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Merge pull request #9658 from pennae/env-diet

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reduce the size of Env by one pointer

(cherry picked from commit 83f5622545a2fc31eb7e7d5105f64ed6dd3058b3)
Change-Id: I5636290526d0165cfc61aee1e7a5b94db4a26cef
This commit is contained in:
eldritch horrors
2024-03-04 07:37:45 +01:00
parent cd326a2aa4
commit 6b279cd10e
9 changed files with 75 additions and 34 deletions
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src/libexpr/eval.cc
+14 -15
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@@ -519,7 +519,7 @@ EvalState::EvalState(
, env1AllocCache(std::allocate_shared<void *>(traceable_allocator<void *>(), nullptr))
#endif
, baseEnv(allocEnv(128))
, staticBaseEnv{std::make_shared<StaticEnv>(false, nullptr)}
, staticBaseEnv{std::make_shared<StaticEnv>(nullptr, nullptr)}
{
countCalls = getEnv("NIX_COUNT_CALLS").value_or("0") != "0";
@@ -788,7 +788,7 @@ void printStaticEnvBindings(const SymbolTable & st, const StaticEnv & se)
// just for the current level of Env, not the whole chain.
void printWithBindings(const SymbolTable & st, const Env & env)
{
if (env.type == Env::HasWithAttrs) {
if (!env.values[0]->isThunk()) {
std::cout << "with: ";
std::cout << ANSI_MAGENTA;
Bindings::iterator j = env.values[0]->attrs->begin();
@@ -842,7 +842,7 @@ void mapStaticEnvBindings(const SymbolTable & st, const StaticEnv & se, const En
if (env.up && se.up) {
mapStaticEnvBindings(st, *se.up, *env.up, vm);
if (env.type == Env::HasWithAttrs) {
if (!env.values[0]->isThunk()) {
// add 'with' bindings.
Bindings::iterator j = env.values[0]->attrs->begin();
while (j != env.values[0]->attrs->end()) {
@@ -980,22 +980,23 @@ inline Value * EvalState::lookupVar(Env * env, const ExprVar & var, bool noEval)
if (!var.fromWith) return env->values[var.displ];
// This early exit defeats the `maybeThunk` optimization for variables from `with`,
// The added complexity of handling this appears to be similarly in cost, or
// the cases where applicable were insignificant in the first place.
if (noEval) return nullptr;
auto * fromWith = var.fromWith;
while (1) {
if (env->type == Env::HasWithExpr) {
if (noEval) return 0;
Value * v = allocValue();
evalAttrs(*env->up, (Expr *) env->values[0], *v, noPos, "<borked>");
env->values[0] = v;
env->type = Env::HasWithAttrs;
}
forceAttrs(*env->values[0], fromWith->pos, "while evaluating the first subexpression of a with expression");
Bindings::iterator j = env->values[0]->attrs->find(var.name);
if (j != env->values[0]->attrs->end()) {
if (countCalls) attrSelects[j->pos]++;
return j->value;
}
if (!env->prevWith)
if (!fromWith->parentWith)
error("undefined variable '%1%'", symbols[var.name]).atPos(var.pos).withFrame(*env, var).debugThrow<UndefinedVarError>();
for (size_t l = env->prevWith; l; --l, env = env->up) ;
for (size_t l = fromWith->prevWith; l; --l, env = env->up) ;
fromWith = fromWith->parentWith;
}
}
@@ -1854,9 +1855,7 @@ void ExprWith::eval(EvalState & state, Env & env, Value & v)
{
Env & env2(state.allocEnv(1));
env2.up = &env;
env2.prevWith = prevWith;
env2.type = Env::HasWithExpr;
env2.values[0] = (Value *) attrs;
env2.values[0] = attrs->maybeThunk(state, env);
body->eval(state, env2, v);
}