Refactor the DIExpression fragment query interface (NFC)
... so it becomes available to DIExpressionCursor.

llvm-svn: 290322
diff --git a/llvm/lib/CodeGen/AsmPrinter/CodeViewDebug.cpp b/llvm/lib/CodeGen/AsmPrinter/CodeViewDebug.cpp
index 3d0ae1a..8dde4a1 100644
--- a/llvm/lib/CodeGen/AsmPrinter/CodeViewDebug.cpp
+++ b/llvm/lib/CodeGen/AsmPrinter/CodeViewDebug.cpp
@@ -944,9 +944,10 @@
       unsigned StructOffset = 0;
 
       // Handle fragments.
-      if (DIExpr && DIExpr->isFragment()) {
+      auto Fragment = DIExpr->getFragmentInfo();
+      if (DIExpr && Fragment) {
         IsSubfield = true;
-        StructOffset = DIExpr->getFragmentOffsetInBits() / 8;
+        StructOffset = Fragment->OffsetInBits / 8;
       } else if (DIExpr && DIExpr->getNumElements() > 0) {
         continue; // Ignore unrecognized exprs.
       }