Start deciding earlier what to link.

A traditional linker is roughly split in symbol resolution and "copying
stuff".

The two tasks are badly mixed in lib/Linker.

This starts splitting them apart.

With this patch there are no direct call to linkGlobalValueBody or
linkGlobalValueProto. Everything is linked via WapValue.

This also includes a few fixes:
* A GV goes undefined if the comdat is dropped (comdat11.ll).
* We error if an internal GV goes undefined (comdat13.ll).
* We don't link an unused comdat.

The first two match the behavior of an ELF linker. The second one is
equivalent to running globaldce on the input.

llvm-svn: 254336

1 files changed, 3 insertions, 3 deletions

diff --git a/llvm/lib/Transforms/Utils/ValueMapper.cpp b/llvm/lib/Transforms/Utils/ValueMapper.cpp
index 0a63c1d5153..00a8984845d 100644
--- a/llvm/lib/Transforms/Utils/ValueMapper.cpp
+++ b/llvm/lib/Transforms/Utils/ValueMapper.cpp
@@ -41,9 +41,9 @@ Value *llvm::MapValue(const Value *V, ValueToValueMapTy &VM, RemapFlags Flags,
     if (Value *NewV =
             Materializer->materializeDeclFor(const_cast<Value *>(V))) {
       VM[V] = NewV;
-      if (auto *GV = dyn_cast<GlobalValue>(V))
-        Materializer->materializeInitFor(cast<GlobalValue>(NewV),
-                                         const_cast<GlobalValue *>(GV));
+      if (auto *NewGV = dyn_cast<GlobalValue>(NewV))
+        Materializer->materializeInitFor(
+            NewGV, const_cast<GlobalValue *>(cast<GlobalValue>(V)));
       return NewV;
     }
   }