Mail Archives: djgpp/1998/09/20/03:46:04
On Fri, 18 Sep 1998, John S. Fine wrote:
> What happened? I really did have the "-O2". I can make tiny
> changes in the above code and suddenly get decent output. What
> about the above code makes the optimizer go insane?
I don't know, it's pretty tricky. Unless you really need to understand
how the optimizer works, you should be fine just rearranging the source so
it emits a better code.
One thing that sometimes helps in C is to explicitly tell the compiler
that the functions called inside the loop have no side effects, by
declaring it with __attribute__((const)). This is described in GCC docs,
and sometimes has a dramatic effect on code generated for loops that call
functions.
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