Object: Downgrade invalid weak externals from an assert fail to an llvm::Error when creating an irsymtab.

This fixes bitcode emission for modules containing invalid weak externals.

llvm-svn: 312686

2 files changed, 17 insertions, 3 deletions

diff --git a/llvm/lib/Object/IRSymtab.cpp b/llvm/lib/Object/IRSymtab.cpp
index 668cf62d1e8..7fc84e2046c 100644
--- a/llvm/lib/Object/IRSymtab.cpp
+++ b/llvm/lib/Object/IRSymtab.cpp
@@ -231,11 +231,14 @@ Error Builder::addSymbol(const ModuleSymbolTable &Msymtab,
 
     if ((Flags & object::BasicSymbolRef::SF_Weak) &&
         (Flags & object::BasicSymbolRef::SF_Indirect)) {
+      auto *Fallback = dyn_cast<GlobalValue>(
+          cast<GlobalAlias>(GV)->getAliasee()->stripPointerCasts());
+      if (!Fallback)
+        return make_error<StringError>("Invalid weak external",
+                                       inconvertibleErrorCode());
       std::string FallbackName;
       raw_string_ostream OS(FallbackName);
-      Msymtab.printSymbolName(
-          OS, cast<GlobalValue>(
-                  cast<GlobalAlias>(GV)->getAliasee()->stripPointerCasts()));
+      Msymtab.printSymbolName(OS, Fallback);
       OS.flush();
       setStr(Uncommon().COFFWeakExternFallbackName, Saver.save(FallbackName));
     }
diff --git a/llvm/test/Bitcode/invalid-weak-external.ll b/llvm/test/Bitcode/invalid-weak-external.ll
new file mode 100644
index 00000000000..def93ec51da
--- /dev/null
+++ b/llvm/test/Bitcode/invalid-weak-external.ll
@@ -0,0 +1,11 @@
+; REQUIRES: x86-registered-target
+; RUN: opt -o %t %s
+; RUN: not llvm-lto2 dump-symtab %t 2>&1 | FileCheck %s
+
+target datalayout = "e-m:x-p:32:32-i64:64-f80:32-n8:16:32-a:0:32-S32"
+target triple = "x86_64-pc-windows-msvc"
+
+@bar = global i32 0
+
+; CHECK: Invalid weak external
+@foo = weak alias i32, i32* getelementptr (i32, i32* @bar, i32 1)