Jason Thorpe wrote:

> No, the compiler is not allowed to keep cached in a register a memory 
> access across a function call, precisely because it cannot know if that 
> function call modifies the memory.

That's why the C99 introduced the "restrict" keyword, to indicate that a 
variable is pointed to by only one pointer, which avoid aliases, and 
allow those kind of optimizations. There is a good review, that belongs 
more to scientific computing about aliasing, Fortran and C++ valarray 
STL container.

Vincent