1 files changed, 10 insertions, 0 deletions
diff --git a/llvm/utils/TableGen/Common/CodeGenRegisters.cpp b/llvm/utils/TableGen/Common/CodeGenRegisters.cpp
index 3c868b1e8f4f..b5a6c1395c60 100644
--- a/llvm/utils/TableGen/Common/CodeGenRegisters.cpp
+++ b/llvm/utils/TableGen/Common/CodeGenRegisters.cpp
@@ -22,6 +22,7 @@
 #include "llvm/ADT/SmallSet.h"
 #include "llvm/ADT/SmallVector.h"
 #include "llvm/ADT/StringRef.h"
+#include "llvm/ADT/StringSet.h"
 #include "llvm/ADT/Twine.h"
 #include "llvm/Support/Debug.h"
 #include "llvm/Support/raw_ostream.h"
@@ -618,6 +619,9 @@ struct TupleExpander : SetTheory::Expander {
   // the synthesized definitions for their lifetime.
   std::vector<std::unique_ptr<Record>> &SynthDefs;
 
+  // Track all synthesized tuple names in order to detect duplicate definitions.
+  llvm::StringSet<> TupleNames;
+
   TupleExpander(std::vector<std::unique_ptr<Record>> &SynthDefs)
       : SynthDefs(SynthDefs) {}
 
@@ -684,6 +688,12 @@ struct TupleExpander : SetTheory::Expander {
       Record *NewReg = SynthDefs.back().get();
       Elts.insert(NewReg);
 
+      // Detect duplicates among synthesized registers.
+      const auto Res = TupleNames.insert(NewReg->getName());
+      if (!Res.second)
+        PrintFatalError(Def->getLoc(),
+                        "Register tuple redefines register '" + Name + "'.");
+
       // Copy Proto super-classes.
       ArrayRef<std::pair<Record *, SMRange>> Supers = Proto->getSuperClasses();
       for (const auto &SuperPair : Supers)