SpGEMM - c_nz_idx in gustavsons kernel goes out of bounds

[marjerie]

Describe the bug
The calculation of c_nz_idx in SpGEMM (line 176) for the output C goes out of bounds. The dependence of c_nz_idx to the column of B is wrong as the estimated_nz_per_row can be less than the number of vertices which leads to the c_nz_idx going out of bounds for the allocated space per row.

To Reproduce
Add this assert(c_nz_idx < estimated_nzs); after line 176 in the gustavsons kernel in the file (https://github.com/gunrock/gunrock/blob/main/include/gunrock/algorithms/spgemm.hxx).
The assert fails for the dataset Chesapeake. The size of non-zero values for C is estimated_nzs as done in line 151. So the assertion has to pass.

Expected behavior
The expected behavior is that the c_nz_idx should not go above what was allocated per row.

Environment (please complete the following information):

• Linux
• Driver Version: 525.105.17
• CUDA Version: 12.0
• GCC version 11.3.0