------- Comment #4 from daniel dot sherwood at sepura dot com 2008-12-18 17:22 ------- Following comment received from richard.earns...@arm.com by e-mail.
====== Hmm, yes, I think this is happening because the body of the function contains branch instructions. The Thumb branch instructions have quite limited range, and in the worst case the compiler needs to use the BL instruction (which of course, will destroy the contents of r14). Unfortunately, it's nearly impossible to say exactly when it will be necessary to fall back to this method, so all branches are assumed to do so. It's relatively unusual to find leaf functions that have branches but do not need to stack any other registers (non-leaf functions have to save r14 anyway), but you've managed to find a couple. R. [I've just had a quick look at the sources. There appears to be code in there that is supposed to deal with this case, but it clearly contains broken assumptions (fortunately, the broken assumptions essentially mean that we always get correct, though at times sub-optimal, code).] -- http://gcc.gnu.org/bugzilla/show_bug.cgi?id=38570
