On Wed, Sep 2, 2015 at 5:48 AM, Bin Cheng <bin.ch...@arm.com> wrote: > Hi, > Generally we don't try to fold (long)(A-B) into (long)A - (long)B because it > results in more operations. On the other hand, this fold is wanted when we > want to explore as many canonical opportunities as possible. Tree affine is > definitely such a place. This patch supports this in > tree_to_aff_combination, so it can produce canonical affines rather than > stupid expressions like "&arr + (sizetype) (t_4(D) + t_4(D)) * 4 - > (sizetype)t_4(D) * 8". > > Bootstrap and test on x86_64 and aarch64 along with other patches. Is it > OK?
Hmm, but we also do code-gen from affine combinations and we can't reverse that operation. So eventually we end up generating an expensive wide plus/minus instead of a narrow one and an extension. But I see we already do this transform, just only for constant 2nd operand and in aff_combination_expand. Any reason you chose tree_to_aff_combination only? I suppose if we need it in both places it would be good to factor it out to a helper function. Richard. > > 2015-08-31 Bin Cheng <bin.ch...@arm.com> > > * tree-affine.c (tree_to_aff_combination): Try to fold (long)(A-B) > by adding CASE_CONVERT support.
