[TableGen] Fix null pointer dereferencing in token parser.

Reported in https://www.viva64.com/en/b/0629/

llvm-svn: 359559

1 files changed, 10 insertions, 8 deletions

diff --git a/llvm/lib/TableGen/TGParser.cpp b/llvm/lib/TableGen/TGParser.cpp
index 937de9e5c52..6a460870aa9 100644
--- a/llvm/lib/TableGen/TGParser.cpp
+++ b/llvm/lib/TableGen/TGParser.cpp
@@ -2189,14 +2189,15 @@ Init *TGParser::ParseValue(Record *CurRec, RecTy *ItemType, IDParseMode Mode) {
       // Create a !strconcat() operation, first casting each operand to
       // a string if necessary.
       if (LHS->getType() != StringRecTy::get()) {
-        LHS = dyn_cast<TypedInit>(
+        auto CastLHS = dyn_cast<TypedInit>(
             UnOpInit::get(UnOpInit::CAST, LHS, StringRecTy::get())
                 ->Fold(CurRec));
-        if (!LHS) {
-          Error(PasteLoc, Twine("can't cast '") + LHS->getAsString() +
-                              "' to string");
+        if (!CastLHS) {
+          Error(PasteLoc,
+                Twine("can't cast '") + LHS->getAsString() + "' to string");
           return nullptr;
         }
+        LHS = CastLHS;
       }
 
       TypedInit *RHS = nullptr;
@@ -2223,14 +2224,15 @@ Init *TGParser::ParseValue(Record *CurRec, RecTy *ItemType, IDParseMode Mode) {
         }
 
         if (RHS->getType() != StringRecTy::get()) {
-          RHS = dyn_cast<TypedInit>(
+          auto CastRHS = dyn_cast<TypedInit>(
               UnOpInit::get(UnOpInit::CAST, RHS, StringRecTy::get())
                   ->Fold(CurRec));
-          if (!RHS) {
-            Error(PasteLoc, Twine("can't cast '") + RHS->getAsString() +
-                                "' to string");
+          if (!CastRHS) {
+            Error(PasteLoc,
+                  Twine("can't cast '") + RHS->getAsString() + "' to string");
             return nullptr;
           }
+          RHS = CastRHS;
         }
 
         break;