Hewlett-packard Company

Lucent Technologies Inc.

Agere Systems Guardian Corp.

Ramesh V Peri

Sanjay Jinturkar

Paul Gerard D'Arcy

David Whalley

Jay Patrick Wilshire

Lincoln A Fajardo

Kamesh Peri

Pamela C Deschler

A method for simulating a first processor (e.g., target processor) on a second processor (e.g., host processor) includes translating assembly language instructions associated with the first processor into 'C' language code. The 'C' language code is then compiled by a compiler program running on the second processor. The compiled code is then executed by the second processor to simulate the first processor. For example, the code may be checked to determine whether it is functionally correct and/or run-time statistics may be collected regarding the program associated with the first processor.

Methods and apparatus for simulating external linkage points and control transfers in source translation systems

The inventive system and method separates the tracking of the loop entry and exit points and loop optimization information, from the generation of the instrumentation code at the loop entry and exit points. Thus, the different phases in the compiler can proceed in an optimal manner with respect to producing the best optimized code. This invention allows the correlation of the source code loops to the object code loops, even though different optimizations are being applied to loops. A loop information database is used to store a history of optimizations about loops, as well as loop entry and exit points, instead of using loop data structures that must be globally maintained. The invention detects the loops in the program code, and assigns a unique identifier to each detected loop. The entry and exit points, as well as the identifier are stored in the database. Any changes to the loops from optimizations are also stored in the database. This technique enables profilers to collect and report the profile information about loops to the user in an intelligible manner.

Tracking loop entry and exit points in a compiler

A system for debugging the computer program present in read-only memory (ROM) contains a debugger, a processor, read-only memory, a bus and a hardware debugging support module. The hardware debugging support module contains a first register called the range start register, a second register called the range end register and a comparator. The debugger uses a list of &ldquo;n&rdquo; user specified break points to divide a computer program into &ldquo;n&plus;1&rdquo; regions, each of which has a start address and an end address. The first register and the second register of the hardware debugging support module are programmed with the start address and end address of a region which contains a specific address. The comparator is connected to the first register and second register of the hardware debugging support module and is also connected to the bus which connects the read-only memory to the processor. The comparator monitors addresses traveling on the bus and causes the hardware debugging support module to interrupt the processor and transfer control of the computer program to the debugger if a specific address traveling on the bus does not fall within the range defined by the first register and the second register. The debugger then searches the remaining &ldquo;n&plus;1&rdquo; regions to see if the specific address lies within a second region. If such a region is found, then the start address and end address of that second region are entered into the first register and the second register and the computer program is run. However, if such a region is not found, then the computer program has reached a break point and the debugger transfers control of the program to the user. The computer program can then be single stepped to execute the instruction at which the break point was placed to obtain an output address. The start address and end address of the region that contain this output address are programmed into the first register and the second register and the computer program is run. This process is repeated until the entire computer program has been executed.

System for debugging (N) break points by dividing a computer program to (n&plus;1) regions each contains no break point and using two registers to define the start and end addresses of each region

The inventive system and method prepares a loop within a section of program code for profiling by placing instrumentation slots into the section at particular points. Entry slots are inserted just prior to the entry point of the loop. If there is a target within the loop of a branch instruction that is located outside of the loop, then the target is changed to point to the first instruction of the entry slots. If there is a fall through within the loop to the entry slots, then a branch instruction is inserted before the first instruction of the entry slots to branch around the entry slots. Exit slots are inserted immediately subsequent to the implicit exit point of the loop, and exit slots are also inserted just prior to the target of the explicit exit instruction. If there is a fall through within the section to the exit slots, then a branch instruction is inserted before a first instruction of the exit slots to branch around the exit slots. The target of the explicit exit instruction is changed to point to the first instruction of the exit slots.

Loop profiling by instrumentation

A method of analyzing performance of a program executing in a computer system. A user provides a set of user defined region of the program. Thus, a user has the flexibility to choose the regions of program code profiled. The performance of user defined regions of the program is measured by a set of run-time metrics. Each user defined region is associated with a range break point. Run-time metrics measuring the performance of user defined regions of the program are updated, during execution, whenever a range break point is set. The handling of range break points may be implemented, for example, by specialized hardware and software. This method may be less intrusive than instrumentation based profiling but more accurate than sampling based profiling.

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Allentown, PA, United States of America

Ramesh V Peri