Optimize empty sets

This reduces the number of Bindings allocations by about 10%.
This commit is contained in:
Eelco Dolstra 2015-07-23 23:11:08 +02:00
parent 16c9935fa9
commit c8bb2371eb
3 changed files with 14 additions and 4 deletions

View file

@ -29,13 +29,17 @@ Bindings * EvalState::allocBindings(Bindings::size_t capacity)
}
void EvalState::mkAttrs(Value & v, unsigned int expected)
void EvalState::mkAttrs(Value & v, unsigned int capacity)
{
if (capacity == 0) {
v = vEmptySet;
return;
}
clearValue(v);
v.type = tAttrs;
v.attrs = allocBindings(expected);
v.attrs = allocBindings(capacity);
nrAttrsets++;
nrAttrsInAttrsets += expected;
nrAttrsInAttrsets += capacity;
}

View file

@ -281,6 +281,10 @@ EvalState::EvalState(const Strings & _searchPath)
for (auto & i : paths) addToSearchPath(i);
addToSearchPath("nix=" + settings.nixDataDir + "/nix/corepkgs");
clearValue(vEmptySet);
vEmptySet.type = tAttrs;
vEmptySet.attrs = allocBindings(0);
createBaseEnv();
}

View file

@ -80,6 +80,8 @@ public:
path or to environment variables. */
bool restricted;
Value vEmptySet;
private:
SrcToStore srcToStore;
@ -227,7 +229,7 @@ public:
Bindings * allocBindings(Bindings::size_t capacity);
void mkList(Value & v, unsigned int length);
void mkAttrs(Value & v, unsigned int expected);
void mkAttrs(Value & v, unsigned int capacity);
void mkThunk_(Value & v, Expr * expr);
void mkPos(Value & v, Pos * pos);