config_compile

Description

Configures the default behavior of front-end compiling.

Syntax

config_compile [OPTIONS]

Options

-name_max_length <value>
Specifies the maximum length of function names. If the length of the name is longer than the threshold, the last part of the name is truncated. The default is 256.
-no_signed_zeros [true | false]
Ignores the signedness of floating-point zero so that the compiler can perform aggressive optimizations on floating-point operations. The default is off.
IMPORTANT: Using this option might change the result of any floating point calculations and result in a mismatch in C/RTL co-simulation. Please ensure your test bench is tolerant of differences and checks for a margin of difference, not exact values.
-pipeline_loops <threshold>

Specifies the lower limit used when automatically pipelining loops. The default is 64, causing Vitis HLS is to automatically pipeline loops with a tripcount of 64, or greater.

If the option is applied, the innermost loop with a tripcount higher than the threshold is pipelined, or if the tripcount of the innermost loop is less than or equal to the threshold, its parent loop is pipelined. If the innermost loop has no parent loop, the innermost loop is pipelined regardless of its tripcount.

TIP: The higher the threshold, the more likely it is that the parent loop is pipelined and the run time is increased.
-pipeline_style <stp | frp>

Specifies the type of pipeline used by Vitis HLS for the PIPELINE pragma or directive, or for loop pipelining due to the -pipeline_loops threshold specified above. For more information on pipeline styles refer to Flushing Pipelines.

IMPORTANT: This is a hint not a hard constraint. The tool checks design conditions for enabling pipelining, and uses the default style if necessary.
  • stp: Stall pipeline. Runs only when input data is available otherwise it stalls. This is the default setting, and is the type of pipeline used by Vitis HLS for both loop and function pipelining.. Use this when a flushable pipeline is not required. For example, when there are no performance or deadlock issue due to stalls.
  • frp: Free-running, flushable pipeline. Runs even when input data is not available. Use this when you need better timing due to reduced pipeline control signal fanout, or when you need improved performance to avoid deadlocks. However, this pipeline style may consume more power, as the pipeline registers are clocked even if there is no data.
-pragma_strict_mode [true | false]
Enable error messages for misplaced or misused pragmas.
-unsafe_math_optimizations [true | false]
Ignores the signedness of floating-point zero and enables associative floating-point operations so that compiler can perform aggressive optimizations on floating-point operations. The default is off.
Note: Using this option might change the result of any floating point calculations and result in a mismatch in C/RTL co-simulation. Please ensure your test bench is tolerant of differences and checks for a margin of difference, not exact values.

Examples

Pipeline the innermost loop with a tripcount higher than 30, or pipeline the parent loop of the innermost loop when its tripcount is less than or equal 30:

config_compile -pipeline_loops 30

Ignore the signedness of floating-point zero:

config_compile -no_signed_zeros

Ignore the signedness of floating-point zero and enable the associative floating-point operations:

config_compile -unsafe_math_optimizations