Profile driven optimization of frequently executed paths with inlining of code fragment (one or more lines of code from a child procedure to a parent procedure)

DETAILED DESCRIPTION Unfortunately, traditional inlining is often unable to substantially reduce the procedure call overhead of a program where to do so would be highly advantageous.
In particular, when calling a procedure that usually executes only a small number of instructions before returning to its parent, the procedure call overhead is a large fraction of the cost of executing the procedure.
For example, it is typical for a computer program to include a fairly large procedure that checks for error conditions.
If no error condition has occurred, the procedure returns, after executing only a small number of statements.
Only if there is an error condition, will any of the rest of the statements of the procedure be executed (e.
g.
, to create screen displays warning of the error, etc.
) If a procedure of this kind contains a significant number of instructions that are not usually executed, traditional methods are unlikely to inline the procedure.
The present invention builds on the recognition that most of the statements in many large procedures found in typical computer programs are rarely if ever executed, and provides a form of inlining optimization that appropriately handles large procedures in which most of the statements in the large procedure are rarely or never used.
In accordance with principles of the present invention, an optimizing compiler utilizes inlining to improve the performance of a computer program having a parent procedure which calls a child procedure.
Instead of inlining an entire child procedure into the parent procedure, one or more selected paths through the child procedure are identified and inlined into the parent procedure, without inlining at least one path through the child procedure into the parent procedure.
Because only one or more selected paths through the child procedure have been inlined, the procedure call overhead of the program can be reduced, at a reduced total increase in program size as compared to total inlining of the child procedure.
In disclosed specific embodiments, the computer program is evaluated to determine path frequencies for each procedure prior to operation of the optimizing compiler