Add tests where an instruction gets instrumented more than once

tests/expected/uninit/multiple-instrumentations.expected

@@ -0,0 +1,20 @@
+multiple_instrumentations_different_vars.assertion.3\
+	 - Status: FAILURE\
+	 - Description: "Undefined Behavior: Reading from an uninitialized pointer of type `u128`"
+
+multiple_instrumentations_different_vars.assertion.4\
+	 - Status: FAILURE\
+	 - Description: "Undefined Behavior: Reading from an uninitialized pointer of type `u64`"
+
+multiple_instrumentations.assertion.2\
+	 - Status: FAILURE\
+	 - Description: "Undefined Behavior: Reading from an uninitialized pointer of type `u128`"
+
+multiple_instrumentations.assertion.3\
+	 - Status: FAILURE\
+	 - Description: "Undefined Behavior: Reading from an uninitialized pointer of type `u128`"
+
+Summary:
+Verification failed for - multiple_instrumentations_different_vars
+Verification failed for - multiple_instrumentations
+Complete - 0 successfully verified harnesses, 2 failures, 2 total.

tests/expected/uninit/multiple-instrumentations.rs

@@ -0,0 +1,42 @@
+// Copyright Kani Contributors
+// SPDX-License-Identifier: Apache-2.0 OR MIT
+// kani-flags: -Z uninit-checks
+
+/// Ensure instrumentation works correctly when a single instruction gets multiple instrumentations.
+#[kani::proof]
+fn multiple_instrumentations() {
+    unsafe {
+        let mut value: u128 = 0;
+        // Cast between two pointers of different padding.
+        let ptr = &mut value as *mut _ as *mut (u8, u32, u64);
+        *ptr = (4, 4, 4);
+        // Here, instrumentation is added 2 times before the function call and 1 time after.
+        value = helper_1(value, value);
+    }
+}
+
+fn helper_1(a: u128, b: u128) -> u128 {
+    a + b
+}
+
+/// Ensure instrumentation works correctly when a single instruction gets multiple instrumentations
+/// (and variables are different).
+#[kani::proof]
+fn multiple_instrumentations_different_vars() {
+    unsafe {
+        let mut a: u128 = 0;
+        let mut b: u64 = 0;
+        // Cast between two pointers of different padding.
+        let ptr_a = &mut a as *mut _ as *mut (u8, u32, u64);
+        *ptr_a = (4, 4, 4);
+        // Cast between two pointers of different padding.
+        let ptr_b = &mut b as *mut _ as *mut (u8, u32);
+        *ptr_b = (4, 4);
+        // Here, instrumentation is added 2 times before the function call and 1 time after.
+        a = helper_2(a, b);
+    }
+}
+
+fn helper_2(a: u128, b: u64) -> u128 {
+    a + (b as u128)
+}