Skip to content

ROR the callable_convert_cache key for better hash distribution #20052

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Open
wants to merge 2 commits into
base: master
Choose a base branch
from
+15 −3
Open

ROR the callable_convert_cache key for better hash distribution #20052

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
2 commits
Select commit Hold shift + click to select a range
66ef2f4
ROR the callable_convert_cache key for better hash distribution
nielsdos Oct 3, 2025
e6cc914
Adjust
nielsdos Oct 5, 2025
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
6 changes: 5 additions & 1 deletion Zend/zend_vm_def.h
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -9719,7 +9719,11 @@ ZEND_VM_HANDLER(202, ZEND_CALLABLE_CONVERT, UNUSED, UNUSED, NUM|CACHE_SLOT)
if (closure) {
ZVAL_OBJ_COPY(EX_VAR(opline->result.var), closure);
} else {
zval *closure_zv = zend_hash_index_lookup(&EG(callable_convert_cache), (zend_ulong)(uintptr_t)call->func);
/* Rotate the key for better hash distribution. */
const int shift = sizeof(size_t) == 4 ? 6 : 7;
zend_ulong key = (zend_ulong)(uintptr_t)call->func;
key = (key >> shift) | (key << ((sizeof(key) * 8) - shift));
zval *closure_zv = zend_hash_index_lookup(&EG(callable_convert_cache), key);
Comment on lines -9722 to +9726
Copy link
Member

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Rotated address is not significantly better. It's better to choose one of the well known hash function for integers e.g. from https://arxiv.org/pdf/1504.06804

if (Z_TYPE_P(closure_zv) == IS_NULL) {
zend_closure_from_frame(closure_zv, call);
}
Expand Down
12 changes: 10 additions & 2 deletions Zend/zend_vm_execute.h
View file
Open in desktop

Some generated files are not rendered by default. Learn more about how customized files appear on GitHub.