> On 03/23/2015 09:07 AM, Jakub Jelinek wrote: > >Hi! > > > >As expand_set_or_movmem_prologue_epilogue_by_misaligned_moves uses > >src = src - (adjusted_dest - dest) > >without proper REG_POINTER flags the aliasing code is very easily confused > >on what is really a pointer and what is not - as REG_POINTER was used > >after forwprop only on dest, but not on anything else, aliasing code thinks > >that the memcpy reads dest based memory, when it really reads src based > >memory (in the testcase frame pointer based in the end, but CSE did not see > >it through). > > > >Fixed by marking pseudos that must hold pointers with REG_POINTER during > >the expansion. Bootstrapped/regtested on x86_64-linux and i686-linux, ok > >for trunk? > FWIW, you have to be very careful depending on REG_POINTER. I > believe Ada can still set REG_POINTER on things that are not > pointers (via virtual origins) and cross jumping can cause problems > too where one arm has x + y with X as the pointer and the other arm > has x + y with Y as the pointer. > > But yes, in general, if we're marking things that must be pointers > with REG_POINTER, that is a good thing.
Yep, the patch is OK. Even if Ada gets things partly wrong it seems independent issue. Honza > > jeff >
