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[JITLink][ELF] Don't skip debug info sections by default.
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By default ELFLinkGraphBuilder will now create LinkGraph sections with NoAlloc
lifetime for debug info sections in the original object. Debug sections are not
kept alive by default, and will be dead-stripped unless some plugin marks them
as live in the pre-prune phase.
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@lhames
lhames committed Mar 19, 2023
1 parent ede78c1 commit 57aeb30
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Showing 3 changed files with 213 additions and 258 deletions.
35 changes: 18 additions & 17 deletions llvm/lib/ExecutionEngine/JITLink/ELFLinkGraphBuilder.h
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Original file line number Diff line number Diff line change
Expand Up @@ -62,6 +62,14 @@ class ELFLinkGraphBuilder : public ELFLinkGraphBuilderBase {
StringRef FileName,
LinkGraph::GetEdgeKindNameFunction GetEdgeKindName);

/// Debug sections are included in the graph by default. Use
/// setProcessDebugSections(false) to ignore them if debug info is not
/// needed.
ELFLinkGraphBuilder &setProcessDebugSections(bool ProcessDebugSections) {
this->ProcessDebugSections = ProcessDebugSections;
return *this;
}

/// Attempt to construct and return the LinkGraph.
Expected<std::unique_ptr<LinkGraph>> buildGraph();

Expand Down Expand Up @@ -115,8 +123,7 @@ class ELFLinkGraphBuilder : public ELFLinkGraphBuilderBase {
///
template <typename RelocHandlerMethod>
Error forEachRelaRelocation(const typename ELFT::Shdr &RelSect,
RelocHandlerMethod &&Func,
bool ProcessDebugSections = false);
RelocHandlerMethod &&Func);

/// Traverse all matching ELFT::Rel relocation records in the given section.
/// The handler function Func should be callable with this signature:
Expand All @@ -125,44 +132,40 @@ class ELFLinkGraphBuilder : public ELFLinkGraphBuilderBase {
///
template <typename RelocHandlerMethod>
Error forEachRelRelocation(const typename ELFT::Shdr &RelSect,
RelocHandlerMethod &&Func,
bool ProcessDebugSections = false);
RelocHandlerMethod &&Func);

/// Traverse all matching rela relocation records in the given section.
/// Convenience wrapper to allow passing a member function for the handler.
///
template <typename ClassT, typename RelocHandlerMethod>
Error forEachRelaRelocation(const typename ELFT::Shdr &RelSect,
ClassT *Instance, RelocHandlerMethod &&Method,
bool ProcessDebugSections = false) {
ClassT *Instance, RelocHandlerMethod &&Method) {
return forEachRelaRelocation(
RelSect,
[Instance, Method](const auto &Rel, const auto &Target, auto &GS) {
return (Instance->*Method)(Rel, Target, GS);
},
ProcessDebugSections);
});
}

/// Traverse all matching rel relocation records in the given section.
/// Convenience wrapper to allow passing a member function for the handler.
///
template <typename ClassT, typename RelocHandlerMethod>
Error forEachRelRelocation(const typename ELFT::Shdr &RelSect,
ClassT *Instance, RelocHandlerMethod &&Method,
bool ProcessDebugSections = false) {
ClassT *Instance, RelocHandlerMethod &&Method) {
return forEachRelRelocation(
RelSect,
[Instance, Method](const auto &Rel, const auto &Target, auto &GS) {
return (Instance->*Method)(Rel, Target, GS);
},
ProcessDebugSections);
});
}

const ELFFile &Obj;

typename ELFFile::Elf_Shdr_Range Sections;
const typename ELFFile::Elf_Shdr *SymTabSec = nullptr;
StringRef SectionStringTab;
bool ProcessDebugSections = true;

// Maps ELF section indexes to LinkGraph Blocks.
// Only SHF_ALLOC sections will have graph blocks.
Expand Down Expand Up @@ -318,7 +321,7 @@ template <typename ELFT> Error ELFLinkGraphBuilder<ELFT>::graphifySections() {

// If the name indicates that it's a debug section then skip it: We don't
// support those yet.
if (isDwarfSection(*Name)) {
if (!ProcessDebugSections && isDwarfSection(*Name)) {
LLVM_DEBUG({
dbgs() << " " << SecIndex << ": \"" << *Name
<< "\" is a debug section: "
Expand Down Expand Up @@ -522,8 +525,7 @@ template <typename ELFT> Error ELFLinkGraphBuilder<ELFT>::graphifySymbols() {
template <typename ELFT>
template <typename RelocHandlerFunction>
Error ELFLinkGraphBuilder<ELFT>::forEachRelaRelocation(
const typename ELFT::Shdr &RelSect, RelocHandlerFunction &&Func,
bool ProcessDebugSections) {
const typename ELFT::Shdr &RelSect, RelocHandlerFunction &&Func) {
// Only look into sections that store relocation entries.
if (RelSect.sh_type != ELF::SHT_RELA)
return Error::success();
Expand Down Expand Up @@ -569,8 +571,7 @@ Error ELFLinkGraphBuilder<ELFT>::forEachRelaRelocation(
template <typename ELFT>
template <typename RelocHandlerFunction>
Error ELFLinkGraphBuilder<ELFT>::forEachRelRelocation(
const typename ELFT::Shdr &RelSect, RelocHandlerFunction &&Func,
bool ProcessDebugSections) {
const typename ELFT::Shdr &RelSect, RelocHandlerFunction &&Func) {
// Only look into sections that store relocation entries.
if (RelSect.sh_type != ELF::SHT_REL)
return Error::success();
Expand Down
195 changes: 195 additions & 0 deletions llvm/test/ExecutionEngine/JITLink/X86/ELF_debug_section_lifetime_is_NoAlloc.yaml
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Original file line number Diff line number Diff line change
@@ -0,0 +1,195 @@
# REQUIRES: asserts
# RUN: yaml2obj -o %t.o %s
# RUN: llvm-jitlink -debug-only=jitlink -noexec %t.o 2>&1 | FileCheck %s
#
# Check that debug sections get NoAlloc lifetimes.
#
# CHECK: ".debug_str" is not a SHF_ALLOC section. Using NoAlloc lifetime.
# CHECK: ".debug_abbrev" is not a SHF_ALLOC section. Using NoAlloc lifetime.
# CHECK: ".debug_info" is not a SHF_ALLOC section. Using NoAlloc lifetime.
# CHECK: ".debug_line" is not a SHF_ALLOC section. Using NoAlloc lifetime.


--- !ELF
FileHeader:
Class: ELFCLASS64
Data: ELFDATA2LSB
Type: ET_REL
Machine: EM_X86_64
SectionHeaderStringTable: .strtab
Sections:
- Name: .text
Type: SHT_PROGBITS
Flags: [ SHF_ALLOC, SHF_EXECINSTR ]
AddressAlign: 0x10
Content: B82A000000C3662E0F1F840000000000B82A000000C3
- Name: .debug_abbrev
Type: SHT_PROGBITS
AddressAlign: 0x1
Content: 011101250E1305030E10171B0E110112060000022E00110112064018974219030E3A0B3B0B271949133F190000032E01110112064018974219030E3A0B3B0B271949133F1900000405000218030E3A0B3B0B49130000052400030E3E0B0B0B0000060F004913000000
- Name: .debug_info
Type: SHT_PROGBITS
AddressAlign: 0x1
Content: 8C0000000400000000000801000000000C000000000000000000000000000000000000000000160000000200000000000000000600000001570000000001017700000003000000000000000006000000015700000000010577000000040155000000000105770000000401540000000001057E0000000005000000000504068300000006880000000500000000060100
- Name: .comment
Type: SHT_PROGBITS
Flags: [ SHF_MERGE, SHF_STRINGS ]
AddressAlign: 0x1
EntSize: 0x1
Content: 00636C616E672076657273696F6E2031302E302E302D347562756E7475312000
- Name: .note.GNU-stack
Type: SHT_PROGBITS
AddressAlign: 0x1
- Name: .debug_line
Type: SHT_PROGBITS
AddressAlign: 0x1
Content: 58000000040036000000010101FB0E0D0001010101000000010000012F746D700000454C465F736B69705F64656275675F73656374696F6E732E63000100000000090200000000000000000105030A130500F505030A130206000101
- Name: .eh_frame
Type: SHT_X86_64_UNWIND
Flags: [ SHF_ALLOC ]
AddressAlign: 0x8
Content: 1400000000000000017A5200017810011B0C070890010000100000001C0000000000000006000000000000001000000030000000000000000600000000000000
- Name: .rela.debug_info
Type: SHT_RELA
Flags: [ SHF_INFO_LINK ]
Link: .symtab
AddressAlign: 0x8
Info: .debug_info
Relocations:
- Offset: 0x6
Symbol: .debug_abbrev
Type: R_X86_64_32
- Offset: 0xC
Symbol: .debug_str
Type: R_X86_64_32
- Offset: 0x12
Symbol: .debug_str
Type: R_X86_64_32
Addend: 31
- Offset: 0x16
Symbol: .debug_line
Type: R_X86_64_32
- Offset: 0x1A
Symbol: .debug_str
Type: R_X86_64_32
Addend: 57
- Offset: 0x1E
Symbol: .text
Type: R_X86_64_64
- Offset: 0x2B
Symbol: .text
Type: R_X86_64_64
- Offset: 0x39
Symbol: .debug_str
Type: R_X86_64_32
Addend: 62
- Offset: 0x44
Symbol: .text
Type: R_X86_64_64
Addend: 16
- Offset: 0x52
Symbol: .debug_str
Type: R_X86_64_32
Addend: 70
- Offset: 0x5F
Symbol: .debug_str
Type: R_X86_64_32
Addend: 75
- Offset: 0x6C
Symbol: .debug_str
Type: R_X86_64_32
Addend: 80
- Offset: 0x78
Symbol: .debug_str
Type: R_X86_64_32
Addend: 66
- Offset: 0x89
Symbol: .debug_str
Type: R_X86_64_32
Addend: 85
- Name: .rela.debug_line
Type: SHT_RELA
Flags: [ SHF_INFO_LINK ]
Link: .symtab
AddressAlign: 0x8
Info: .debug_line
Relocations:
- Offset: 0x43
Symbol: .text
Type: R_X86_64_64
- Name: .rela.eh_frame
Type: SHT_RELA
Flags: [ SHF_INFO_LINK ]
Link: .symtab
AddressAlign: 0x8
Info: .eh_frame
Relocations:
- Offset: 0x20
Symbol: .text
Type: R_X86_64_PC32
- Offset: 0x34
Symbol: .text
Type: R_X86_64_PC32
Addend: 16
- Name: .llvm_addrsig
Type: SHT_LLVM_ADDRSIG
Flags: [ SHF_EXCLUDE ]
Link: .symtab
AddressAlign: 0x1
Offset: 0x4C0
Symbols: [ ]
- Type: SectionHeaderTable
Sections:
- Name: .strtab
- Name: .text
- Name: .debug_str
- Name: .debug_abbrev
- Name: .debug_info
- Name: .rela.debug_info
- Name: .comment
- Name: .note.GNU-stack
- Name: .debug_line
- Name: .rela.debug_line
- Name: .eh_frame
- Name: .rela.eh_frame
- Name: .llvm_addrsig
- Name: .symtab
Symbols:
- Name: ELF_skip_debug_sections.c
Type: STT_FILE
Index: SHN_ABS
- Name: .text
Type: STT_SECTION
Section: .text
- Name: .debug_str
Type: STT_SECTION
Section: .debug_str
- Name: .debug_abbrev
Type: STT_SECTION
Section: .debug_abbrev
- Name: .debug_line
Type: STT_SECTION
Section: .debug_line
- Name: foo
Type: STT_FUNC
Section: .text
Binding: STB_GLOBAL
Size: 0x6
- Name: main
Type: STT_FUNC
Section: .text
Binding: STB_GLOBAL
Value: 0x10
Size: 0x6
DWARF:
debug_str:
- 'clang version 10.0.0-4ubuntu1 '
- ELF_skip_debug_sections.c
- '/tmp'
- foo
- int
- main
- argc
- argv
- char
...
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