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
global-reg-cost.diff
PR rtl-optimization/79728
* regs.h (struct target_regs): New field
x_contains_allocatable_regs_of_mode.
(contains_allocatable_regs_of_mode): New macro.
* reginfo.c (init_reg_sets_1): Initialize it, and change
contains_reg_of_mode so it includes global regs as well.
* reload.c (push_reload): Use contains_allocatable_regs_of_mode
rather thanc ontains_regs_of_mode.
PR rtl-optimization/79728
* gcc.target/i386/sse-globalreg.c: New test.