On Wed, Jan 15, 2014 at 10:46 AM, Jeff Law <l...@redhat.com> wrote: > On 01/15/14 10:07, Teresa Johnson wrote: >> >> Handle NULL vdef for call in the case where we have a matching vnresult >> that has a vdef (it already handles the NULL vdef case when !vnresult). >> This >> can happen for promoted indirect calls if the fallback indirect call >> (which has a vdef) can be proven equivalent to the promoted direct call >> (which might not have a vdef). >> >> This occurred for a case where we had a promoted indirect call, >> where FRE determined that the promoted direct call and the fall-back >> indirect >> call were equivalent (since earlier it determined that the function >> pointer >> was always set to that target). The indirect call had been analyzed by >> visit_reference_op_call first, and had a VDEF. The direct call did not >> have a >> VDEF, presumably because it was a leaf function in the same module without >> any >> stores. But visit_reference_op_call unconditionally calls set_ssa_val_to >> when >> the previous vnresult had a vdef, leading to a seg fault in this case. >> If we had analyzed the direct call first the failure wouldn't have >> occurred >> since the !vnresult case guards the call to set_ssa_val_to with a check >> for a NULL vdef, and the subsequent handling of the indirect call would >> also not call set_ssa_val_to since vnresult would have had a null >> result_vdef. >> >> Bootstrapped and tested on x86_64-unknown-linux-gnu. Ok for trunk? >> >> 2014-01-15 Teresa Johnson <tejohn...@google.com> >> >> * tree-ssa-sccvn.c (visit_reference_op_call): Handle NULL vdef. > > The patch is OK. Given this was an ICE, do you have a reduced test we can > add to the regression suite? I realize that order of visiting in the SCC is > important to trigger, but a regression test would still be useful.
Unfortunately it was hit using LIPO on the google/4_8 branch, and only occurred with a specific profile. That's why I don't have a trunk test case. I suppose I could create a test case that has a similar opportunity. It does look like there are some indirect call promotion with FDO tests already (e.g. gcc.dg/tree-prof/indir-call-prof.c), but I'm not sure whether they even trigger the same type of FRE opportunity. I will take a look. Teresa > > Thanks, > Jeff > > -- Teresa Johnson | Software Engineer | tejohn...@google.com | 408-460-2413
