[llvm-objdump] Add call_frame_cfa locations to variable display

[jhenderson]

llvm/unittests/DebugInfo/DWARF/DWARFExpressionCompactPrinterTest.cpp

157

I'm not up to speed on the DW_OP values. What does this value represent?

Assuming that the "0x78" is something to do with the -8, you probably want more values, and to test the bounds of whatever it can be.

[MaskRay]

ping @ostannard

llvm/lib/DebugInfo/DWARF/DWARFExpression.cpp

case dwarf::DW_OP_fbreg: {
         S << "<unknown frame base>";
       }
       int64_t Offset = Op.getRawOperand(0);
       if (Offset)
         S << format("%+" PRId64, Offset);
 
       break;
     }
+    case dwarf::DW_OP_call_frame_cfa: {
+      // The canonical frame address, typically defined as the stack pointer at
+      // function entry.
+      raw_svector_ostream S(Stack.emplace_back().String);
+      S << "CFA";
+      break;
+    }
     default:
       if (Opcode >= dwarf::DW_OP_reg0 && Opcode <= dwarf::DW_OP_reg31) {
         // DW_OP_reg<N>: A register, with the register num implied by the
         // opcode. Printed as the plain register name.
         uint64_t DwarfRegNum = Opcode - dwarf::DW_OP_reg0;
         Optional<unsigned> LLVMRegNum = MRI.getLLVMRegNum(DwarfRegNum, false);
         if (!LLVMRegNum) {
           OS << "<unknown register " << DwarfRegNum << ">";

llvm/unittests/DebugInfo/DWARF/DWARFExpressionCompactPrinterTest.cpp

TEST_F(DWARFExpressionCompactPrinterTest, Test_OP_entry_value_mem) {
   TestExprPrinter(
       {DW_OP_entry_value, 0x02, DW_OP_breg13, 0x10, DW_OP_stack_value},
       "entry([SP+16])");
 }
 
 TEST_F(DWARFExpressionCompactPrinterTest, Test_OP_fbreg) {
   TestExprPrinter({DW_OP_fbreg, 0x8}, "[R11+8]", {DW_OP_reg11});
 }
+
+TEST_F(DWARFExpressionCompactPrinterTest, Test_OP_cfa) {
+  TestExprPrinter({DW_OP_call_frame_cfa}, "[CFA]");
+}
+
+TEST_F(DWARFExpressionCompactPrinterTest, Test_OP_fbreg_cfa) {
+  TestExprPrinter({DW_OP_fbreg, 0x78}, "[CFA-8]", {DW_OP_call_frame_cfa});
+}