ThinLTOBitcodeWriter: Include globals associated with type metadata globals in the...

Globals that are associated with globals with type metadata need to appear
in the merged module because they will reference the global's section directly.

Differential Revision: https://reviews.llvm.org/D65312

llvm-svn: 367242

diff --git a/llvm/lib/Transforms/IPO/ThinLTOBitcodeWriter.cpp b/llvm/lib/Transforms/IPO/ThinLTOBitcodeWriter.cpp
index 24c4763..f0dea11 100644 (file)
--- a/llvm/lib/Transforms/IPO/ThinLTOBitcodeWriter.cpp
+++ b/llvm/lib/Transforms/IPO/ThinLTOBitcodeWriter.cpp
@@ -218,10 +218,18 @@ void splitAndWriteThinLTOBitcode(
 
   promoteTypeIds(M, ModuleId);
 
-  // Returns whether a global has attached type metadata. Such globals may
-  // participate in CFI or whole-program devirtualization, so they need to
-  // appear in the merged module instead of the thin LTO module.
+  // Returns whether a global or its associated global has attached type
+  // metadata. The former may participate in CFI or whole-program
+  // devirtualization, so they need to appear in the merged module instead of
+  // the thin LTO module. Similarly, globals that are associated with globals
+  // with type metadata need to appear in the merged module because they will
+  // reference the global's section directly.
   auto HasTypeMetadata = [](const GlobalObject *GO) {
+    if (MDNode *MD = GO->getMetadata(LLVMContext::MD_associated))
+      if (auto *AssocVM = dyn_cast_or_null<ValueAsMetadata>(MD->getOperand(0)))
+        if (auto *AssocGO = dyn_cast<GlobalObject>(AssocVM->getValue()))
+          if (AssocGO->hasMetadata(LLVMContext::MD_type))
+            return true;
     return GO->hasMetadata(LLVMContext::MD_type);
   };
 

diff --git a/llvm/test/Transforms/ThinLTOBitcodeWriter/associated.ll b/llvm/test/Transforms/ThinLTOBitcodeWriter/associated.ll
new file mode 100644 (file)
index 0000000..600791d
--- /dev/null
+++ b/llvm/test/Transforms/ThinLTOBitcodeWriter/associated.ll
@@ -0,0 +1,14 @@
+; RUN: opt -thinlto-bc -thinlto-split-lto-unit -o %t %s
+; RUN: llvm-modextract -b -n 0 -o - %t | llvm-dis | FileCheck --check-prefix=M0 %s
+; RUN: llvm-modextract -b -n 1 -o - %t | llvm-dis | FileCheck --check-prefix=M1 %s
+
+; M0: @g = external constant
+; M0-NOT: @assoc
+; M1: @g = constant i8 1
+; M1: @assoc = private constant i8 2
+
+@g = constant i8 1, !type !0
+@assoc = private constant i8 2, !associated !1
+
+!0 = !{i32 0, !"typeid"}
+!1 = !{i8* @g}