R600/SI: Fix live range error hidden by SIFoldOperands

m0 is treated as a virtual register class with a single register
rather than the physical register it really is. This was updating
the live range of the used virtual copy of m0 from the first ds_read
instruction, and leaving the unused copy unchanged. This resulted in a
"Live segment doesn't end at a valid instruction" verifier error because
the erased instructions. Update the live range of the second copy (which
should be dead).

No test since I'm not sure how to trigger this with SIFoldOperands
enabled.
R600/SI: Fix running SILowerI1Copies a second time
R600/SI: Fix suspicious indexing

The loop is over the operands of an instruction, and checks the
register with the sub reg index of the dest register. This probably
meant to be checking the sub reg index of the same operand.
R600/SI: Remove i1 pseudo VALU ops

Select i1 logical ops directly to 64-bit SALU instructions.
Vector i1 values are always really in SGPRs, with each
bit for each item in the wave. This saves about 4 instructions
when and/or/xoring any condition, and also helps write conditions
that need to be passed in vcc.

This should work correctly now that the SGPR live range
fixing pass works. More work is needed to eliminate the VReg_1
pseudo regclass and possibly the entire SILowerI1Copies pass.
R600/SI: Remove incorrect assertion

This can be a COPY to a physical register, such as VCC
R600/SI: Fix SIFixSGPRCopies for copies to physical registers

This shows up when operands required to be passed in VCC are copied
to.