[DebugInfo] Convert intrinsic llvm.dbg.label to MachineInstr.

In order to convert LLVM IR to MachineInstr, we need a new TargetOpcode,
DBG_LABEL, to ‘lower’ intrinsic llvm.dbg.label. The patch
creates this new TargetOpcode and convert intrinsic llvm.dbg.label to
MachineInstr through SelectionDAG.

In SelectionDAG, debug information is stored in SDDbgInfo. We create a
new data member of SDDbgInfo for labels and use the new data member,
SDDbgLabel, to create DBG_LABEL MachineInstr.

The new DBG_LABEL MachineInstr uses label metadata from LLVM IR as its
parameter. So, the backend could get metadata information of labels from
DBG_LABEL MachineInstr.

Differential Revision: https://reviews.llvm.org/D45341

Patch by Hsiangkai Wang.

llvm-svn: 331842

1 files changed, 22 insertions, 0 deletions

diff --git a/llvm/lib/CodeGen/SelectionDAG/SDNodeDbgValue.h b/llvm/lib/CodeGen/SelectionDAG/SDNodeDbgValue.h
index 166ff7127da..703eaa453ab 100644
--- a/llvm/lib/CodeGen/SelectionDAG/SDNodeDbgValue.h
+++ b/llvm/lib/CodeGen/SelectionDAG/SDNodeDbgValue.h
@@ -128,6 +128,28 @@ public:
   bool isInvalidated() const { return Invalid; }
 };
 
+/// Holds the information from a dbg_label node through SDISel.
+/// We do not use SDValue here to avoid including its header.
+class SDDbgLabel {
+  MDNode *Label;
+  DebugLoc DL;
+  unsigned Order;
+
+public:
+  SDDbgLabel(MDNode *Label, DebugLoc dl, unsigned O)
+      : Label(Label), DL(std::move(dl)), Order(O) {}
+
+  /// Returns the MDNode pointer for the label.
+  MDNode *getLabel() const { return Label; }
+
+  /// Returns the DebugLoc.
+  DebugLoc getDebugLoc() const { return DL; }
+
+  /// Returns the SDNodeOrder.  This is the order of the preceding node in the
+  /// input.
+  unsigned getOrder() const { return Order; }
+};
+
 } // end llvm namespace
 
 #endif