lix/src/libexpr/eval-inline.hh
pennae 6526d1676b replace most Pos objects/ptrs with indexes into a position table
Pos objects are somewhat wasteful as they duplicate the origin file name and
input type for each object. on files that produce more than one Pos when parsed
this a sizeable waste of memory (one pointer per Pos). the same goes for
ptr<Pos> on 64 bit machines: parsing enough source to require 8 bytes to locate
a position would need at least 8GB of input and 64GB of expression memory. it's
not likely that we'll hit that any time soon, so we can use a uint32_t index to
locate positions instead.
2022-04-21 21:46:06 +02:00

138 lines
3.3 KiB
C++

#pragma once
#include "eval.hh"
namespace nix {
/* Note: Various places expect the allocated memory to be zeroed. */
[[gnu::always_inline]]
inline void * allocBytes(size_t n)
{
void * p;
#if HAVE_BOEHMGC
p = GC_MALLOC(n);
#else
p = calloc(n, 1);
#endif
if (!p) throw std::bad_alloc();
return p;
}
[[gnu::always_inline]]
Value * EvalState::allocValue()
{
#if HAVE_BOEHMGC
/* We use the boehm batch allocator to speed up allocations of Values (of which there are many).
GC_malloc_many returns a linked list of objects of the given size, where the first word
of each object is also the pointer to the next object in the list. This also means that we
have to explicitly clear the first word of every object we take. */
if (!*valueAllocCache) {
*valueAllocCache = GC_malloc_many(sizeof(Value));
if (!*valueAllocCache) throw std::bad_alloc();
}
/* GC_NEXT is a convenience macro for accessing the first word of an object.
Take the first list item, advance the list to the next item, and clear the next pointer. */
void * p = *valueAllocCache;
*valueAllocCache = GC_NEXT(p);
GC_NEXT(p) = nullptr;
#else
void * p = allocBytes(sizeof(Value));
#endif
nrValues++;
return (Value *) p;
}
[[gnu::always_inline]]
Env & EvalState::allocEnv(size_t size)
{
nrEnvs++;
nrValuesInEnvs += size;
Env * env;
#if HAVE_BOEHMGC
if (size == 1) {
/* see allocValue for explanations. */
if (!*env1AllocCache) {
*env1AllocCache = GC_malloc_many(sizeof(Env) + sizeof(Value *));
if (!*env1AllocCache) throw std::bad_alloc();
}
void * p = *env1AllocCache;
*env1AllocCache = GC_NEXT(p);
GC_NEXT(p) = nullptr;
env = (Env *) p;
} else
#endif
env = (Env *) allocBytes(sizeof(Env) + size * sizeof(Value *));
env->type = Env::Plain;
/* We assume that env->values has been cleared by the allocator; maybeThunk() and lookupVar fromWith expect this. */
return *env;
}
[[gnu::always_inline]]
void EvalState::forceValue(Value & v, const PosIdx pos)
{
forceValue(v, [&]() { return pos; });
}
template<typename Callable>
void EvalState::forceValue(Value & v, Callable getPos)
{
if (v.isThunk()) {
Env * env = v.thunk.env;
Expr * expr = v.thunk.expr;
try {
v.mkBlackhole();
//checkInterrupt();
expr->eval(*this, *env, v);
} catch (...) {
v.mkThunk(env, expr);
throw;
}
}
else if (v.isApp())
callFunction(*v.app.left, *v.app.right, v, noPos);
else if (v.isBlackhole())
throwEvalError(getPos(), "infinite recursion encountered");
}
[[gnu::always_inline]]
inline void EvalState::forceAttrs(Value & v, const PosIdx pos)
{
forceAttrs(v, [&]() { return pos; });
}
template <typename Callable>
[[gnu::always_inline]]
inline void EvalState::forceAttrs(Value & v, Callable getPos)
{
forceValue(v, getPos);
if (v.type() != nAttrs)
throwTypeError(getPos(), "value is %1% while a set was expected", v);
}
[[gnu::always_inline]]
inline void EvalState::forceList(Value & v, const PosIdx pos)
{
forceValue(v, pos);
if (!v.isList())
throwTypeError(pos, "value is %1% while a list was expected", v);
}
}