From: George Rimar <grimar@accesssoftek.com>
Date: Thu, 18 Apr 2019 11:02:07 +0000 (+0000)
Subject: [yaml2elf/obj2yaml] - Allow normal parsing/dumping of the .rela.dyn section
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=f7dff4c501c76972cf8a2bf96c04ac9a4b6be867;p=llvm

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

.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.

Differential revision: https://reviews.llvm.org/D60820

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@358656 91177308-0d34-0410-b5e6-96231b3b80d8
---

diff --git a/test/tools/obj2yaml/elf-reladyn-section-shinfo.yaml b/test/tools/obj2yaml/elf-reladyn-section-shinfo.yaml
new file mode 100644
index 00000000000..0f2906470f3
--- /dev/null
+++ b/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 needing 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
diff --git a/tools/yaml2obj/yaml2elf.cpp b/tools/yaml2obj/yaml2elf.cpp
index 1507504239b..a30093a042f 100644
--- a/tools/yaml2obj/yaml2elf.cpp
+++ b/tools/yaml2obj/yaml2elf.cpp
@@ -278,8 +278,9 @@ bool ELFState<ELFT>::initSectionHeaders(std::vector<Elf_Shdr> &SHeaders,
         // 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))