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//===- lib/Support/IntervalMap.cpp - A sorted interval map ----------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file implements the few non-templated functions in IntervalMap.
//
//===----------------------------------------------------------------------===//
#include "llvm/ADT/IntervalMap.h"
namespace llvm {
namespace IntervalMapImpl {
IdxPair distribute(unsigned Nodes, unsigned Elements, unsigned Capacity,
const unsigned *CurSize, unsigned NewSize[],
unsigned Position, bool Grow) {
assert(Elements + Grow <= Nodes * Capacity && "Not enough room for elements");
assert(Position <= Elements && "Invalid position");
if (!Nodes)
return IdxPair();
// Trivial algorithm: left-leaning even distribution.
const unsigned PerNode = (Elements + Grow) / Nodes;
const unsigned Extra = (Elements + Grow) % Nodes;
IdxPair PosPair = IdxPair(Nodes, 0);
unsigned Sum = 0;
for (unsigned n = 0; n != Nodes; ++n) {
Sum += NewSize[n] = PerNode + (n < Extra);
if (PosPair.first == Nodes && Sum > Position)
PosPair = IdxPair(n, Position - (Sum - NewSize[n]));
}
assert(Sum == Elements + Grow && "Bad distribution sum");
// Subtract the Grow element that was added.
if (Grow) {
assert(PosPair.first < Nodes && "Bad algebra");
assert(NewSize[PosPair.first] && "Too few elements to need Grow");
--NewSize[PosPair.first];
}
#ifndef NDEBUG
Sum = 0;
for (unsigned n = 0; n != Nodes; ++n) {
assert(NewSize[n] <= Capacity && "Overallocated node");
Sum += NewSize[n];
}
assert(Sum == Elements && "Bad distribution sum");
#endif
return PosPair;
}
} // namespace IntervalMapImpl
} // namespace llvm
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