[Lldb-commits] [PATCH] D44157: [elf] Remove one copy of the section merging code

[Pavel Labath via Phabricator via lldb-commits]

labath created this revision.
labath added reviewers: fjricci, jankratochvil.
Herald added subscribers: arichardson, emaste.

Besides being superfluous, this double merging was actually wrong and
causing some sections to be added twice. The reason for that was that
the code assumes sectoin IDs are unique in the section list, but this is
only true if all sections in the list come from the same object file.


https://reviews.llvm.org/D44157

Files:
  lit/Modules/elf-duplicate-section.yaml
  source/Plugins/ObjectFile/ELF/ObjectFileELF.cpp


Index: source/Plugins/ObjectFile/ELF/ObjectFileELF.cpp
===================================================================
--- source/Plugins/ObjectFile/ELF/ObjectFileELF.cpp
+++ source/Plugins/ObjectFile/ELF/ObjectFileELF.cpp
@@ -1986,38 +1986,10 @@
     }
   }
 
-  if (m_sections_ap.get()) {
-    if (GetType() == eTypeDebugInfo) {
-      static const SectionType g_sections[] = {
-          eSectionTypeDWARFDebugAbbrev,   eSectionTypeDWARFDebugAddr,
-          eSectionTypeDWARFDebugAranges,  eSectionTypeDWARFDebugCuIndex,
-          eSectionTypeDWARFDebugFrame,    eSectionTypeDWARFDebugInfo,
-          eSectionTypeDWARFDebugLine,     eSectionTypeDWARFDebugLoc,
-          eSectionTypeDWARFDebugMacInfo,  eSectionTypeDWARFDebugPubNames,
-          eSectionTypeDWARFDebugPubTypes, eSectionTypeDWARFDebugRanges,
-          eSectionTypeDWARFDebugStr,      eSectionTypeDWARFDebugStrOffsets,
-          eSectionTypeELFSymbolTable,
-      };
-      SectionList *elf_section_list = m_sections_ap.get();
-      for (size_t idx = 0; idx < sizeof(g_sections) / sizeof(g_sections[0]);
-           ++idx) {
-        SectionType section_type = g_sections[idx];
-        SectionSP section_sp(
-            elf_section_list->FindSectionByType(section_type, true));
-        if (section_sp) {
-          SectionSP module_section_sp(
-              unified_section_list.FindSectionByType(section_type, true));
-          if (module_section_sp)
-            unified_section_list.ReplaceSection(module_section_sp->GetID(),
-                                                section_sp);
-          else
-            unified_section_list.AddSection(section_sp);
-        }
-      }
-    } else {
-      unified_section_list = *m_sections_ap;
-    }
-  }
+  // For eTypeDebugInfo files, the Symbol Vendor will take care of updating the
+  // unified section list.
+  if (GetType() != eTypeDebugInfo)
+    unified_section_list = *m_sections_ap;
 }
 
 // Find the arm/aarch64 mapping symbol character in the given symbol name.
Index: lit/Modules/elf-duplicate-section.yaml
===================================================================
--- /dev/null
+++ lit/Modules/elf-duplicate-section.yaml
@@ -0,0 +1,42 @@
+# RUN: mkdir -p %t/.build-id/1b
+# RUN: yaml2obj %s > %t/.build-id/1b/8a73ac238390e32a7ff4ac8ebe4d6a41ecf5c9.debug
+# RUN: cd %t
+# RUN: llvm-objcopy --strip-all --add-gnu-debuglink=.build-id/1b/8a73ac238390e32a7ff4ac8ebe4d6a41ecf5c9.debug %t/.build-id/1b/8a73ac238390e32a7ff4ac8ebe4d6a41ecf5c9.debug %t/stripped.out
+# RUN: lldb-test module-sections %t/stripped.out | FileCheck %s
+
+# Make sure that the debug_frame section is present only once.
+# CHECK: Name: .debug_frame
+# CHECK-NOT: .debug_frame
+
+--- !ELF
+FileHeader:
+  Class:           ELFCLASS64
+  Data:            ELFDATA2LSB
+  Type:            ET_EXEC
+  Machine:         EM_X86_64
+  Entry:           0x00000000004003D0
+Sections:
+  - Name:            .note.gnu.build-id
+    Type:            SHT_NOTE
+    Flags:           [ SHF_ALLOC ]
+    Address:         0x0000000000400274
+    AddressAlign:    0x0000000000000004
+    Content:         040000001400000003000000474E55001B8A73AC238390E32A7FF4AC8EBE4D6A41ECF5C9
+  - Name:            .text
+    Type:            SHT_PROGBITS
+    Flags:           [ SHF_ALLOC, SHF_EXECINSTR ]
+    Address:         0x00000000004003D0
+    AddressAlign:    0x0000000000000010
+    Content:         DEADBEEFBAADF00D
+  - Name:            .debug_frame
+    Type:            SHT_PROGBITS
+    AddressAlign:    0x0000000000000008
+    Content:         DEADBEEFBAADF00D
+Symbols:
+  Local:
+    - Name:            main
+      Type:            STT_FUNC
+      Section:         .text
+      Value:           0x00000000004003D0
+      Size:            0x0000000000000008
+...


-------------- next part --------------
A non-text attachment was scrubbed...
Name: D44157.137209.patch
Type: text/x-patch
Size: 3772 bytes
Desc: not available
URL: <http://lists.llvm.org/pipermail/lldb-commits/attachments/20180306/d8147d73/attachment.bin>