Good question! In a simply word, GCC&LLVM compilers are good at traditional RISC-like hardware, namely, IR expected to be load/store/compute/branch, etc. More important is, these compilers do not allow user to add custom IR at will. AI chip operator evoloing rapidly, adding IR means the compiler needs to be overhauled. XOC is multi-level IR compiler, MLIR is not. MLIR open source later than XOC. Moreover, MLIR lack s of powerful optimizations.