Hello, Ref: https://bugs.linaro.org/show_bug.cgi?id=5479
Statically built independent programs that implement their own program entry points (i.e. -ffreestanding -nostartfiles) and call __builtin_* functions break when the builtin function in question is implemented as an IFUNC in glibc and the builtin results in a glibc call instead of some inline code. This happens because the startup code where ifuncs are resolved never gets executed (since glibc's startup code is never executed) and hence the PLT jumps fail. The bug report talks about this as an aarch64 problem but I've been able to reproduce the problem on x86_64 as well. One just needs to make sure that the __builtin_foo call results in a glibc call. I spent some time thinking about this and while it's trivial to fix by disabling ifuncs for static glibc, I wanted a solution that wasn't such a big hammer. The other alternative I could think of is to have an exported alias (called __builtin_strlen for example instead of strlen) of a default implementation of the builtin function in glibc that gcc generates a call to if freestanding && nostartfiles && static. Any thoughts or other ideas on how this could be implemented? Thanks, Siddhesh
