Methods and apparatus for optimizing programs in the presence of exceptions

A method of optimizing a computer program written in a language that supports exceptions, the method comprising the steps of:

• transforming each code region to be optimized by performing optimizations without any constraints on ordering between potentially excepting instructions;
• and
• generating compensation code which executes only if an exception is thrown by the region transformed in the transforming step.

Apparatus for optimizing a computer program written in a language that supports exceptions with a constraint that a write statement can not be moved across a potentially excepting instruction, the apparatus comprising:

• at least one processor operative to:
• (i) identify in the computer program a statement that writes into a variable and a statement corresponding to a potentially excepting instruction, and (ii) remove a constraint on moving the write statement across the potentially excepting instruction when the variable written by the write statement is determined not to be live at an exception handler that catches the exception when thrown.

Apparatus for optimizing a computer program written in a language that supports exceptions, the apparatus comprising:

• at least one processor operative to:
• (i) transform each code region to be optimized by performing optimizations without any constraints on ordering between potentially excepting instructions, and (ii) generate compensation code which executes only if an exception is thrown by the region transformed in the transforming operation.

An article of manufacture for optimizing a computer program written in a language that supports exceptions with a constraint that a write statement can not be moved across a potentially excepting instruction, comprising a machine readable medium containing one or more programs which when executed implement the steps of:

• identifying in the computer program a statement that writes into a variable and a statement corresponding to a potentially excepting instruction;
• and
• removing a constraint on moving the write statement across the potentially excepting instruction when the variable written by the write statement is determined not to be live at an exception handler that catches the exception when thrown.

An article of manufacture for optimizing a computer program written in a language that supports exceptions, comprising a machine readable medium containing one or more programs which when executed implement the steps of:

• transforming each code region to be optimized by performing optimizations without any constraints on ordering between potentially excepting instructions;
• and
• generating compensation code which executes only if an exception is thrown by the region transformed in the transforming step.

A method of optimizing a computer program written in a language that supports exceptions with a constraint that a write statement can not be moved across a potentially excepting instruction, the method comprising the steps of:

• identifying in the computer program a statement that writes into a variable and a statement corresponding to a potentially excepting instruction;
• and
• removing a constraint on moving the write statement across the potentially excepting instruction when the variable written by the write statement is determined not to be interprocedurally live at an exception handler that catches the exception when thrown.