Compilation error for TTM with CSF,CSC as input formats and CSF output

[amirsh]

On the master branch (as well as the web interface), for the TTM example, the mentioned data formats lead to the following compilation error:

/var/folders/43/fyr6y1h116q7yw4m8vczbq440000gq/T/taco_tmp_8eTr18/wz1tmu3amdu1.c:195:11: error: use of undeclared identifier 'pA853_begin'; did you mean 'pA852_begin'?
      if (pA853_begin < i154A85) {
          ^~~~~~~~~~~
          pA852_begin
/var/folders/43/fyr6y1h116q7yw4m8vczbq440000gq/T/taco_tmp_8eTr18/wz1tmu3amdu1.c:157:13: note: 'pA852_begin' declared here
    int32_t pA852_begin = i153A85;
            ^
1 error generated.

[rohany]

Can you share the link of the web interface that led to the error (it includes the schedules and formats). Trying it myself, it looks like this particular case works.

[amirsh]

@rohany I believe this is what you are looking for? http://tensor-compiler.org/codegen.html?expr=A(i,j,k)%20=%20B(i,j,l)%20*%20C(k,%20l)&format=A:sss:0,1,2;B:sss:0,1,2;C:ds:1,0

If you take a look at the generated assembly code:

      if (pA3_begin < kA) {
        if (A2_crd_size <= jA) {
          A2_crd = (int32_t*)realloc(A2_crd, sizeof(int32_t) * (A2_crd_size * 2));
          A2_crd_size *= 2;
        }
        A2_crd[jA] = j;
        jA++;
      }

The variable pA3_begin is not defined.

[rohany]

Thanks, I see the problem now.

[stephenchouca]

This seems to be caused by the fact that the expression scatters into the result, which is not directly supported when the output format is sparse. By (manually) introducing a workspace, you can avoid scattering into the sparse output, which I believe should resolve the issue: http://tensor-compiler.org/codegen.html?expr=A(i,j,k)%20=%20B(i,j,l)%20*%20C(k,%20l)&format=A:sss:0,1,2;B:sss:0,1,2;C:ds:1,0&sched=precompute:B(i,j,l)%20*%20C(k,l):k:k

A longer-term fix for bugs like this though would probably require some sort of mechanism that detects scatters into sparse outputs and that automatically inserts workspaces to eliminate the scatter.