Improve the --expand-relocs handling of MachO.

In a relocation target can take 3 basic forms

* A r_value in scattered relocations.
* A symbol in external relocations.
* A section is non-external relocations.

Have the dump reflect that. With this change we go from

CHECK-NEXT:       Extern: 0
CHECK-NEXT:       Type: X86_64_RELOC_SUBTRACTOR (5)
CHECK-NEXT:       Symbol: 0x2
CHECK-NEXT:       Scattered: 0

To just

// CHECK-NEXT:       Type: X86_64_RELOC_SUBTRACTOR (5)
// CHECK-NEXT:       Section: __data (2)

Since the relocation is with a section, we print the seciton name and don't
need to say that it is not scattered or external.

Someone motivated can add further special cases for things like
ARM64_RELOC_ADDEND and ARM_RELOC_PAIR.

llvm-svn: 240073

1 files changed, 4 insertions, 2 deletions

diff --git a/llvm/lib/Object/MachOObjectFile.cpp b/llvm/lib/Object/MachOObjectFile.cpp
index adb8cab..f76dd0d 100644
--- a/llvm/lib/Object/MachOObjectFile.cpp
+++ b/llvm/lib/Object/MachOObjectFile.cpp
@@ -2012,9 +2012,11 @@ MachOObjectFile::getAnyRelocationSection(
                                    const MachO::any_relocation_info &RE) const {
   if (isRelocationScattered(RE) || getPlainRelocationExternal(RE))
     return *section_end();
-  unsigned SecNum = getPlainRelocationSymbolNum(RE) - 1;
+  unsigned SecNum = getPlainRelocationSymbolNum(RE);
+  if (SecNum == MachO::R_ABS || SecNum > Sections.size())
+    return *section_end();
   DataRefImpl DRI;
-  DRI.d.a = SecNum;
+  DRI.d.a = SecNum - 1;
   return SectionRef(DRI, this);
 }