[JITLink][ELF] Don't skip debug info sections by default.

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.
2023-03-18 22:34:07 -07:00
parent ede78c1704
commit 57aeb30546
3 changed files with 213 additions and 258 deletions
--- a/llvm/lib/ExecutionEngine/JITLink/ELFLinkGraphBuilder.h
+++ b/llvm/lib/ExecutionEngine/JITLink/ELFLinkGraphBuilder.h
@@ -62,6 +62,14 @@ public:
                      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();

@@ -115,8 +123,7 @@ protected:
  ///
  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:
@@ -125,22 +132,19 @@ protected:
  ///
  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.
@@ -148,14 +152,12 @@ protected:
  ///
  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;
@@ -163,6 +165,7 @@ protected:
  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.
@@ -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: "
@@ -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();
@@ -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();
--- a/llvm/test/ExecutionEngine/JITLink/X86/ELF_debug_section_lifetime_is_NoAlloc.yaml
+++ b/llvm/test/ExecutionEngine/JITLink/X86/ELF_debug_section_lifetime_is_NoAlloc.yaml
@@ -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
+...
--- a/llvm/test/ExecutionEngine/JITLink/X86/ELF_skip_debug_sections.s
+++ b/llvm/test/ExecutionEngine/JITLink/X86/ELF_skip_debug_sections.s
@@ -1,241 +0,0 @@
-# REQUIRES: asserts
-# RUN: llvm-mc -triple=x86_64-pc-linux-gnu -filetype=obj -o %t %s
-# RUN: llvm-jitlink -debug-only=jitlink -noexec %t 2>&1 | FileCheck %s
-#
-# Check that debug sections are not emitted.
-#
-# CHECK: ".debug_info" is a debug section: No graph section will be created.
-
-	.text
-	.file	"ELF_skip_debug_sections.c"
-	.globl	foo
-	.p2align	4, 0x90
-	.type	foo,@function
-foo:
-.Lfunc_begin0:
-	.file	1 "/tmp" "ELF_skip_debug_sections.c"
-	.loc	1 1 0
-	.cfi_startproc
-
-	.loc	1 2 3 prologue_end
-	movl	$42, %eax
-	retq
-.Ltmp0:
-.Lfunc_end0:
-	.size	foo, .Lfunc_end0-foo
-	.cfi_endproc
-
-	.globl	main
-	.p2align	4, 0x90
-	.type	main,@function
-main:
-.Lfunc_begin1:
-	.loc	1 5 0
-	.cfi_startproc
-
-
-
-	.loc	1 6 3 prologue_end
-	movl	$42, %eax
-	retq
-.Ltmp1:
-.Lfunc_end1:
-	.size	main, .Lfunc_end1-main
-	.cfi_endproc
-
-	.section	.debug_str,"MS",@progbits,1
-.Linfo_string0:
-	.asciz	"clang version 10.0.0-4ubuntu1 "
-.Linfo_string1:
-	.asciz	"ELF_skip_debug_sections.c"
-.Linfo_string2:
-	.asciz	"/tmp"
-.Linfo_string3:
-	.asciz	"foo"
-.Linfo_string4:
-	.asciz	"int"
-.Linfo_string5:
-	.asciz	"main"
-.Linfo_string6:
-	.asciz	"argc"
-.Linfo_string7:
-	.asciz	"argv"
-.Linfo_string8:
-	.asciz	"char"
-	.section	.debug_abbrev,"",@progbits
-	.byte	1
-	.byte	17
-	.byte	1
-	.byte	37
-	.byte	14
-	.byte	19
-	.byte	5
-	.byte	3
-	.byte	14
-	.byte	16
-	.byte	23
-	.byte	27
-	.byte	14
-	.byte	17
-	.byte	1
-	.byte	18
-	.byte	6
-	.byte	0
-	.byte	0
-	.byte	2
-	.byte	46
-	.byte	0
-	.byte	17
-	.byte	1
-	.byte	18
-	.byte	6
-	.byte	64
-	.byte	24
-	.ascii	"\227B"
-	.byte	25
-	.byte	3
-	.byte	14
-	.byte	58
-	.byte	11
-	.byte	59
-	.byte	11
-	.byte	39
-	.byte	25
-	.byte	73
-	.byte	19
-	.byte	63
-	.byte	25
-	.byte	0
-	.byte	0
-	.byte	3
-	.byte	46
-	.byte	1
-	.byte	17
-	.byte	1
-	.byte	18
-	.byte	6
-	.byte	64
-	.byte	24
-	.ascii	"\227B"
-	.byte	25
-	.byte	3
-	.byte	14
-	.byte	58
-	.byte	11
-	.byte	59
-	.byte	11
-	.byte	39
-	.byte	25
-	.byte	73
-	.byte	19
-	.byte	63
-	.byte	25
-	.byte	0
-	.byte	0
-	.byte	4
-	.byte	5
-	.byte	0
-	.byte	2
-	.byte	24
-	.byte	3
-	.byte	14
-	.byte	58
-	.byte	11
-	.byte	59
-	.byte	11
-	.byte	73
-	.byte	19
-	.byte	0
-	.byte	0
-	.byte	5
-	.byte	36
-	.byte	0
-	.byte	3
-	.byte	14
-	.byte	62
-	.byte	11
-	.byte	11
-	.byte	11
-	.byte	0
-	.byte	0
-	.byte	6
-	.byte	15
-	.byte	0
-	.byte	73
-	.byte	19
-	.byte	0
-	.byte	0
-	.byte	0
-	.section	.debug_info,"",@progbits
-.Lcu_begin0:
-	.long	.Ldebug_info_end0-.Ldebug_info_start0
-.Ldebug_info_start0:
-	.short	4
-	.long	.debug_abbrev
-	.byte	8
-	.byte	1
-	.long	.Linfo_string0
-	.short	12
-	.long	.Linfo_string1
-	.long	.Lline_table_start0
-	.long	.Linfo_string2
-	.quad	.Lfunc_begin0
-	.long	.Lfunc_end1-.Lfunc_begin0
-	.byte	2
-	.quad	.Lfunc_begin0
-	.long	.Lfunc_end0-.Lfunc_begin0
-	.byte	1
-	.byte	87
-
-	.long	.Linfo_string3
-	.byte	1
-	.byte	1
-
-	.long	119
-
-	.byte	3
-	.quad	.Lfunc_begin1
-	.long	.Lfunc_end1-.Lfunc_begin1
-	.byte	1
-	.byte	87
-
-	.long	.Linfo_string5
-	.byte	1
-	.byte	5
-
-	.long	119
-
-	.byte	4
-	.byte	1
-	.byte	85
-	.long	.Linfo_string6
-	.byte	1
-	.byte	5
-	.long	119
-	.byte	4
-	.byte	1
-	.byte	84
-	.long	.Linfo_string7
-	.byte	1
-	.byte	5
-	.long	126
-	.byte	0
-	.byte	5
-	.long	.Linfo_string4
-	.byte	5
-	.byte	4
-	.byte	6
-	.long	131
-	.byte	6
-	.long	136
-	.byte	5
-	.long	.Linfo_string8
-	.byte	6
-	.byte	1
-	.byte	0
-.Ldebug_info_end0:
-	.ident	"clang version 10.0.0-4ubuntu1 "
-	.section	".note.GNU-stack","",@progbits
-	.addrsig
-	.section	.debug_line,"",@progbits
-.Lline_table_start0: