[mlir](convert-vector-to-xegpu) mlir-opt crashes at Operation.cpp:617 with assertion `false && "incorrect fold result type"' failed.

git version: b7c56b5b0a54a6c966a74dfe311fcddcffade521

MLIR Program:
```mlir
module {
func.func @m(%arg0: memref<4x2xf32>, %arg1: vector<4xi32>, %arg2: vector<4xi1>, %arg3: vector<4xf32>) -> vector<4xf32> {
%c0 = arith.constant 0 : index
%0 = vector.gather %arg0[%c0, %c0] [%arg1], %arg2, %arg3 : memref<4x2xf32>, vector<4xi32>, vector<4xi1>, vector<4xf32> into vector<4xf32>
return %0 : vector<4xf32>
}
}
```

Reproduce Command: `mlir-opt -convert-vector-to-xegpu a.mlir`

StackTrace:
```
a.mlir:4:10: error: 'arith.addi' op folder produced a value of incorrect type: 'vector<4xi32>', expected: 'vector<4xindex>'
%0 = vector.gather %arg0[%c0, %c0] [%arg1], %arg2, %arg3 : memref<4x2xf32>, vector<4xi32>, vector<4xi1>, vector<4xf32> into vector<4xf32>
^
a.mlir:4:10: note: see current operation: %8 = "arith.addi"(%6, %7) <{overflowFlags = #arith.overflow}> : (vector<4xi32>, vector<4xindex>) -> vector<4xindex>
mlir-opt: /data2/dependency/dev/llvm-project/mlir/lib/IR/Operation.cpp:617: void checkFoldResultTypes(mlir::Operation*, llvm::SmallVectorImpl&): Assertion `false && "incorrect fold result type"' failed.
PLEASE submit a bug report to https://github.com/llvm/llvm-project/issues/ and include the crash backtrace and instructions to reproduce the bug.
Stack dump:
0. Program arguments: /data2/dependency/dev/llvm-project/build/bin/mlir-opt -convert-vector-to-xegpu a.mlir
#0 0x000055dda730c1df llvm::sys::PrintStackTrace(llvm::raw_ostream&, int) (/data2/dependency/dev/llvm-project/build/bin/mlir-opt+0x25e71df)
#1 0x000055dda730899c llvm::sys::RunSignalHandlers() (/data2/dependency/dev/llvm-project/build/bin/mlir-opt+0x25e399c)
#2 0x000055dda7308b37 SignalHandler(int, siginfo_t*, void*) Signals.cpp:0:0
#3 0x00007fc2eda43420 __restore_rt (/lib/x86_64-linux-gnu/libpthread.so.0+0x14420)
#4 0x00007fc2ed52e00b raise (/lib/x86_64-linux-gnu/libc.so.6+0x4300b)
#5 0x00007fc2ed50d859 abort (/lib/x86_64-linux-gnu/libc.so.6+0x22859)
#6 0x00007fc2ed50d729 (/lib/x86_64-linux-gnu/libc.so.6+0x22729)
#7 0x00007fc2ed51efd6 (/lib/x86_64-linux-gnu/libc.so.6+0x33fd6)
#8 0x000055ddb0514d92 checkFoldResultTypes(mlir::Operation*, llvm::SmallVectorImpl&) (.part.0) Operation.cpp:0:0
#9 0x000055ddb051653c mlir::Operation::fold(llvm::ArrayRef, llvm::SmallVectorImpl&) (/data2/dependency/dev/llvm-project/build/bin/mlir-opt+0xb7f153c)
#10 0x000055ddb0516850 mlir::Operation::fold(llvm::SmallVectorImpl&) (/data2/dependency/dev/llvm-project/build/bin/mlir-opt+0xb7f1850)
#11 0x000055ddb00f41f6 (anonymous namespace)::GreedyPatternRewriteDriver::processWorklist() GreedyPatternRewriteDriver.cpp:0:0
#12 0x000055ddb00f82d6 mlir::applyPatternsGreedily(mlir::Region&, mlir::FrozenRewritePatternSet const&, mlir::GreedyRewriteConfig, bool*) (/data2/dependency/dev/llvm-project/build/bin/mlir-opt+0xb3d32d6)
#13 0x000055ddabe375f7 (anonymous namespace)::ConvertVectorToXeGPUPass::runOnOperation() VectorToXeGPU.cpp:0:0
#14 0x000055ddb01945b1 mlir::detail::OpToOpPassAdaptor::run(mlir::Pass*, mlir::Operation*, mlir::AnalysisManager, bool, unsigned int) (/data2/dependency/dev/llvm-project/build/bin/mlir-opt+0xb46f5b1)
#15 0x000055ddb0194940 mlir::detail::OpToOpPassAdaptor::runPipeline(mlir::OpPassManager&, mlir::Operation*, mlir::AnalysisManager, bool, unsigned int, mlir::PassInstrumentor*, mlir::PassInstrumentation::PipelineParentInfo const*) (/data2/dependency/dev/llvm-project/build/bin/mlir-opt+0xb46f940)
#16 0x000055ddb01969f4 mlir::PassManager::runPasses(mlir::Operation*, mlir::AnalysisManager) (/data2/dependency/dev/llvm-project/build/bin/mlir-opt+0xb4719f4)
#17 0x000055ddb0197a81 mlir::PassManager::run(mlir::Operation*) (/data2/dependency/dev/llvm-project/build/bin/mlir-opt+0xb472a81)
#18 0x000055dda73d227b performActions(llvm::raw_ostream&, std::shared_ptr const&, mlir::MLIRContext*, mlir::MlirOptMainConfig const&) MlirOptMain.cpp:0:0
#19 0x000055dda73d2d23 processBuffer(llvm::raw_ostream&, std::unique_ptr>, llvm::MemoryBufferRef, mlir::MlirOptMainConfig const&, mlir::DialectRegistry&, mlir::SourceMgrDiagnosticVerifierHandler*, llvm::ThreadPoolInterface*) MlirOptMain.cpp:0:0
#20 0x000055dda73d2fab llvm::LogicalResult llvm::function_ref>, llvm::MemoryBufferRef const&, llvm::raw_ostream&)>::callback_fn>, mlir::DialectRegistry&, mlir::MlirOptMainConfig const&)::'lambda'(std::unique_ptr>, llvm::MemoryBufferRef, llvm::raw_ostream&)>(long, std::unique_ptr>, llvm::MemoryBufferRef const&, llvm::raw_ostream&) MlirOptMain.cpp:0:0
#21 0x000055ddb056da75 mlir::splitAndProcessBuffer(std::unique_ptr>, llvm::function_ref>, llvm::MemoryBufferRef const&, llvm::raw_ostream&)>, llvm::raw_ostream&, llvm::StringRef, llvm::StringRef) (/data2/dependency/dev/llvm-project/build/bin/mlir-opt+0xb848a75)
#22 0x000055dda73c90b4 mlir::MlirOptMain(llvm::raw_ostream&, std::unique_ptr>, mlir::DialectRegistry&, mlir::MlirOptMainConfig const&) (.part.0) MlirOptMain.cpp:0:0
#23 0x000055dda73d34c7 mlir::MlirOptMain(int, char**, llvm::StringRef, llvm::StringRef, mlir::DialectRegistry&) (/data2/dependency/dev/llvm-project/build/bin/mlir-opt+0x26ae4c7)
#24 0x000055dda73d3703 mlir::MlirOptMain(int, char**, llvm::StringRef, mlir::DialectRegistry&) (/data2/dependency/dev/llvm-project/build/bin/mlir-opt+0x26ae703)
#25 0x000055dda7238b2c main (/data2/dependency/dev/llvm-project/build/bin/mlir-opt+0x2513b2c)
#26 0x00007fc2ed50f083 __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x24083)
#27 0x000055dda72e88ce _start (/data2/dependency/dev/llvm-project/build/bin/mlir-opt+0x25c38ce)
Aborted (core dumped)
```

Reproduce the crash with the supplied MLIR input and `mlir-opt -convert-vector-to-xegpu a.mlir`. Read the folding assertion at `Operation.cpp:617` and the conversion pass entry in `VectorToXeGPU.cpp` to trace the incorrect result type. Done means the reproducer no longer aborts and coverage preserves the reported case.

Written by the indexing model from the issue text.