rts: specify deallocator of allocating functions

This patch adds a new `STG_MALLOC1` macro (and its counterpart
`STG_MALLOC2` for completeness) which allows to specify the deallocation
function to be used with allocations of allocating functions, and
applies it to `stg*allocBytes`.

It also fixes a case where `free` was used to free up an
`stgMallocBytes` allocation, found by the above change.

See: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-malloc-function-attribute
See: https://gitlab.haskell.org/ghc/ghc/-/issues/22381

1 files changed, 12 insertions, 5 deletions

diff --git a/rts/RtsUtils.h b/rts/RtsUtils.h
index d3618d6435..5282be2035 100644
--- a/rts/RtsUtils.h
+++ b/rts/RtsUtils.h
@@ -17,18 +17,25 @@
 void initAllocator(void);
 void shutdownAllocator(void);
 
+void stgFree(void* p);
+
 void *stgMallocBytes(size_t n, char *msg)
-    STG_MALLOC;
+    STG_MALLOC STG_MALLOC1(stgFree);
 
-void *stgReallocBytes(void *p, size_t n, char *msg);
+void *stgReallocBytes(void *p, size_t n, char *msg)
+    STG_MALLOC1(stgFree);
+/* Note: `stgRallocBytes` can *not* be tagged as `STG_MALLOC`
+ * since its return value *can* alias an existing pointer (i.e.,
+ * the given pointer `p`).
+ * See the documentation of the `malloc` attribute in the GCC manual
+ * for more information.
+ */
 
 void *stgCallocBytes(size_t count, size_t size, char *msg)
-    STG_MALLOC;
+    STG_MALLOC STG_MALLOC1(stgFree);
 
 char *stgStrndup(const char *s, size_t n);
 
-void stgFree(void* p);
-
 /* -----------------------------------------------------------------------------
  * Misc other utilities
  * -------------------------------------------------------------------------- */