptr<DWARFContext> DICtx = DWARFContext::create(ObjF, nullptr);
std::unique_ptr<DWARFContext> DICtx = DWARFContext::create(
ObjF, DWARFContext::ProcessDebugRelocations::Process, nullptr);
DWARFDataExtractor DE(DICtx->getDWARFObj(),
DICtx->getDWARFObj().getEHFrameSection(),
ELFT::TargetEndianness == support::endianness::little,

5
llvm/tools/llvm-rtdyld/llvm-rtdyld.cpp
View file

@ -413,8 +413,9 @@ static int printLineInfoForInput(bool LoadObjects, bool UseDebugObj) {
}
}
std::unique_ptr<DIContext> Context =
DWARFContext::create(*SymbolObj, LoadedObjInfo.get());
std::unique_ptr<DIContext> Context = DWARFContext::create(
*SymbolObj, DWARFContext::ProcessDebugRelocations::Process,
LoadedObjInfo.get());
std::vector<std::pair<SymbolRef, uint64_t>> SymAddr =
object::computeSymbolSizes(*SymbolObj);

5
llvm/unittests/DebugInfo/DWARF/DWARFDebugInfoTest.cpp
View file

@ -2519,8 +2519,9 @@ TEST(DWARFDebugInfo, TestErrorReporting) {
// DWARFContext parses whole file and finds the two errors we expect.
int Errors = 0;
std::unique_ptr<DWARFContext> Ctx1 =
DWARFContext::create(**Obj, nullptr, "", [&](Error E) {
std::unique_ptr<DWARFContext> Ctx1 = DWARFContext::create(
**Obj, DWARFContext::ProcessDebugRelocations::Process, nullptr, "",
[&](Error E) {
++Errors;
consumeError(std::move(E));
});