Compilation optimization method for conditional transfer prediction direction transformation

Abstract

The invention discloses a compilation optimization method for conditional transfer prediction direction transformation. When serious performance loss caused by frequent branch prediction failure is found, the following steps are executed: S1, recompiling a source program, and adding compilation optimization options for transfer prediction direction transformation during compilation; S2, performingcontrol flow analysis on the source program, dividing the source program into a plurality of basic blocks, identifying conditional branch statements contained in the innermost layer of circulation ofthe source program, dividing the conditional branch statements into a plurality of independent basic blocks, and marking the first basic block with a special attribute of branch prediction failure; S3, inserting a transfer predictor direction switching instruction into the initial position of the basic block with the branch prediction failure special attribute; S4, enabling the compiler to continue to perform the remaining compiling process to generate the target code. According to the method, the problems of performance loss and potential errors caused by an embedded assembly mode can be avoided, the condition transfer prediction accuracy can be improved, and the purpose of reducing the performance loss is achieved.

Description

technical field [0001] The invention relates to a compilation optimization method for conditional transfer prediction direction transformation, belonging to the technical field of computer compilation optimization. Background technique [0002] Pipeline technology is an optimization technology commonly used in current processors. For branch instructions, if there is no branch prediction, the processor needs to wait for the execution of the branch instruction to end before sending the next instruction to the first stage of the pipeline (instruction fetch stage), which will cause the pipeline to stall and seriously affect performance. There are many mechanisms for branch prediction, and the transfer prediction bit is one of the important means. When using the branch prediction bit for branch prediction, the implementation mechanism is as follows: if the branch prediction bit is "0", it is predicted that no jump will occur, and the next instruction immediately following the cu...

AI Technical Summary

Problems solved by technology

The first is the inherent disadvantage of embedded assembly: it will cut the original complete program into two independent sections, which will affect the instruction scheduling of the compiler and reduce the performance of the program.

In addition, whether the location of the direction switching instruction inserted into the branch predictor is appropriate directly affects whether its function can be effectively played. Using embedded assembly requires the programmer to analyze the control flow behavior characteristics of the program in detail, and find out the location where the branch prediction often fails according to the actual running results. This is also a lot of work and challenges

Images