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

7 files changed, 56 insertions, 5 deletions

diff --git a/llvm/lib/CodeGen/AsmPrinter/CodeViewDebug.cpp b/llvm/lib/CodeGen/AsmPrinter/CodeViewDebug.cpp
index 218f8db9cde..e4084856272 100644
--- a/llvm/lib/CodeGen/AsmPrinter/CodeViewDebug.cpp
+++ b/llvm/lib/CodeGen/AsmPrinter/CodeViewDebug.cpp
@@ -860,6 +860,30 @@ void CodeViewDebug::emitDebugInfoForFunction(const Function *GV,
       emitInlinedCallSite(FI, InlinedAt, I->second);
     }
 
+    for (auto Annot : FI.Annotations) {
+      MCSymbol *Label = Annot.first;
+      MDTuple *Strs = cast<MDTuple>(Annot.second);
+      MCSymbol *AnnotBegin = MMI->getContext().createTempSymbol(),
+               *AnnotEnd = MMI->getContext().createTempSymbol();
+      OS.AddComment("Record length");
+      OS.emitAbsoluteSymbolDiff(AnnotEnd, AnnotBegin, 2);
+      OS.EmitLabel(AnnotBegin);
+      OS.AddComment("Record kind: S_ANNOTATION");
+      OS.EmitIntValue(SymbolKind::S_ANNOTATION, 2);
+      OS.EmitCOFFSecRel32(Label, /*Offset=*/0);
+      // FIXME: Make sure we don't overflow the max record size.
+      OS.EmitCOFFSectionIndex(Label);
+      OS.EmitIntValue(Strs->getNumOperands(), 2);
+      for (Metadata *MD : Strs->operands()) {
+        // MDStrings are null terminated, so we can do EmitBytes and get the
+        // nice .asciz directive.
+        StringRef Str = cast<MDString>(MD)->getString();
+        assert(Str.data()[Str.size()] == '\0' && "non-nullterminated MDString");
+        OS.EmitBytes(StringRef(Str.data(), Str.size() + 1));
+      }
+      OS.EmitLabel(AnnotEnd);
+    }
+
     if (SP != nullptr)
       emitDebugInfoForUDTs(LocalUDTs);
 
@@ -2195,6 +2219,8 @@ void CodeViewDebug::endFunctionImpl(const MachineFunction *MF) {
     return;
   }
 
+  CurFn->Annotations = MF->getCodeViewAnnotations();
+
   CurFn->End = Asm->getFunctionEnd();
 
   CurFn = nullptr;
diff --git a/llvm/lib/CodeGen/AsmPrinter/CodeViewDebug.h b/llvm/lib/CodeGen/AsmPrinter/CodeViewDebug.h
index fe4f0a0092c..b87b1ce2cbb 100644
--- a/llvm/lib/CodeGen/AsmPrinter/CodeViewDebug.h
+++ b/llvm/lib/CodeGen/AsmPrinter/CodeViewDebug.h
@@ -119,6 +119,8 @@ class LLVM_LIBRARY_VISIBILITY CodeViewDebug : public DebugHandlerBase {
 
     SmallVector<LocalVariable, 1> Locals;
 
+    std::vector<std::pair<MCSymbol *, MDNode *>> Annotations;
+
     const MCSymbol *Begin = nullptr;
     const MCSymbol *End = nullptr;
     unsigned FuncId = 0;
diff --git a/llvm/lib/CodeGen/MachineFunction.cpp b/llvm/lib/CodeGen/MachineFunction.cpp
index c4c0dff7bdf..ae7efe2fde6 100644
--- a/llvm/lib/CodeGen/MachineFunction.cpp
+++ b/llvm/lib/CodeGen/MachineFunction.cpp
@@ -166,6 +166,7 @@ void MachineFunction::clear() {
   InstructionRecycler.clear(Allocator);
   OperandRecycler.clear(Allocator);
   BasicBlockRecycler.clear(Allocator);
+  CodeViewAnnotations.clear();
   VariableDbgInfos.clear();
   if (RegInfo) {
     RegInfo->~MachineRegisterInfo();
diff --git a/llvm/lib/CodeGen/SelectionDAG/InstrEmitter.cpp b/llvm/lib/CodeGen/SelectionDAG/InstrEmitter.cpp
index 1d20c5a67b6..7a123e3e92e 100644
--- a/llvm/lib/CodeGen/SelectionDAG/InstrEmitter.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/InstrEmitter.cpp
@@ -935,10 +935,14 @@ EmitSpecialNode(SDNode *Node, bool IsClone, bool IsCloned,
     EmitCopyFromReg(Node, 0, IsClone, IsCloned, SrcReg, VRBaseMap);
     break;
   }
-  case ISD::EH_LABEL: {
-    MCSymbol *S = cast<EHLabelSDNode>(Node)->getLabel();
+  case ISD::EH_LABEL:
+  case ISD::ANNOTATION_LABEL: {
+    unsigned Opc = (Node->getOpcode() == ISD::EH_LABEL)
+                       ? TargetOpcode::EH_LABEL
+                       : TargetOpcode::ANNOTATION_LABEL;
+    MCSymbol *S = cast<LabelSDNode>(Node)->getLabel();
     BuildMI(*MBB, InsertPos, Node->getDebugLoc(),
-            TII->get(TargetOpcode::EH_LABEL)).addSym(S);
+            TII->get(Opc)).addSym(S);
     break;
   }
 
diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp b/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
index d00ecafd580..29901fb174f 100644
--- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
@@ -1680,15 +1680,20 @@ SDValue SelectionDAG::getRegisterMask(const uint32_t *RegMask) {
 
 SDValue SelectionDAG::getEHLabel(const SDLoc &dl, SDValue Root,
                                  MCSymbol *Label) {
+  return getLabelNode(ISD::EH_LABEL, dl, Root, Label);
+}
+
+SDValue SelectionDAG::getLabelNode(unsigned Opcode, const SDLoc &dl,
+                                   SDValue Root, MCSymbol *Label) {
   FoldingSetNodeID ID;
   SDValue Ops[] = { Root };
-  AddNodeIDNode(ID, ISD::EH_LABEL, getVTList(MVT::Other), Ops);
+  AddNodeIDNode(ID, Opcode, getVTList(MVT::Other), Ops);
   ID.AddPointer(Label);
   void *IP = nullptr;
   if (SDNode *E = FindNodeOrInsertPos(ID, IP))
     return SDValue(E, 0);
 
-  auto *N = newSDNode<EHLabelSDNode>(dl.getIROrder(), dl.getDebugLoc(), Label);
+  auto *N = newSDNode<LabelSDNode>(dl.getIROrder(), dl.getDebugLoc(), Label);
   createOperands(N, Ops);
 
   CSEMap.InsertNode(N, IP);
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());
 
diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
index 4d43a3b41f8..48dc09339a6 100644
--- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
@@ -2911,6 +2911,7 @@ void SelectionDAGISel::SelectCodeCommon(SDNode *NodeToMatch,
   case ISD::CopyFromReg:
   case ISD::CopyToReg:
   case ISD::EH_LABEL:
+  case ISD::ANNOTATION_LABEL:
   case ISD::LIFETIME_START:
   case ISD::LIFETIME_END:
     NodeToMatch->setNodeId(-1); // Mark selected.