[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, 16 insertions, 0 deletions

diff --git a/llvm/lib/CodeGen/MachineInstr.cpp b/llvm/lib/CodeGen/MachineInstr.cpp
index 92abd84c56b..c0e1a7bef04 100644
--- a/llvm/lib/CodeGen/MachineInstr.cpp
+++ b/llvm/lib/CodeGen/MachineInstr.cpp
@@ -613,6 +613,11 @@ int MachineInstr::findInlineAsmFlagIdx(unsigned OpIdx,
   return -1;
 }
 
+const DILabel *MachineInstr::getDebugLabel() const {
+  assert(isDebugLabel() && "not a DBG_LABEL");
+  return cast<DILabel>(getOperand(0).getMetadata());
+}
+
 const DILocalVariable *MachineInstr::getDebugVariable() const {
   assert(isDebugValue() && "not a DBG_VALUE");
   return cast<DILocalVariable>(getOperand(2).getMetadata());
@@ -1383,6 +1388,17 @@ void MachineInstr::print(raw_ostream &OS, ModuleSlotTracker &MST,
         MO.print(OS, MST, TypeToPrint, /*PrintDef=*/true, IsStandalone,
                  ShouldPrintRegisterTies, TiedOperandIdx, TRI, IntrinsicInfo);
       }
+    } else if (isDebugLabel() && MO.isMetadata()) {
+      // Pretty print DBG_LABEL instructions.
+      auto *DIL = dyn_cast<DILabel>(MO.getMetadata());
+      if (DIL && !DIL->getName().empty())
+        OS << "\"" << DIL->getName() << '\"';
+      else {
+        LLT TypeToPrint = MRI ? getTypeToPrint(i, PrintedTypes, *MRI) : LLT{};
+        unsigned TiedOperandIdx = getTiedOperandIdx(i);
+        MO.print(OS, MST, TypeToPrint, /*PrintDef=*/true, IsStandalone,
+                 ShouldPrintRegisterTies, TiedOperandIdx, TRI, IntrinsicInfo);
+      }
     } else if (i == AsmDescOp && MO.isImm()) {
       // Pretty print the inline asm operand descriptor.
       OS << '$' << AsmOpCount++;