3 files changed, 19 insertions, 1 deletions
diff --git a/llvm/lib/CodeGen/AsmPrinter/DwarfExpression.cpp b/llvm/lib/CodeGen/AsmPrinter/DwarfExpression.cpp
index 55397c3ac09..f65dc151f30 100644
--- a/llvm/lib/CodeGen/AsmPrinter/DwarfExpression.cpp
+++ b/llvm/lib/CodeGen/AsmPrinter/DwarfExpression.cpp
@@ -226,8 +226,15 @@ bool DwarfExpression::addMachineRegExpression(const TargetRegisterInfo &TRI,
     return true;
   }
 
-  // FIXME:
   // Don't emit locations that cannot be expressed without DW_OP_stack_value.
+  if (DwarfVersion < 4)
+    if (std::any_of(ExprCursor.begin(), ExprCursor.end(),
+                    [](DIExpression::ExprOperand Op) -> bool {
+                      return Op.getOp() == dwarf::DW_OP_stack_value;
+                    })) {
+      DwarfRegs.clear();
+      return false;
+    }
 
   assert(DwarfRegs.size() == 1);
   auto Reg = DwarfRegs[0];
diff --git a/llvm/lib/CodeGen/AsmPrinter/DwarfExpression.h b/llvm/lib/CodeGen/AsmPrinter/DwarfExpression.h
index 203990dd3c9..de861320006 100644
--- a/llvm/lib/CodeGen/AsmPrinter/DwarfExpression.h
+++ b/llvm/lib/CodeGen/AsmPrinter/DwarfExpression.h
@@ -72,6 +72,8 @@ public:
   }
   /// Determine whether there are any operations left in this expression.
   operator bool() const { return Start != End; }
+  DIExpression::expr_op_iterator begin() const { return Start; }
+  DIExpression::expr_op_iterator end() const { return End; }
 
   /// Retrieve the fragment information, if any.
   Optional<DIExpression::FragmentInfo> getFragmentInfo() const {
diff --git a/llvm/test/DebugInfo/X86/dw_op_minus_direct.ll b/llvm/test/DebugInfo/X86/dw_op_minus_direct.ll
index a204b29848f..8d346be532e 100644
--- a/llvm/test/DebugInfo/X86/dw_op_minus_direct.ll
+++ b/llvm/test/DebugInfo/X86/dw_op_minus_direct.ll
@@ -1,11 +1,20 @@
 ; Test dwarf codegen of DW_OP_minus.
 ; RUN: llc -filetype=obj < %s | llvm-dwarfdump - | FileCheck %s
+; RUN: llc -dwarf-version=2 -filetype=obj < %s | llvm-dwarfdump - \
+; RUN:   | FileCheck %s --check-prefix=DWARF2
+; RUN: llc -dwarf-version=3 -filetype=obj < %s | llvm-dwarfdump - \
+; RUN:   | FileCheck %s --check-prefix=DWARF2
 
 ; This was derived manually from:
 ; int inc(int i) {
 ;  return i+1;
 ; }
 
+; DWARF2: .debug_info
+; DWARF2: DW_TAG_formal_parameter
+; DWARF2-NEXT: DW_AT_name {{.*}}"i"
+; DWARF2-NOT:  DW_AT_location
+
 ; CHECK: Beginning address offset: 0x0000000000000000
 ; CHECK:    Ending address offset: 0x0000000000000004
 ; CHECK:     Location description: 70 00 10 ff ff ff ff 0f 1a 10 01 1c 9f