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Niels Lohmann
eef9aab5ba
The DOM SAX parser looked up the innermost open container for every value: the end of its frame stack, then the object or array pointer in the frame. Compilers have to reload all of that after each value is stored, since a store of a value may alias the frame. The parser now keeps the innermost container's kind and, for an array that stores directly, the array itself in members, updated when a container opens or closes. Flat arrays of numbers are the case that mattered: parsing floats.json (1 000 000 doubles) into a DOM took 2 % more cycles than before the previous commit on macOS and now takes 0.4 % fewer than the code before it (signed_ints.json -0.8 %). Linux Ir is unchanged (canada -6.1 % GCC / -6.9 % Clang, citm -0.3 % / -0.8 %, twitter +0.2 % / 0.0 %). Signed-off-by: Niels Lohmann <mail@nlohmann.me>