Make DIExpression::createFragmentExpression() return an Optional.

We can't safely split arithmetic into multiple fragments because we
can't express carry-over between fragments.

llvm-svn: 317534

1 files changed, 4 insertions, 2 deletions

diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
index f45e264f6e2..5579449107e 100644
--- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
@@ -4873,11 +4873,13 @@ bool SelectionDAGBuilder::EmitFuncArgumentDbgValue(
           for (unsigned E = I + RegCount; I != E; ++I) {
             // The vregs are guaranteed to be allocated in sequence.
             Op = MachineOperand::CreateReg(VMI->second + I, false);
-            auto *FragmentExpr = DIExpression::createFragmentExpression(
+            auto FragmentExpr = DIExpression::createFragmentExpression(
                 Expr, Offset, RegisterSize);
+            if (!FragmentExpr)
+              continue;
             FuncInfo.ArgDbgValues.push_back(
                 BuildMI(MF, DL, TII->get(TargetOpcode::DBG_VALUE), IsDbgDeclare,
-                        Op->getReg(), Variable, FragmentExpr));
+                        Op->getReg(), Variable, *FragmentExpr));
             Offset += RegisterSize;
           }
         }