Method for transforming a multithreaded program for general execution
A technique is disclosed for executing a program designed for multi-threaded operation on a general purpose processor. Original source code for the program is transformed from a multi-threaded structure into a computationally equivalent single-threaded structure. A transform operation modifies the original source code to insert code constructs for serial thread execution. The transform operation also replaces synchronization barrier constructs in the original source code with synchronization barrier code that is configured to facilitate serialization. The transformed source code may then be conventionally compiled and advantageously executed on the general purpose processor.
1. A computer-implemented method for executing a multi-threaded program on a single-threaded processor core, the method comprising:
identifying a kernel function included within the multi-threaded program;
enumerating a plurality of barrier synchronization calls within the kernel function;
modifying the kernel function by replacing each enumerated barrier synchronization call within the kernel function with a plurality of barrier commands and inserting a plurality of execution control commands into the kernel function, wherein the plurality of execution control commands includes a switch command within a nested loop, the switch command configured to include a different case for each of the enumerated barrier synchronization calls; and
transferring the modified kernel function to a transformed source file.
2. The method of claim 1 , wherein the execution control commands comprise at least one of a while-loop, a nested for-loop, and a switch command within the nested for-loop.
3. The method of claim 2 , wherein the while-loop is configured to execute one iteration for each enumerated barrier synchronization call within the kernel function.
4. The method of claim 3 , wherein the nested for-loop is configured to execute a number of times within each iteration of the while-loop equal to the number of threads that are supposed to execute the kernel function concurrently.
5. The method of claim 4 , wherein the switch command includes a different case for each enumerated barrier synchronization call within the kernel function.
6. The method of claim 5 , wherein the execution control commands further comprise a first variable configured to store a current starting point for execution, and second variable configured to store a next starting point for execution, and wherein the first variable and the second variable are updated for each iteration of the while-loop.
7. The method of claim 6 , wherein the barrier commands related to a particular enumerated barrier synchronization call within the kernel function comprise an assignment to the second variable corresponding to an enumeration number for a barrier label, a thread-end goto command, and the barrier label.
8. The method of claim 7 , wherein the enumeration number corresponds to a case in the switch command associated with the particular enumerated barrier synchronization call within the kernel function and having an associated goto command that targets the barrier label.
9. The method of claim 7 , wherein the thread-end goto command jumps to a label in the nested for-loop that advances the nested for-loop by one iteration.
10. The method of claim 1 , further comprising compiling at least the transformed source file to generate an executable object for execution on the single-threaded processor core.
11. A non-transitory computer-readable storage medium including instructions that, when executed by a processing unit, cause the processing unit to execute a multi-threaded program on a single-threaded processor core, by performing the steps of:
identifying a kernel function included within the multi-threaded program;
enumerating a plurality of barrier synchronization calls within the kernel function;
modifying the kernel function by replacing each enumerated barrier synchronization call within the kernel function with a plurality of barrier commands and inserting a plurality of execution control commands into the kernel function, wherein the plurality of execution control commands includes a switch command within a nested loop, the switch command configured to include a different case for each of the enumerated barrier synchronization calls; and
transferring the modified kernel function to a transformed source file.
12. The non-transitory computer-readable storage medium of claim 11 , wherein the execution control commands comprise at least one of a while-loop, a nested for-loop, and a switch command within the nested for-loop.
13. The non-transitory computer-readable storage medium of claim 12 , wherein the while-loop is configured to execute one iteration for each enumerated barrier synchronization call within the kernel function.
14. The non-transitory computer-readable storage medium of claim 13 , wherein the nested for-loop is configured to execute a number of times within each iteration of the while-loop equal to the number of threads that are supposed to execute the kernel function concurrently.
15. The non-transitory computer-readable storage medium of claim 14 , wherein the switch command includes a different case for each enumerated barrier synchronization call within the kernel function.
16. The non-transitory computer-readable storage medium of claim 15 , wherein the execution control commands further comprise a first variable configured to store a current starting point for execution, and second variable configured to store a next starting point for execution, and wherein the first variable and the second variable are updated for each iteration of the while-loop.
17. The non-transitory computer-readable storage medium of claim 16 , wherein the barrier commands related to a particular enumerated barrier synchronization call within the kernel function comprise an assignment to the second variable corresponding to an enumeration number for a barrier label, a thread-end goto command that advances the nested for-loop by one iteration, and the barrier label.
18. The non-transitory computer-readable storage medium of claim 17 , wherein the enumeration number corresponds to a case in the switch command associated with the particular enumerated barrier synchronization call within the kernel function and having an associated goto command that targets the barrier label.
19. The non-transitory computer-readable storage medium of claim 11 , further comprising compiling at least the transformed source file to generate an executable object for execution on the single-threaded processor core.
20. A computing device, comprising:
a mass storage system configured to store at least a multi-threaded program and a transformed source file;
a processing unit coupled to the mass storage system and configured to:
identify a kernel function included within the multi-threaded program;
enumerate a plurality of barrier synchronization calls within the kernel function;
modify the kernel function by replacing each enumerated barrier synchronization call within the kernel function with a plurality of barrier commands and inserting a plurality of execution control commands into the kernel function, wherein the plurality of execution control commands includes a switch command within a nested loop, the switch command configured to include a different case for each of the enumerated barrier synchronization calls; and
transfer the modified kernel function to the transformed source file.
21. The computing device of claim 20 , wherein the execution control commands comprise at least one of a while-loop, a nested for-loop, and a switch command within the nested for-loop that is configured to include a different case for each enumerated barrier synchronization call within the kernel function.
22. A computing device, comprising:
a mass storage system configured to store at least a multi-threaded program and a transformed source file;
a processing unit coupled to the mass storage system and configured to:
identify a kernel function included within the multi-threaded program;
enumerate a plurality of barrier synchronization calls within the kernel function;
modify the kernel function by replacing each enumerated barrier synchronization call within the kernel function with a plurality of barrier commands and inserting a plurality of execution control commands into the kernel function, wherein the execution control commands comprise at least one of a while-loop, a nested for-loop, and a switch command within the nested for-loop that is configured to include a different case for each enumerated barrier synchronization call within the kernel function, and wherein the plurality of barrier commands relate to a particular enumerated barrier synchronization call within the kernel function comprise:
an assignment to a variable corresponding to an enumeration number for a barrier label;
a thread-end goto command; and
the barrier label; and
transfer the modified kernel function to the transformed source file.