From d35bed041f8f30a73a034ed7d34b43d96d1fbdbf Mon Sep 17 00:00:00 2001
From: Hodan <plodeada@fit.cvut.cz>
Date: Wed, 29 Jan 2025 13:19:17 +0100
Subject: [PATCH] loops test and fixes

---
 .../test_common_subexpression_elimination.py  | 32 +++++++++++++++++++
 vyper/venom/analysis/available_expression.py  |  6 ++--
 2 files changed, 35 insertions(+), 3 deletions(-)

diff --git a/tests/unit/compiler/venom/test_common_subexpression_elimination.py b/tests/unit/compiler/venom/test_common_subexpression_elimination.py
index a49515b7ed..22a0368ffe 100644
--- a/tests/unit/compiler/venom/test_common_subexpression_elimination.py
+++ b/tests/unit/compiler/venom/test_common_subexpression_elimination.py
@@ -319,3 +319,35 @@ def call(callname: str, i: int, var_name: str):
     """
 
     _check_no_change(pre)
+
+
+def test_common_subexpression_elimination_loop():
+    pre = """
+    main:
+        %par = param
+        %data0 = mload 0
+        %add0 = add 1, %par
+        %mul0 = mul %add0, %data0
+        jmp @loop
+    loop:
+        %data1 = mload 0
+        %add1 = add 1, %par
+        %mul1 = mul %add1, %data1
+        jmp @loop
+    """
+
+    post = """
+    main:
+        %par = param
+        %data0 = mload 0
+        %add0 = add 1, %par
+        %mul0 = mul %add0, %data0
+        jmp @loop
+    loop:
+        %data1 = mload 0
+        %add1 = %add0
+        %mul1 = %mul0
+        jmp @loop
+    """
+
+    _check_pre_post(pre, post)
diff --git a/vyper/venom/analysis/available_expression.py b/vyper/venom/analysis/available_expression.py
index 1c7bb9977a..b593ecdb70 100644
--- a/vyper/venom/analysis/available_expression.py
+++ b/vyper/venom/analysis/available_expression.py
@@ -221,10 +221,10 @@ def copy(self) -> "_AvailableExpression":
         return res
 
     @staticmethod
-    def intersection(*others: "_AvailableExpression"):
+    def intersection(*others: "_AvailableExpression | None"):
         if len(others) == 0:
             return _AvailableExpression()
-        tmp = list(others)
+        tmp = list(o for o in others if o is not None)
         res = tmp[0].copy()
         for item in tmp[1:]:
             buckets = res.buckets.keys() & item.buckets.keys()
@@ -283,7 +283,7 @@ def _contains_msize(self) -> bool:
 
     def _handle_bb(self, bb: IRBasicBlock) -> bool:
         available_expr: _AvailableExpression = _AvailableExpression.intersection(
-            *(self.bb_outs.get(out_bb, _AvailableExpression()) for out_bb in bb.cfg_in)
+            *(self.bb_outs.get(out_bb, None) for out_bb in bb.cfg_in)
         )
 
         change = False