[ASTImporter] Import fix of GCCAsmStmts w/ missing symbolic operands

Patch by Zoltan Gera!

Differential Revision: https://reviews.llvm.org/D30831

llvm-svn: 297627
diff --git a/clang/lib/AST/ASTImporter.cpp b/clang/lib/AST/ASTImporter.cpp
index 525d82e..2a7768a 100644
--- a/clang/lib/AST/ASTImporter.cpp
+++ b/clang/lib/AST/ASTImporter.cpp
@@ -5218,13 +5218,17 @@
   SmallVector<IdentifierInfo *, 4> Names;
   for (unsigned I = 0, E = S->getNumOutputs(); I != E; I++) {
     IdentifierInfo *ToII = Importer.Import(S->getOutputIdentifier(I));
-    if (!ToII)
+    // ToII is nullptr when no symbolic name is given for output operand
+    // see ParseStmtAsm::ParseAsmOperandsOpt
+    if (!ToII && S->getOutputIdentifier(I))
       return nullptr;
     Names.push_back(ToII);
   }
   for (unsigned I = 0, E = S->getNumInputs(); I != E; I++) {
     IdentifierInfo *ToII = Importer.Import(S->getInputIdentifier(I));
-    if (!ToII)
+    // ToII is nullptr when no symbolic name is given for input operand
+    // see ParseStmtAsm::ParseAsmOperandsOpt
+    if (!ToII && S->getInputIdentifier(I))
       return nullptr;
     Names.push_back(ToII);
   }