[mlir][spirv] Fix extended insts deserialization generation

[kdobros]

Summary

This change replaces container used for storing temporary strings for generated code to std::list.
SmallVector may reallocate internal data, which will invalidate references when more than one extended instruction set is generated.

[kdobros]

Hi @antiagainst,
Could you merge on my behalf? I don't have write access.

[kdobros]

In D88626#2306612, @kdobros wrote:

Hi @antiagainst,
Could you merge on my behalf? I don't have write access.

Courtesy ping.
This change is rather important for me, it's blocking my next patch with few OpenCL extended instructions.
Could you help me with this?

[antiagainst]

Oops, sorry this slipped my attention list. Will land shortly.

mlir/tools/mlir-tblgen/SPIRVUtilsGen.cpp

 #include "llvm/ADT/StringRef.h"
 #include "llvm/ADT/StringSet.h"
 #include "llvm/Support/FormatVariadic.h"
 #include "llvm/Support/raw_ostream.h"
 #include "llvm/TableGen/Error.h"
 #include "llvm/TableGen/Record.h"
 #include "llvm/TableGen/TableGenBackend.h"
 
+#include <list>
+
 using llvm::ArrayRef;
 using llvm::formatv;
 using llvm::raw_ostream;
 using llvm::raw_string_ostream;
 using llvm::Record;
 using llvm::RecordKeeper;
 using llvm::SmallVector;
 using llvm::SMLoc;
emitExtendedSetDeserializationDispatch(const RecordKeeper &recordKeeper,
   // First iterate over all ops derived from SPV_ExtensionSetOps to get all
   // extensionSets.
 
   // For each of the extensions a separate raw_string_ostream is used to
   // generate code into. These are then concatenated at the end. Since
   // raw_string_ostream needs a string&, use a vector to store all the string
   // that are captured by reference within raw_string_ostream.
   StringMap<raw_string_ostream> extensionSets;
-  SmallVector<std::string, 1> extensionSetNames;
+  std::list<std::string> extensionSetNames;
 
   initExtendedSetDeserializationDispatch(extensionSetName, instructionID, words,
                                          os);
   auto defs = recordKeeper.getAllDerivedDefinitions("SPV_ExtInstOp");
   for (const auto *def : defs) {
     if (!def->getValueAsBit("autogenSerialization")) {
       continue;
     }