Add getMD API

It's useful for clang codegen.

Author: Pierre-vh

llvm/include/llvm/IR/MemoryModelRelaxationAnnotations.h

@@ -24,6 +24,9 @@
 
 namespace llvm {
 
+template<typename T>
+class ArrayRef;
+
 class MDNode;
 class MDTuple;
 class Metadata;
@@ -72,6 +75,10 @@ class MMRAMetadata {
     return getTagMD(Ctx, T.first, T.second);
   }
 
+  /// Creates !mmra metadata from \p Tags.
+  /// \returns nullptr or a MDTuple* from \p Tags.
+  static MDTuple *getMD(LLVMContext &Ctx, ArrayRef<TagT> Tags);
+
   /// \returns true if \p MD is a well-formed MMRA tag.
   static bool isTagMD(const Metadata *MD);
 

llvm/lib/IR/MemoryModelRelaxationAnnotations.cpp

@@ -62,6 +62,19 @@ MDTuple *MMRAMetadata::getTagMD(LLVMContext &Ctx, StringRef Prefix,
                       {MDString::get(Ctx, Prefix), MDString::get(Ctx, Suffix)});
 }
 
+MDTuple *MMRAMetadata::getMD(LLVMContext &Ctx, ArrayRef<MMRAMetadata::TagT> Tags) {
+  if (Tags.empty())
+    return nullptr;
+
+  if (Tags.size() == 1)
+    return getTagMD(Ctx, Tags.front());
+
+  SmallVector<Metadata*> MMRAs;
+  for(const auto &Tag: Tags)
+    MMRAs.push_back(getTagMD(Ctx, Tag));
+  return MDTuple::get(Ctx, MMRAs);
+}
+
 MDNode *MMRAMetadata::combine(LLVMContext &Ctx, const MMRAMetadata &A,
                               const MMRAMetadata &B) {
   // Let A and B be two tags set, and U be the prefix-wise union of A and B.

llvm/unittests/IR/MemoryModelRelaxationAnnotationsTest.cpp

@@ -52,6 +52,27 @@ TEST(MMRATest, MDParse) {
   checkMMRA(NestedMMRA, {{"foo", "bar"}, {"bux", "qux"}});
 }
 
+TEST(MMRATest, GetMD) {
+  LLVMContext Ctx;
+
+  EXPECT_EQ(MMRAMetadata::getMD(Ctx, {}), nullptr);
+
+  MDTuple* SingleMD = MMRAMetadata::getMD(Ctx, {{"foo", "bar"}});
+  EXPECT_EQ(SingleMD->getNumOperands(), 2);
+  EXPECT_EQ(cast<MDString>(SingleMD->getOperand(0))->getString(), "foo");
+  EXPECT_EQ(cast<MDString>(SingleMD->getOperand(1))->getString(), "bar");
+
+  MDTuple* MultiMD = MMRAMetadata::getMD(Ctx, {{"foo", "bar"}, {"bux", "qux"}});
+  EXPECT_EQ(MultiMD->getNumOperands(), 2);
+
+  MDTuple* FooBar = cast<MDTuple>(MultiMD->getOperand(0));
+  EXPECT_EQ(cast<MDString>(FooBar->getOperand(0))->getString(), "foo");
+  EXPECT_EQ(cast<MDString>(FooBar->getOperand(1))->getString(), "bar");
+  MDTuple* BuxQux = cast<MDTuple>(MultiMD->getOperand(1));
+  EXPECT_EQ(cast<MDString>(BuxQux->getOperand(0))->getString(), "bux");
+  EXPECT_EQ(cast<MDString>(BuxQux->getOperand(1))->getString(), "qux");
+}
+
 TEST(MMRATest, Utility) {
   LLVMContext Ctx;
   MMRAMetadata MMRA =