The Blub Paradox

If Lisp is more expressive than C, why Lisp can be compiled into C and C cannot be compiled into Lisp?

OpenCL,CUDA

These are not C you stupid faggot

OpenCL is C89 with hardware extensions.
CUDA supports C++11 partially.

Embedded C is a set of language extensions for the C Programming language

Extensions, not to mention that you need to use different address space specifiers for every architecture.

C is often used with compiler extensions. C is designed to exploit the hardware for maximum performance and this requires close interaction with the machine(and sometimes inline assembler).

and basic I/O operations

Nobody, I say, nobody that matters implements iohw.h except QNX

Plenty of hardware-specific non-standard extensions exist. Its not the C committee privilege to decide what extensions are used.

A declaration of an identifier for an object with storage-class specifier register suggests that access to the object be as fast as possible. The extent to which such suggestions are effective is implementation-defined.

And?

This a quote from the C standard that clarifies the C 'register' does not create any dependency on hardware registers.
section 1.9 (the as-if rule) -

The semantic descriptions in this International Standard define a parameterized nondeterministic abstract machine. This International Standard places no requirement on the structure of conforming implementations. In particular, they need not copy or emulate the structure of the abstract machine. Rather, conforming implementations are required to emulate (only) the observable behavior of the abstract machine ...

an implementation is free to disregard any requirement of this International Standard as long as the result is as if the requirement had been obeyed, as far as can be determined from the observable behavior of the program. For instance, an actual implementation need not evaluate part of an expression if it can deduce that its value is not used and that no side effects affecting the observable behavior of the program are produced