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libexpr: move the ExprLet::attrs allocations into the arena #14635

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Merged
Ericson2314 merged 2 commits into from
Nov 24, 2025
Merged

libexpr: move the ExprLet::attrs allocations into the arena #14635

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43a1831
libexpr: factor out functions for moving data to a new allocator
Radvendii Nov 24, 2025
60f0992
libexpr: move ExprLet::attrs data to arena as well
Radvendii Nov 24, 2025
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2 changes: 2 additions & 0 deletions src/libexpr/include/nix/expr/nixexpr.hh
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Original file line number Diff line number Diff line change
Expand Up @@ -438,6 +438,7 @@ struct ExprAttrs : Expr
std::shared_ptr<const StaticEnv> bindInheritSources(EvalState & es, const std::shared_ptr<const StaticEnv> & env);
Env * buildInheritFromEnv(EvalState & state, Env & up);
void showBindings(const SymbolTable & symbols, std::ostream & str) const;
void moveDataToAllocator(std::pmr::polymorphic_allocator<char> & alloc);
};

struct ExprList : Expr
Expand Down Expand Up @@ -622,6 +623,7 @@ struct ExprCall : Expr

virtual void resetCursedOr() override;
virtual void warnIfCursedOr(const SymbolTable & symbols, const PosTable & positions) override;
void moveDataToAllocator(std::pmr::polymorphic_allocator<char> & alloc);
COMMON_METHODS
};

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35 changes: 19 additions & 16 deletions src/libexpr/nixexpr.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -399,18 +399,19 @@ ExprAttrs::bindInheritSources(EvalState & es, const std::shared_ptr<const Static
return inner;
}

void ExprAttrs::moveDataToAllocator(std::pmr::polymorphic_allocator<char> & alloc)
{
AttrDefs newAttrs{std::move(*attrs), alloc};
attrs.emplace(std::move(newAttrs), alloc);
DynamicAttrDefs newDynamicAttrs{std::move(*dynamicAttrs), alloc};
dynamicAttrs.emplace(std::move(newDynamicAttrs), alloc);
if (inheritFromExprs)
inheritFromExprs = std::make_unique<std::pmr::vector<Expr *>>(std::move(*inheritFromExprs), alloc);
}

void ExprAttrs::bindVars(EvalState & es, const std::shared_ptr<const StaticEnv> & env)
{
// Move storage into the Exprs arena
{
auto arena = es.mem.exprs.alloc;
AttrDefs newAttrs{std::move(*attrs), arena};
attrs.emplace(std::move(newAttrs), arena);
DynamicAttrDefs newDynamicAttrs{std::move(*dynamicAttrs), arena};
dynamicAttrs.emplace(std::move(newDynamicAttrs), arena);
if (inheritFromExprs)
inheritFromExprs = std::make_unique<std::pmr::vector<Expr *>>(std::move(*inheritFromExprs), arena);
}
moveDataToAllocator(es.mem.exprs.alloc);

if (es.debugRepl)
es.exprEnvs.insert(std::make_pair(this, env));
Expand Down Expand Up @@ -484,14 +485,15 @@ void ExprLambda::bindVars(EvalState & es, const std::shared_ptr<const StaticEnv>
body->bindVars(es, newEnv);
}

void ExprCall::moveDataToAllocator(std::pmr::polymorphic_allocator<char> & alloc)
{
std::pmr::vector<Expr *> newArgs{std::move(*args), alloc};
args.emplace(std::move(newArgs), alloc);
}

void ExprCall::bindVars(EvalState & es, const std::shared_ptr<const StaticEnv> & env)
{
// Move storage into the Exprs arena
{
auto arena = es.mem.exprs.alloc;
std::pmr::vector<Expr *> newArgs{std::move(*args), arena};
args.emplace(std::move(newArgs), arena);
}
moveDataToAllocator(es.mem.exprs.alloc);
if (es.debugRepl)
es.exprEnvs.insert(std::make_pair(this, env));

Expand All @@ -502,6 +504,7 @@ void ExprCall::bindVars(EvalState & es, const std::shared_ptr<const StaticEnv> &

void ExprLet::bindVars(EvalState & es, const std::shared_ptr<const StaticEnv> & env)
{
attrs->moveDataToAllocator(es.mem.exprs.alloc);
auto newEnv = [&]() -> std::shared_ptr<const StaticEnv> {
auto newEnv = std::make_shared<StaticEnv>(nullptr, env, attrs->attrs->size());

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