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datatype: generalize the format used for isptr handling
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This lets us scan a datatype slightly easier,
and opens up a future possibility where we don't have a one-to-one
relationship between fields and contained pointers.
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@carnaval @vtjnash
carnaval authored and vtjnash committed Nov 1, 2019
1 parent 0f55fd7 commit 85c5468
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Showing 9 changed files with 124 additions and 139 deletions.
10 changes: 5 additions & 5 deletions base/reflection.jl
View file
Original file line number Diff line number Diff line change
Expand Up @@ -317,10 +317,10 @@ datatype_fieldtypes(x::DataType) = ccall(:jl_get_fieldtypes, Any, (Any,), x)

struct DataTypeLayout
nfields::UInt32
npointers::UInt32
alignment::UInt32
# alignment : 28;
# alignment : 9;
# haspadding : 1;
# pointerfree : 1;
# fielddesc_type : 2;
end

Expand Down Expand Up @@ -380,8 +380,8 @@ Can be called on any `isconcretetype`.
function datatype_pointerfree(dt::DataType)
@_pure_meta
dt.layout == C_NULL && throw(UndefRefError())
alignment = unsafe_load(convert(Ptr{DataTypeLayout}, dt.layout)).alignment
return (alignment >> 10) & 0xFFFFF == 0
npointers = unsafe_load(convert(Ptr{DataTypeLayout}, dt.layout)).npointers
return npointers == 0
end

"""
Expand All @@ -397,7 +397,7 @@ function datatype_fielddesc_type(dt::DataType)
@_pure_meta
dt.layout == C_NULL && throw(UndefRefError())
alignment = unsafe_load(convert(Ptr{DataTypeLayout}, dt.layout)).alignment
return (alignment >> 30) & 3
return (alignment >> 10) & 3
end

"""
Expand Down
81 changes: 44 additions & 37 deletions src/datatype.c
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Original file line number Diff line number Diff line change
Expand Up @@ -99,29 +99,22 @@ jl_datatype_t *jl_new_uninitialized_datatype(void)
}

static jl_datatype_layout_t *jl_get_layout(uint32_t nfields,
uint32_t npointers,
uint32_t alignment,
int haspadding,
jl_fielddesc32_t desc[]) JL_NOTSAFEPOINT
jl_fielddesc32_t desc[],
uint32_t pointers[]) JL_NOTSAFEPOINT
{
// compute the smallest fielddesc type that can hold the layout description
int fielddesc_type = 0;
uint32_t npointers = 0;
// First pointer field
uint32_t first_ptr = (uint32_t)-1;
// Last pointer field
uint32_t last_ptr = 0;
if (nfields > 0) {
uint32_t max_size = 0;
uint32_t max_offset = desc[nfields - 1].offset;
if (npointers > 0 && pointers[npointers - 1] > max_offset)
max_offset = pointers[npointers - 1];
for (size_t i = 0; i < nfields; i++) {
if (desc[i].size > max_size)
max_size = desc[i].size;
if (desc[i].isptr) {
npointers++;
if (first_ptr == (uint32_t)-1)
first_ptr = i;
last_ptr = i;
}
}
jl_fielddesc8_t maxdesc8 = { 0, max_size, max_offset };
jl_fielddesc16_t maxdesc16 = { 0, max_size, max_offset };
Expand All @@ -140,24 +133,14 @@ static jl_datatype_layout_t *jl_get_layout(uint32_t nfields,
// allocate a new descriptor
// TODO: lots of these are the same--take advantage of the fact these are immutable to combine them
uint32_t fielddesc_size = jl_fielddesc_size(fielddesc_type);
int has_padding = nfields && npointers;
jl_datatype_layout_t *flddesc =
(jl_datatype_layout_t*)jl_gc_perm_alloc(sizeof(jl_datatype_layout_t) +
nfields * fielddesc_size +
(has_padding ? sizeof(uint32_t) : 0), 0, 4, 0);
if (has_padding) {
if (first_ptr > UINT16_MAX)
first_ptr = UINT16_MAX;
last_ptr = nfields - last_ptr - 1;
if (last_ptr > UINT16_MAX)
last_ptr = UINT16_MAX;
flddesc = (jl_datatype_layout_t*)(((char*)flddesc) + sizeof(uint32_t));
jl_datatype_layout_n_nonptr(flddesc) = (first_ptr << 16) | last_ptr;
}
jl_datatype_layout_t *flddesc = (jl_datatype_layout_t*)jl_gc_perm_alloc(
sizeof(jl_datatype_layout_t) + nfields * fielddesc_size + (npointers << fielddesc_type),
0, 4, 0);
flddesc->nfields = nfields;
flddesc->alignment = alignment;
flddesc->haspadding = haspadding;
flddesc->fielddesc_type = fielddesc_type;
flddesc->npointers = npointers;

// fill out the fields of the new descriptor
jl_fielddesc8_t* desc8 = (jl_fielddesc8_t*)jl_dt_layout_fields(flddesc);
Expand All @@ -180,12 +163,20 @@ static jl_datatype_layout_t *jl_get_layout(uint32_t nfields,
desc32[i].isptr = desc[i].isptr;
}
}
uint32_t nexp = 0;
while (npointers >= 0x10000) {
nexp++;
npointers = npointers >> 1;
uint8_t* ptrs8 = (uint8_t*)jl_dt_layout_ptrs(flddesc);
uint16_t* ptrs16 = (uint16_t*)jl_dt_layout_ptrs(flddesc);
uint32_t* ptrs32 = (uint32_t*)jl_dt_layout_ptrs(flddesc);
for (size_t i = 0; i < npointers; i++) {
if (fielddesc_type == 0) {
ptrs8[i] = pointers[i];
}
else if (fielddesc_type == 1) {
ptrs16[i] = pointers[i];
}
else {
ptrs32[i] = pointers[i];
}
}
flddesc->npointers = npointers | (nexp << 16);
return flddesc;
}

Expand Down Expand Up @@ -340,18 +331,18 @@ void jl_compute_field_offsets(jl_datatype_t *st)
// if we have no fields, we can trivially skip the rest
if (st == jl_symbol_type || st == jl_string_type) {
// opaque layout - heap-allocated blob
static const jl_datatype_layout_t opaque_byte_layout = {0, 1, 0, 1, 0};
static const jl_datatype_layout_t opaque_byte_layout = {0, 1, 1, 0, 0};
st->layout = &opaque_byte_layout;
return;
}
else if (st == jl_simplevector_type || st->name == jl_array_typename) {
static const jl_datatype_layout_t opaque_ptr_layout = {0, sizeof(void*), 0, 1, 0};
static const jl_datatype_layout_t opaque_ptr_layout = {0, 1, sizeof(void*), 0, 0};
st->layout = &opaque_ptr_layout;
return;
}
else {
// reuse the same layout for all singletons
static const jl_datatype_layout_t singleton_layout = {0, 1, 0, 0, 0};
static const jl_datatype_layout_t singleton_layout = {0, 0, 1, 0, 0};
st->layout = &singleton_layout;
}
}
Expand Down Expand Up @@ -396,6 +387,7 @@ void jl_compute_field_offsets(jl_datatype_t *st)
if (st->layout == NULL) {
size_t descsz = nfields * sizeof(jl_fielddesc32_t);
jl_fielddesc32_t *desc;
uint32_t *pointers;
int should_malloc = descsz >= jl_page_size;
if (should_malloc)
desc = (jl_fielddesc32_t*)malloc_s(descsz);
Expand All @@ -406,6 +398,7 @@ void jl_compute_field_offsets(jl_datatype_t *st)
int zeroinit = 0;
int haspadding = 0;
int homogeneous = 1;
uint32_t npointers = 0;
jl_value_t *firstty = jl_field_type(st, 0);
for (i = 0; i < nfields; i++) {
jl_value_t *fld = jl_field_type(st, i);
Expand Down Expand Up @@ -434,6 +427,7 @@ void jl_compute_field_offsets(jl_datatype_t *st)
al = fsz;
desc[i].isptr = 1;
zeroinit = 1;
npointers++;
}
assert(al <= JL_HEAP_ALIGNMENT && (JL_HEAP_ALIGNMENT % al) == 0);
if (al != 0) {
Expand Down Expand Up @@ -464,9 +458,22 @@ void jl_compute_field_offsets(jl_datatype_t *st)
st->size = LLT_ALIGN(sz, alignm);
if (st->size > sz)
haspadding = 1;
st->layout = jl_get_layout(nfields, alignm, haspadding, desc);
if (should_malloc)
if (should_malloc && npointers)
pointers = (uint32_t*)malloc_s(npointers * sizeof(uint32_t));
else
pointers = (uint32_t*)alloca(npointers * sizeof(uint32_t));
size_t ptr_i = 0;
for (i = 0; i < nfields; i++) {
if (desc[i].isptr)
pointers[ptr_i++] = desc[i].offset / sizeof(jl_value_t**);
}
assert(ptr_i == npointers);
st->layout = jl_get_layout(nfields, npointers, alignm, haspadding, desc, pointers);
if (should_malloc) {
free(desc);
if (npointers)
free(pointers);
}
}
// now finish deciding if this instantiation qualifies for special properties
assert(!isbitstype || st->layout->npointers == 0); // the definition of isbits
Expand Down Expand Up @@ -577,7 +584,7 @@ JL_DLLEXPORT jl_datatype_t *jl_new_primitivetype(jl_value_t *name, jl_module_t *
alignm = MAX_ALIGN;
bt->isbitstype = bt->isinlinealloc = (parameters == jl_emptysvec);
bt->size = nbytes;
bt->layout = jl_get_layout(0, alignm, 0, NULL);
bt->layout = jl_get_layout(0, 0, alignm, 0, NULL, NULL);
bt->instance = NULL;
return bt;
}
Expand Down
22 changes: 10 additions & 12 deletions src/dump.c
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Original file line number Diff line number Diff line change
Expand Up @@ -394,12 +394,12 @@ static void jl_serialize_datatype(jl_serializer_state *s, jl_datatype_t *dt) JL_
if (layout == 0) {
uint32_t nf = dt->layout->nfields;
write_int32(s->s, nf);
uint32_t alignment = ((uint32_t*)dt->layout)[1];
uint32_t np = dt->layout->npointers;
write_int32(s->s, np);
uint32_t alignment = ((uint32_t*)dt->layout)[2];
write_int32(s->s, alignment);
if (dt->layout->npointers && nf)
write_int32(s->s, ((uint32_t*)dt->layout)[-1]);
size_t fieldsize = jl_fielddesc_size(dt->layout->fielddesc_type);
ios_write(s->s, (char*)(&dt->layout[1]), nf * fieldsize);
ios_write(s->s, (char*)(dt->layout + 1), nf * fieldsize + (np << dt->layout->fielddesc_type));
}
}

Expand Down Expand Up @@ -1442,28 +1442,26 @@ static jl_value_t *jl_deserialize_datatype(jl_serializer_state *s, int pos, jl_v
else {
assert(layout == 0);
uint32_t nf = read_int32(s->s);
uint32_t np = read_int32(s->s);
uint32_t alignment = read_int32(s->s);
union {
struct {
uint32_t nf;
uint32_t np;
uint32_t alignment;
} buffer;
jl_datatype_layout_t layout;
} header;
header.buffer.nf = nf;
header.buffer.np = np;
header.buffer.alignment = alignment;
int has_padding = header.layout.npointers && nf;
uint8_t fielddesc_type = header.layout.fielddesc_type;
size_t fielddesc_size = nf > 0 ? jl_fielddesc_size(fielddesc_type) : 0;
jl_datatype_layout_t *layout = (jl_datatype_layout_t*)jl_gc_perm_alloc(
sizeof(jl_datatype_layout_t) + nf * fielddesc_size +
(has_padding ? sizeof(uint32_t) : 0), 0, 4, 0);
if (has_padding) {
layout = (jl_datatype_layout_t*)(((char*)layout) + sizeof(uint32_t));
jl_datatype_layout_n_nonptr(layout) = read_int32(s->s);
}
sizeof(jl_datatype_layout_t) + nf * fielddesc_size + (np << fielddesc_type),
0, 4, 0);
*layout = header.layout;
ios_read(s->s, (char*)&layout[1], nf * fielddesc_size);
ios_read(s->s, (char*)(layout + 1), nf * fielddesc_size + (np << fielddesc_type));
dt->layout = layout;
}
}
Expand Down
6 changes: 3 additions & 3 deletions src/gc-debug.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -1310,7 +1310,7 @@ NOINLINE void gc_mark_loop_unwind(jl_ptls_t ptls, jl_gc_mark_sp_t sp, int pc_off
break;
}
jl_datatype_t *vt = (jl_datatype_t*)jl_typeof(data->parent);
jl_fielddesc8_t *desc = (jl_fielddesc8_t*)jl_dt_layout_fields(vt->layout);
uint8_t *desc = (uint8_t*)jl_dt_layout_ptrs(vt->layout);
jl_safe_printf("%p: %s Object (8bit) %p :: %p -- [%d, %d)\n of type ",
(void*)data, prefix, (void*)data->parent, ((void**)data->parent)[-1],
(int)(data->begin - desc), (int)(data->end - desc));
Expand All @@ -1323,7 +1323,7 @@ NOINLINE void gc_mark_loop_unwind(jl_ptls_t ptls, jl_gc_mark_sp_t sp, int pc_off
break;
}
jl_datatype_t *vt = (jl_datatype_t*)jl_typeof(data->parent);
jl_fielddesc16_t *desc = (jl_fielddesc16_t*)jl_dt_layout_fields(vt->layout);
uint16_t *desc = (uint16_t*)jl_dt_layout_ptrs(vt->layout);
jl_safe_printf("%p: %s Object (16bit) %p :: %p -- [%d, %d)\n of type ",
(void*)data, prefix, (void*)data->parent, ((void**)data->parent)[-1],
(int)(data->begin - desc), (int)(data->end - desc));
Expand All @@ -1336,7 +1336,7 @@ NOINLINE void gc_mark_loop_unwind(jl_ptls_t ptls, jl_gc_mark_sp_t sp, int pc_off
break;
}
jl_datatype_t *vt = (jl_datatype_t*)jl_typeof(data->parent);
jl_fielddesc32_t *desc = (jl_fielddesc32_t*)jl_dt_layout_fields(vt->layout);
uint32_t *desc = (uint32_t*)jl_dt_layout_ptrs(vt->layout);
jl_safe_printf("%p: %s Object (32bit) %p :: %p -- [%d, %d)\n of type ",
(void*)data, prefix, (void*)data->parent, ((void**)data->parent)[-1],
(int)(data->begin - desc), (int)(data->end - desc));
Expand Down
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