There is no need to compile C for any specific assemblies or any assembly in general, they are left to the compiler developer, and are not part of the language specification. Typically, each CPU manufacturer will develop a C compiler to target its specific architecture.
There are more general compilers, such as GCC and Clang, although they can target many different sets of instructions.
Clang , , " " , LLVM IR. , LLVM LLVM IR , , , LLVM IR, , LLVM.
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GCC, , , . , GCC-, LLVM.