Handle out of memory tests (https://github.com/Shopify/ruby/pull/393)

.cirrus.yml

@@ -160,10 +160,8 @@ yjit_task:
     bootstraptest/test_yjit_30k_ifelse.rb \
     bootstraptest/test_yjit_30k_methods.rb \
     bootstraptest/test_yjit_new_backend.rb \
-    bootstraptest/test_yjit_rust_port.rb
-
-  # These are the btests we can't run yet on arm:
-  #bootstraptest/test_yjit.rb (out of executable memory not handled)
+    bootstraptest/test_yjit_rust_port.rb \
+    bootstraptest/test_yjit.rb
 
   # FIXME: not currently working on CI, missing cargo
   # Check that we can do a full ruby build

yjit/src/backend/arm64/mod.rs

@@ -866,7 +866,10 @@ impl Assembler
         }
 
         let gc_offsets = asm.arm64_emit(cb);
-        cb.link_labels();
+
+        if !cb.has_dropped_bytes() {
+            cb.link_labels();
+        }
 
         gc_offsets
     }

yjit/src/backend/x86_64/mod.rs

@@ -561,7 +561,9 @@ impl Assembler
 
         let gc_offsets = asm.x86_emit(cb);
 
-        cb.link_labels();
+        if !cb.has_dropped_bytes() {
+            cb.link_labels();
+        }
 
         gc_offsets
     }