Moving jl_genericmemory_t objects to the immix space

Author: Luis Eduardo de Souza Amorim

src/gc-mmtk.c

@@ -877,6 +877,8 @@ static void jl_gc_free_memory(jl_genericmemory_t *m, int isaligned) JL_NOTSAFEPO
     gc_num.freecall++;
 }
 
+extern void* mmtk_get_possibly_forwarded(void* object);
+
 JL_DLLEXPORT void jl_gc_mmtk_sweep_malloced_memory(void) JL_NOTSAFEPOINT
 {
     void* iter = mmtk_new_mutator_iterator();
@@ -889,6 +891,11 @@ JL_DLLEXPORT void jl_gc_mmtk_sweep_malloced_memory(void) JL_NOTSAFEPOINT
         while (n < l) {
             jl_genericmemory_t *m = (jl_genericmemory_t*)((uintptr_t)lst[n] & ~1);
             if (mmtk_is_live_object(m)) {
+                jl_genericmemory_t *maybe_forwarded = (jl_genericmemory_t*)mmtk_get_possibly_forwarded(m);
+                if(maybe_forwarded != m) {
+                    int isaligned = (uintptr_t)lst[n] & 1;
+                    lst[n] = (void*)((uintptr_t)maybe_forwarded | !!isaligned);
+                }
                 n++;
             }
             else {
@@ -925,6 +932,11 @@ JL_DLLEXPORT void jl_gc_update_inlined_array(void* from, void* to) {
                 b->ptr = (void*)((size_t) b + offset_of_data);
             }
         }
+
+        // make sure we update the owner pointer when we're copying the generic memory
+        if (how == 1) {
+            jl_genericmemory_data_owner_field(b) = (jl_value_t*)b;
+        }
     }
 }
 

src/genericmemory.c

@@ -38,7 +38,7 @@ JL_DLLEXPORT jl_genericmemory_t *jl_alloc_genericmemory_unchecked(jl_ptls_t ptls
         data = (char*)jl_gc_managed_malloc(nbytes);
         tot = sizeof(jl_genericmemory_t) + sizeof(void*);
     }
-    m = (jl_genericmemory_t*)jl_gc_alloc_nonmoving(ptls, tot, mtype);
+    m = (jl_genericmemory_t*)jl_gc_alloc(ptls, tot, mtype);
     if (pooled) {
         data = (char*)m + JL_SMALL_BYTE_ALIGNMENT;
     }

src/julia_internal.h

@@ -586,8 +586,6 @@ typedef void jl_gc_tracked_buffer_t; // For the benefit of the static analyzer
 STATIC_INLINE jl_gc_tracked_buffer_t *jl_gc_alloc_buf(jl_ptls_t ptls, size_t sz)
 {
     jl_gc_tracked_buffer_t *buf = jl_gc_alloc_nonmoving(ptls, sz, (void*)jl_buff_tag);
-    // FIXME: we might not need to pin buffers since the introduction of jl_genericmemory_t objects
-    // but removing the pin below will currently fail an assertion in the binding
     return buf;
 }