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Adventurer
Adventurer
459 Views
Registered: ‎04-25-2017

Vivado hls synthesis is hanging in 2018.2, but finishing succesfully in 2017.2

Hi,

1. I am synthesizing a code in vivado hls 2018.2 which contains two arrays each of size 256 elements. To achieve initiation interval 1, I am using

   #pragma HLS ARRAY_PARTITION.   Initiation interval 1 is achieved, but synthesis is hanging during RTL generation. However, in vivado hls 2017.2 synthesis is finishing succesfully with initiation interval 1.

2.  In 2017.2, we were defining pipeline pragma inside our operator function and data flow pragma in our top function definition and we were obtaining initiation interval 1. But In 2018.2, although we are doing the same thing, initiation interval is not getting 1 for the same code. Thus, we tried avoiding the usage of data flow pragma in our codes while using 2018.2 and kept pipeline pragma in top function. By doing so, we got II = 1 . Can any one tell me why is this happening ?

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3 Replies
Xilinx Employee
Xilinx Employee
452 Views
Registered: ‎06-04-2018

Re: Vivado hls synthesis is hanging in 2018.2, but finishing succesfully in 2017.2

Hi @astrome,

Until beofre 2018.2 the pipeline pragma is default for the outer loop and unroll will be done for inner loops.

But from 2018.2 release we need to manually set the pipeline pragma in outer loop to get II=1.

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Xilinx Employee
Xilinx Employee
451 Views
Registered: ‎06-04-2018

Re: Vivado hls synthesis is hanging in 2018.2, but finishing succesfully in 2017.2

Hi @astrome,

Regarding the synthesis stage hang issue, can you follow the steps and check if the hang issue is resolved:

1. create one hls_config.tcl file

2. Add "config_rtl –mult_keep_attribute=true" in the hls_config.tcl file

3. This .tcl file should be added into xocc during compilation as below:

4. --xp prop:solution.hls_pre_tcl=hls_config.tcl

you can use the idct example for reference

https://github.com/Xilinx/SDAccel_Examples/tree/master/vision/idct

 

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Adventurer
Adventurer
413 Views
Registered: ‎04-25-2017

Re: Vivado hls synthesis is hanging in 2018.2, but finishing succesfully in 2017.2

I followed the steps that you mentioned and tried to synthesize the code. But, the synthesis  hang issue is not resolved.

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