From 327e9bd399f8c1846b1cb967b03cd9f1e54af1e7 Mon Sep 17 00:00:00 2001
From: "Duncan P. N. Exon Smith" <dexonsmith@apple.com>
Date: Fri, 24 Apr 2015 21:53:27 +0000
Subject: [PATCH] Verifier: Function metadata attachments require a body

Add a verifier check that only functions with bodies have metadata
attachments.  This should help catch bugs in frontends and
transformation passes.  Part of PR23340.

llvm-svn: 235784
---
 llvm/lib/IR/Verifier.cpp           | 13 +++++++++++++
 llvm/unittests/IR/MetadataTest.cpp | 18 ++++++++++++++++++
 2 files changed, 31 insertions(+)

diff --git a/llvm/lib/IR/Verifier.cpp b/llvm/lib/IR/Verifier.cpp
index 099cbd9..afce3e2 100644
--- a/llvm/lib/IR/Verifier.cpp
+++ b/llvm/lib/IR/Verifier.cpp
@@ -1669,11 +1669,20 @@ void Verifier::visitFunction(const Function &F) {
              "Function takes metadata but isn't an intrinsic", I, &F);
   }
 
+  // Get the function metadata attachments.
+  SmallVector<std::pair<unsigned, MDNode *>, 4> MDs;
+  F.getAllMetadata(MDs);
+  assert(F.hasMetadata() != MDs.empty() && "Bit out-of-sync");
+
   if (F.isMaterializable()) {
     // Function has a body somewhere we can't see.
+    Assert(MDs.empty(), "unmaterialized function cannot have metadata", &F,
+           MDs.empty() ? nullptr : MDs.front().second);
   } else if (F.isDeclaration()) {
     Assert(F.hasExternalLinkage() || F.hasExternalWeakLinkage(),
            "invalid linkage type for function declaration", &F);
+    Assert(MDs.empty(), "function without a body cannot have metadata", &F,
+           MDs.empty() ? nullptr : MDs.front().second);
   } else {
     // Verify that this function (which has a body) is not named "llvm.*".  It
     // is not legal to define intrinsics.
@@ -1689,6 +1698,10 @@ void Verifier::visitFunction(const Function &F) {
       Assert(!BlockAddress::lookup(Entry)->isConstantUsed(),
              "blockaddress may not be used with the entry block!", Entry);
     }
+
+    // Visit metadata attachments.
+    for (const auto &I : MDs)
+      visitMDNode(*I.second);
   }
 
   // If this function is actually an intrinsic, verify that it is only used in
diff --git a/llvm/unittests/IR/MetadataTest.cpp b/llvm/unittests/IR/MetadataTest.cpp
index 3368221..cb882e7 100644
--- a/llvm/unittests/IR/MetadataTest.cpp
+++ b/llvm/unittests/IR/MetadataTest.cpp
@@ -17,6 +17,7 @@
 #include "llvm/IR/Metadata.h"
 #include "llvm/IR/Module.h"
 #include "llvm/IR/Type.h"
+#include "llvm/IR/Verifier.h"
 #include "llvm/Support/raw_ostream.h"
 #include "gtest/gtest.h"
 using namespace llvm;
@@ -2233,4 +2234,21 @@ TEST_F(FunctionAttachmentTest, dropUnknownMetadata) {
   EXPECT_FALSE(F->hasMetadata());
 }
 
+TEST_F(FunctionAttachmentTest, Verifier) {
+  Function *F = getFunction("foo");
+  F->setMetadata("attach", getTuple());
+
+  // Confirm this has no body.
+  ASSERT_TRUE(F->empty());
+
+  // Functions without a body cannot have metadata attachments (they also can't
+  // be verified directly, so check that the module fails to verify).
+  EXPECT_TRUE(verifyModule(*F->getParent()));
+
+  // Functions with a body can.
+  (void)new UnreachableInst(Context, BasicBlock::Create(Context, "bb", F));
+  EXPECT_FALSE(verifyModule(*F->getParent()));
+  EXPECT_FALSE(verifyFunction(*F));
+}
+
 }
-- 
2.7.4