Trip-counted loops which use 64-bit arithmetic. Generalize the strip-mining transform operate on This observation leads to a suggested approach to this RFE. Into a sequence (outer loop) of loops of with appropriately Problem, by strip-mining a single very long running loop Luckily, we haveĪ (relatively new) optimization which can address this ThisĪssumption is invalid in the 64-bit case. Non-responsive thread stuck in such a counted loop. JVM's safepoint mechanism to malfunction due to a Iteration (across 32 bits of dynamic range) won't cause the No safepoints, on the assumption that the largest possible This RFE is a request for that story.Ī complicating factor is that sometimes counted loops have There needs to be a story for transforming such long-running Naturally use 64-bit values, either as direct Java longs, orĪs wrapped cursor structure with incrementing long Unsafe API routinely works with 64-bit addresses and addressĪrithmetic. Introduce 64-bit indexes, such as Panama's native arrays and Newer APIs for larger blocks of bulk data will Java arrays, since those arrays can only span a 31-bit index This makes sense as long as bulk operations apply only to Most or all of these pattern matches and transformationsĪpply to loops with 32-bit control variables and arithmetic. The optimizer performs manyĬomplicated pattern matches to detect and transform counted Include unrolling, iteration range splitting (array RCE),Īnd strip mining (JDK-8186027). Many core loop transformations apply to counted loops, whichĪre those with a calculated trip count.
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