Just tried with mesa-10.2.6/llvm-3.4.2 and the trace works fine except the
following from LLVM:
LLVM ERROR: ran out of registers during register allocation

Here are the flags used:
CPPFLAGS="-D_FORTIFY_SOURCE=2"
CFLAGS="-march=x86-64 -mtune=generic -O2 -pipe -fstack-protector-strong
--param=ssp-buffer-size=4"
CXXFLAGS="-march=x86-64 -mtune=generic -O2 -pipe -fstack-protector-strong
--param=ssp-buffer-size=4"
LDFLAGS="-Wl,-O1,--sort-common,--as-needed,-z,relro"
DEBUG_CFLAGS="-g -fvar-tracking-assignments"
DEBUG_CXXFLAGS="-g -fvar-tracking-assignments"