Zebediah Figura (@zfigura) commented about tests/hlsl/abs.shader_test:
-[pixel shader] +[pixel shader fail(sm>=6)]
So this is apparently because sm6 doesn't let you put uniforms in the entry point parameter list anymore. Rather than marking it as fail, I'd just move the uniform to a global.
(We should keep at least one test for uniforms in parameter lists, but that would then be its dedicated purpose.)
It probably wouldn't hurt to make some of these compatibility tweaks their own commit, since this one is huge and hard to review, but I won't insist on it.