A plan for eliminating cc0

[Zack Weinberg]

Ian Lance Taylor <ian@airs.com> writes:

> 3) Write a new CC0 collapse pass.  This pass is run immediately
> after RTL expansion.  It walks the instruction stream looking for
> instructions which set and use CC_REG.  At this point these
> instructions will always be adjacent.  The pass combines them into
> the combined instruction defined in step 2c above.

I'm not understanding why this is a separate pass, instead of
generating the combined instructions directly in the expander.  I
think generic expander support for compare-and-branch instructions
already exists...

zw