Add support for the notion of "hidden" relocations. On MachO, these are relocation entries that are used as additional information for other, real relocations, rather than being relocations themselves.

I'm not familiar enough with ELF or COFF to know if they should have any relocations marked hidden.

llvm-svn: 142961

1 files changed, 32 insertions, 0 deletions

diff --git a/llvm/lib/Object/MachOObjectFile.cpp b/llvm/lib/Object/MachOObjectFile.cpp
index 96db34f4114..a4d7cb542fb 100644
--- a/llvm/lib/Object/MachOObjectFile.cpp
+++ b/llvm/lib/Object/MachOObjectFile.cpp
@@ -952,6 +952,38 @@ error_code MachOObjectFile::getRelocationValueString(DataRefImpl Rel,
   return object_error::success;
 }
 
+error_code MachOObjectFile::getRelocationHidden(DataRefImpl Rel,
+                                                bool &Result) const {
+  InMemoryStruct<macho::RelocationEntry> RE;
+  getRelocation(Rel, RE);
+
+  unsigned Type = (RE->Word1 >> 28) & 0xF;
+  unsigned Arch = getArch();
+
+  Result = false;
+
+  // On arches that use the generic relocations, GENERIC_RELOC_PAIR
+  // is always hidden.
+  if (Arch == Triple::x86 || Arch == Triple::arm) {
+    if (Type == 1) Result = true;
+  } else if (Arch == Triple::x86_64) {
+    // On x86_64, X86_64_RELOC_UNSIGNED is hidden only when it follows
+    // an X864_64_RELOC_SUBTRACTOR.
+    if (Type == 0 && Rel.d.a > 0) {
+      DataRefImpl RelPrev = Rel;
+      RelPrev.d.a--;
+      InMemoryStruct<macho::RelocationEntry> REPrev;
+      getRelocation(RelPrev, REPrev);
+
+      unsigned PrevType = (REPrev->Word1 >> 28) & 0xF;
+
+      if (PrevType == 5) Result = true;
+    }
+  }
+
+  return object_error::success;
+}
+
 /*===-- Miscellaneous -----------------------------------------------------===*/
 
 uint8_t MachOObjectFile::getBytesInAddress() const {