IR: Do not consider available_externally linkage to be linker-weak.

From the linker's perspective, an available_externally global is equivalent
to an external declaration (per isDeclarationForLinker()), so it is incorrect
to consider it to be a weak definition.

Also clean up some logic in the dead argument elimination pass and clarify
its comments to better explain how its behavior depends on linkage,
introduce GlobalValue::isStrongDefinitionForLinker() and start using
it throughout the optimizers and backend.

Differential Revision: http://reviews.llvm.org/D10941

llvm-svn: 241413

1 files changed, 3 insertions, 3 deletions

diff --git a/llvm/lib/Target/ARM/ARMISelLowering.cpp b/llvm/lib/Target/ARM/ARMISelLowering.cpp
index ba109e61982..607ce767be2 100644
--- a/llvm/lib/Target/ARM/ARMISelLowering.cpp
+++ b/llvm/lib/Target/ARM/ARMISelLowering.cpp
@@ -1734,12 +1734,12 @@ ARMTargetLowering::LowerCall(TargetLowering::CallLoweringInfo &CLI,
   } else if (GlobalAddressSDNode *G = dyn_cast<GlobalAddressSDNode>(Callee)) {
     const GlobalValue *GV = G->getGlobal();
     isDirect = true;
-    bool isExt = GV->isDeclaration() || GV->isWeakForLinker();
-    bool isStub = (isExt && Subtarget->isTargetMachO()) &&
+    bool isDef = GV->isStrongDefinitionForLinker();
+    bool isStub = (!isDef && Subtarget->isTargetMachO()) &&
                    getTargetMachine().getRelocationModel() != Reloc::Static;
     isARMFunc = !Subtarget->isThumb() || (isStub && !Subtarget->isMClass());
     // ARM call to a local ARM function is predicable.
-    isLocalARMFunc = !Subtarget->isThumb() && (!isExt || !ARMInterworking);
+    isLocalARMFunc = !Subtarget->isThumb() && (isDef || !ARMInterworking);
     // tBX takes a register source operand.
     if (isStub && Subtarget->isThumb1Only() && !Subtarget->hasV5TOps()) {
       assert(Subtarget->isTargetMachO() && "WrapperPIC use on non-MachO?");