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prim_concatMap: allocate intermediate list on stack

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volth 2018-07-05 12:37:37 +00:00 committed by GitHub
parent ee218f99ca
commit 841747b0e6
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1 changed files with 15 additions and 7 deletions
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22
src/libexpr/primops.cc
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@ -1651,22 +1651,30 @@ static void prim_concatMap(EvalState & state, const Pos & pos, Value * * args, V
{
state.forceFunction(*args[0], pos);
state.forceList(*args[1], pos);
auto len = args[1]->listSize();
auto nrLists = args[1]->listSize();
Value vList;
state.mkList(vList, len);
Value lists[nrLists];
size_t len = 0;
for (unsigned int n = 0; n < len; ++n) {
for (unsigned int n = 0; n < nrLists; ++n) {
Value * vElem = args[1]->listElems()[n];
state.forceValue(*vElem);
state.callFunction(*args[0], *vElem, *(vList.listElems()[n] = state.allocValue()), pos);
state.callFunction(*args[0], *vElem, lists[n], pos);
state.forceList(lists[n], pos);
len += lists[n].listSize();
}
state.concatLists(v, len, vList.listElems(), pos);
state.mkList(v, len);
auto out = v.listElems();
for (unsigned int n = 0, pos = 0; n < nrLists; ++n) {
auto l = lists[n].listSize();
if (l)
memcpy(out + pos, lists[n].listElems(), l * sizeof(Value *));
pos += l;
}
}
/*************************************************************
* Integer arithmetic
*************************************************************/