https://bugs.freedesktop.org/show_bug.cgi?id=64201
--- Comment #24 from Aaron Watry awatry@gmail.com --- I haven't managed to finish bisecting this yet, but I believe that this bug has been present since at least January 9th, 2013:
mesa: 4f2d9a8f520cda llvm: 1db9b6957c clang: 50767d8c8f2f667255bd
libclc was latest from my git repo on fd.o, with the following commits reverted to make it build against older llvm: f617f2dfa68 1114e99b296
I'll keep going in trying to nail down the commit that this broke in, although I'll soon be back into having to build Tom's llvm tree to get the AMDGPU back-end again.