[GitHub] [incubator-tvm] Presburger commented on pull request #6785: fix a bug in convertSSA.

[GitBox <gi...@apache.org>]

Presburger commented on pull request #6785:
URL: https://github.com/apache/incubator-tvm/pull/6785#issuecomment-717884931


   OK, @leandron 
   I find a IR look like this before Loop Partition.
   ```cc
   for(i1: int32, 0, 36){
       attr [IterVar(x.inner, (nullptr), "DataPar", "")]{
       for (x.inner, 0, 9) {
           if(likely(i1<18))
           .....
           else
           .....
   }
   }
   } 
   ```
   Loop Partition will transform this IR to
   ```cc
   for(i1: int32, 0, 18){
       attr [IterVar(x.inner, (nullptr), "DataPar", "")]{
       for (x.inner, 0, 9) {
           .....
   }
   }
   }
   for(i1: int32, 18, 36){
       attr [IterVar(x.inner, (nullptr), "DataPar", "")]{
       for (x.inner, 0, 9) {
           .....
   }
   }
   }
   ```
   then IR pass to ConvertSSA, when visited secnd for loop 's x.inner, tvm may crash.
   because try to call vector::back when the vector container is empty.
   
   
   


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