[WebAssembly] Only mark non-hidden symbols as live if they are also defined

Previously we were also marking undefined symbols (i.e. imports)
as live.

Differential Revision: https://reviews.llvm.org/D48299

llvm-svn: 335243

1 files changed, 3 insertions, 2 deletions

diff --git a/lld/wasm/MarkLive.cpp b/lld/wasm/MarkLive.cpp
index 6b90690cca5..c9dbbf59c95 100644
--- a/lld/wasm/MarkLive.cpp
+++ b/lld/wasm/MarkLive.cpp
@@ -40,6 +40,7 @@ void lld::wasm::markLive() {
   auto Enqueue = [&](Symbol *Sym) {
     if (!Sym || Sym->isLive())
       return;
+    LLVM_DEBUG(dbgs() << "markLive: " << Sym->getName() << "\n");
     Sym->markLive();
     if (Sym->SignatureMismatch)
       error("function signature mismatch: " + Sym->getName());
@@ -52,9 +53,9 @@ void lld::wasm::markLive() {
     Enqueue(Symtab->find(Config->Entry));
   Enqueue(WasmSym::CallCtors);
 
-  // By default we export all non-hidden, so they are gc roots too
+  // We export all defined, non-hidden symbols so they are all gc roots too
   for (Symbol *Sym : Symtab->getSymbols())
-    if (!Sym->isHidden())
+    if (Sym->isDefined() && !Sym->isHidden())
       Enqueue(Sym);
 
   // The ctor functions are all used in the synthetic __wasm_call_ctors