Re: [PATCH] Fix make_rename_temp to work at -O0

[Paolo Bonzini <paolo dot bonzini at polimi dot it>]

> Actually, if you're going to move the tree-complex bits,
> why not change them to use just create_tmp_var in the first place?

Because my plan is to have complex and vector lowering happen at 
different times depending on whether optimization is active.

At -O0, they would happen last, just before expanding; they would happen 
together to save a bit of compilation time.  At higher optimization 
level, however, complex lowering would stay where it is now, after DCE 
and before DOM/loop passes; while vector lowering needs to go at least 
after the vectorizer.

Moving complex before CFG and SSA construction makes sense. 
Unfortunately, this is not true for the other users of make_rename_temp, 
such as phiopt and the vector lowering pass.  This patch to 
make_rename_temp is just preparatory work to make the gimplify_buildN 
patch work whether SSA is used or not.

That's because complex arithmetic could be subject to vectorization 
(though it is not right now).