关键词: C2VHDL编译器, 低级虚拟系统中间表示（LLVM IR）, 非计数类循环

Abstract: At present，most C2VHDL compilers use the design method of Finite State Mechine（FSM），it compiles count loop easily as the loop of initial value and final value and the step value are known in compile.Because non-count loop’s index can not be known before program execution，FSM is complex to achieve，most C2VHDL compiler tools do not support non-count loop.This paper，based on Low Level Virtual Machine（LLVM），presents a compilation method which adaptes one cycle of high signal instead of FSM to support multiple nested format non-count loops.Experiment proves that the generated control structure is simple and it is flexible and extendible and can achieve all kinds of non-count loops’ C2VHDL conversion.

Key words: C2VHDL compiler, Low Level Virtual Machine Intermediate Representation（LLVM IR）, non-count loop