Fix quantize pass error when excluding a quantization supported op

[ciyongch]

Description

This PR is to address the error when excluding a quantization supported op in a model like the case below, where both op1 and op2 support quantization.
op1 -> op2
When excluding op1 from the model, the pattern is changed to
op1 -> _contrib_quantize -> quantized_op2
There's an incorrect connection (incorrect entry index) between _contrib_quantize and quantize_op2 for min/max inputs in current code base.

Checklist

Essentials

Please feel free to remove inapplicable items for your PR.

• The PR title starts with [MXNET-$JIRA_ID], where $JIRA_ID refers to the relevant JIRA issue created (except PRs with tiny changes)
• Changes are complete (i.e. I finished coding on this PR)
• All changes have test coverage:
• Unit tests are added for small changes to verify correctness (e.g. adding a new operator)
• Nightly tests are added for complicated/long-running ones (e.g. changing distributed kvstore)
• Build tests will be added for build configuration changes (e.g. adding a new build option with NCCL)
• Code is well-documented:
• For user-facing API changes, API doc string has been updated.
• For new C++ functions in header files, their functionalities and arguments are documented.
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• To the my best knowledge, examples are either not affected by this change, or have been fixed to be compatible with this change

Changes

• Feature1, tests, (and when applicable, API doc)
• Feature2, tests, (and when applicable, API doc)

Comments

• If this change is a backward incompatible change, why must this change be made.
• Interesting edge cases to note here

@TaoLv @pengzhao-intel @apeforest

[pengzhao-intel]

Thanks for the fix.
Could you attach the picture of the graph before and after the change?

[ciyongch]

@pengzhao-intel The picture of graph might not reflect the error, an enhanced test was added to cover this kind of cases. I paste the full symbol file of the test case w/ and w/o the fix.

• symbol file w/o fix exclude_pool0.txt
• symbol file w/ fix exclude_pool0_fix.txt

The incorrect connection (error entry index) is located at 3nd/4th input (counting from 0), [21, 4294967295, 0], [21, 0, 0]

    {
      "op": "_contrib_quantized_conv", 
      "name": "quantized_conv1", 
      "attrs": {
        "kernel": "(1, 1)", 
        "no_bias": "False", 
        "num_filter": "4", 
        "pad": "(0, 0)"
      }, 
      "inputs": [[21, 0, 0], [22, 0, 0], [23, 0, 0], [21, 4294967295, 0], [21, 0, 0], [24, 0, 0], [25, 0, 0], [26, 0, 0], [27, 0, 0]]
    },

After fixed, the connection is as below, 3nd/4th inputs are correct now [21, 1, 0], [21, 2, 0]

    {
      "op": "_contrib_quantized_conv", 
      "name": "quantized_conv1", 
      "attrs": {
        "kernel": "(1, 1)", 
        "no_bias": "False", 
        "num_filter": "4", 
        "pad": "(0, 0)"
      }, 
      "inputs": [[21, 0, 0], [22, 0, 0], [23, 0, 0], [21, 1, 0], [21, 2, 0], [24, 0, 0], [25, 0, 0], [26, 0, 0], [27, 0, 0]]
    }, 
    {

[pengzhao-intel]

Thanks for the explanation. It makes sense.

[ciyongch]

ping @apeforest @TaoLv to have a reveiw :)

[TaoLv]

LGTM. Thank you for the fix.

[roywei]

@mxnet-label-bot add [Operator, pr-awaiting-review]
@ciyongch Thanks for the contribution, is there an issue related to this fix?

[ciyongch]

@roywei No open issue related to it so far. We found this error when trying to quantize Resnet50_v1 at local (with excluding some ops which supports quantization from the model script manually). In this case, NeedQuantize(e.node, excluded_nodes) is much more accurate than quantized_op_map.count(e.node->op()).
A test case is also added to cover this kind of error.