[PATCH] D16059: [Verifier] Check parentage of GVs in dbg metadata

[Keno Fischer via llvm-commits]

loladiro created this revision.
loladiro added reviewers: dexonsmith, rafael.
loladiro added a subscriber: llvm-commits.

Before this the Verifier didn't complain if the GlobalVariable
referenced from a DIGlobalVariable was not in fact in the correct
module (it would crash while writing bitcode though). Fix this by
always checking parantage of GlobalValues while walking constant
expressions and changing the DIGlobalVariable visitor to also
visit the constant it contains.

http://reviews.llvm.org/D16059

Files:
  lib/IR/Verifier.cpp
  unittests/IR/VerifierTest.cpp

Index: unittests/IR/VerifierTest.cpp
===================================================================
--- unittests/IR/VerifierTest.cpp
+++ unittests/IR/VerifierTest.cpp
@@ -9,6 +9,7 @@
 
 #include "llvm/IR/Verifier.h"
 #include "llvm/IR/Constants.h"
+#include "llvm/IR/DIBuilder.h"
 #include "llvm/IR/DerivedTypes.h"
 #include "llvm/IR/Function.h"
 #include "llvm/IR/GlobalAlias.h"
@@ -105,7 +106,28 @@
   F3->eraseFromParent();
 }
 
+TEST(VerifierTest, CrossModuleMetadataRef) {
+  LLVMContext &C = getGlobalContext();
+  Module M1("M1", C);
+  Module M2("M2", C);
+  GlobalVariable *newGV =
+      new GlobalVariable(M1, Type::getInt8Ty(C), false,
+                         GlobalVariable::ExternalLinkage, NULL, "Some Global");
+
+  DIBuilder dbuilder(M2);
+  auto CU = dbuilder.createCompileUnit(dwarf::DW_LANG_Julia, "test.jl", ".",
+                                       "unittest", false, "", 0);
+  auto File = dbuilder.createFile("test.jl", ".");
+  auto Ty = dbuilder.createBasicType("Int8", 8, 8, dwarf::DW_ATE_signed);
+  dbuilder.createGlobalVariable(CU, "_SOME_GLOBAL", "_SOME_GLOBAL", File, 1, Ty,
+                                false, newGV);
+  dbuilder.finalize();
 
-
+  std::string Error;
+  raw_string_ostream ErrorOS(Error);
+  EXPECT_TRUE(verifyModule(M2, &ErrorOS));
+  EXPECT_TRUE(StringRef(ErrorOS.str())
+                  .startswith("Referencing global in another module!"));
+}
 }
 }
Index: lib/IR/Verifier.cpp
===================================================================
--- lib/IR/Verifier.cpp
+++ lib/IR/Verifier.cpp
@@ -1047,6 +1047,7 @@
     Assert(isa<ConstantAsMetadata>(V) &&
                !isa<Function>(cast<ConstantAsMetadata>(V)->getValue()),
            "invalid global varaible ref", &N, V);
+    visitConstantExprsRecursively(cast<ConstantAsMetadata>(V)->getValue());
   }
   if (auto *Member = N.getRawStaticDataMemberDeclaration()) {
     Assert(isa<DIDerivedType>(Member), "invalid static data member declaration",
@@ -1511,13 +1512,19 @@
     if (const auto *CE = dyn_cast<ConstantExpr>(C))
       visitConstantExpr(CE);
 
+    if (const auto *GV = dyn_cast<GlobalValue>(C)) {
+      // Global Values get visited separately, but we do need to make sure
+      // that the global value is in the correct module
+      Assert(GV->getParent() == M, "Referencing global in another module!",
+             EntryC, M, GV, GV->getParent());
+      continue;
+    }
+
     // Visit all sub-expressions.
     for (const Use &U : C->operands()) {
       const auto *OpC = dyn_cast<Constant>(U);
       if (!OpC)
         continue;
-      if (isa<GlobalValue>(OpC))
-        continue; // Global values get visited separately.
       if (!ConstantExprVisited.insert(OpC).second)
         continue;
       Stack.push_back(OpC);


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