Implement match/case statement code generation

- Add _emit_match() using LLVM switch instruction
- Handle value patterns and wildcard (case _:) patterns
- Each case gets its own basic block with branch to end
- Wildcard case becomes default label in switch
- All tests passing (30/30)
- Tabs.wasm size: 1908 → 3185 bytes

ritz/llvm_codegen_signals.py

@@ -225,6 +225,8 @@ class SignalLLVMIRGenerator:
             return self._emit_yield(stmt)
         elif stmt["type"] == "if":
             return self._emit_if(stmt)
+        elif stmt["type"] == "match":
+            return self._emit_match(stmt)
         return None
 
     def _emit_if(self, stmt: dict[str, Any]) -> str | None:
@@ -267,6 +269,59 @@ class SignalLLVMIRGenerator:
 
         return None
 
+    def _emit_match(self, stmt: dict[str, Any]) -> str | None:
+        """Emit a match/case statement using LLVM switch."""
+        # Generate unique labels
+        match_id = self._new_var()
+
+        # Evaluate subject expression
+        subject_var = self._emit_expr(stmt["subject"])
+
+        # Create labels for each case and the end
+        case_labels = [f"match.case{i}.{match_id}" for i in range(len(stmt["cases"]))]
+        end_label = f"match.end.{match_id}"
+        default_label = f"match.default.{match_id}"
+
+        # Build switch instruction
+        # Find wildcard case (case _:) to use as default
+        default_case_idx = None
+        switch_cases = []
+        for i, case in enumerate(stmt["cases"]):
+            pattern = case["pattern"]
+            if pattern["type"] == "wildcard":
+                default_case_idx = i
+            elif pattern["type"] == "value":
+                # Extract the constant value
+                value = pattern["value"]["value"]
+                switch_cases.append(f"i32 {value}, label %{case_labels[i]}")
+
+        # Emit switch
+        if default_case_idx is not None:
+            self.lines.append(f"  switch i32 %{subject_var}, label %{case_labels[default_case_idx]} [")
+        else:
+            self.lines.append(f"  switch i32 %{subject_var}, label %{default_label} [")
+
+        for case_spec in switch_cases:
+            self.lines.append(f"    {case_spec}")
+        self.lines.append("  ]")
+
+        # Emit each case body
+        for i, case in enumerate(stmt["cases"]):
+            self.lines.append(f"{case_labels[i]}:")
+            for case_stmt in case["body"]:
+                self._emit_statement(case_stmt)
+            self.lines.append(f"  br label %{end_label}")
+
+        # Emit default case if needed (no wildcard)
+        if default_case_idx is None:
+            self.lines.append(f"{default_label}:")
+            self.lines.append(f"  br label %{end_label}")
+
+        # Emit end label
+        self.lines.append(f"{end_label}:")
+
+        return None
+
     def _emit_expr(self, expr: dict[str, Any]) -> str:
         """Emit an expression and return the result variable name."""
         if expr["type"] == "name":