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Make Env smaller

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Commit 20866a7031 added a ‘withAttrs’
field to Env, which is annoying because it makes every Env structure
bigger and we allocate millions of them.  E.g. NixOS evaluation took
18 MiB more.  So this commit squeezes ‘withAttrs’ into values[0].
Probably should use a union...
This commit is contained in:
Eelco Dolstra 2013-07-31 12:44:21 +02:00
parent 8ae6d55db1
commit 0a470fc345
2 changed files with 23 additions and 21 deletions
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38
src/libexpr/eval.cc
View file

@ -308,24 +308,25 @@ inline Value * EvalState::lookupVar(Env * env, const VarRef & var, bool noEval)
{
for (unsigned int l = var.level; l; --l, env = env->up) ;
if (var.fromWith) {
while (1) {
if (!env->values[0]) {
if (noEval) return 0;
env->values[0] = allocValue();
evalAttrs(*env->up, env->withAttrs, *env->values[0]);
}
Bindings::iterator j = env->values[0]->attrs->find(var.name);
if (j != env->values[0]->attrs->end()) {
if (countCalls && j->pos) attrSelects[*j->pos]++;
return j->value;
}
if (env->prevWith == 0)
throwEvalError("undefined variable `%1%'", var.name);
for (unsigned int l = env->prevWith; l; --l, env = env->up) ;
if (!var.fromWith) return env->values[var.displ];
while (1) {
if (!env->haveWithAttrs) {
if (noEval) return 0;
Expr * attrs = (Expr *) env->values[0];
env->values[0] = allocValue();
evalAttrs(*env->up, attrs, *env->values[0]);
env->haveWithAttrs = true;
}
} else
return env->values[var.displ];
Bindings::iterator j = env->values[0]->attrs->find(var.name);
if (j != env->values[0]->attrs->end()) {
if (countCalls && j->pos) attrSelects[*j->pos]++;
return j->value;
}
if (!env->prevWith)
throwEvalError("undefined variable `%1%'", var.name);
for (unsigned int l = env->prevWith; l; --l, env = env->up) ;
}
}
@ -829,7 +830,8 @@ void ExprWith::eval(EvalState & state, Env & env, Value & v)
Env & env2(state.allocEnv(1));
env2.up = &env;
env2.prevWith = prevWith;
env2.withAttrs = attrs;
env2.haveWithAttrs = false;
env2.values[0] = (Value *) attrs;
body->eval(state, env2, v);
}

4
src/libexpr/eval.hh
View file

@ -52,8 +52,8 @@ struct PrimOp
struct Env
{
Env * up;
unsigned int prevWith; // nr of levels up to next `with' environment
Expr * withAttrs;
unsigned short prevWith; // nr of levels up to next `with' environment
bool haveWithAttrs;
Value * values[0];
};