[SR-7556] [String] Improve Int(_:String, radix:Int) size and performance #50098
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bug
A deviation from expected or documented behavior. Also: expected but undesirable behavior.
standard library
Area: Standard library umbrella
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A re-written implementation that is less overly generic, thereby permitting inlining without seriously increasing code size, has been merged in PR #36623. Performance on microbenchmarks is improved up to 50%. Further optimizations for bit width ≤ 64 and/or for common bases may be possible. |
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Additional Detail from JIRA
md5: 6c726c2bcb53150bc4c96ab17a6f1588
relates to:
Issue Description:
Constructing an Int from a String eventually involves calling
parseASCII, which is slow and bloated if not properly specialized. A serious of unfortunate events played out over time where this function was overly generic and so was markedinline(__always)to be fast, then it was discovered this function was about 20KB large and the callers were all marked with@inline(never)and various@semanticsto disable specialization for size (and perhaps compilation time). The end result was something bloated, slow, and yet is still emitted into the user module, increasing code size.However, a simpler and more efficient implementation should be easily implementable. At the very least, it could hard code fast-paths for radices of 10 or 16, and fall back to slow paths for the rest.
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