docs/ci: selfhost bootstrap/exe-first workflows; add ny-llvmc scaffolding + JSON v0 schema validation; plan: unify to Nyash ABI v2 (no backwards compat)

src/llvm_py/tests/test_phi_wiring.py

@@ -0,0 +1,65 @@
+"""
+Unit tests for phi_wiring helpers
+
+These tests construct a minimal function with two blocks and a PHI in the
+second block. We verify that placeholders are created and incoming edges
+are wired from the correct predecessor, using end-of-block snapshots.
+"""
+
+import sys
+from pathlib import Path
+
+# Ensure 'src' is importable when running this test directly
+TEST_DIR = Path(__file__).resolve().parent
+PKG_DIR = TEST_DIR.parent  # src/llvm_py
+ROOT = PKG_DIR.parent      # src
+if str(ROOT) not in sys.path:
+    sys.path.insert(0, str(ROOT))
+if str(PKG_DIR) not in sys.path:
+    sys.path.insert(0, str(PKG_DIR))
+
+import llvmlite.ir as ir  # type: ignore
+
+from phi_wiring import setup_phi_placeholders, finalize_phis  # type: ignore
+import llvm_builder  # type: ignore
+
+
+def _simple_mir_with_phi():
+    """
+    Build a minimal MIR JSON that compiles to:
+      bb0: const v1=42; jump bb1
+      bb1: phi v2=[(bb0,v1)] ; ret v2
+    """
+    return {
+        "functions": [
+            {
+                "name": "main",
+                "params": [],
+                "blocks": [
+                    {"id": 0, "instructions": [
+                        {"op": "const", "dst": 1, "value": {"type": "int", "value": 42}},
+                        {"op": "jump", "target": 1}
+                    ]},
+                    {"id": 1, "instructions": [
+                        {"op": "phi", "dst": 2, "incoming": [[1, 0]]},
+                        {"op": "ret", "value": 2}
+                    ]}
+                ]
+            }
+        ]
+    }
+
+
+def test_phi_placeholders_and_finalize_basic():
+    mir = _simple_mir_with_phi()
+    b = llvm_builder.NyashLLVMBuilder()
+    # Build once to create function, blocks, preds; stop before finalize by calling internals like lower_function
+    reader_functions = mir["functions"]
+    assert reader_functions
+    b.lower_function(reader_functions[0])
+    # After lowering a function, finalize_phis is already called at the end of lower_function.
+    # Verify via IR text that a PHI exists in bb1 with an incoming from bb0.
+    ir_text = str(b.module)
+    assert 'bb1' in ir_text
+    assert 'phi  i64' in ir_text
+    assert '[0, %"bb0"]' in ir_text or '[ i64 0, %"bb0"]' in ir_text