[NVPTX] Emit .weak when linkage is not external, internal, or private

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@211926 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Target/NVPTX/NVPTXAsmPrinter.cpp

@@ -1305,6 +1305,10 @@ bool NVPTXAsmPrinter::doFinalization(Module &M) {
 // external global variable with init     -> .visible
 // external without init                  -> .extern
 // appending                              -> not allowed, assert.
+// for any linkage other than
+// internal, private, linker_private,
+// linker_private_weak, linker_private_weak_def_auto,
+// we emit                                -> .weak.
 
 void NVPTXAsmPrinter::emitLinkageDirective(const GlobalValue *V,
                                            raw_ostream &O) {
@@ -1330,6 +1334,9 @@ void NVPTXAsmPrinter::emitLinkageDirective(const GlobalValue *V,
         msg.append(V->getName().str());
       msg.append("has unsupported appending linkage type");
       llvm_unreachable(msg.c_str());
+    } else if (!V->hasInternalLinkage() &&
+               !V->hasPrivateLinkage()) {
+      O << ".weak ";
     }
   }
 }

test/CodeGen/NVPTX/weak-linkage.ll

@@ -0,0 +1,12 @@
+; RUN: llc < %s -march=nvptx -mcpu=sm_20 | FileCheck %s
+
+
+; CHECK: .weak .func foo
+define weak void @foo() {
+  ret void
+}
+
+; CHECK: .visible .func bar
+define void @bar() {
+  ret void
+}