Method and apparatus for generating code for array range check and method and apparatus for versioning

A method for versioning a loop in a program, comprising the steps of:

• collecting first set information of array range checks for array accesses which are always performed even if passing through any execution path in said loop, and storing in a memory storage the collection result;
• by using said collection result, generating and storing in a memory storage a check code for the versioning;
• eliminating a redundant array range check by using said collection result, and generating and storing in a memory storage a version in a case that an array range check by said check code is successful, said version including a code for unremovable array range check;
• and generating and storing in a memory storage a version in a case that an array range check by said check code is unsuccessful.

An apparatus for generating a code for an array range check for an array access in a program, said apparatus comprising:

• a memory storage;
• storage area available to a processor;
• first means for generating and storing in said memory storage a first code for storing in said storage area a result of combined array range check which combines a plurality of array accesses;
• and second means for generating and storing in said memory storage a third code for checking said storage area and for invalidating a second code for an array range check included in said plurality of array range checks if said storage area indicates said combined array range check is successful.

An apparatus for generating a code for an array range check or an array access in a program, said apparatus comprising:

• a memory storage;
• means for generating and storing in said memory storage a second portion for performing an array range check for necessary range corresponding to the array access included, said second portion of the program to be processed corresponding to a first portion to be processed;
• means for performing for said first portion, an optimization process for array range checks and an elimination process for redundant array range checks regardless of the existence of side effect instruction so that a side effect is caused by moving an array range check issuing an exception before said side effect instruction, and for storing in said storage for each basic block in said first portion information about necessary array range checks;
• and
• means for generating and storing in said storage a conditional branch code for performing said necessary array range check and for jumping to a basic block in said second portion if said array range check is not successful, said basic block corresponding to a basic block which includes said unsuccessful array range check.

An apparatus for versioning a loop in a program, said apparatus comprising:

• a memory storage;
• means for collecting first set information of array range checks for array accesses which are always performed even if passing through any execution path in said loop, and for storing in said storage a collection result;
• means for, by using said collection result, generating and storing in said storage a check code for the versioning;
• means for eliminating a redundant array range check by using said collection result, and for generating and storing in said memory storage a version in the case that an array range check by said check code is successful, said version including a code for unremovable array range check;
• and
• means for generating and storing in said memory storage a version in the case that an array range check by said check code is unsuccessful.

A storage medium storing a program for versioning a loop in a program to be processed, wherein said program has a computer execute the steps of:

• collecting first set information of array range checks for array accesses which are always performed even if passing through any execution path in said loop, and storing in a memory storage a collection result;
• by using said collection result, generating and storing in a storage a check code for the versioning;
• eliminating a redundant array range check by using said collection result, and generating and storing in a memory storage a version in the case that an array range check by said check code is successful, said version including a code for unremovable array range check;
• and
• generating and storing in a memory storage a version in the case that an array range check by said check code is unsuccessful.

A method for versioning a certain portion in a program, comprising the steps of:

• collecting first set information of array range checks for array accesses which are always performed even if passing through any execution path in said certain portion, and storing in a memory storage a collection result;
• by using said collection result, generating and storing in a storage a check code for the versioning;
• eliminating a redundant array range check by using said collection result, and generating and storing in a memory storage a version in the case that an array range check by said check code is successful, and version including a code for unremovable array range check;
• and generating and storing in a memory storage a version in the case that an array range check by said check code is unsuccessful.