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

2 files changed, 11 insertions, 8 deletions

diff --git a/llvm/lib/CodeGen/SelectionDAG/LegalizeTypes.cpp b/llvm/lib/CodeGen/SelectionDAG/LegalizeTypes.cpp
index b42edf8e751..0d85bccdeac 100644
--- a/llvm/lib/CodeGen/SelectionDAG/LegalizeTypes.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/LegalizeTypes.cpp
@@ -849,13 +849,14 @@ static void transferDbgValues(SelectionDAG &DAG, SDValue From, SDValue To,
       break;
 
     DIVariable *Var = Dbg->getVariable();
-    auto *Fragment = DIExpression::createFragmentExpression(
-        Dbg->getExpression(), OffsetInBits, To.getValueSizeInBits());
-    SDDbgValue *Clone =
-        DAG.getDbgValue(Var, Fragment, ToNode, To.getResNo(), Dbg->isIndirect(),
-                        Dbg->getDebugLoc(), Dbg->getOrder());
+    if (auto Fragment = DIExpression::createFragmentExpression(
+            Dbg->getExpression(), OffsetInBits, To.getValueSizeInBits())) {
+      SDDbgValue *Clone = DAG.getDbgValue(Var, *Fragment, ToNode, To.getResNo(),
+                                          Dbg->isIndirect(), Dbg->getDebugLoc(),
+                                          Dbg->getOrder());
+      ClonedDVs.push_back(Clone);
+    }
     Dbg->setIsInvalidated();
-    ClonedDVs.push_back(Clone);
   }
 
   for (SDDbgValue *Dbg : ClonedDVs)
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;
           }
         }