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AR# 47249

2012.1 Vivado HLS - Mutually exclusive memory access is not implemented with MUX on addresses, and reports: "@W [SCHED-69] Unable to schedule 'load' operation on array 'x' due to limited resources (II = 1) "

Description

In the following example, Vivado HLS reports a warning message and less than expected II and pipeline results.

Pseudo code:

If (condition) 
R = M[ax] ;
Else
R = M[ay];

@W [SCHED-69] Unable to schedule 'load' operation on array 'M' due to limited resources (II = 1).
@I [SCHED-61] Pipelining result: Target II: 1, Final II: 2, Depth: 3.

Solution

To ensure Vivado HLS can optimize HDL outputs, modify the code as shown below. 

If (condition) 
   A = ax ;
Else
   A = ay;
// next do the actual read
R=M[A];

This issue is fixed  from release 2012.2 on.

AR# 47249
Date Created 08/31/2012
Last Updated 06/25/2014
Status Active
Type Solution Center
Tools
  • AutoESL - 2010.b
  • AutoESL - 2011.1
  • AutoESL - 2011.3
  • AutoESL - 2011.4