https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114759
--- Comment #2 from Segher Boessenkool <segher at gcc dot gnu.org> --- > 1. We always define the __ROP_PROTECT__ predefined macro when using > -mrop-protect, even when we've silently disabled ROP protection because of a > too old -mcpu=CPU value. We should only emit __ROP_PROTECT__ when it's legal > to emit the ROP insns. No. Whenever the -mrop-protect option is in effect, we should do that predefine. If you want to refuse the option without a -mcpu= that can generate useful code for it, that's fine, but that is not what we do. Instead, we generate code that will do the ROP-protection boogaloo on CPUs that implement support for that, and does nothing otherwise. > 2. We always disable shrink-wrapping when -mrop-protect is used, [...] Yes, this is problematic, and seems to be completely unnecessary. When using SWS at least -- but then we need to define a component for doing the ROP-protection thing, of course. After all, it has to be done before anything else in the function. By exactly the same argument we should *also* do ROP-protection in all leaf functions, btw! > 3. We silently disable ROP protection for everything other than > -mcpu=power10. The binutils assembler accepts the ROP insns back to Power8, > so we should emit them for Power8 and later. The ISA claims it will work for anything after ISA 2.04, even. > 4. We give an error when -mrop-protect is used with any -mabi=ABI value not > equal to ELFv2, [...] Yes, we should make it work everywhere. Even on -m32. But it requires adjusting the ABI as well! 2) should be fixed, and 4) should be fixed by actually implementing it everywhere!
