Check isDiscardableIfUnused, rather than hasLocalLinkage, when bumping

GlobalValue linkage up to ExternalLinkage in the ExtractGV pass. This
prevents linkonce and linkonce_odr symbols from being DCE'd.

llvm-svn: 176459

1 files changed, 23 insertions, 0 deletions

diff --git a/llvm/test/Other/extract-linkonce.ll b/llvm/test/Other/extract-linkonce.ll
new file mode 100644
index 00000000000..31fbf3ac463
--- /dev/null
+++ b/llvm/test/Other/extract-linkonce.ll
@@ -0,0 +1,23 @@
+; RUN: llvm-extract -func foo -S < %s | FileCheck %s
+; RUN: llvm-extract -delete -func foo -S < %s | FileCheck --check-prefix=DELETE %s
+
+; Test that we don't convert weak_odr to external definitions.
+
+; CHECK:      @bar = external hidden global i32
+; CHECK:      define hidden i32* @foo() {
+; CHECK-NEXT:  ret i32* @bar
+; CHECK-NEXT: }
+
+; DELETE: @bar = hidden global i32 42
+; DELETE: declare hidden i32* @foo()
+
+@bar = linkonce global i32 42
+
+define linkonce i32* @foo() {
+  ret i32* @bar
+}
+
+define void @g() {
+  call i32* @foo()
+  ret void
+}