Method and System for Auto Parallelization of Zero-Trip Loops Through the Induction Variable Substitution

A data processing system having a processor for auto parallelization of zero-trip loops through induction variable substitution, the data processing system comprising:

• detecting means for detecting basic induction variables in an inner loop;
• identifying means for identifying nested induction variables within the basic induction variables for an outer loop;
• first substituting means for substituting an induction variable in the inner loop for the nested induction variables of the outer loop, wherein substituting comprises adding a max operator;
• performing means for performing loop normalization;
• and
• removing means for removing the max operator, wherein removing eliminates loop dependencies on the induction variable.

A computer program product in a computer readable storage medium for auto parallelization of zero-trip loops through induction variable substitution, the computer program product comprising:

• instructions for detecting basic induction variables in an inner loop;
• instructions for identifying nested induction variables within the detected basic induction variables for an outer loop;
• instructions for substituting an induction variable in the inner loop for the nested induction variables of the outer loop, wherein substituting comprises adding a max operator;
• instructions for performing loop normalization;
• and
• instructions for removing the max operator, wherein removing eliminates loop dependencies on the induction variable.

A data processing system having a processor for auto parallelization of zero-trip loops through induction variable substitution, the data processing system comprising:

• detecting means for detecting basic induction variables in an inner loop;
• identifying means for identifying nested induction variables within the detected basic induction variables for an outer loop, wherein identifying nested induction variables within the detected basic induction variables for an outer loop includes:
• certifying means for certifying that no definitions of the induction variable are in a parent loop;
• verifying means for verifying that the inner loops body is enclosed by the outer loop;
• and
• ensuring means for ensuring that no branch goes out of or comes into the outer loop;
• substituting means for substituting an induction variable in the inner loop for the nested induction variables of the outer loop, wherein substituting an induction variable in the inner loop for the nested induction variables of the outer loop includes:
• performing means for performing a dead store and copy propagation process;
• and
• adding means for adding a max operator;
• performing means for performing loop normalization of the outer loop;
• removing means for removing the induction variable from the outer loop;
• substituting means for substituting at least one additional induction variable in the inner loop for the nested induction variables of an intermediate loop;
• performing means for performing loop normalization of the intermediate loop;
• removing means for removing the at least one additional induction variable from the intermediate loop;
• and
• removing means for removing the max operator through a copy propagation pass of a compiler.

A computer program product in a computer readable storage medium for auto parallelization of zero-trip loops through induction variable substitution, the computer program product comprising:

• instructions for detecting basic induction variables in an inner loop;
• instructions for identifying nested induction variables within the detected basic induction variables for an outer loop, wherein identifying nested induction variables within the detected basic induction variables for an outer loop includes:
• instructions for certifying that no definitions of the induction variable are in a parent loop;
• instructions for verifying that the inner loops body is enclosed by the outer loop;
• and
• instructions for ensuring that no branch goes out of or comes into the outer loop;
• instructions for substituting an induction variable in the inner loop for the nested induction variables of the outer loop, wherein substituting an induction variable in the inner loop for the nested induction variables of the outer loop includes:
• instructions for performing a dead store and copy propagation process;
• and
• instructions for adding a max operator;
• instructions for performing loop normalization of the outer loop;
• instructions for removing the induction variable from the outer loop;
• instructions for substituting at least one additional induction variable in the inner loop for the nested induction variables of an intermediate loop;
• instructions for performing loop normalization of the intermediate loop;
• instructions for removing the at least one additional induction variable from the intermediate loop;
• and
• instructions for removing the max operator through a copy propagation pass of a compiler.