Add mark for GC objects

1 files changed, 10 insertions, 6 deletions

diff --git a/src/main/java/org/shedlang/compiler/patio/PatioCodeGenGc.java b/src/main/java/org/shedlang/compiler/patio/PatioCodeGenGc.java
index 4178510f..78f19a19 100644
--- a/src/main/java/org/shedlang/compiler/patio/PatioCodeGenGc.java
+++ b/src/main/java/org/shedlang/compiler/patio/PatioCodeGenGc.java
@@ -1,9 +1,6 @@
 package org.shedlang.compiler.patio;
 
-import org.shedlang.compiler.patio.ast.types.PatioDataLayout;
-import org.shedlang.compiler.patio.ast.types.PatioDataLayouts;
-import org.shedlang.compiler.patio.ast.types.PatioDataValue;
-import org.shedlang.compiler.patio.ast.types.PatioDataValues;
+import org.shedlang.compiler.patio.ast.types.*;
 import org.shedlang.compiler.util.Lists;
 
 import java.util.List;
@@ -14,7 +11,10 @@ public class PatioCodeGenGc {
 
     public static PatioDataLayout gcObjectDataLayout(PatioDataLayout valueLayout) {
         return PatioDataLayouts.struct(List.of(
-            PatioDataLayouts.DATA_POINTER,
+            PatioDataLayouts.struct(List.of(
+                PatioDataLayouts.DATA_POINTER, // next
+                PatioDataLayouts.INT // mark
+            )),
             valueLayout
         ));
     }
@@ -29,7 +29,11 @@ public class PatioCodeGenGc {
      */
     public static PatioDataValue gcObjectStaticDataValue(PatioDataValue value) {
         return PatioDataValues.struct(List.of(
-            PatioDataValues.int_(0),
+            PatioDataValues.struct(List.of(
+                PatioDataValues.int_(0),
+                // Static values are always marked: see gc.c
+                PatioDataValues.int_(0b110)
+            )),
             value
         ));
     }