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Merge pull request #5964 from pennae/fix-bulk-alloc

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allocate a GC root value for the Value cache pointer
This commit is contained in:
Eelco Dolstra 2022-01-24 12:43:14 +01:00 committed by GitHub
commit 8c778e3d9d
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2 changed files with 11 additions and 6 deletions
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15
src/libexpr/eval.cc
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@ -435,6 +435,11 @@ EvalState::EvalState(
, store(store)
, buildStore(buildStore ? buildStore : store)
, regexCache(makeRegexCache())
#if HAVE_BOEHMGC
, valueAllocCache(std::allocate_shared<void *>(traceable_allocator<void *>(), nullptr))
#else
, valueAllocCache(std::make_shared<void *>(nullptr))
#endif
, baseEnv(allocEnv(128))
, staticBaseEnv(false, 0)
{
@ -852,15 +857,15 @@ Value * EvalState::allocValue()
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();
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;
GC_PTR_STORE_AND_DIRTY(&valueAllocCache, GC_NEXT(p));
void * p = *valueAllocCache;
GC_PTR_STORE_AND_DIRTY(&*valueAllocCache, GC_NEXT(p));
GC_NEXT(p) = nullptr;
nrValues++;

2
src/libexpr/eval.hh
View file

@ -133,7 +133,7 @@ private:
std::shared_ptr<RegexCache> regexCache;
/* Allocation cache for GC'd Value objects. */
void * valueAllocCache = nullptr;
std::shared_ptr<void *> valueAllocCache;
public: