forked from OSchip/llvm-project
Rewrite a function so that it doesn't use pointers to pointers. NFC.
Previous code was a bit puzzling because of its use of pointers. In this patch, we pass a vector and its offsets, instead of pointers to vector elements. llvm-svn: 314756
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llvm/lib/MC
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@ -82,28 +82,29 @@ static int charTailAt(StringPair *P, size_t Pos) {
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// Three-way radix quicksort. This is much faster than std::sort with strcmp
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// because it does not compare characters that we already know the same.
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static void multikey_qsort(StringPair **Begin, StringPair **End, int Pos) {
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static void multikey_qsort(std::vector<StringPair *> &Vec, size_t Begin,
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size_t End, int Pos) {
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tailcall:
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if (End - Begin <= 1)
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return;
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// Partition items. Items in [Begin, P) are greater than the pivot,
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// Partition items so that items in [Begin, P) are greater than the pivot,
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// [P, Q) are the same as the pivot, and [Q, End) are less than the pivot.
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int Pivot = charTailAt(*Begin, Pos);
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StringPair **P = Begin;
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StringPair **Q = End;
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for (StringPair **R = Begin + 1; R < Q;) {
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int C = charTailAt(*R, Pos);
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int Pivot = charTailAt(Vec[Begin], Pos);
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size_t P = Begin;
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size_t Q = End;
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for (size_t R = Begin + 1; R < Q;) {
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int C = charTailAt(Vec[R], Pos);
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if (C > Pivot)
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std::swap(*P++, *R++);
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std::swap(Vec[P++], Vec[R++]);
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else if (C < Pivot)
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std::swap(*--Q, *R);
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std::swap(Vec[--Q], Vec[R]);
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else
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R++;
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}
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multikey_qsort(Begin, P, Pos);
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multikey_qsort(Q, End, Pos);
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multikey_qsort(Vec, Begin, P, Pos);
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multikey_qsort(Vec, Q, End, Pos);
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if (Pivot != -1) {
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// qsort(P, Q, Pos + 1), but with tail call optimization.
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Begin = P;
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@ -133,7 +134,7 @@ void StringTableBuilder::finalizeStringTable(bool Optimize) {
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if (!Strings.empty()) {
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// If we're optimizing, sort by name. If not, sort by previously assigned
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// offset.
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multikey_qsort(&Strings[0], &Strings[0] + Strings.size(), 0);
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multikey_qsort(Strings, 0, Strings.size(), 0);
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}
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initSize();
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