The bitwidth minimization pass repeatedly traverses the CDFG to reduce the number of bits used in each variable. Every forward traversal of the CDFG is followed by a backward traversal. This parameter specifies the maximum number of times the analysis should traverse backwards on the CDFG.

Setting this parameter to -1 instructs the analysis to continually traverse the CDFG until no further bitwidth reduction can be achieved.


HLS Constraints

Value Type


Valid Values

-1, 0 to INT_MAX

Default Value


Location Where Default is Specified



Need to set MB_MINIMIZE_HW to 1 for this parameter to take effect on the generated Verilog.

Related parameters: MB_RANGE_FILE, :ref: MB_PRINT_STATS

Applicable Flows

All devices and flows

Test Status

Prototype functionality


set_parameter MB_MAX_BACK_PASSES -1