Rename DynamicReloc::getAddend() to computeAddend(). NFC

Summary:
Before the name of the function sounded like it was just a getter for the
private class member Addend. However, it actually calculates the final
value for the r_addend field in Elf_Rela that is used when writing the
.rela.dyn section. I also added a comment to the UseSymVA member to
explain how it interacts with computeAddend().

Differential Revision: https://reviews.llvm.org/D43161

llvm-svn: 325485

lld/ELF/SyntheticSections.cpp

@@ -1184,7 +1184,7 @@ uint64_t DynamicReloc::getOffset() const {
   return InputSec->getOutputSection()->Addr + InputSec->getOffset(OffsetInSec);
 }
 
-int64_t DynamicReloc::getAddend() const {
+int64_t DynamicReloc::computeAddend() const {
   if (UseSymVA)
     return Sym->getVA(Addend);
   return Addend;
@@ -1239,7 +1239,7 @@ template <class ELFT>
 static void encodeDynamicReloc(typename ELFT::Rela *P,
                                const DynamicReloc &Rel) {
   if (Config->IsRela)
-    P->r_addend = Rel.getAddend();
+    P->r_addend = Rel.computeAddend();
   P->r_offset = Rel.getOffset();
   if (Config->EMachine == EM_MIPS && Rel.getInputSec() == InX::MipsGot)
     // The MIPS GOT section contains dynamic relocations that correspond to TLS

lld/ELF/SyntheticSections.h

@@ -316,16 +316,24 @@ class DynamicReloc {
         UseSymVA(UseSymVA), Addend(Addend) {}
 
   uint64_t getOffset() const;
-  int64_t getAddend() const;
   uint32_t getSymIndex() const;
   const InputSectionBase *getInputSec() const { return InputSec; }
 
+  // Computes the addend of the dynamic relocation. Note that this is not the
+  // same as the Addend member variable as it also includes the symbol address
+  // if UseSymVA is true.
+  int64_t computeAddend() const;
+
   RelType Type;
 
 private:
   Symbol *Sym;
   const InputSectionBase *InputSec = nullptr;
   uint64_t OffsetInSec;
+  // If this member is true, the dynamic relocation will not be against the
+  // symbol but will instead be a relative relocation that simply adds the
+  // load address. This means we need to write the symbol virtual address
+  // plus the original addend as the final relocation addend.
   bool UseSymVA;
   int64_t Addend;
 };