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See https://bugs.gentoo.org/984178. Taken from (merged)
https://github.com/jemalloc/jemalloc/pull/3034
From b832f91554076dced14cc66658f6ca76d4baee16 Mon Sep 17 00:00:00 2001
From: h2h <h2h@meta.com>
Date: Thu, 8 Oct 2026 13:41:06 -0700
Subject: [PATCH] Explicitly specify pointer type arithmetics to avoid UB in
clang build
---
include/jemalloc/internal/edata.h | 5 -----
src/emap.c | 6 +++---
2 files changed, 3 insertions(+), 8 deletions(-)
diff --git a/include/jemalloc/internal/edata.h b/include/jemalloc/internal/edata.h
index 8f85ff1eac..13dcb5b5c7 100644
--- a/include/jemalloc/internal/edata.h
+++ b/include/jemalloc/internal/edata.h
@@ -516,11 +516,6 @@ edata_ps_get(const edata_t *edata) {
return edata->e_ps;
}
-static inline void *
-edata_before_get(const edata_t *edata) {
- return (void *)((byte_t *)edata_base_get(edata) - PAGE);
-}
-
static inline void *
edata_last_get(const edata_t *edata) {
return (void *)((byte_t *)edata_base_get(edata) + edata_size_get(edata)
diff --git a/src/emap.c b/src/emap.c
index 6863c2ae08..ff634e1fca 100644
--- a/src/emap.c
+++ b/src/emap.c
@@ -53,8 +53,8 @@ emap_try_acquire_edata_neighbor_impl(tsdn_t *tsdn, emap_t *emap, edata_t *edata,
|| expected_state == extent_state_retained
|| expected_state == extent_state_pinned);
- void *neighbor_addr = forward ? edata_past_get(edata)
- : edata_before_get(edata);
+ uintptr_t neighbor_addr = forward ? (uintptr_t)edata_past_get(edata)
+ : (uintptr_t)edata_base_get(edata) - PAGE;
/*
* This is subtle; the rtree code asserts that its input pointer is
* non-NULL, and this is a useful thing to check. But it's possible
@@ -63,7 +63,7 @@ emap_try_acquire_edata_neighbor_impl(tsdn_t *tsdn, emap_t *emap, edata_t *edata,
* randomization is on, but it could in principle happen anywhere). In
* this case, edata_before_get(edata) is NULL, triggering the assert.
*/
- if (neighbor_addr == NULL) {
+ if (neighbor_addr == 0) {
return NULL;
}
|
