[llvm] r226532 - IR: Canonicalize GenericDwarfNode empty headers to null

[Duncan P. N. Exon Smith]

Author: dexonsmith
Date: Mon Jan 19 18:58:46 2015
New Revision: 226532

URL: http://llvm.org/viewvc/llvm-project?rev=226532&view=rev
Log:
IR: Canonicalize GenericDwarfNode empty headers to null

Modified:
    llvm/trunk/lib/IR/Metadata.cpp
    llvm/trunk/unittests/IR/MetadataTest.cpp

Modified: llvm/trunk/lib/IR/Metadata.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/IR/Metadata.cpp?rev=226532&r1=226531&r2=226532&view=diff
==============================================================================
--- llvm/trunk/lib/IR/Metadata.cpp (original)
+++ llvm/trunk/lib/IR/Metadata.cpp Mon Jan 19 18:58:46 2015
@@ -753,6 +753,10 @@ GenericDwarfNode *GenericDwarfNode::getI
                                             ArrayRef<Metadata *> DwarfOps,
                                             StorageType Storage,
                                             bool ShouldCreate) {
+  // Canonicalize empty string to a nullptr.
+  if (Header && Header->getString().empty())
+    Header = nullptr;
+
   unsigned Hash = 0;
   if (Storage == Uniqued) {
     GenericDwarfNodeInfo::KeyTy Key(Tag, Header, DwarfOps);

Modified: llvm/trunk/unittests/IR/MetadataTest.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/unittests/IR/MetadataTest.cpp?rev=226532&r1=226531&r2=226532&view=diff
==============================================================================
--- llvm/trunk/unittests/IR/MetadataTest.cpp (original)
+++ llvm/trunk/unittests/IR/MetadataTest.cpp Mon Jan 19 18:58:46 2015
@@ -596,6 +596,14 @@ TEST_F(GenericDwarfNodeTest, get) {
   EXPECT_EQ(N, GenericDwarfNode::get(Context, 15, Header, Ops1));
 }
 
+TEST_F(GenericDwarfNodeTest, getEmptyHeader) {
+  // Canonicalize !"" to null.
+  auto *Header = MDString::get(Context, "");
+  EXPECT_NE(nullptr, Header);
+  auto *N = GenericDwarfNode::get(Context, 15, Header, None);
+  EXPECT_EQ(nullptr, N->getHeader());
+}
+
 typedef MetadataTest MetadataAsValueTest;
 
 TEST_F(MetadataAsValueTest, MDNode) {