Method and apparatus for using static branch predictions hints with dynamically translated code traces to improve performance

An apparatus implemented in a computer system that uses static branch prediction hints to improve performance of translated code at run time, the apparatus comprising:

• a native code pool that stores program instructions;
• a code cache storing translated hot traces of basic blocks of instructions and from which translated hot traces of basic blocks of instructions are executed;
• a trace picker that identifies hot traces of basic blocks of instructions from the native code pool based on execution of instructions in the native code pool, wherein each basic block of instructions includes a branch instruction;
• and
• a translator that receives selected hot traces of basic blocks of instructions from the trace picker and translates the selected hot traces of basic blocks of instructions and places the basic blocks of instructions of the translated hot traces in the code cache in a trace order, wherein each translated hot trace includes first and last basic blocks of instructions, wherein the translator associates static branch predictions with branch instructions in the translated hot trace stored in the code cache and for each hot trace being stored in the code cache, the translator adjusts a static prediction of the branch instruction of the last basic block of instructions of the hot trace to branch to a first instruction of the first basic block of instructions of the hot trace, and adjusts a static prediction of each branch instruction in each basic block of instructions between the first basic block of instructions, inclusive, to the last basic block of instructions, exclusive, to branch to a first instruction of a next basic block in the trace order.

A program storage medium having computer readable program code thereon for causing native code to be optimized at run time, the program storage medium comprising:

• a first code segment of computer readable program code for executing native code instructions contained in a native code pool;
• a second code segment of computer readable program code for identifying a hot trace of basic blocks of instructions from the native code instructions based on executing native code instructions contained in the native code pool, wherein each basic block of instructions includes a branch instruction;
• a third code segment of computer readable program code for translating the hot trace and storing the basic blocks of instructions of the translated hot trace in a code cache in a trace order, wherein the translated hot trace includes first and last basic blocks of instructions;
• a fourth code segment of computer readable program code for associating static predictions derived from executing native code instruction contained in the native code pool with branch instructions in the translated hot trace stored in the code cache, and adjusting a static prediction of the branch instruction of the last basic block of instructions to branch to a first instruction of the first basic block of instructions, and adjusting a static prediction of each branch instruction in each basic block of instructions between the first basic block of instructions, inclusive, to the last basic block of instructions, exclusive, to branch to a first instruction of a next basic block in the trace order;
• and
• a fifth code segment of computer readable program code for executing the translated hot trace from the code cache.