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Use bitfields in igc_header (IN_MY_FORK)

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This commit is contained in:
Gerd Möllmann 2024-11-10 07:33:07 +01:00
parent c425f10a30
commit ee31d5a2a2
1 changed files with 74 additions and 23 deletions
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97
src/igc.c
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@ -474,15 +474,74 @@ enum
static_assert (IGC_OBJ_NUM_TYPES - 1 < (1 << IGC_HEADER_TYPE_BITS));
struct igc_exthdr
{
EMACS_UINT nwords;
EMACS_UINT hash;
enum igc_obj_type obj_type;
Lisp_Object extra_dependency;
};
enum igc_tag
{
IGC_TAG_NULL = 0, /* entire value must be 0 to avoid MPS issues */
IGC_TAG_OBJ = 1, /* IGC object */
IGC_TAG_EXTHDR = 2, /* pointer to aligned external header */
};
#ifdef IN_MY_FORK
/* After Pip Cet's header changes, Lisp objects include a gc_header
union, which has an uint64_t member 'v'. struct igc_header then
contained the same 'v', and not bitfields anymore. This makes things
inconvinient in LLDB. */
struct igc_header
{
enum igc_tag tag : IGC_HEADER_TAG_BITS;
enum igc_obj_type obj_type : IGC_HEADER_TYPE_BITS;
mps_word_t hash : IGC_HEADER_HASH_BITS;
mps_word_t nwords : IGC_HEADER_NWORDS_BITS;
};
static unsigned
header_nwords (const struct igc_header *h)
{
return h->nwords;
}
static unsigned
header_hash (const struct igc_header *h)
{
return h->hash;
}
static enum igc_obj_type
header_type (const struct igc_header *h)
{
return h->obj_type;
}
static uint64_t
header_tag (const struct igc_header *h)
{
return h->tag;
}
static struct igc_exthdr *
header_exthdr (const struct igc_header *h)
{
uint64_t v = *(uint64_t *) h;
return ((struct igc_exthdr *)(intptr_t)(v & ~IGC_HEADER_TAG_MASK));
}
#else
struct igc_header
{
uint64_t v;
};
unsigned igc_header_hash (struct igc_header *h);
size_t igc_header_nwords (const struct igc_header *h);
enum igc_obj_type igc_header_type (struct igc_header *h);
static unsigned
header_nwords (const struct igc_header *h)
{
@ -507,26 +566,17 @@ header_tag (const struct igc_header *h)
return h->v & IGC_HEADER_TAG_MASK;
}
struct igc_exthdr
{
EMACS_UINT nwords;
EMACS_UINT hash;
enum igc_obj_type obj_type;
Lisp_Object extra_dependency;
};
static struct igc_exthdr *
header_exthdr (const struct igc_header *h)
{
return ((struct igc_exthdr *)(intptr_t)(h->v & ~IGC_HEADER_TAG_MASK));
}
enum igc_tag
{
IGC_TAG_NULL = 0, /* entire value must be 0 to avoid MPS issues */
IGC_TAG_OBJ = 1, /* IGC object */
IGC_TAG_EXTHDR = 2, /* pointer to aligned external header */
};
#endif /* not IN_MY_FORK */
unsigned igc_header_hash (struct igc_header *h);
size_t igc_header_nwords (const struct igc_header *h);
enum igc_obj_type igc_header_type (struct igc_header *h);
enum igc_obj_type
igc_header_type (struct igc_header *h)
@ -610,10 +660,10 @@ set_header (struct igc_header *h, enum igc_obj_type type,
/* Make sure upper 32-bit word is unaligned on IA-32. */
if (INTPTR_MAX <= INT_MAX)
tag += (1LL << 32);
h->v = (((uint64_t) to_words (nbytes) << IGC_HEADER_NWORDS_SHIFT) +
((hash & IGC_HEADER_HASH_MASK) << (IGC_HEADER_HASH_SHIFT)) +
(type << IGC_HEADER_TYPE_SHIFT) +
tag);
uint64_t v = (((uint64_t) to_words (nbytes) << IGC_HEADER_NWORDS_SHIFT)
+ ((hash & IGC_HEADER_HASH_MASK) << (IGC_HEADER_HASH_SHIFT))
+ (type << IGC_HEADER_TYPE_SHIFT) + tag);
*(uint64_t *) h = v;
}
static unsigned alloc_hash (void);
@ -4456,7 +4506,8 @@ igc_external_header (struct igc_header *h)
exthdr->obj_type = header_type (h);
exthdr->extra_dependency = Qnil;
/* On IA-32, the upper 32-bit word is 0 after this, which is okay. */
h->v = (intptr_t)exthdr + IGC_TAG_EXTHDR;
uint64_t v = (intptr_t)exthdr + IGC_TAG_EXTHDR;
*(uint64_t *) h = v;
mps_addr_t ref = (mps_addr_t) h;
mps_res_t res = mps_finalize (global_igc->arena, &ref);
IGC_CHECK_RES (res);