[PATCH] D60820: [yaml2elf/obj2yaml] - Allow normal parsing/dumping of the .rela.dyn section.

[George Rimar via Phabricator via llvm-commits]

grimar created this revision.
grimar added a reviewer: jhenderson.
Herald added a subscriber: jakehehrlich.

`.rela.dyn` is a section that has sh_info normally set to zero.
And `Info` is an optional field in the description of the relocation section in YAML.

But currently, yaml2obj would fail to produce the object when
`Info` is not explicitly listed.

The patch fixes the issue.


https://reviews.llvm.org/D60820

Files:
  test/tools/obj2yaml/elf-reladyn-section-shinfo.yaml
  tools/yaml2obj/yaml2elf.cpp


Index: tools/yaml2obj/yaml2elf.cpp
===================================================================
--- tools/yaml2obj/yaml2elf.cpp
+++ tools/yaml2obj/yaml2elf.cpp
@@ -278,8 +278,9 @@
         // For relocation section set link to .symtab by default.
         SHeader.sh_link = getDotSymTabSecNo();
 
-      unsigned Index;
-      if (!convertSectionIndex(SN2I, S->Name, S->RelocatableSec, Index))
+      unsigned Index = 0;
+      if (!S->RelocatableSec.empty() &&
+          !convertSectionIndex(SN2I, S->Name, S->RelocatableSec, Index))
         return false;
       SHeader.sh_info = Index;
       if (!writeSectionContent(SHeader, *S, CBA))
Index: test/tools/obj2yaml/elf-reladyn-section-shinfo.yaml
===================================================================
--- /dev/null
+++ test/tools/obj2yaml/elf-reladyn-section-shinfo.yaml
@@ -0,0 +1,44 @@
+# RUN: yaml2obj %s -o %t
+# RUN: llvm-readobj -sections %t | FileCheck %s
+# RUN: obj2yaml %t | FileCheck %s --check-prefix=YAML
+
+## .rela.dyn is a dynamic relocation section that normally has
+## no value in sh_info field. Check we are able to use
+## yaml2obj/obj2yaml without need to explicitly set it.
+
+# CHECK:      Name: .rela.dyn
+# CHECK-NEXT: Type: SHT_RELA
+# CHECK-NEXT: Flags [
+# CHECK-NEXT:   SHF_ALLOC
+# CHECK-NEXT: ]
+# CHECK-NEXT: Address:
+# CHECK-NEXT: Offset:
+# CHECK-NEXT: Size:
+# CHECK-NEXT: Link:
+# CHECK-NEXT: Info: 0
+# CHECK-NEXT: AddressAlignment:
+# CHECK-NEXT: EntrySize:
+
+# YAML:      - Name:    .rela.dyn
+# YAML-NEXT:   Type:    SHT_RELA
+# YAML-NEXT:   Flags:   [ SHF_ALLOC ]
+# YAML-NEXT:   Link:    .dynsym
+# YAML-NEXT:   EntSize: 0x0000000000000018
+
+--- !ELF
+FileHeader:
+  Class:   ELFCLASS64
+  Data:    ELFDATA2LSB
+  Type:    ET_DYN
+  Machine: EM_X86_64
+  Entry:   0x0000000000001000
+Sections:
+  - Name:    .rela.dyn
+    Type:    SHT_RELA
+    Flags:   [ SHF_ALLOC ]
+    Link:    .dynsym
+    EntSize: 0x0000000000000018
+# Add at least one symbol to trigger the .dynsym emission
+DynamicSymbols:
+  - Name:    bar
+    Binding: STB_GLOBAL


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