perf: fast-path Num stringify in OP_+ string concatenation#684
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He-Pin wants to merge 1 commit intodatabricks:masterfrom
Open
perf: fast-path Num stringify in OP_+ string concatenation#684He-Pin wants to merge 1 commit intodatabricks:masterfrom
He-Pin wants to merge 1 commit intodatabricks:masterfrom
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Add direct RenderUtils.renderDouble() call for Num+Str and Str+Num cases in binary OP_+ to avoid Materializer.stringify() dispatch overhead. stringify() performs a full pattern match on Val type just to extract the double for rendering. The direct call skips this dispatch entirely, which is significant for string template operations that concatenate many numbers with strings. Uses n.asDouble (not raw destructured double) to preserve the NaN guard that exists in Val.Num.asDouble — this ensures consistency with Materializer.stringify() error behavior for not-a-number values. Upstream: jit branch commit 4b1cd03
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Motivation
When concatenating strings with
+, if one operand is a number, it must be converted to string. The current path goes throughMaterializer.stringifywhich has overhead from format dispatching and intermediate string creation.Key Design Decision
Add a fast path in
OP_+that detectsVal.Numoperands and converts them directly using the existingrenderDoubleutility, bypassing the fullMaterializer.stringifychain.Modification
Evaluator.scala: Added 2-line fast path check inOP_+string concatenation forVal.NumoperandsBenchmark Results
JMH (JVM, 3 iterations)
Analysis
References
he-pin/sjsonnetjit branch commit4b1cd032Result
Massive ROI optimization: 2 lines of code for -10% to -19% JVM improvement on number-to-string concatenation paths.