From 4bd058fc1b10e6382a9fb72f6f4c3c2fa728ff53 Mon Sep 17 00:00:00 2001
From: Bilal Mahmoud <7252775+indietyp@users.noreply.github.com>
Date: Sun, 5 Apr 2026 21:00:09 +0200
Subject: [PATCH 1/3] fix: behaviour

---
 libs/@local/hashql/compiletest/src/lib.rs     |   1 -
 libs/@local/hashql/eval/src/lib.rs            |   1 -
 libs/@local/hashql/mir/src/lib.rs             |   3 +-
 .../pass/analysis/data_dependency/resolve.rs  | 144 +++++++-----------
 .../pass/analysis/data_dependency/tests.rs    |  43 ++++++
 .../data-dependency/load_param_mixed.snap     |  21 +++
 6 files changed, 124 insertions(+), 89 deletions(-)
 create mode 100644 libs/@local/hashql/mir/tests/ui/pass/data-dependency/load_param_mixed.snap

diff --git a/libs/@local/hashql/compiletest/src/lib.rs b/libs/@local/hashql/compiletest/src/lib.rs
index 51e9b74cf78..c2280893dcd 100644
--- a/libs/@local/hashql/compiletest/src/lib.rs
+++ b/libs/@local/hashql/compiletest/src/lib.rs
@@ -7,7 +7,6 @@
 
     // Library Features
     allocator_api,
-    assert_matches,
     duration_millis_float,
     exitcode_exit_method,
     file_buffered,
diff --git a/libs/@local/hashql/eval/src/lib.rs b/libs/@local/hashql/eval/src/lib.rs
index 627b7411bc5..06d48157bb7 100644
--- a/libs/@local/hashql/eval/src/lib.rs
+++ b/libs/@local/hashql/eval/src/lib.rs
@@ -11,7 +11,6 @@
 
     // Library Features
     iterator_try_collect,
-    assert_matches,
     allocator_api,
     iter_array_chunks,
     maybe_uninit_fill,
diff --git a/libs/@local/hashql/mir/src/lib.rs b/libs/@local/hashql/mir/src/lib.rs
index dcbb5b2831a..e83d45234d7 100644
--- a/libs/@local/hashql/mir/src/lib.rs
+++ b/libs/@local/hashql/mir/src/lib.rs
@@ -21,14 +21,15 @@
     get_mut_unchecked,
     iter_array_chunks,
     iter_collect_into,
+    iterator_try_reduce,
     likely_unlikely,
     maybe_uninit_fill,
+    maybe_uninit_uninit_array_transpose,
     option_into_flat_iter,
     step_trait,
     temporary_niche_types,
     try_trait_v2,
     variant_count,
-    maybe_uninit_uninit_array_transpose
 )]
 #![cfg_attr(test, feature(
     // Library Features
diff --git a/libs/@local/hashql/mir/src/pass/analysis/data_dependency/resolve.rs b/libs/@local/hashql/mir/src/pass/analysis/data_dependency/resolve.rs
index 254394474da..2066bec724e 100644
--- a/libs/@local/hashql/mir/src/pass/analysis/data_dependency/resolve.rs
+++ b/libs/@local/hashql/mir/src/pass/analysis/data_dependency/resolve.rs
@@ -181,11 +181,12 @@ fn traverse<'heap, A: Allocator + Clone>(
     }
 }
 
-/// Attempts to resolve a block parameter by checking all predecessor edges.
+/// Attempts to resolve a block parameter by checking all predecessor values.
 ///
-/// A block parameter may receive values from multiple predecessor blocks. This function
-/// traverses all [`Param`] edges and checks whether they resolve to the same source.
-/// If all predecessors agree, resolution continues through that common source.
+/// A block parameter may receive values from multiple predecessor blocks, either as
+/// graph edges (when arguments are places) or constant bindings (when arguments are
+/// constants). This function checks whether all predecessors, from both sources,
+/// resolve to the same value.
 ///
 /// Handles cycle detection: if we encounter a local already in the `visited` set,
 /// we return [`Backtrack`] to unwind. The cycle root (where `visited` was first
@@ -198,45 +199,70 @@ fn resolve_params<'heap, A: Allocator + Clone>(
     mut state: ResolutionState<'_, '_, 'heap, A>,
     place: PlaceRef<'_, 'heap>,
 ) -> ControlFlow<ResolutionResult<'heap, A>, Local> {
-    let mut edges = state.graph.outgoing_edges(place.local);
-    let Some(head) = edges.next() else {
-        unreachable!("caller must guarantee that at least one Param edge exists")
-    };
+    let graph = state.graph;
+
+    // Check whether graph Param edges exist (cycle detection is only relevant for graph edges,
+    // which are the only source of back-edges).
+    let has_graph_edges = graph.outgoing_edges(place.local).next().is_some();
 
     // Cycle detection: if we've already visited this local, backtrack.
-    if let Some(visited) = &mut state.visited
+    if has_graph_edges
+        && let Some(visited) = &mut state.visited
         && !visited.insert(place.local)
     {
         return ControlFlow::Break(ResolutionResult::Backtrack);
     }
 
-    // Initialize cycle tracking if this is the first Param traversal.
+    // Initialize cycle tracking if this is the first Param traversal with graph edges.
     let mut owned_visited = None;
-    let visited_ref = state.visited.as_deref_mut().or_else(|| {
-        let mut set = DenseBitSet::new_empty(state.graph.graph.node_count());
-        set.insert(place.local);
-
-        owned_visited = Some(set);
-        owned_visited.as_mut()
-    });
+    let visited_ref = if has_graph_edges {
+        state.visited.as_deref_mut().or_else(|| {
+            let mut set = DenseBitSet::new_empty(graph.graph.node_count());
+            set.insert(place.local);
+
+            owned_visited = Some(set);
+            owned_visited.as_mut()
+        })
+    } else {
+        state.visited.as_deref_mut()
+    };
 
     let mut rec_state = ResolutionState {
-        graph: state.graph,
+        graph,
         interner: state.interner,
         alloc: state.alloc.clone(),
         visited: visited_ref,
     };
 
-    let first = traverse(rec_state.cloned(), place, head);
+    // Graph Param edges (when a local has Param edges, all its outgoing edges are Param).
+    let graph_edges = graph
+        .outgoing_edges(place.local)
+        .map(|edge| traverse(rec_state.cloned(), place, edge));
+    let constant_edges = graph
+        .constant_bindings
+        .iter_by_kind(place.local, EdgeKind::Param)
+        .map(|constant| {
+            ControlFlow::Break(ResolutionResult::Resolved(Operand::Constant(constant)))
+        });
 
-    // Check consensus: all predecessors must resolve to the same result.
-    let all_agree = edges.all(|edge| traverse(rec_state.cloned(), place, edge) == first);
+    // `try_reduce` returns:
+    //   `Some(Some(v))` when all predecessors agree on `v`
+    //   `Some(None)` when the iterator is empty (unreachable: caller guarantees predecessors)
+    //   `None` when the closure short-circuits (predecessors disagree)
+    let consensus = match graph_edges
+        .chain(constant_edges)
+        .try_reduce(|lhs, rhs| (lhs == rhs).then_some(lhs))
+    {
+        Some(None) => unreachable!("caller must guarantee at least one Param predecessor exists"),
+        Some(consensus) => consensus,
+        None => None,
+    };
 
-    if all_agree {
+    if let Some(consensus) = consensus {
         // If we initiated backtracking (owned_visited is Some) and got Backtrack,
         // we are the cycle root and should treat this as incomplete.
         let is_cycle_root =
-            first == ControlFlow::Break(ResolutionResult::Backtrack) && owned_visited.is_some();
+            consensus == ControlFlow::Break(ResolutionResult::Backtrack) && owned_visited.is_some();
 
         if !is_cycle_root {
             // Clean up visited state before returning.
@@ -244,7 +270,7 @@ fn resolve_params<'heap, A: Allocator + Clone>(
                 visited.remove(place.local);
             }
 
-            return first;
+            return consensus;
         }
     }
 
@@ -263,46 +289,6 @@ fn resolve_params<'heap, A: Allocator + Clone>(
     }))
 }
 
-/// Attempts to resolve a block parameter by checking constant bindings from all predecessors.
-///
-/// This handles the case where a block parameter receives constant values from predecessor
-/// blocks, but has no graph edges (only constant bindings with [`Param`] kind). The function
-/// checks whether all predecessors provide the same constant value.
-///
-/// Unlike [`resolve_params`], this function does not need cycle detection because it only
-/// examines constant bindings, not graph edges that could form back-edges.
-///
-/// # Returns
-///
-/// - [`Resolved(Constant)`] if all predecessor constants agree on the same value
-/// - [`Resolved(Place)`] if predecessors diverge (the place remains valid but has no constant)
-///
-/// [`Param`]: EdgeKind::Param
-/// [`Resolved(Constant)`]: ResolutionResult::Resolved
-/// [`Resolved(Place)`]: ResolutionResult::Resolved
-fn resolve_params_const<'heap, A: Allocator + Clone>(
-    state: &ResolutionState<'_, '_, 'heap, A>,
-    place: PlaceRef<'_, 'heap>,
-) -> ResolutionResult<'heap, A> {
-    debug_assert!(place.projections.is_empty());
-    let mut constants = state
-        .graph
-        .constant_bindings
-        .iter_by_kind(place.local, EdgeKind::Param);
-    let Some(head) = constants.next() else {
-        unreachable!("caller must guarantee that at least one Param edge exists")
-    };
-
-    let all_agree = constants.all(|constant| constant == head);
-    if all_agree {
-        ResolutionResult::Resolved(Operand::Constant(head))
-    } else {
-        // We have finished (we have terminated on a param, which is divergent, therefore the place
-        // is still valid, just doesn't have a constant value)
-        ResolutionResult::Resolved(Operand::Place(Place::local(place.local)))
-    }
-}
-
 /// Resolves a place to its ultimate data source by traversing the dependency graph.
 ///
 /// Starting from `place`, this function follows edges in the dependency graph to find where
@@ -332,13 +318,10 @@ pub(crate) fn resolve<'heap, A: Allocator + Clone>(
     mut place: PlaceRef<'_, 'heap>,
 ) -> ResolutionResult<'heap, A> {
     // Scan outgoing edges to find Load and count Param edges.
-    let mut edges = 0_usize;
     let mut params = 0_usize;
     let mut load_edge = None;
 
     for edge in state.graph.outgoing_edges(place.local) {
-        edges += 1;
-
         match edge.data.kind {
             EdgeKind::Load => load_edge = Some(edge),
             EdgeKind::Param => params += 1,
@@ -355,26 +338,15 @@ pub(crate) fn resolve<'heap, A: Allocator + Clone>(
     }
 
     // Attempt to resolve through Param edges, if all predecessors agree.
-    // There are fundamentally two cases:
-    // - Either all graph edges are Param edges, or
-    // - all constant bindings are Param edges
-    if edges == 0
-        && state
-            .graph
-            .constant_bindings
-            .find_by_kind(place.local, EdgeKind::Param)
-            .is_some()
-    {
-        return resolve_params_const(&state, place);
-    }
+    // Predecessors may arrive as graph edges (place arguments), constant bindings
+    // (constant arguments), or a mix of both. All sources are checked for consensus.
+    let has_param_constants = state
+        .graph
+        .constant_bindings
+        .find_by_kind(place.local, EdgeKind::Param)
+        .is_some();
 
-    if params > 0
-        && state
-            .graph
-            .constant_bindings
-            .find_by_kind(place.local, EdgeKind::Param)
-            .is_none()
-    {
+    if params > 0 || has_param_constants {
         place.local = tri!(resolve_params(state.cloned(), place));
     }
 
diff --git a/libs/@local/hashql/mir/src/pass/analysis/data_dependency/tests.rs b/libs/@local/hashql/mir/src/pass/analysis/data_dependency/tests.rs
index b840c7435f0..6e3b5a26275 100644
--- a/libs/@local/hashql/mir/src/pass/analysis/data_dependency/tests.rs
+++ b/libs/@local/hashql/mir/src/pass/analysis/data_dependency/tests.rs
@@ -544,3 +544,46 @@ fn projection_prepending_opaque_source() {
         },
     );
 }
+
+/// Tests mixed Param resolution through nested tuple wrapping where predecessors provide
+/// a mix of constants and projections that all resolve to the same value.
+#[test]
+fn load_param_mixed() {
+    let heap = Heap::new();
+    let interner = Interner::new(&heap);
+    let env = Environment::new(&heap);
+
+    let body = body!(interner, env; fn@0/0 -> Int {
+        decl _1: (Int), _3: Int, _4: (Int), _5: Int;
+        @proj _1_0 = _1.0: Int, _4_0 = _4.0: Int;
+
+        bb0() {
+            goto bb2(42);
+        },
+        bb1() {
+            _1 = tuple 42;
+            goto bb2(_1_0);
+        },
+        bb2(_3) {
+            _4 = tuple _3;
+            goto bb4(_4_0);
+        },
+        bb3() {
+            goto bb4(42);
+        },
+        bb4(_5) {
+            return _5;
+        }
+    });
+
+    assert_data_dependency(
+        "load_param_mixed",
+        &body,
+        &mut MirContext {
+            heap: &heap,
+            env: &env,
+            interner: &interner,
+            diagnostics: DiagnosticIssues::new(),
+        },
+    );
+}
diff --git a/libs/@local/hashql/mir/tests/ui/pass/data-dependency/load_param_mixed.snap b/libs/@local/hashql/mir/tests/ui/pass/data-dependency/load_param_mixed.snap
new file mode 100644
index 00000000000..d641ecea391
--- /dev/null
+++ b/libs/@local/hashql/mir/tests/ui/pass/data-dependency/load_param_mixed.snap
@@ -0,0 +1,21 @@
+---
+source: libs/@local/hashql/mir/src/pass/analysis/data_dependency/tests.rs
+assertion_line: 32
+expression: "format!(\"{graph}\\n\\n=====\\n\\n{transient}\")"
+---
+%1 -> %0 [Param, projections: .0]
+%2 -> %1 [Index(FieldIndex(0))]
+%3 -> %2 [Param, projections: .0]
+%0 -> 42 [Index(FieldIndex(0))]
+%1 -> 42 [Param]
+%3 -> 42 [Param]
+
+
+=====
+
+%0 -> 42 [Index(FieldIndex(0))]
+%1 -> 42 [Param]
+%1 -> 42 [Param]
+%2 -> 42 [Index(FieldIndex(0))]
+%3 -> 42 [Param]
+%3 -> 42 [Param]

From 9297e69b010e37d6f45ec781eb56846ceead3d4f Mon Sep 17 00:00:00 2001
From: Bilal Mahmoud <7252775+indietyp@users.noreply.github.com>
Date: Sun, 5 Apr 2026 21:43:23 +0200
Subject: [PATCH 2/3] feat: allow for recursive loops

---
 libs/@local/hashql/mir/src/builder/mod.rs     |   3 +-
 libs/@local/hashql/mir/src/lib.rs             |   2 +-
 .../pass/analysis/data_dependency/resolve.rs  |  59 +++++---
 .../pass/analysis/data_dependency/tests.rs    | 131 ++++++++++++++++++
 .../param_cycle_detection.snap                |   5 +-
 ...aram_cycle_multi_node_with_const_init.snap |  17 +++
 ...aram_cycle_visited_cleanup_on_diverge.snap |  19 +++
 .../param_cycle_with_const_init.snap          |  15 ++
 8 files changed, 226 insertions(+), 25 deletions(-)
 create mode 100644 libs/@local/hashql/mir/tests/ui/pass/data-dependency/param_cycle_multi_node_with_const_init.snap
 create mode 100644 libs/@local/hashql/mir/tests/ui/pass/data-dependency/param_cycle_visited_cleanup_on_diverge.snap
 create mode 100644 libs/@local/hashql/mir/tests/ui/pass/data-dependency/param_cycle_with_const_init.snap

diff --git a/libs/@local/hashql/mir/src/builder/mod.rs b/libs/@local/hashql/mir/src/builder/mod.rs
index b56c57f31f0..67057786240 100644
--- a/libs/@local/hashql/mir/src/builder/mod.rs
+++ b/libs/@local/hashql/mir/src/builder/mod.rs
@@ -119,10 +119,9 @@ pub use self::{
 /// # Unary Operators
 ///
 /// ```
-/// use hashql_hir::node::operation::UnOp;
+/// use hashql_mir::body::rvalue::UnOp;
 /// use hashql_mir::op;
 ///
-/// assert!(matches!(op![!], UnOp::Not));
 /// assert!(matches!(op![neg], UnOp::Neg)); // `neg` is used since `-` alone is ambiguous
 /// assert!(matches!(op![~], UnOp::BitNot));
 /// ```
diff --git a/libs/@local/hashql/mir/src/lib.rs b/libs/@local/hashql/mir/src/lib.rs
index e83d45234d7..ee755063446 100644
--- a/libs/@local/hashql/mir/src/lib.rs
+++ b/libs/@local/hashql/mir/src/lib.rs
@@ -21,7 +21,6 @@
     get_mut_unchecked,
     iter_array_chunks,
     iter_collect_into,
-    iterator_try_reduce,
     likely_unlikely,
     maybe_uninit_fill,
     maybe_uninit_uninit_array_transpose,
@@ -30,6 +29,7 @@
     temporary_niche_types,
     try_trait_v2,
     variant_count,
+    iterator_try_reduce
 )]
 #![cfg_attr(test, feature(
     // Library Features
diff --git a/libs/@local/hashql/mir/src/pass/analysis/data_dependency/resolve.rs b/libs/@local/hashql/mir/src/pass/analysis/data_dependency/resolve.rs
index 2066bec724e..8dfbaa8f1fb 100644
--- a/libs/@local/hashql/mir/src/pass/analysis/data_dependency/resolve.rs
+++ b/libs/@local/hashql/mir/src/pass/analysis/data_dependency/resolve.rs
@@ -185,12 +185,13 @@ fn traverse<'heap, A: Allocator + Clone>(
 ///
 /// A block parameter may receive values from multiple predecessor blocks, either as
 /// graph edges (when arguments are places) or constant bindings (when arguments are
-/// constants). This function checks whether all predecessors, from both sources,
-/// resolve to the same value.
+/// constants). This function checks whether all non-cyclic predecessors, from both
+/// sources, resolve to the same value.
 ///
-/// Handles cycle detection: if we encounter a local already in the `visited` set,
-/// we return [`Backtrack`] to unwind. The cycle root (where `visited` was first
-/// initialized) catches the backtrack and returns [`Incomplete`].
+/// Cyclic predecessors ([`Backtrack`]) are filtered out before consensus checking.
+/// Since [`Param`] edges are identity transfers, the value is fully determined by
+/// the non-cyclic init edges. If only cyclic predecessors exist (no external source),
+/// the cycle root returns [`Incomplete`] and non-root nodes propagate [`Backtrack`].
 ///
 /// [`Param`]: EdgeKind::Param
 /// [`Backtrack`]: ResolutionResult::Backtrack
@@ -234,7 +235,10 @@ fn resolve_params<'heap, A: Allocator + Clone>(
         visited: visited_ref,
     };
 
-    // Graph Param edges (when a local has Param edges, all its outgoing edges are Param).
+    // Resolve all predecessor candidates and check consensus.
+    // Cyclic predecessors (Backtrack) are skipped: since Param edges are identity transfers,
+    // the value is fully determined by the non-cyclic init edges. If only cyclic predecessors
+    // exist, we cannot resolve (the value has no external source).
     let graph_edges = graph
         .outgoing_edges(place.local)
         .map(|edge| traverse(rec_state.cloned(), place, edge));
@@ -249,22 +253,22 @@ fn resolve_params<'heap, A: Allocator + Clone>(
     //   `Some(Some(v))` when all predecessors agree on `v`
     //   `Some(None)` when the iterator is empty (unreachable: caller guarantees predecessors)
     //   `None` when the closure short-circuits (predecessors disagree)
-    let consensus = match graph_edges
+    let mut backtrack_occurred = false;
+    let consensus = graph_edges
         .chain(constant_edges)
-        .try_reduce(|lhs, rhs| (lhs == rhs).then_some(lhs))
-    {
-        Some(None) => unreachable!("caller must guarantee at least one Param predecessor exists"),
-        Some(consensus) => consensus,
-        None => None,
-    };
+        .filter(|candidate| {
+            if matches!(candidate, ControlFlow::Break(ResolutionResult::Backtrack)) {
+                backtrack_occurred = true;
+                return false;
+            }
 
-    if let Some(consensus) = consensus {
-        // If we initiated backtracking (owned_visited is Some) and got Backtrack,
-        // we are the cycle root and should treat this as incomplete.
-        let is_cycle_root =
-            consensus == ControlFlow::Break(ResolutionResult::Backtrack) && owned_visited.is_some();
+            true
+        })
+        .try_reduce(|lhs, rhs| (lhs == rhs).then_some(lhs));
 
-        if !is_cycle_root {
+    match consensus {
+        // Predecessors agree on a value.
+        Some(Some(consensus)) => {
             // Clean up visited state before returning.
             if let Some(visited) = state.visited {
                 visited.remove(place.local);
@@ -272,6 +276,21 @@ fn resolve_params<'heap, A: Allocator + Clone>(
 
             return consensus;
         }
+
+        // All candidates were cyclic (no non-cyclic predecessors to determine the value).
+        // If we're not the cycle root, propagate Backtrack so the root can handle it.
+        Some(None) if backtrack_occurred && owned_visited.is_none() => {
+            if let Some(visited) = &mut state.visited {
+                visited.remove(place.local);
+            }
+
+            return ControlFlow::Break(ResolutionResult::Backtrack);
+        }
+        // Pure cycle at root: fall through to Incomplete.
+        Some(None) if backtrack_occurred => {}
+        Some(None) => unreachable!("caller must guarantee at least one Param predecessor exists"),
+        // Predecessors disagree.
+        None => {}
     }
 
     // Clean up visited state before returning incomplete.
@@ -279,7 +298,7 @@ fn resolve_params<'heap, A: Allocator + Clone>(
         visited.remove(place.local);
     }
 
-    // Predecessors diverge or a cycle was detected; cannot resolve through this param.
+    // Non-cyclic predecessors diverge, or pure cycle at root.
     let mut projections = VecDeque::new_in(state.alloc.clone());
     projections.extend(place.projections);
 
diff --git a/libs/@local/hashql/mir/src/pass/analysis/data_dependency/tests.rs b/libs/@local/hashql/mir/src/pass/analysis/data_dependency/tests.rs
index 6e3b5a26275..a3d53b7b5eb 100644
--- a/libs/@local/hashql/mir/src/pass/analysis/data_dependency/tests.rs
+++ b/libs/@local/hashql/mir/src/pass/analysis/data_dependency/tests.rs
@@ -300,6 +300,137 @@ fn param_cycle_detection() {
     );
 }
 
+/// Tests that a loop-carried parameter resolves through the non-cyclic init edge
+/// when the back-edge just passes the value through unchanged.
+///
+/// The init edge provides constant 42, the back-edge creates a cycle (x depends on x).
+/// Since cyclic predecessors are identity transfers, the non-cyclic init edge determines
+/// the value: x should resolve to 42.
+#[test]
+fn param_cycle_with_const_init() {
+    let heap = Heap::new();
+    let interner = Interner::new(&heap);
+    let env = Environment::new(&heap);
+
+    let body = body!(interner, env; fn@0/0 -> Int {
+        decl x: Int, cond: Int;
+
+        bb0() {
+            cond = input.load! "cond";
+            goto bb1(42);
+        },
+        bb1(x) {
+            if cond then bb1(x) else bb2(x);
+        },
+        bb2(x) {
+            return x;
+        }
+    });
+
+    assert_data_dependency(
+        "param_cycle_with_const_init",
+        &body,
+        &mut MirContext {
+            heap: &heap,
+            env: &env,
+            interner: &interner,
+            diagnostics: DiagnosticIssues::new(),
+        },
+    );
+}
+
+/// Tests that a multi-node cycle with a constant init edge resolves correctly,
+/// even when the node with the init edge is not the cycle root.
+///
+/// The cycle is x -> y -> x (through bb1 -> bb2 -> bb1). The init edge provides
+/// constant 42 to x from bb0. During resolution of y, x is encountered as a non-root
+/// participant in the cycle. x must skip the cyclic Backtrack from y and use its
+/// non-cyclic constant init edge to resolve to 42, which then propagates through y
+/// and out to the consumer (result).
+#[test]
+fn param_cycle_multi_node_with_const_init() {
+    let heap = Heap::new();
+    let interner = Interner::new(&heap);
+    let env = Environment::new(&heap);
+
+    let body = body!(interner, env; fn@0/0 -> Int {
+        decl x: Int, y: Int, cond: Int, result: Int;
+
+        bb0() {
+            cond = input.load! "cond";
+            goto bb1(42);
+        },
+        bb1(x) {
+            goto bb2(x);
+        },
+        bb2(y) {
+            if cond then bb1(y) else bb3(y);
+        },
+        bb3(result) {
+            return result;
+        }
+    });
+
+    assert_data_dependency(
+        "param_cycle_multi_node_with_const_init",
+        &body,
+        &mut MirContext {
+            heap: &heap,
+            env: &env,
+            interner: &interner,
+            diagnostics: DiagnosticIssues::new(),
+        },
+    );
+}
+
+/// Tests that the visited set is cleaned up when non-cyclic predecessors disagree
+/// inside another node's cycle resolution.
+///
+/// y has a self-loop (creating a cycle). When resolving y, the cycle root tracks
+/// visited locals. x is resolved inside y's resolution and has disagreeing predecessors
+/// (constant 42 from bb0, opaque `input` from bb1). x must remove itself from the
+/// visited set before returning Incomplete, otherwise later resolutions would see
+/// false cycle detections.
+#[test]
+fn param_cycle_visited_cleanup_on_diverge() {
+    let heap = Heap::new();
+    let interner = Interner::new(&heap);
+    let env = Environment::new(&heap);
+
+    let body = body!(interner, env; fn@0/0 -> Int {
+        decl input: Int, x: Int, y: Int, cond: Int;
+
+        bb0() {
+            input = input.load! "x";
+            cond = input.load! "cond";
+            goto bb3(42);
+        },
+        bb1() {
+            goto bb3(input);
+        },
+        bb3(x) {
+            goto bb4(x);
+        },
+        bb4(y) {
+            if cond then bb4(y) else bb5(y);
+        },
+        bb5(y) {
+            return y;
+        }
+    });
+
+    assert_data_dependency(
+        "param_cycle_visited_cleanup_on_diverge",
+        &body,
+        &mut MirContext {
+            heap: &heap,
+            env: &env,
+            interner: &interner,
+            diagnostics: DiagnosticIssues::new(),
+        },
+    );
+}
+
 /// Tests constant propagation through edges.
 #[test]
 fn constant_propagation() {
diff --git a/libs/@local/hashql/mir/tests/ui/pass/data-dependency/param_cycle_detection.snap b/libs/@local/hashql/mir/tests/ui/pass/data-dependency/param_cycle_detection.snap
index 78e219ea059..e174f7581df 100644
--- a/libs/@local/hashql/mir/tests/ui/pass/data-dependency/param_cycle_detection.snap
+++ b/libs/@local/hashql/mir/tests/ui/pass/data-dependency/param_cycle_detection.snap
@@ -1,5 +1,6 @@
 ---
 source: libs/@local/hashql/mir/src/pass/analysis/data_dependency/tests.rs
+assertion_line: 32
 expression: "format!(\"{graph}\\n\\n=====\\n\\n{transient}\")"
 ---
 %1 -> %0 [Param]
@@ -10,5 +11,5 @@ expression: "format!(\"{graph}\\n\\n=====\\n\\n{transient}\")"
 =====
 
 %1 -> %0 [Param]
-%3 -> %1 [Param]
-%1 -> %1 [Param]
+%3 -> %0 [Param]
+%1 -> %0 [Param]
diff --git a/libs/@local/hashql/mir/tests/ui/pass/data-dependency/param_cycle_multi_node_with_const_init.snap b/libs/@local/hashql/mir/tests/ui/pass/data-dependency/param_cycle_multi_node_with_const_init.snap
new file mode 100644
index 00000000000..5627aa46982
--- /dev/null
+++ b/libs/@local/hashql/mir/tests/ui/pass/data-dependency/param_cycle_multi_node_with_const_init.snap
@@ -0,0 +1,17 @@
+---
+source: libs/@local/hashql/mir/src/pass/analysis/data_dependency/tests.rs
+assertion_line: 32
+expression: "format!(\"{graph}\\n\\n=====\\n\\n{transient}\")"
+---
+%1 -> %0 [Param]
+%3 -> %1 [Param]
+%0 -> %1 [Param]
+%0 -> 42 [Param]
+
+
+=====
+
+%0 -> 42 [Param]
+%0 -> 42 [Param]
+%1 -> 42 [Param]
+%3 -> 42 [Param]
diff --git a/libs/@local/hashql/mir/tests/ui/pass/data-dependency/param_cycle_visited_cleanup_on_diverge.snap b/libs/@local/hashql/mir/tests/ui/pass/data-dependency/param_cycle_visited_cleanup_on_diverge.snap
new file mode 100644
index 00000000000..4417a007b7c
--- /dev/null
+++ b/libs/@local/hashql/mir/tests/ui/pass/data-dependency/param_cycle_visited_cleanup_on_diverge.snap
@@ -0,0 +1,19 @@
+---
+source: libs/@local/hashql/mir/src/pass/analysis/data_dependency/tests.rs
+assertion_line: 32
+expression: "format!(\"{graph}\\n\\n=====\\n\\n{transient}\")"
+---
+%1 -> %0 [Param]
+%2 -> %1 [Param]
+%2 -> %2 [Param]
+%2 -> %2 [Param]
+%1 -> 42 [Param]
+
+
+=====
+
+%1 -> %0 [Param]
+%2 -> %1 [Param]
+%2 -> %1 [Param]
+%2 -> %1 [Param]
+%1 -> 42 [Param]
diff --git a/libs/@local/hashql/mir/tests/ui/pass/data-dependency/param_cycle_with_const_init.snap b/libs/@local/hashql/mir/tests/ui/pass/data-dependency/param_cycle_with_const_init.snap
new file mode 100644
index 00000000000..3e000a7998f
--- /dev/null
+++ b/libs/@local/hashql/mir/tests/ui/pass/data-dependency/param_cycle_with_const_init.snap
@@ -0,0 +1,15 @@
+---
+source: libs/@local/hashql/mir/src/pass/analysis/data_dependency/tests.rs
+assertion_line: 32
+expression: "format!(\"{graph}\\n\\n=====\\n\\n{transient}\")"
+---
+%0 -> %0 [Param]
+%0 -> %0 [Param]
+%0 -> 42 [Param]
+
+
+=====
+
+%0 -> 42 [Param]
+%0 -> 42 [Param]
+%0 -> 42 [Param]

From 77eb677126f8d1a6380a1fb6077ab449c85d160b Mon Sep 17 00:00:00 2001
From: Bilal Mahmoud <7252775+indietyp@users.noreply.github.com>
Date: Mon, 6 Apr 2026 21:27:32 +0200
Subject: [PATCH 3/3] chore: follow projections on param edges

---
 .../pass/analysis/data_dependency/resolve.rs  |  49 +++++-
 .../pass/analysis/data_dependency/tests.rs    | 148 ++++++++++++++++++
 .../src/pass/transform/inst_simplify/mod.rs   |   4 +
 ...param_consensus_projected_field_const.snap |  22 +++
 ...param_consensus_projected_field_place.snap |  22 +++
 ...param_cycle_invariant_projected_field.snap |  22 +++
 6 files changed, 263 insertions(+), 4 deletions(-)
 create mode 100644 libs/@local/hashql/mir/tests/ui/pass/data-dependency/param_consensus_projected_field_const.snap
 create mode 100644 libs/@local/hashql/mir/tests/ui/pass/data-dependency/param_consensus_projected_field_place.snap
 create mode 100644 libs/@local/hashql/mir/tests/ui/pass/data-dependency/param_cycle_invariant_projected_field.snap

diff --git a/libs/@local/hashql/mir/src/pass/analysis/data_dependency/resolve.rs b/libs/@local/hashql/mir/src/pass/analysis/data_dependency/resolve.rs
index 8dfbaa8f1fb..f57dc651b3d 100644
--- a/libs/@local/hashql/mir/src/pass/analysis/data_dependency/resolve.rs
+++ b/libs/@local/hashql/mir/src/pass/analysis/data_dependency/resolve.rs
@@ -188,6 +188,20 @@ fn traverse<'heap, A: Allocator + Clone>(
 /// constants). This function checks whether all non-cyclic predecessors, from both
 /// sources, resolve to the same value.
 ///
+/// # Projection-aware consensus
+///
+/// When the queried place has a projection suffix (e.g., resolving `x.0` where `x` is a
+/// block parameter), consensus is checked on the *fully resolved* result per predecessor,
+/// not on the partially resolved predecessor bases. This is necessary because different
+/// predecessor locals can still agree on a projected field.
+///
+/// For example, if predecessor A passes `(42, u)` and predecessor B passes `(42, v)`,
+/// the bases disagree but `A.0 == B.0 == 42`. The algorithm resolves each predecessor
+/// through the full projection suffix before comparing, so this case correctly yields
+/// `Resolved(42)` rather than `Incomplete(x.0)`.
+///
+/// # Cycle handling
+///
 /// Cyclic predecessors ([`Backtrack`]) are filtered out before consensus checking.
 /// Since [`Param`] edges are identity transfers, the value is fully determined by
 /// the non-cyclic init edges. If only cyclic predecessors exist (no external source),
@@ -236,12 +250,35 @@ fn resolve_params<'heap, A: Allocator + Clone>(
     };
 
     // Resolve all predecessor candidates and check consensus.
+    //
+    // When the queried place has projections (e.g., `x.field`), each predecessor is resolved
+    // through the full projection suffix before consensus comparison. If `traverse` returns
+    // `Continue(local)` (predecessor base resolved to a bare local), we call `resolve` on
+    // `local.projections` to complete the resolution. This ensures consensus is checked on
+    // the final value, not intermediate bases that may differ structurally but agree on the
+    // projected component.
+    //
     // Cyclic predecessors (Backtrack) are skipped: since Param edges are identity transfers,
     // the value is fully determined by the non-cyclic init edges. If only cyclic predecessors
     // exist, we cannot resolve (the value has no external source).
-    let graph_edges = graph
-        .outgoing_edges(place.local)
-        .map(|edge| traverse(rec_state.cloned(), place, edge));
+    let graph_edges = graph.outgoing_edges(place.local).map(|edge| {
+        let result = traverse(rec_state.cloned(), place, edge);
+
+        match result {
+            // Predecessor resolved to a bare local, but the query has remaining projections.
+            // Finish resolving through the projection suffix so consensus compares final values.
+            ControlFlow::Continue(local) if !place.projections.is_empty() => {
+                ControlFlow::Break(resolve(
+                    rec_state.cloned(),
+                    PlaceRef {
+                        local,
+                        projections: place.projections,
+                    },
+                ))
+            }
+            ControlFlow::Continue(_) | ControlFlow::Break(_) => result,
+        }
+    });
     let constant_edges = graph
         .constant_bindings
         .iter_by_kind(place.local, EdgeKind::Param)
@@ -314,7 +351,11 @@ fn resolve_params<'heap, A: Allocator + Clone>(
 /// the data ultimately originates. The algorithm handles three types of edges:
 ///
 /// - **[`Load`]**: Always followed transitively (a load has exactly one source)
-/// - **[`Param`]**: Followed only if all predecessors agree on the same source (consensus)
+/// - **[`Param`]**: Followed only if all predecessors agree on the same source (consensus).
+///   Consensus is checked on fully resolved results: when the queried place has projections, each
+///   predecessor is resolved through the complete projection suffix before comparison. This allows
+///   resolution through φ-nodes where predecessor bases differ but the projected component agrees
+///   (e.g., `(42, a)` and `(42, b)` agree on field `.0`).
 /// - **[`Index`]/[`Field`]**: Matched against projections to trace through aggregates
 ///
 /// Resolution terminates with:
diff --git a/libs/@local/hashql/mir/src/pass/analysis/data_dependency/tests.rs b/libs/@local/hashql/mir/src/pass/analysis/data_dependency/tests.rs
index a3d53b7b5eb..ee724ed3cf6 100644
--- a/libs/@local/hashql/mir/src/pass/analysis/data_dependency/tests.rs
+++ b/libs/@local/hashql/mir/src/pass/analysis/data_dependency/tests.rs
@@ -718,3 +718,151 @@ fn load_param_mixed() {
         },
     );
 }
+
+/// Tests that Param consensus resolves through projections when predecessors are
+/// different tuples but the queried field is the same constant.
+///
+/// Both paths construct different tuples (`a = (42, u)`, `b = (42, v)`) but the
+/// `.0` field is the same constant `42` in both. Current algorithm compares the
+/// tuple bases (`a` vs `b`), which disagree, so it returns `Incomplete(x.0)`.
+/// Correct behavior: resolve `a.0` and `b.0` individually, find they both yield
+/// `42`, and return `Resolved(42)`.
+#[test]
+fn param_consensus_projected_field_const() {
+    let heap = Heap::new();
+    let interner = Interner::new(&heap);
+    let env = Environment::new(&heap);
+
+    let body = body!(interner, env; fn@0/0 -> Int {
+        decl u: Int, v: Int, a: (Int, Int), b: (Int, Int), cond: Int, x: (Int, Int), result: Int;
+        @proj x_0 = x.0: Int;
+
+        bb0() {
+            u = input.load! "u";
+            v = input.load! "v";
+            cond = input.load! "cond";
+            a = tuple 42, u;
+            b = tuple 42, v;
+            if cond then bb1() else bb2();
+        },
+        bb1() {
+            goto bb3(a);
+        },
+        bb2() {
+            goto bb3(b);
+        },
+        bb3(x) {
+            result = load x_0;
+            return result;
+        }
+    });
+
+    assert_data_dependency(
+        "param_consensus_projected_field_const",
+        &body,
+        &mut MirContext {
+            heap: &heap,
+            env: &env,
+            interner: &interner,
+            diagnostics: DiagnosticIssues::new(),
+        },
+    );
+}
+
+/// Tests that Param consensus resolves through projections when predecessors are
+/// different tuples but the queried field is the same place.
+///
+/// Both paths construct different tuples (`a = (src, u)`, `b = (src, v)`) but the
+/// `.0` field is the same local `src` in both. Current algorithm compares the
+/// tuple bases (`a` vs `b`), which disagree, so it returns `Incomplete(x.0)`.
+/// Correct behavior: resolve `a.0` and `b.0` individually, find they both yield
+/// `src`, and return `Resolved(src)`.
+#[test]
+fn param_consensus_projected_field_place() {
+    let heap = Heap::new();
+    let interner = Interner::new(&heap);
+    let env = Environment::new(&heap);
+
+    let body = body!(interner, env; fn@0/0 -> Int {
+        decl src: Int, u: Int, v: Int, a: (Int, Int), b: (Int, Int), cond: Int, x: (Int, Int), result: Int;
+        @proj x_0 = x.0: Int;
+
+        bb0() {
+            src = input.load! "src";
+            u = input.load! "u";
+            v = input.load! "v";
+            cond = input.load! "cond";
+            a = tuple src, u;
+            b = tuple src, v;
+            if cond then bb1() else bb2();
+        },
+        bb1() {
+            goto bb3(a);
+        },
+        bb2() {
+            goto bb3(b);
+        },
+        bb3(x) {
+            result = load x_0;
+            return result;
+        }
+    });
+
+    assert_data_dependency(
+        "param_consensus_projected_field_place",
+        &body,
+        &mut MirContext {
+            heap: &heap,
+            env: &env,
+            interner: &interner,
+            diagnostics: DiagnosticIssues::new(),
+        },
+    );
+}
+
+/// Tests that a cycle with a loop-invariant projected field resolves correctly.
+///
+/// The cycle is `x -> x` via the back-edge in `bb1`. The init edge provides
+/// `init = (src, other)`. The back-edge reconstructs `t = (x.0, other)`,
+/// preserving `x.0` across iterations. So `x.0` is loop-invariant and should
+/// resolve to `src`. Current algorithm compares `init` vs `t` as bases, which
+/// disagree, yielding `Incomplete(x.0)`. Correct behavior: resolve the full
+/// `init.0 = src` and see that `t.0 = x.0` is a cyclic identity, so the
+/// non-cyclic init determines the answer.
+#[test]
+fn param_cycle_invariant_projected_field() {
+    let heap = Heap::new();
+    let interner = Interner::new(&heap);
+    let env = Environment::new(&heap);
+
+    let body = body!(interner, env; fn@0/0 -> Int {
+        decl src: Int, other: Int, init: (Int, Int), x: (Int, Int), t: (Int, Int), cond: Int, result: Int;
+        @proj x_0 = x.0: Int;
+
+        bb0() {
+            src = input.load! "src";
+            other = input.load! "other";
+            cond = input.load! "cond";
+            init = tuple src, other;
+            goto bb1(init);
+        },
+        bb1(x) {
+            t = tuple x_0, other;
+            if cond then bb1(t) else bb2(x_0);
+        },
+        bb2(result) {
+            return result;
+        }
+    });
+
+    assert_data_dependency(
+        "param_cycle_invariant_projected_field",
+        &body,
+        &mut MirContext {
+            heap: &heap,
+            env: &env,
+            interner: &interner,
+            diagnostics: DiagnosticIssues::new(),
+        },
+    );
+}
diff --git a/libs/@local/hashql/mir/src/pass/transform/inst_simplify/mod.rs b/libs/@local/hashql/mir/src/pass/transform/inst_simplify/mod.rs
index ade4c6e0626..2fc24b17e1c 100644
--- a/libs/@local/hashql/mir/src/pass/transform/inst_simplify/mod.rs
+++ b/libs/@local/hashql/mir/src/pass/transform/inst_simplify/mod.rs
@@ -309,6 +309,8 @@ impl<'heap, A: Allocator> InstSimplifyVisitor<'_, 'heap, A> {
             (BinOp::BitAnd, 0) if is_bool => {
                 Some(RValue::Load(Operand::Constant(Constant::Int(false.into()))))
             }
+            // 0 & rhs => 0 (annihilator)
+            (BinOp::BitAnd, 0) => Some(RValue::Load(Operand::Constant(Constant::Int(0.into())))),
             (BinOp::BitAnd, _) => None,
             // 0 | rhs => rhs (identity)
             (BinOp::BitOr, 0) => Some(RValue::Load(Operand::Place(rhs))),
@@ -369,6 +371,8 @@ impl<'heap, A: Allocator> InstSimplifyVisitor<'_, 'heap, A> {
             (BinOp::BitAnd, 0) if is_bool => {
                 Some(RValue::Load(Operand::Constant(Constant::Int(false.into()))))
             }
+            // 0 & lhs => 0 (annihilator)
+            (BinOp::BitAnd, 0) => Some(RValue::Load(Operand::Constant(Constant::Int(0.into())))),
             (BinOp::BitAnd, _) => None,
             // lhs | 0 => lhs (identity)
             (BinOp::BitOr, 0) => Some(RValue::Load(Operand::Place(lhs))),
diff --git a/libs/@local/hashql/mir/tests/ui/pass/data-dependency/param_consensus_projected_field_const.snap b/libs/@local/hashql/mir/tests/ui/pass/data-dependency/param_consensus_projected_field_const.snap
new file mode 100644
index 00000000000..7efaeecb79c
--- /dev/null
+++ b/libs/@local/hashql/mir/tests/ui/pass/data-dependency/param_consensus_projected_field_const.snap
@@ -0,0 +1,22 @@
+---
+source: libs/@local/hashql/mir/src/pass/analysis/data_dependency/tests.rs
+expression: "format!(\"{graph}\\n\\n=====\\n\\n{transient}\")"
+---
+%2 -> %0 [Index(FieldIndex(1))]
+%3 -> %1 [Index(FieldIndex(1))]
+%5 -> %2 [Param]
+%5 -> %3 [Param]
+%6 -> %5 [Load, projections: .0]
+%2 -> 42 [Index(FieldIndex(0))]
+%3 -> 42 [Index(FieldIndex(0))]
+
+
+=====
+
+%2 -> %0 [Index(FieldIndex(1))]
+%3 -> %1 [Index(FieldIndex(1))]
+%5 -> %2 [Param]
+%5 -> %3 [Param]
+%2 -> 42 [Index(FieldIndex(0))]
+%3 -> 42 [Index(FieldIndex(0))]
+%6 -> 42 [Load]
diff --git a/libs/@local/hashql/mir/tests/ui/pass/data-dependency/param_consensus_projected_field_place.snap b/libs/@local/hashql/mir/tests/ui/pass/data-dependency/param_consensus_projected_field_place.snap
new file mode 100644
index 00000000000..d9c5b6d6de4
--- /dev/null
+++ b/libs/@local/hashql/mir/tests/ui/pass/data-dependency/param_consensus_projected_field_place.snap
@@ -0,0 +1,22 @@
+---
+source: libs/@local/hashql/mir/src/pass/analysis/data_dependency/tests.rs
+expression: "format!(\"{graph}\\n\\n=====\\n\\n{transient}\")"
+---
+%3 -> %0 [Index(FieldIndex(0))]
+%3 -> %1 [Index(FieldIndex(1))]
+%4 -> %0 [Index(FieldIndex(0))]
+%4 -> %2 [Index(FieldIndex(1))]
+%6 -> %3 [Param]
+%6 -> %4 [Param]
+%7 -> %6 [Load, projections: .0]
+
+
+=====
+
+%3 -> %0 [Index(FieldIndex(0))]
+%3 -> %1 [Index(FieldIndex(1))]
+%4 -> %0 [Index(FieldIndex(0))]
+%4 -> %2 [Index(FieldIndex(1))]
+%6 -> %3 [Param]
+%6 -> %4 [Param]
+%7 -> %0 [Load]
diff --git a/libs/@local/hashql/mir/tests/ui/pass/data-dependency/param_cycle_invariant_projected_field.snap b/libs/@local/hashql/mir/tests/ui/pass/data-dependency/param_cycle_invariant_projected_field.snap
new file mode 100644
index 00000000000..601e7e15f75
--- /dev/null
+++ b/libs/@local/hashql/mir/tests/ui/pass/data-dependency/param_cycle_invariant_projected_field.snap
@@ -0,0 +1,22 @@
+---
+source: libs/@local/hashql/mir/src/pass/analysis/data_dependency/tests.rs
+expression: "format!(\"{graph}\\n\\n=====\\n\\n{transient}\")"
+---
+%2 -> %0 [Index(FieldIndex(0))]
+%2 -> %1 [Index(FieldIndex(1))]
+%3 -> %2 [Param]
+%4 -> %3 [Index(FieldIndex(0)), projections: .0]
+%4 -> %1 [Index(FieldIndex(1))]
+%6 -> %3 [Param, projections: .0]
+%3 -> %4 [Param]
+
+
+=====
+
+%2 -> %0 [Index(FieldIndex(0))]
+%2 -> %1 [Index(FieldIndex(1))]
+%3 -> %2 [Param]
+%4 -> %0 [Index(FieldIndex(0))]
+%4 -> %1 [Index(FieldIndex(1))]
+%6 -> %0 [Param]
+%3 -> %4 [Param]