On Sun, Jun 25, 2017 at 2:46 PM, Ian Lance Taylor via gcc-help <gcc-help@xxxxxxxxxxx> wrote: > On Sun, Jun 25, 2017 at 11:41 AM, Maxim Blinov <maxim.a.blinov@xxxxxxxxx> wrote: >> >> However, what is a static chain pointer exactly? After some reading, I >> understand it to be used for retrieving locals from the caller's >> frame, but how would this functionality be relevant to C? > > GCC supports nested functions as a C extension. > https://gcc.gnu.org/onlinedocs/gcc-7.1.0/gcc/Nested-Functions.html#Nested-Functions > > I don't know why you get the error in code that doesn't use static > functions. It may be a minor bug--an unnecessary call to to the > static_chain hook. It may be more than a minor bug. The trampoline often requires an executable stack, and that's usually a SDLC violation. Maybe worse, you could silently lose NX-stacks because GCC does not warn about it. To produce a warning, you need -Wtrampoline, which is off by default. I know very few people who configure with the warning to detect loss of NX-stacks. And of course, if you don't care about SDLCs, then everything is fine. Jeff
