Phase ordering in compiler

[Ian Lance Taylor]

On Sun, Oct 21, 2012 at 11:47 PM, vikram1729 <vsp1729@gmail.com> wrote:
> Dear Sir,
>         I want to understand the phase-ordering problem in compilers. My basic
> doubt is what is the  difference between the pass and phase in compilers?

There is no significant difference.  One might think of a phase a
group of passes.  Still, it would be reasonable to describe the
phase-ordering problem as a pass-ordering problem.

> How the user can handle/alter phase-ordering in GCC?

You can edit the source code (gcc/passes.c) or you could write a
plugin but there is no way to change the ordering from the command
line.

> Will there be any impact of repeating optimization options or reordering the
> optimization options in GCC?

Yes.

Ian