Ok, so I’m looking at the code generation and your compiler is pure and utter shit. Adding Jakub to the cc, because gcc-4.9.0 seems to be terminally broken.
Lookie here, your compiler does some absolutely insane things with the spilling, including spilling a constant. For chrissake, that compiler shouldn’t have been allowed to graduate from kindergarten. We’re talking “sloth that was dropped on the head as a baby” level retardation levels here.
Somebody needs to raise that as a gcc bug. Because it damn well is some seriously crazy shit. However, that constant spilling part just counts as “too stupid to live”.
Anyway, this is not a kernel bug. This is your compiler creating completely broken code. We may need to add a warning to make sure nobody compiles with gcc-4.9.0, and the Debian people should probably downgrate their shiny new compiler.
Linus Torvalds on the Linux Kernel Mailing List: http://lkml.iu.edu/hypermail/linux/kernel/1407.3/00650.html