Does it make more games run?
Does it make games faster?
It allow for execution of code that require double precision. That is good for OpenCL on radeonSI (as there may be some apps that are just needed double precision to run). But it have no imediate result for OpenGL, as double precision is used with OpenGL 3/4 which aint supported by radeonSI right now.
So it could enable some computational apps to run on radeonSI, but it will not improve current apps/games (as those use single precision, which performance is unrelated to support of double precision).