[sgen] Fix invalid value passed to write barrier (mono/mono#17236)

When doing memory copy dest is the destination address and src is the source address. If we are copying a single reference, we need to emit a write barrier and pass to the write barrier the value, not the pointer where the value is stored.

Commit migrated from https://github.com/mono/mono/commit/8e649c35450e77e68ff468ced77987e4c0b51f99

diff --git a/src/mono/mono/mini/memory-access.c b/src/mono/mono/mini/memory-access.c
index 7d1e42f..da695ad 100644 (file)
--- a/src/mono/mono/mini/memory-access.c
+++ b/src/mono/mono/mini/memory-access.c
@@ -400,7 +400,7 @@ mini_emit_memory_copy_internal (MonoCompile *cfg, MonoInst *dest, MonoInst *src,
                NEW_STORE_MEMBASE (cfg, store, OP_STORE_MEMBASE_REG, dest->dreg, 0, dreg);
                MONO_ADD_INS (cfg->cbb, store);
 
-               mini_emit_write_barrier (cfg, dest, src);
+               mini_emit_write_barrier (cfg, dest, load);
                return;
 
        } else if (cfg->gen_write_barriers && (m_class_has_references (klass) || size_ins) && !native) {        /* if native is true there should be no references in the struct */