Add llvm.codeview.annotation to implement MSVC __annotation

Summary:
This intrinsic represents a label with a list of associated metadata
strings. It is modelled as reading and writing inaccessible memory so
that it won't be removed as dead code. I think the intention is that the
annotation strings should appear at most once in the debug info, so I
marked it noduplicate. We are allowed to inline code with annotations as
long as we strip the annotation, but that can be done later.

Reviewers: majnemer

Subscribers: eraman, llvm-commits, hiraditya

Differential Revision: https://reviews.llvm.org/D36904

llvm-svn: 312569

1 files changed, 12 insertions, 0 deletions

diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
index 4da821e6c55..da0a9516fd1 100644
--- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
@@ -5651,6 +5651,18 @@ SelectionDAGBuilder::visitIntrinsicCall(const CallInst &I, unsigned Intrinsic) {
     // Discard annotate attributes and assumptions
     return nullptr;
 
+  case Intrinsic::codeview_annotation: {
+    // Emit a label associated with this metadata.
+    MachineFunction &MF = DAG.getMachineFunction();
+    MCSymbol *Label =
+        MF.getMMI().getContext().createTempSymbol("annotation", true);
+    Metadata *MD = cast<MetadataAsValue>(I.getArgOperand(0))->getMetadata();
+    MF.addCodeViewAnnotation(Label, cast<MDNode>(MD));
+    Res = DAG.getLabelNode(ISD::ANNOTATION_LABEL, sdl, getRoot(), Label);
+    DAG.setRoot(Res);
+    return nullptr;
+  }
+
   case Intrinsic::init_trampoline: {
     const Function *F = cast<Function>(I.getArgOperand(1)->stripPointerCasts());