This is an ICE where setup_pressure_classes fails if xmm0 is a global
reg. Instead of GENERAL/FLOAT/SSE/MMX_REGS, it computes only
SSE_FIRST_REG as the third register class. The problem is that the costs
for moving between SSE_FIRST_REG and SSE_REGS are inflated because we
think we have no available registers in SSE_FIRST_REG (since the only
register in that class is global), and that somewhat confuses the
algorithm.
The following fixes it by tweaking contains_regs_of_mode. Out of
caution, I've retained the old meaning for code in reload which uses this.
Bootstrapped and tested on x86_64-linux. Ok?
Bernd