Changelog and test for the KeccakCaching bug

test/libsolidity/semanticTests/inlineAssembly/keccak256_optimization.sol

@@ -0,0 +1,16 @@
+contract C {
+    function f() public view returns (bool ret) {
+        assembly {
+            let x := calldataload(0)
+            mstore(0, x)
+            mstore(0x20, x)
+            let a := keccak256(0, 4)
+            let b := keccak256(0x20, 4)
+            ret := eq(a, b)
+        }
+    }
+}
+// ====
+// compileViaYul: also
+// ----
+// f() -> true

test/libsolidity/semanticTests/inlineAssembly/keccak256_optimizer_bug_different_memory_location.sol

@@ -0,0 +1,16 @@
+contract C {
+    function f() public view returns (bool ret) {
+        assembly {
+            let x := calldataload(0)
+            mstore(0, x)
+            mstore(0x20, x)
+            let a := keccak256(0, 4)
+            let b := keccak256(0x20, 8)
+            ret := eq(a, b)
+        }
+    }
+}
+// ====
+// compileViaYul: also
+// ----
+// f() -> false

test/libsolidity/semanticTests/inlineAssembly/keccak256_optimizer_cache_bug.sol

@@ -0,0 +1,21 @@
+contract C {
+  uint[] data;
+
+  function val() public returns (bool) {
+    assembly {
+        sstore(0, 2)
+        mstore(0, 0)
+        sstore(keccak256(0, 32), 234)
+        // A bug in the caching mechanism previously caused keccak256(0, 23) to be the same as
+        // keccak256(0, 32), leading to `data[1] == 123` being true.
+        sstore(add(keccak256(0, 23), 1), 123)
+    }
+    assert(data[1] != 123);
+    assert(data[1] == 0);
+    return true;
+  }
+}
+// ====
+// compileViaYul: also
+// ----
+// val() -> true

test/libsolidity/semanticTests/inlineAssembly/keccak_optimization_bug_string.sol

@@ -0,0 +1,15 @@
+contract C {
+    function f(string memory s) public returns (bool ret) {
+        assembly {
+            let a := keccak256(s, 32)
+            let b := keccak256(s, 8)
+            ret := eq(a, b)
+        }
+    }
+}
+// ====
+// compileViaYul: also
+// ----
+// f(string): "" -> false
+// f(string): 0x20, 5, "hello" -> false
+// f(string): 0x20, 0x2e, 29457663690442756349866640336617293820574110049925353194191585327958485180523, 45859201465615193776739262511799714667061496775486067316261261194408342061056 -> false