wingo pushed a commit to branch wip-whippet
in repository guile.
commit cacc28b5777f13412b8e8f053d8fa070abeb9921
Author: Andy Wingo <wi...@igalia.com>
AuthorDate: Tue Aug 9 16:14:47 2022 +0200
Always add a header onto objects
We're targetting systems that need to be able to inspect the kind of an
object, so this information has to be somewhere. If it's out-of-line,
we might save memory, but we would lose locality. Concretely in Guile
the tag bits are in the object itself.
---
bdw.h | 2 --
gc-api.h | 4 ++++
mt-gcbench.c | 18 ++++++++----------
quads.c | 6 ++----
semi.h | 2 --
whippet.h | 2 --
6 files changed, 14 insertions(+), 20 deletions(-)
diff --git a/bdw.h b/bdw.h
index 142e5bccb..bda8beb56 100644
--- a/bdw.h
+++ b/bdw.h
@@ -80,8 +80,6 @@ allocate_small(void **freelist, size_t idx, enum
gc_inline_kind kind) {
return head;
}
-#define GC_HEADER /**/
-
static inline void* allocate(struct mutator *mut, enum alloc_kind kind,
size_t size) {
size_t idx = gc_inline_bytes_to_freelist_index(size);
diff --git a/gc-api.h b/gc-api.h
index c88fcde7b..d23c1c5f4 100644
--- a/gc-api.h
+++ b/gc-api.h
@@ -91,4 +91,8 @@ GC_API_ void gc_finish_for_thread(struct mutator *mut);
GC_API_ void* gc_call_without_gc(struct mutator *mut, void* (*f)(void*),
void *data) GC_NEVER_INLINE;
+struct gc_header {
+ uintptr_t tag;
+};
+
#endif // GC_API_H_
diff --git a/mt-gcbench.c b/mt-gcbench.c
index c3d92fef0..f1fe9df3d 100644
--- a/mt-gcbench.c
+++ b/mt-gcbench.c
@@ -57,20 +57,20 @@ static const int min_tree_depth = 4;
static const int max_tree_depth = 16;
struct Node {
- GC_HEADER;
- struct Node * left;
- struct Node * right;
+ struct gc_header header;
+ struct Node *left;
+ struct Node *right;
int i, j;
};
struct DoubleArray {
- GC_HEADER;
+ struct gc_header header;
size_t length;
double values[0];
};
struct Hole {
- GC_HEADER;
+ struct gc_header header;
size_t length;
uintptr_t values[0];
};
@@ -373,13 +373,11 @@ static void *join_thread(void *data) {
}
int main(int argc, char *argv[]) {
- // Define size of Node without any GC header.
- size_t sizeof_node = 2 * sizeof(Node*) + 2 * sizeof(int);
size_t sizeof_double_array = sizeof(size_t);
size_t heap_max_live =
- tree_size(long_lived_tree_depth) * sizeof_node +
- tree_size(max_tree_depth) * sizeof_node +
- sizeof_double_array + sizeof(double) * array_size;
+ tree_size(long_lived_tree_depth) * sizeof(Node) +
+ tree_size(max_tree_depth) * sizeof(Node) +
+ sizeof(DoubleArray) + sizeof(double) * array_size;
if (argc != 4) {
fprintf(stderr, "usage: %s MULTIPLIER NTHREADS PARALLELISM\n", argv[0]);
return 1;
diff --git a/quads.c b/quads.c
index 9c6dedfaf..ef639712f 100644
--- a/quads.c
+++ b/quads.c
@@ -7,7 +7,7 @@
#include "gc.h"
typedef struct Quad {
- GC_HEADER;
+ struct gc_header header;
struct Quad *kids[4];
} Quad;
static inline size_t quad_size(Quad *obj) {
@@ -125,10 +125,8 @@ int main(int argc, char *argv[]) {
return 1;
}
- // Compute byte size not counting any header word, so as to compute the same
- // heap size whether a header word is there or not.
size_t nquads = tree_size(depth);
- size_t tree_bytes = nquads * 4 * sizeof(Quad*);
+ size_t tree_bytes = nquads * sizeof(Quad);
size_t heap_size = tree_bytes * multiplier;
unsigned long gc_start = current_time();
diff --git a/semi.h b/semi.h
index 944ab88f0..2c1421d11 100644
--- a/semi.h
+++ b/semi.h
@@ -48,8 +48,6 @@ static uintptr_t align_up(uintptr_t addr, size_t align) {
return (addr + align - 1) & ~(align-1);
}
-#define GC_HEADER uintptr_t _gc_header
-
static inline void clear_memory(uintptr_t addr, size_t size) {
memset((char*)addr, 0, size);
}
diff --git a/whippet.h b/whippet.h
index db59bc2db..3cbcee9a8 100644
--- a/whippet.h
+++ b/whippet.h
@@ -392,8 +392,6 @@ static inline struct heap* mutator_heap(struct mutator
*mutator) {
return mutator->heap;
}
-#define GC_HEADER uintptr_t _gc_header
-
static inline void clear_memory(uintptr_t addr, size_t size) {
memset((char*)addr, 0, size);
}
