So if we are about to fix this in if-conversion, we need to do both in tree & rtl as both ifcvt & ce passes cannot handle it.
I am still not convinced jump threading is good for target with predicated execution (assuming no fix for if-conversion). I am doing benchmarking on our target now. Bingfeng -----Original Message----- From: Jeff Law [mailto:l...@redhat.com] Sent: 22 November 2013 16:58 To: Bingfeng Mei; Andrew Pinski Cc: gcc@gcc.gnu.org Subject: Re: Jump threading in tree dom pass prevents if-conversion & following vectorization On 11/22/13 04:03, Bingfeng Mei wrote: > Well, in your modified example, it is still due to jump threading that produce > code of bad control flow that cannot be if-converted and vectorized, though in > tree-vrp pass this time. > > Try this > ~/install-4.8/bin/gcc vect-ifconv-2.c -O2 -fdump-tree-ifcvt-details > -ftree-vectorize -save-temps -fno-tree-vrp > > The code can be vectorized. > > Grep "threading" in gcc, it seems that dom and vrp passes are two places that > apply > jump threading. Any other place? I think we need an target hook to control it. No no. The right thing to do is fix if-conversion. jeff
