PERF: Make IndexRange iterators _much_ faster, by m_Position data member#5808
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hjmjohnson merged 1 commit intoInsightSoftwareConsortium:mainfrom Feb 17, 2026
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Added a numeric data member to the iterator types of IndexRange, denoting the
position of an iterator relative to the begin of its IndexRange. Used to speed
up its comparison operators.
The following code became more than 4x as fast, using Visual Studio 2026
(Release build). For a region size of around 100'000 x 10'000, the duration went
from ~1.9 sec (before this commit) down to ~0.4 sec (after this commit).
for (const auto & index: ImageRegionIndexRange<2>(region))
{
result += index[0] - index[1];
}
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bot
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type:Performance
dzenanz
approved these changes
Feb 17, 2026
N-Dekker
commented
Feb 17, 2026
hjmjohnson
approved these changes
Feb 17, 2026
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Added a numeric data member to the iterator types of IndexRange, denoting the position of an iterator relative to the begin of its IndexRange. Used to speed up its comparison operators.
The following code became more than 4x as fast, using Visual Studio 2026 (Release build). For a region size of around 100'000 x 10'000, the duration went from ~1.9 sec (before this commit) down to ~0.4 sec (after this commit).