Available Logic Optimizations

Available Logic Optimizations - 2021.1 English

Vivado Design Suite User Guide: Implementation (UG904)

Document ID

UG904

Release Date

2021-08-30

Version

2021.1 English

The Vivado tools can perform the logic optimizations on the in-memory design.

Important: Logic optimization can be limited to specific optimizations by choosing the corresponding command options. Only those specified optimizations are run, while all others are disabled, even those normally performed by default.

The following table describes the order in which the optimizations are performed when more than one option is selected. This ordering ensures that the most efficient optimization is performed.

Table 1. Optimization Ordering for Multiple Options
Phase	Name	Option	Default
1	Retargeting	`-retarget`	X
2	Constant Propagation	`-propconst`	X
3	Sweep	`-sweep`	X
4¹	Mux Optimization	`-muxf_remap`
5¹	Carry Optimization	`-carry_remap`
6	Control Set Merging	`-control_set_merge`
7	Equivalent Driver Merging	`-merge_equivalent_drivers`
8	BUFG Optimization	`-bufg_opt`	X
9	Shift Register Optimization	`-shift_register_opt`	X
10	MBUFG Optimization	`-mbufg_opt`
11	DSP Register Opt	`-dsp_register_opt`
12	Control Set Reduction	`(property controlled)`	X
13	Module-Based Fanout Opt	`-hier_fanout_limit <arg>`
14	Remap	`-remap`
15	Resynth Remap	`-resynth_remap`
16	Resynth Area	`-resynth_area`
17	Resynth Sequential Area	`-resynth_seq_area`
18	Block RAM Power Opt	`-bram_power_opt`	X
Phase 4 and 5 are not supported for Versal. Phase 10 is only supported for Versal.

When an optimization is performed on a primitive cell, the OPT_MODIFIED property of the cell is updated to reflect the optimizations performed on the cell. When multiple optimizations are performed on the same cell, the OPT_MODIFIED value contains a list of optimizations in the order they occurred. The following table lists the OPT_MODIFIED property value for the various opt_design options:

Table 2. Optimization Options and Values
opt_design Option	OPT_MODIFIED Value
`-bufg_opt`	BUFG_OPT
`-carry_remap`	CARRY_REMAP
`-control_set_merge`	CONTROL_SET_MERGE
`-hier_fanout_limit`	HIER_FANOUT_LIMIT
`-merge_equivalent_drivers`	MERGE_EQUIVALENT_DRIVERS
`-muxf_remap`	MUXF_REMAP
`-propconst`	PROPCONST
`-remap`	REMAP
`-resynth_remap`	REMAP
`-resynth_area`	RESYNTH_AREA
`-resynth_seq_area`	RESYNTH_AREA
`-retarget`	RETARGET
`-shift_register_opt`	SHIFT_REGISTER_OPT
`-sweep`	SWEEP