refactor(tvix/eval): enhance debug output for bytecode dumps r/5868

This adds addresses of thunk and closure chunks to the debug output
displayed when dumping bytecode.

This makes it possible to see in the dump which thunks are referenced
by constants in other thunks.

Change-Id: I2c98de5227e7cb415666cd3134c947a56979dc80
Reviewed-on: https://cl.tvl.fyi/c/depot/+/8137
Autosubmit: tazjin <tazjin@tvl.su>
Reviewed-by: flokli <flokli@flokli.de>
Tested-by: BuildkiteCI

2 files changed, 25 insertions, 1 deletions

diff --git a/tvix/eval/src/chunk.rs b/tvix/eval/src/chunk.rs
index 35fd7e78e6..04b58bde20 100644
--- a/tvix/eval/src/chunk.rs
+++ b/tvix/eval/src/chunk.rs
@@ -143,7 +143,15 @@ impl Chunk {
         }
 
         match self[idx] {
-            OpCode::OpConstant(idx) => writeln!(writer, "OpConstant({}@{})", self[idx], idx.0),
+            OpCode::OpConstant(idx) => {
+                let val_str = match &self[idx] {
+                    Value::Thunk(t) => t.debug_repr(),
+                    Value::Closure(c) => format!("closure({:p})", c.lambda),
+                    val => format!("{}", val),
+                };
+
+                writeln!(writer, "OpConstant({}@{})", val_str, idx.0)
+            }
             op => writeln!(writer, "{:?}", op),
         }?;
 
diff --git a/tvix/eval/src/value/thunk.rs b/tvix/eval/src/value/thunk.rs
index e30d58e728..747cd413e2 100644
--- a/tvix/eval/src/value/thunk.rs
+++ b/tvix/eval/src/value/thunk.rs
@@ -73,6 +73,17 @@ enum ThunkRepr {
     Evaluated(Value),
 }
 
+impl ThunkRepr {
+    fn debug_repr(&self) -> String {
+        match self {
+            ThunkRepr::Evaluated(v) => format!("thunk(val|{})", v),
+            ThunkRepr::Blackhole => "thunk(blackhole)".to_string(),
+            ThunkRepr::Native(_) => "thunk(native)".to_string(),
+            ThunkRepr::Suspended { lambda, .. } => format!("thunk({:p})", *lambda),
+        }
+    }
+}
+
 /// A thunk is created for any value which requires non-strict
 /// evaluation due to self-reference or lazy semantics (or both).
 /// Every reference cycle involving `Value`s will contain at least
@@ -428,6 +439,11 @@ impl Thunk {
             _ => false,
         }
     }
+
+    /// Helper function to format thunks in observer output.
+    pub(crate) fn debug_repr(&self) -> String {
+        self.0.borrow().debug_repr()
+    }
 }
 
 impl TotalDisplay for Thunk {