[llvm-readobj] - Don't abort when dumping dynamic relocations when an object has both REL and RELA.

[grimar]

Summary

Currently, llvm-readobj calls report_fatal_error when an object has
both REL and RELA dynamic relocations.

llvm-readelf is able to handle this case properly. This patch adds such a test case
and adjusts the llvm-readobj code to follow (and be consistent with its own RELR and PLTREL cases).

[jhenderson]

llvm/test/tools/llvm-readobj/ELF/broken-dynamic-reloc.test

499–512

The input here is a little subtle, i.e. reusing the same data for both REL and RELA relocations. Perhaps it would be clearer to have them point at different sections? If that's not possible, it might be worth pointing out how this works in a comment.

[grimar]

• Addressed review comments.

llvm/test/tools/llvm-readobj/ELF/broken-dynamic-reloc.test

499–512

Fixed.

[jhenderson]

LGTM, with one suggestion.

llvm/test/tools/llvm-readobj/ELF/broken-dynamic-reloc.test

499

Consider specifying on offset for one of these relocations, to distinguish it from the other, and show that the same region isn't being read for both now.

llvm/test/tools/llvm-readobj/ELF/broken-dynamic-reloc.test

Entries:
         Value: 0x0
 DynamicSymbols:
   - Name: foo
 ProgramHeaders:
   - Type:  PT_LOAD
     Sections:
       - Section: .rela.dyn
       - Section: .dynamic
+
+## Show that when we have both REL and RELA relocations, we dump both sets.
+# RUN: yaml2obj --docnum=13 %s -o %t13
+# RUN: llvm-readobj --dyn-relocations %t13 2>&1 | FileCheck %s -DFILE=%t13 --check-prefix=BOTH-RELA-REL-LLVM
+# RUN: llvm-readelf --dyn-relocations %t13 2>&1 | FileCheck %s -DFILE=%t13 --check-prefix=BOTH-RELA-REL-GNU
+
+# BOTH-RELA-REL-LLVM:      Dynamic Relocations {
+# BOTH-RELA-REL-LLVM-NEXT:   0x1 R_X86_64_NONE - 0x0
+# BOTH-RELA-REL-LLVM-NEXT:   0x2 R_X86_64_NONE - 0x0
+# BOTH-RELA-REL-LLVM-NEXT: }
+
+# BOTH-RELA-REL-GNU:       'RELA' relocation section at offset 0x78 contains 24 bytes:
+# BOTH-RELA-REL-GNU-NEXT:    Offset             Info             Type               Symbol's Value  Symbol's Name + Addend
+# BOTH-RELA-REL-GNU-NEXT:  0000000000000001  0000000000000000 R_X86_64_NONE                     0
+# BOTH-RELA-REL-GNU-EMPTY:
+# BOTH-RELA-REL-GNU:       'REL' relocation section at offset 0x90 contains 16 bytes:
+# BOTH-RELA-REL-GNU-NEXT:    Offset             Info             Type               Symbol's Value  Symbol's Name
+# BOTH-RELA-REL-GNU-NEXT:  0000000000000002  0000000000000000 R_X86_64_NONE
+
+--- !ELF
+FileHeader:
+  Class:   ELFCLASS64
+  Data:    ELFDATA2LSB
+  Type:    ET_DYN
+  Machine: EM_X86_64
+Sections:
+  - Name: .rela.dyn
+    Type: SHT_RELA
+    Relocations:
+      - Type:   R_X86_64_NONE
+        Offset: 0x1
+  - Name: .rel.dyn
+    Type: SHT_REL
+    Relocations:
+      - Type: R_X86_64_NONE
+        Offset: 0x2
+  - Name: .dynamic
+    Type: SHT_DYNAMIC
+    Entries:
+      - Tag:   DT_RELA
+        Value: 0x0
+      - Tag:   DT_RELASZ
+        Value: 0x18
+      - Tag:   DT_RELAENT
+        Value: 0x18
+## 0x18 == offset of .rel.dyn == size of .rela.dyn section.
+      - Tag:   DT_REL
+        Value: 0x18
+      - Tag:   DT_RELSZ
+        Value: 0x10
+      - Tag:   DT_RELENT
+        Value: 0x10
+      - Tag:   DT_NULL
+        Value: 0x0
+DynamicSymbols: []
+ProgramHeaders:
+  - Type:  PT_LOAD
+    Sections:
+      - Section: .rela.dyn
+      - Section: .rel.dyn
+      - Section: .dynamic

llvm/tools/llvm-readobj/ELFDumper.cpp

 }
 
 template <class ELFT>
 void LLVMStyle<ELFT>::printDynamicRelocations(const ELFO *Obj) {
   const DynRegionInfo &DynRelRegion = this->dumper()->getDynRelRegion();
   const DynRegionInfo &DynRelaRegion = this->dumper()->getDynRelaRegion();
   const DynRegionInfo &DynRelrRegion = this->dumper()->getDynRelrRegion();
   const DynRegionInfo &DynPLTRelRegion = this->dumper()->getDynPLTRelRegion();
-  if (DynRelRegion.Size && DynRelaRegion.Size)
-    report_fatal_error("There are both REL and RELA dynamic relocations");
+
   W.startLine() << "Dynamic Relocations {\n";
   W.indent();
-  if (DynRelaRegion.Size > 0)
+  if (DynRelaRegion.Size > 0) {
     for (const Elf_Rela &Rela : this->dumper()->dyn_relas())
       printDynamicRelocation(Obj, Rela);
-  else
+  }
+  if (DynRelRegion.Size > 0) {
     for (const Elf_Rel &Rel : this->dumper()->dyn_rels()) {
       Elf_Rela Rela;
       Rela.r_offset = Rel.r_offset;
       Rela.r_info = Rel.r_info;
       Rela.r_addend = 0;
       printDynamicRelocation(Obj, Rela);
     }
+  }
+
   if (DynRelrRegion.Size > 0) {
     Elf_Relr_Range Relrs = this->dumper()->dyn_relrs();
     std::vector<Elf_Rela> RelrRelas =
         unwrapOrError(this->FileName, Obj->decode_relrs(Relrs));
     for (const Elf_Rela &Rela : RelrRelas)
       printDynamicRelocation(Obj, Rela);
   }
   if (DynPLTRelRegion.EntSize == sizeof(Elf_Rela))