SPARC had instructions (BP, Branch with Prediction) which hinted the branch predictor whether the branch was likely or unlikely. Presumably this script just edi

SPARC had instructions (BP, Branch with Prediction) which hinted the branch predictor whether the branch was likely or unlikely. Presumably this script just edited the opcodes in memory to avoid needing to figure out how to change the generated code from the compiler, recompile, and replace the kernel.