Daniele Cono D'Elia edited experim.tex  over 8 years ago

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For {\tt b-trees} - the only benchmark showing a recursive pattern - we insert an OSR point in the body of the method that accounts for the largest {\em self} execution time of the program. Such an OSR point might be useful to trigger recompilation of the code at a higher degree of optimization, or to enable some form of dynamic optimization (for instance, in a recursive search algorithm we might want to inline the comparator method provided by the user at the call).  Results for the unoptimized and optimized versions of the benchmarks are reported in \myfigure\ref{fig:code-quality-base} and \myfigure\ref{fig:code-quality-O1}, respectively. For both scenarios we observe that the overhead is very small, i.e. less than $1\%$ for most benchmarks and less than $2\%$ in the worst case. For some benchmarks, code might run slightly faster after OSR point insertion due to instruction cache effects. We analyzed the code produced by the x86\_64 x86-64  back-end: the OSR machinery is lowered into three native instructions that load a counter in a register, compare it against a constant value and jump to the OSR block accordingly. The number of times the OSR condition is checked for each benchmark is the same as in the experiments reported in \mytable\ref{tab:sameFun}.   \paragraph{Overhead of OSR Transitions.}