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Niels Lohmann
3eb414f832
Benchmarking found the get()/get_ignoring_pending_unget() split in skip_whitespace() made long whitespace runs (e.g. indentation in pretty-printed JSON) 1.75x-3.2x SLOWER instead of faster, reproducible with both Apple Clang and GCC. Root cause: rewriting the loop from a plain do-while into an initial get() followed by a while-loop defeated the compiler's ability to keep the input adapter's read/end pointers in registers across iterations; both compilers instead reloaded them from memory on every character. The function split itself was not the problem (it still fully inlines); the loop's control-flow shape was. The fix keeps the same two-function structure but restores a do-while shape (guarded by an if for the "first char not whitespace" case), which lets both compilers hoist the pointers back into registers, matching or beating pre-#5490 performance. Signed-off-by: Niels Lohmann <mail@nlohmann.me>