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2b983a2458
Motivation: amdgpu buffer load instruction will return all zeros when loading sub-word values. For example, assuming the buffer size is exactly one word and we attempt to invoke `llvm.amdgcn.raw.ptr.buffer.load.v2i32` starting from byte 2 of the word, we will not receive the actual value of the buffer but all zeros for the first word. This is because the boundary has been crossed for the first word. This PR come up with a fix to this problem, such that, it creates a bounds check against the buffer load instruction. It will compare the offset + vector size to see if the upper bound of the address will exceed the buffer size. If it does, masked transfer read will be optimized to `vector.load` + `arith.select`, else, it will continue to fall back to default lowering of the masked vector load.