[GitHub] [incubator-mxnet] szha commented on issue #18937: Floating point exception in mxnet.ndarray.op.random_pdf_poisson

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

szha commented on issue #18937:
URL: https://github.com/apache/incubator-mxnet/issues/18937#issuecomment-678065471


   Here's the problem:
   ```
   % DMLC_LOG_STACK_TRACE_DEPTH=150 MXNET_ENGINE_TYPE=NaiveEngine lldb python3.7 -- test_18937.py
   (lldb) target create "python3.7"
   Current executable set to 'python3.7' (x86_64).
   (lldb) settings set -- target.run-args  "test_18937.py"
   (lldb) run
   Process 36591 launched: '/usr/local/bin/python3.7' (x86_64)
   Process 36591 stopped
   * thread #2, stop reason = exec
       frame #0: 0x0000000100006000 dyld`_dyld_start
   dyld`_dyld_start:
   ->  0x100006000 <+0>: popq   %rdi
       0x100006001 <+1>: pushq  $0x0
       0x100006003 <+3>: movq   %rsp, %rbp
       0x100006006 <+6>: andq   $-0x10, %rsp
   (lldb) cont
   Process 36591 resuming
   [23:22:22] ../src/engine/engine.cc:55: MXNet start using engine: NaiveEngine
   [23:22:22] ../src/storage/storage.cc:198: Using Pooled (Naive) StorageManager for CPU
   Process 36591 stopped
   * thread #2, queue = 'com.apple.main-thread', stop reason = EXC_ARITHMETIC (code=EXC_I386_DIV, subcode=0x0)
       frame #0: 0x0000000115bca540 libmxnet.dylib`mxnet::op::PdfCaller<mshadow::cpu, float, mxnet::op::PDF_Poisson<false>, 1, false>::op(inputs=0x00007ffeefbfcb50, outputs=0x00007ffeefbfcb30, s=0x00000001272d39c9) at pdf_op.h:469
      466 	  static void op(const std::vector<TBlob>& inputs,
      467 	                 const std::vector<TBlob>& outputs,
      468 	                 mshadow::Stream<xpu> *s) {
   -> 469 	    CHECK_EQ(inputs[0].Size()%inputs[1].Size(), 0);
      470 	    CHECK_EQ(inputs[0].Size()%outputs[0].Size(), 0);
      471 	    index_t num_samples(inputs[0].Size() / inputs[1].Size());
      472 	    mxnet_op::Kernel<LaunchExWrapper<pdf>, xpu>::LaunchEx(s, outputs[0].Size(), num_samples,
   ```
   
   https://github.com/apache/incubator-mxnet/blob/9bdd4d6347c284770ee5bfe5ae98f1dabc283829/src/operator/random/pdf_op.h#L469
   
   The code needs to guard against zero-size array for right operand of `%`, and we should add a smoke test to guard against such problem in this op, similar to https://github.com/apache/incubator-mxnet/pull/18972/files.


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