On 10/28/19 4:36 PM, Martin Sebor wrote: > While testing the patch for PR 92226 I posted earlier today > I ran into a few cases where I expected the strlen range > optimization to take place but it didn't. > > In other instances this wouldn't be surprising because > the optimization was only introduced for multi-character stores > and with the expectation that it would be slowly extended to > other functions over time. But these cases were among those > the optimization was meant to be in place for, so its absence > is an oversight. The attached near-trivial patch fills this > gap. > > As with all these changes, enabling the optimization also makes > it possible to detect more instances of buffer overflow. > > Tested on x86_64-linux. > > Martin > > PS There are quite a few remaining opportunities to make use of > the strlen ranges in the pass. Rather than enhancing the whole > pass in one go I think it will be safer to do it one small step > at a time, using little patchlets like in the attachment. > > gcc-92226-2.diff > > gcc/ChangeLog: > > * tree-ssa-strlen.c (get_addr_stridx): Add argument and use it. > (handle_store): Pass argument to get_addr_stridx. > > gcc/testsuite/ChangeLog: > > * gcc.dg/strlenopt-89.c: New test. > * gcc.dg/strlenopt-90.c: New test. > * gcc.dg/Wstringop-overflow-20.c: New test. OK. And patches which do similar stuff (arranging to pass down the range info) are pre-approved.
jeff
