I studied Dhrystone about 30 years ago and found it had a number of flaws back then. For example, most of the loops in the code are only executed 1-3 times, which minimizes the value of hoisting values out of inner loops. Read the Dhrystone wikipedia article for more information.
Going back to what benchmarks might be useful... you might consider the Livermore Loops http://www.netlib.org/benchmark/livermorec These are 24 kernels (tight loops) originally in Fortran but ported to C 30 years ago. They are reasonably representative of floating point computational kernels. They are available without a fee. Even if you have no interest in floating point computation for your target architecture, examining the assembly output of these kernels will be helpful in finding where your port of gcc is doing well and where the machine architecture input to the various optimizer phases need some tuning. You also might review that code and write some modest test loops of your own for integer code patterns. Developing good benchmarks is a skill which requires the developer to know the intended purpose of the benchmark. I.e. is our goal to compare optimizer implementations? or different architectures (i.e. arm vs x86)? or different implementations of an architecture (i.e. intel vs amd or early x86 vs current x86) or ... well, you get the idea. Good luck, - Patrick McGehearty On 2/22/2022 3:49 PM, Paul Koning via Gcc wrote:
On Feb 22, 2022, at 4:26 PM, Gary Oblock via Gcc <gcc@gcc.gnu.org> wrote: Andras, The whole point of benchmarks is to judge a processor's performance. That being said, just crippling GCC is not reasonable because processors must be judged in the appropriate context and that includes the current state of the art compiler technology. If you have a new processor I'd benchmark it using the applications you built it for.Exactly. Part of what you want to see is that GCC optimizes well for the new machine, i.e., that there aren't artifacts of the machine description that get in the way of optimization. So you'd want to use applications that are good exercises not just of the code generator but also the optimizer. Dhrystone isn't really that, because it has evolved into mostly an optimizer test, not a machine or code generator test. paul
