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.
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.