[Relay] Flaky Compilation for Gluoncv SSD model

[kevinthesun]

I'm adding relay support for gluoncv ssd models. The end to end compilation randomly fails:https://github.com/kevinthesun/tvm/blob/RefactorSSDOperator/tutorials/nnvm/deploy_ssd.py

First build RefactorSSDOperator branch under my folk tvm with USE_SORT ON
Then run the test several times:

python deploy_ssd.py -f relay

Sometimes it succeeds but sometimes fails.
The segfault happens inside op fuse pass: https://github.com/kevinthesun/tvm/blob/RefactorSSDOperator/src/relay/pass/fuse_ops.cc#L741

@jroesch

[masahi]

Ok, that line was added by me. I'll take a look.

[masahi]

@kevinthesun I found the bug! deploy_ssd.py works with relay.

please change this line to

for (size_t i = 0; i < new_fields.size() && isolated; ++i) {

I'll send a PR with more proper fix soon.

[kevinthesun]

Thank you for quick response！

[jroesch]

Thanks for showing up with the fix @masahi !! Will you cc me on the PR?

[masahi]

@jroesch ok, I'm still trying to figure out the root cause of the bug. The network is huge and the structure is unusual. Here is the 1600 line dump of Relay text, after compiling this network :)