1 files changed, 51 insertions, 0 deletions
diff --git a/llvm/lib/CodeGen/AsmPrinter/DebugHandlerBase.cpp b/llvm/lib/CodeGen/AsmPrinter/DebugHandlerBase.cpp
index 0971c59..4f647de 100644
--- a/llvm/lib/CodeGen/AsmPrinter/DebugHandlerBase.cpp
+++ b/llvm/lib/CodeGen/AsmPrinter/DebugHandlerBase.cpp
@@ -23,6 +23,57 @@
 
 using namespace llvm;
 
+bool DbgVariableLocation::extractFromMachineInstruction(
+    DbgVariableLocation &Location, const MachineInstr &Instruction) {
+  if (!Instruction.isDebugValue())
+    return false;
+  if (!Instruction.getOperand(0).isReg())
+    return false;
+  Location.Register = Instruction.getOperand(0).getReg();
+  Location.InMemory = Instruction.getOperand(1).isImm();
+  Location.Deref = false;
+  Location.FragmentInfo.reset();
+  // We only handle expressions generated by DIExpression::appendOffset,
+  // which doesn't require a full stack machine.
+  int64_t Offset = 0;
+  const DIExpression *DIExpr = Instruction.getDebugExpression();
+  auto Op = DIExpr->expr_op_begin();
+  while (Op != DIExpr->expr_op_end()) {
+    switch (Op->getOp()) {
+    case dwarf::DW_OP_constu: {
+      int Value = Op->getArg(0);
+      ++Op;
+      if (Op != DIExpr->expr_op_end()) {
+        switch (Op->getOp()) {
+        case dwarf::DW_OP_minus:
+          Offset -= Value;
+          break;
+        case dwarf::DW_OP_plus:
+          Offset += Value;
+        default:
+          continue;
+        }
+      }
+    } break;
+    case dwarf::DW_OP_plus_uconst:
+      Offset += Op->getArg(0);
+      break;
+    case dwarf::DW_OP_LLVM_fragment:
+      Location.FragmentInfo = {Op->getArg(1), Op->getArg(0)};
+      break;
+    case dwarf::DW_OP_deref:
+      Location.Deref = true;
+      break;
+    default:
+      return false;
+    }
+    ++Op;
+  }
+
+  Location.Offset = Offset;
+  return true;
+}
+
 DebugHandlerBase::DebugHandlerBase(AsmPrinter *A) : Asm(A), MMI(Asm->MMI) {}
 
 // Each LexicalScope has first instruction and last instruction to mark