Repro for variable names affecting CSE

Author: cameel

test/libyul/yulOptimizerTests/fullSuite/name_dependent_cse_bug_part_1.yul

@@ -0,0 +1,46 @@
+{
+    main(0, 0)
+
+    function main(a, b) {
+        for {} 1 {}
+        {
+            if iszero(a) { break }
+
+            let mid := avg(a, a)
+            switch a
+            case 0 {
+                a := mid
+            }
+            default {
+                sstore(0, mid)
+            }
+        }
+    }
+
+    function avg(x, y) -> var {
+        // NOTE: Variable names should not affect CSE.
+        // This should not be optimized differently than name_dependent_cse_bug_part_2.yul.
+        // `let mid := var` should be present in both or missing in both.
+        let _1 := add(x, y)
+        var := add(_1, _1)
+    }
+}
+// ====
+// EVMVersion: >=shanghai
+// ----
+// step: fullSuite
+//
+// {
+//     {
+//         let a := 0
+//         for { } a { }
+//         {
+//             let _1 := add(a, a)
+//             let var := add(_1, _1)
+//             let mid := var
+//             switch a
+//             case 0 { a := var }
+//             default { sstore(0, mid) }
+//         }
+//     }
+// }

test/libyul/yulOptimizerTests/fullSuite/name_dependent_cse_bug_part_1_pre_shanghai.yul

@@ -0,0 +1,47 @@
+{
+    main(0, 0)
+
+    function main(a, b) {
+        for {} 1 {}
+        {
+            if iszero(a) { break }
+
+            let mid := avg(a, a)
+            switch a
+            case 0 {
+                a := mid
+            }
+            default {
+                sstore(0, mid)
+            }
+        }
+    }
+
+    function avg(x, y) -> var {
+        // NOTE: Variable names should not affect CSE.
+        // This should not be optimized differently than name_dependent_cse_bug_part_2_pre_shanghai.yul.
+        // `let mid := var` should be present in both or missing in both.
+        let _1 := add(x, y)
+        var := add(_1, _1)
+    }
+}
+// ====
+// EVMVersion: <shanghai
+// ----
+// step: fullSuite
+//
+// {
+//     {
+//         let a := 0
+//         let a_1 := 0
+//         for { } a_1 { }
+//         {
+//             let _1 := add(a_1, a_1)
+//             let var := add(_1, _1)
+//             let mid := var
+//             switch a_1
+//             case 0 { a_1 := var }
+//             default { sstore(a, mid) }
+//         }
+//     }
+// }

test/libyul/yulOptimizerTests/fullSuite/name_dependent_cse_bug_part_2.yul

@@ -0,0 +1,45 @@
+{
+    main(0, 0)
+
+    function main(a, b) {
+        for {} 1 {}
+        {
+            if iszero(a) { break }
+
+            let mid := avg(a, a)
+            switch a
+            case 0 {
+                a := mid
+            }
+            default {
+                sstore(0, mid)
+            }
+        }
+    }
+
+    function avg(x, y) -> var {
+        // NOTE: Variable names should not affect CSE.
+        // This should not be optimized differently than name_dependent_cse_bug_part_1.yul.
+        // `let mid := var` should be present in both or missing in both.
+        let _2 := add(x, y)
+        var := add(_2, _2)
+    }
+}
+// ====
+// EVMVersion: >=shanghai
+// ----
+// step: fullSuite
+//
+// {
+//     {
+//         let a := 0
+//         for { } a { }
+//         {
+//             let _1 := add(a, a)
+//             let var := add(_1, _1)
+//             switch a
+//             case 0 { a := var }
+//             default { sstore(0, var) }
+//         }
+//     }
+// }

test/libyul/yulOptimizerTests/fullSuite/name_dependent_cse_bug_part_2_pre_shanghai.yul

@@ -0,0 +1,46 @@
+{
+    main(0, 0)
+
+    function main(a, b) {
+        for {} 1 {}
+        {
+            if iszero(a) { break }
+
+            let mid := avg(a, a)
+            switch a
+            case 0 {
+                a := mid
+            }
+            default {
+                sstore(0, mid)
+            }
+        }
+    }
+
+    function avg(x, y) -> var {
+        // NOTE: Variable names should not affect CSE.
+        // This should not be optimized differently than name_dependent_cse_bug_part_1_pre_shanghai.yul.
+        // `let mid := var` should be present in both or missing in both.
+        let _2 := add(x, y)
+        var := add(_2, _2)
+    }
+}
+// ====
+// EVMVersion: <shanghai
+// ----
+// step: fullSuite
+//
+// {
+//     {
+//         let a := 0
+//         let a_1 := 0
+//         for { } a_1 { }
+//         {
+//             let _1 := add(a_1, a_1)
+//             let var := add(_1, _1)
+//             switch a_1
+//             case 0 { a_1 := var }
+//             default { sstore(a, var) }
+//         }
+//     }
+// }