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Pin pointer literals in code, and julia values in julia_to_scm #80

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Pin pointer literals in code, and julia values in julia_to_scm #80

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1 change: 1 addition & 0 deletions src/ast.c
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Original file line number Diff line number Diff line change
Expand Up @@ -815,6 +815,7 @@ static value_t julia_to_list2_noalloc(fl_context_t *fl_ctx, jl_value_t *a, jl_va

static value_t julia_to_scm_(fl_context_t *fl_ctx, jl_value_t *v, int check_valid)
{
PTR_PIN(v);
value_t retval;
if (julia_to_scm_noalloc1(fl_ctx, v, &retval))
return retval;
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1 change: 1 addition & 0 deletions src/cgutils.cpp
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Expand Up @@ -578,6 +578,7 @@ static Value *literal_pointer_val(jl_codectx_t &ctx, jl_value_t *p)
{
if (p == NULL)
return Constant::getNullValue(ctx.types().T_pjlvalue);
PTR_PIN(p);
Value *pgv = literal_pointer_val_slot(ctx, p);
jl_aliasinfo_t ai = jl_aliasinfo_t::fromTBAA(ctx, ctx.tbaa().tbaa_const);
auto load = ai.decorateInst(maybe_mark_load_dereferenceable(
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1 change: 1 addition & 0 deletions src/jitlayers.h
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Expand Up @@ -308,6 +308,7 @@ void add_named_global(StringRef name, void *addr) JL_NOTSAFEPOINT;

static inline Constant *literal_static_pointer_val(const void *p, Type *T) JL_NOTSAFEPOINT
{
PTR_PIN((void*)p);
// this function will emit a static pointer into the generated code
// the generated code will only be valid during the current session,
// and thus, this should typically be avoided in new API's
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2 changes: 2 additions & 0 deletions src/julia.h
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Expand Up @@ -2755,6 +2755,8 @@ extern void mmtk_object_reference_write_slow(void* mutator, const void* parent,
#define MMTK_IMMORTAL_BUMP_ALLOCATOR (0)

// VO bit is required to support conservative stack scanning and moving.
// NB: We have to set VO bit even if this is a non_moving build. Otherwise, assertions in mmtk-core
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The reason is that we enable mmtk/is_mmtk_object for all the builds. If the feature mmtk/is_mmtk_object is not enabled, VO bit is not used in MMTk and MMTk will not assert VO bit. We can disable the feature mmtk/is_mmtk_object for a non-moving build, and we will not need VO bit here. But I don't know if that is worth doing.

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Did you measure the performance penalty of having the VO bit? If people don't care about fragmentation or if we want to do an apples to apples comparison with stock (both non-moving) I suppose we might want to disable the VO bit depending on whether it's too expensive to maintain it.

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I didn't measure it with dev. You posted the results for v1.9.2 before: mmtk/mmtk-julia#158 (comment)

// will complain about seeing objects without VO bit.
#define MMTK_NEEDS_VO_BIT (1)

void mmtk_immortal_post_alloc_fast(MMTkMutatorContext* mutator, void* obj, size_t size);
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