[Analysis/Allocation] Allocation passes now assumes that slices always alias (#108)

This code in this branch assumes the `src` operand in
`insert_slice_async` always aliases the result, which shouldn't hold for
generally cases but is just a workaround to make the pipeline pass work.

I'm also working on the complete analysis in another
[branch](https://github.com/openai/triton-mlir/tree/keren/analyze-slice).

lib/Dialect/TritonGPU/Transforms/Pipeline.cpp

@@ -275,7 +275,7 @@ void LoopPipeliner::emitPrologue() {
           loadStageBuffer[op->getResult(0)] = {loadsBuffer[op->getResult(0)]};
         }
         // load => copy async
-        // TODO: check if the hardware supports copyasync
+        // TODO: check if the hardware supports async copy
         if (auto loadOp = llvm::dyn_cast<triton::LoadOp>(op)) {
           newOp = builder.create<triton::gpu::InsertSliceAsyncOp>(
               op->getLoc(), loadsBuffer[loadOp].getType(),