[SYCL-MLIR] Fix build with clang

[whitneywhtsang]

This PR fixes lit failures when building with clang.

Since 9ac759f, when building with clang, there are two lit failures:

Failed Tests (2):
  cgeist :: Verification/memrefaddassign.cpp
  cgeist :: Verification/ptrarith.c

They crash with traceback:

PLEASE submit a bug report to https://github.com/llvm/llvm-project/issues/ and include the crash backtrace.
Stack dump:
0.      Program arguments: /localdisk2/waihungt/llvm/build/bin/cgeist /localdisk2/waihungt/llvm/polygeist/tools/cgeist/Test/Verification/ptrarith.c --function=* -S
1.      <eof> parser at end of file
 #0 0x00007f1836120043 llvm::sys::PrintStackTrace(llvm::raw_ostream&, int) (/localdisk2/waihungt/llvm/build/bin/../lib/libLLVMSupport.so.16git+0x1e8043)
 #1 0x00007f183611de5e llvm::sys::RunSignalHandlers() (/localdisk2/waihungt/llvm/build/bin/../lib/libLLVMSupport.so.16git+0x1e5e5e)
 #2 0x00007f183612052f SignalHandler(int) Signals.cpp:0:0
 #3 0x00007f1849701b20 __restore_rt sigaction.c:0:0
 #4 0x00000000004d9a6e ValueCategory::SubIndex(mlir::OpBuilder&, mlir::Location, mlir::Type, mlir::Value, bool) const (/localdisk2/waihungt/llvm/build/bin/cgeist+0x4d9a6e)
 #5 0x00000000004da11f ValueCategory::GEPOrSubIndex(mlir::OpBuilder&, mlir::Location, mlir::Type, mlir::ValueRange, bool) const (/localdisk2/waihungt/llvm/build/bin/cgeist+0x4da11f)
 #6 0x00000000004da1bd ValueCategory::InBoundsGEPOrSubIndex(mlir::OpBuilder&, mlir::Location, mlir::Type, mlir::ValueRange) const (/localdisk2/waihungt/llvm/build/bin/cgeist+0x4da1bd)
 #7 0x00000000004b0394 MLIRScanner::EmitCheckedInBoundsPtrOffsetOp(mlir::Type, ValueCategory, mlir::ValueRange, bool, bool) (/localdisk2/waihungt/llvm/build/bin/cgeist+0x4b0394)

Signed-off-by: Tsang, Whitney whitney.tsang@intel.com

[victor-eds]

Just for curiosity: Do you know why is this caused?

[whitneywhtsang]

Just for curiosity: Do you know why is this caused?

Good question, not too sure, likely clang expects optional to be used with has_value() and value(), instead of *.