Handle symbols pointing to output sections.

Now that gc sections runs after linker defined symbols are added it
can see symbols that point to an OutputSection.

Should fix a bot failure.

llvm-svn: 320412

2 files changed, 17 insertions, 1 deletions

diff --git a/lld/ELF/MarkLive.cpp b/lld/ELF/MarkLive.cpp
index e2d2ee9c6cf..fbf57a9ee2d 100644
--- a/lld/ELF/MarkLive.cpp
+++ b/lld/ELF/MarkLive.cpp
@@ -219,7 +219,7 @@ template <class ELFT> static void doGcSections() {
 
   auto MarkSymbol = [&](Symbol *Sym) {
     if (auto *D = dyn_cast_or_null<Defined>(Sym))
-      if (auto *IS = cast_or_null<InputSectionBase>(D->Section))
+      if (auto *IS = dyn_cast_or_null<InputSectionBase>(D->Section))
         Enqueue(IS, D->Value);
   };
 
diff --git a/lld/test/ELF/gc-sections-linker-defined-symbol.s b/lld/test/ELF/gc-sections-linker-defined-symbol.s
new file mode 100644
index 00000000000..8720b845091
--- /dev/null
+++ b/lld/test/ELF/gc-sections-linker-defined-symbol.s
@@ -0,0 +1,16 @@
+# REQUIRES: x86
+
+# RUN: llvm-mc -filetype=obj -triple=x86_64-pc-linux %s -o %t.o
+# RUN: ld.lld %t.o -o %t.so --gc-sections -shared
+# RUN: llvm-readobj --dyn-symbols %t.so | FileCheck %s
+
+# CHECK:      Name: _end@
+# CHECK-NEXT: Value:
+# CHECK-NEXT: Size:
+# CHECK-NEXT: Binding: Global
+# CHECK-NEXT: Type: None
+# CHECK-NEXT: Other:
+# CHECK-NEXT: Section: .dynamic
+
+        .data
+        .quad _end