Hello all,

In the generated LocalVariableTable wide variables should allocate 2 stack slots . It is easy to reproduce - just declare several fan Int variables and watch their values in the debugger.

The minimal patch fixing it is follows.

diff -r e94fdf58964c src/sys/java/fanx/emit/FCodeEmit.java
--- a/src/sys/java/fanx/emit/FCodeEmit.java	Sun Oct 18 10:19:31 2009 -0400
+++ b/src/sys/java/fanx/emit/FCodeEmit.java	Mon Oct 19 10:50:48 2009 +0700
@@ -263,8 +263,8 @@
     Box info = attr.info;
     FMethodVar[] vars = fmethod.vars;
     int num = vars.length;  // num of vars including implicit this
-    int offset = 0;         // offset if including implicit this
-    if (!fmethod.isStatic()) { ++offset; ++num; }
+    int offset = 0;
+    if (!fmethod.isStatic()) { ++num; }
 
     // Fan variables never reuse stack registers, so
     // we can declare their scope across entire method
@@ -280,16 +280,19 @@
       info.u2(end);
       info.u2(code.emit.utf("this"));
       info.u2(code.emit.utf(pod.typeRef(parent.type.self).jsig()));
-      info.u2(0);
+      info.u2(offset);
+      ++offset;
     }
     for (int i=0; i<vars.length; ++i)
     {
       FMethodVar var = vars[i];
+      FTypeRef typeref = pod.typeRef(var.type);
       info.u2(start);
       info.u2(end);
       info.u2(code.emit.utf(var.name));
-      info.u2(code.emit.utf(pod.typeRef(var.type).jsig()));
-      info.u2(i+offset);
+      info.u2(code.emit.utf(typeref.jsig()));
+      info.u2(offset);
+      offset += typeref.isWide() ? 2 : 1;
     }
   }

Thank you, Alex

Alex, Thanks for digging into that and submitting a nice clean patch! Surprised that hasn't bitten anyone before.

I actually decided to rework that code to use the Reg data structures I am already calculating which takes wide variables into account.

changeset