[PATCH] D80568: [llvm-objcopy][ELF] Fix removing a group member section.

[Igor Kudrin via Phabricator via llvm-commits]

ikudrin created this revision.
ikudrin added reviewers: MaskRay, jhenderson, rupprecht.
ikudrin added a project: LLVM.
Herald added subscribers: abrachet, emaste.
Herald added a reviewer: espindola.
Herald added a reviewer: alexshap.

When a group member is removed, the corresponding record in the `SHT_GROUP` section has to be also deleted.

This fixes PR46064.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D80568

Files:
  llvm/test/tools/llvm-objcopy/ELF/remove-section-in-group.test
  llvm/tools/llvm-objcopy/ELF/Object.cpp
  llvm/tools/llvm-objcopy/ELF/Object.h


Index: llvm/tools/llvm-objcopy/ELF/Object.h
===================================================================
--- llvm/tools/llvm-objcopy/ELF/Object.h
+++ llvm/tools/llvm-objcopy/ELF/Object.h
@@ -799,6 +799,9 @@
   void accept(SectionVisitor &) const override;
   void accept(MutableSectionVisitor &Visitor) override;
   void finalize() override;
+  Error removeSectionReferences(
+      bool AllowBrokenLinks,
+      function_ref<bool(const SectionBase *)> ToRemove) override;
   Error removeSymbols(function_ref<bool(const Symbol &)> ToRemove) override;
   void markSymbols() override;
   void replaceSectionReferences(
Index: llvm/tools/llvm-objcopy/ELF/Object.cpp
===================================================================
--- llvm/tools/llvm-objcopy/ELF/Object.cpp
+++ llvm/tools/llvm-objcopy/ELF/Object.cpp
@@ -111,7 +111,9 @@
 template <class ELFT>
 void ELFSectionSizer<ELFT>::visit(GnuDebugLinkSection &Sec) {}
 
-template <class ELFT> void ELFSectionSizer<ELFT>::visit(GroupSection &Sec) {}
+template <class ELFT> void ELFSectionSizer<ELFT>::visit(GroupSection &Sec) {
+  Sec.Size = sizeof(Elf_Word) + Sec.GroupMembers.size() * sizeof(Elf_Word);
+}
 
 template <class ELFT>
 void ELFSectionSizer<ELFT>::visit(SectionIndexSection &Sec) {}
@@ -967,6 +969,12 @@
   this->Link = SymTab->Index;
 }
 
+Error GroupSection::removeSectionReferences(
+    bool AllowBrokenLinks, function_ref<bool(const SectionBase *)> ToRemove) {
+  llvm::erase_if(GroupMembers, ToRemove);
+  return Error::success();
+}
+
 Error GroupSection::removeSymbols(function_ref<bool(const Symbol &)> ToRemove) {
   if (ToRemove(*Sym))
     return createStringError(llvm::errc::invalid_argument,
Index: llvm/test/tools/llvm-objcopy/ELF/remove-section-in-group.test
===================================================================
--- /dev/null
+++ llvm/test/tools/llvm-objcopy/ELF/remove-section-in-group.test
@@ -0,0 +1,37 @@
+# RUN: yaml2obj %s -o - \
+# RUN:   | llvm-objcopy -R .foo - - \
+# RUN:   | obj2yaml - \
+# RUN:   | FileCheck %s
+
+## This checks that the group section is shrunk when its member is removed.
+
+--- !ELF
+FileHeader:
+  Class:           ELFCLASS64
+  Data:            ELFDATA2LSB
+  Type:            ET_REL
+  Machine:         EM_X86_64
+Sections:
+  - Name:            .group
+    Type:            SHT_GROUP
+    Link:            .symtab
+    Info:            foo_bar_grp
+    Members:
+      - SectionOrType:   GRP_COMDAT
+      - SectionOrType:   .foo
+      - SectionOrType:   .bar
+  - Name:            .foo
+    Type:            SHT_PROGBITS
+    Flags:           [ SHF_ALLOC, SHF_GROUP ]
+  - Name:            .bar
+    Type:            SHT_PROGBITS
+    Flags:           [ SHF_ALLOC, SHF_GROUP ]
+Symbols:
+  - Name:            foo_bar_grp
+    Section:         .group
+
+# CHECK:      - Name:            .group
+# CHECK:        Members:
+# CHECK-NEXT:     - SectionOrType:   GRP_COMDAT
+# CHECK-NEXT:     - SectionOrType:   .bar
+# CHECK-NOT:      - SectionOrType:


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