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Re: [PATCH] Improve lim for pulling loads from global variable out of loops
> > > > * tree-ssa-loop-im.c (stmt_cost): Gimple variables should be
> > > > pulled out too as they cause memory accesses.
> > > >
> > > Your ChangeLog entry doesn't match the code. Also, testing only for
> > > is_gimple_addressable will not include global variables. You want to
> > > test is_global_var.
> > Diego, I think you are wrong in both points -- is_gimple_addressable
> > includes global variables (any variables, in fact), and the changelog
> > entry seems to match the change.
> You're right, I didn't express myself correctly. Andrew said he wanted
> to consider global variables expensive. Globals are addressable, but
> not every addressable is a global.
> > However the patch is wrong -- is_gimple_addressable also matches SSA
> > names. So the right patch should be
> I thought the intent was to only mark globals as expensive? I think I
> would just say:
the intention of the code is "everything that performs load from
memory". I.e. addressable && ! SSA name.
> if (!is_gimple_reg (rhs))
> cost += 20;
This would cause us to count any operation except for simple reg = reg
copy as expensive, which definitely is not what is wanted.