[SYSTEMDS-921] Error handling for non-existing variables on function calls

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Fix Version/s: SystemML 0.11
• Component/s: Runtime
• Assignee: Matthias Boehm
• Reporter: Matthias Boehm
• Created: 14/Sep/16 21:38
• Updated: 16/Sep/16 18:39
• Resolved: 16/Sep/16 18:38

Description

Due to unbounded scoping in conditional control flow, during runtime certain variables might be non-existing. Consider the following example script

foo = function(Matrix[Double] A, Matrix[Double] B, Double d) 
  return( Matrix[Double] C)
{
   C = A;
   if( d>0 )
      C = C + B;
}


X1 = rand(rows=1000,cols=1000);
if(sum(X1) < 1)
   X2 = rand(rows=1000,cols=1000);

X3 = foo(X1, X2, 7);

print(sum(X3));

Depending on the data, X2 is not existing. We need to improve the error handling of these cases as the user currently gets the following unhelpful error message:

Caused by: org.apache.sysml.runtime.DMLRuntimeException: ERROR: Runtime error in program block generated from statement block between lines 14 and 14 -- Error evaluating instruction: CP°extfunct°.defaultNS°foo°3°1°X1·MATRIX·DOUBLE°X2·MATRIX·DOUBLE°7·SCALAR·INT·true°X3
        at org.apache.sysml.runtime.controlprogram.ProgramBlock.executeSingleInstruction(ProgramBlock.java:335)
        at org.apache.sysml.runtime.controlprogram.ProgramBlock.executeInstructions(ProgramBlock.java:224)
        at org.apache.sysml.runtime.controlprogram.ProgramBlock.execute(ProgramBlock.java:168)
        at org.apache.sysml.runtime.controlprogram.Program.execute(Program.java:145)
        ... 8 more
Caused by: org.apache.sysml.runtime.DMLRuntimeException: Unknown variable: null
        at org.apache.sysml.runtime.controlprogram.context.ExecutionContext.getScalarInput(ExecutionContext.java:395)
        at org.apache.sysml.runtime.instructions.cp.FunctionCallCPInstruction.processInstruction(FunctionCallCPInstruction.java:151)
        at org.apache.sysml.runtime.controlprogram.ProgramBlock.executeSingleInstruction(ProgramBlock.java:305)