[MCJIT] Simplify immediate decoding code in the RuntimeDyldMachO hierarchy.

Cleanup only: no functional change.

This patch makes RuntimeDyldMachO targets directly responsible for decoding
immediates, rather than letting them implement catch a callback from generic
code. Since this is a very target specific operation, it makes sense to let the
target-specific code drive it.

llvm-svn: 215255
diff --git a/llvm/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldMachO.h b/llvm/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldMachO.h
index 30f61e9..b18d167 100644
--- a/llvm/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldMachO.h
+++ b/llvm/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldMachO.h
@@ -52,9 +52,31 @@
 
   RuntimeDyldMachO(RTDyldMemoryManager *mm) : RuntimeDyldImpl(mm) {}
 
-  /// Extract the addend encoded in the instruction.
-  int64_t decodeAddend(uint8_t *LocalAddress, unsigned NumBytes,
-                       MachO::RelocationInfoType RelType) const;
+  /// This convenience method uses memcpy to extract a contiguous addend (the
+  /// addend size and offset are taken from the corresponding fields of the RE).
+  int64_t memcpyAddend(const RelocationEntry &RE) const;
+
+  /// Given a relocation_iterator for a non-scattered relocation, construct a
+  /// RelocationEntry and fill in the common fields. The 'Addend' field is *not*
+  /// filled in, since immediate encodings are highly target/opcode specific.
+  /// For targets/opcodes with simple, contiguous immediates (e.g. X86) the
+  /// memcpyAddend method can be used to read the immediate.
+  RelocationEntry getRelocationEntry(unsigned SectionID, ObjectImage &ObjImg,
+                                     const relocation_iterator &RI) const {
+    const MachOObjectFile &Obj =
+      static_cast<const MachOObjectFile &>(*ObjImg.getObjectFile());
+    MachO::any_relocation_info RelInfo =
+      Obj.getRelocation(RI->getRawDataRefImpl());
+
+    bool IsPCRel = Obj.getAnyRelocationPCRel(RelInfo);
+    unsigned Size = Obj.getAnyRelocationLength(RelInfo);
+    uint64_t Offset;
+    RI->getOffset(Offset);
+    MachO::RelocationInfoType RelType =
+      static_cast<MachO::RelocationInfoType>(Obj.getAnyRelocationType(RelInfo));
+
+    return RelocationEntry(SectionID, Offset, RelType, 0, IsPCRel, Size);
+  }
 
   /// Construct a RelocationValueRef representing the relocation target.
   /// For Symbols in known sections, this will return a RelocationValueRef
@@ -119,33 +141,6 @@
   Impl &impl() { return static_cast<Impl &>(*this); }
   const Impl &impl() const { return static_cast<const Impl &>(*this); }
 
-protected:
-
-  /// Parse the given relocation, which must be a non-scattered, and
-  /// return a RelocationEntry representing the information. The 'Addend' field
-  /// will contain the unmodified instruction immediate.
-  RelocationEntry getBasicRelocationEntry(unsigned SectionID,
-                                          ObjectImage &ObjImg,
-                                          const relocation_iterator &RI) const {
-    const MachOObjectFile &Obj =
-      static_cast<const MachOObjectFile &>(*ObjImg.getObjectFile());
-    MachO::any_relocation_info RelInfo =
-      Obj.getRelocation(RI->getRawDataRefImpl());
-
-    const SectionEntry &Section = Sections[SectionID];
-    bool IsPCRel = Obj.getAnyRelocationPCRel(RelInfo);
-    unsigned Size = Obj.getAnyRelocationLength(RelInfo);
-    uint64_t Offset;
-    RI->getOffset(Offset);
-    uint8_t *LocalAddress = Section.Address + Offset;
-    unsigned NumBytes = 1 << Size;
-    MachO::RelocationInfoType RelType =
-      static_cast<MachO::RelocationInfoType>(Obj.getAnyRelocationType(RelInfo));
-    int64_t Addend = impl().decodeAddend(LocalAddress, NumBytes, RelType);
-
-    return RelocationEntry(SectionID, Offset, RelType, Addend, IsPCRel, Size);
-  }
-
 public:
   RuntimeDyldMachOCRTPBase(RTDyldMemoryManager *mm) : RuntimeDyldMachO(mm) {}