Auto Carry Chains logic option

Allows the Compiler to create carry chains automatically by inserting CARRY_SUM buffers into the design. This option is also required to recognize carry chains in any design containing MAX+PLUS II-style CARRY buffers.

The Carry Chain Length option controls the length of the chains. If this option is turned off, CARRY buffers are ignored, but CARRY_SUM buffers are unaffected.

You must assign this a design entity, or the Compiler ignores it.