Burst Inference Failure 14 - 2022.2 English

Vitis HLS Messaging (UG1448)

Document ID
UG1448
Release Date
2022-12-16
Version
2022.2 English

Description

Warning: [214-353] Could not widen since type i512 size is greater than or equal to the max_widen_bitwidth threshold of 512.

Explanation

Vitis HLS has determined that the given port's width can be automatically widened but is prevented from doing so by the setting of the max_widen_bitwidth parameter.

The rules for the auto port-width widening algorithm is as follows:
  1. The max_widen_bitwidth value should be in the range [0, 1024], and it must be either 0 or a power of 2. If this rule is not satisfied, Vitis HLSwill ignore this value.
  2. If ports are bundled together, one bundle name can have only one max_widen_bitwidth value. If multiple values are specified by the user, the max value will be selected.

There are three ways of defining this parameter. They are as follows:


[Option 1] Pragma specification
void top(ap_int<32> *a, ap_int<32> *b, ap_int<32> *c) {
#pragma HLS INTERFACE m_axi port=a max_widen_bitwidth=256
}

[Option 2] Directive specification
set_directive_interface -mode m_axi -max_widen_bitwidth 256 top a

[Option 3] config_interface -m_axi_max_widen_bitwidth 512
(default value is 512 in Vitis kernel flow while it is 0 in Vivado IP flow)