fix bug in memcopyopt related to killing defined symbols (#6820)

sway-ir/src/optimize/memcpyopt.rs

@@ -301,7 +301,6 @@ fn local_copy_prop(
                                 available_copies.remove(copy);
                             }
                         }
-                        copies.retain(|copy| available_copies.contains(copy));
                     }
                     if let Some(copies) = dest_to_copies.get_mut(&sym) {
                         for copy in &*copies {
@@ -333,9 +332,17 @@ fn local_copy_prop(
                                 available_copies.remove(copy);
                             }
                         }
-                        copies.retain(|copy| available_copies.contains(copy));
                     }
                 }
+                // Update src_to_copies and dest_to_copies to remove every copy not in available_copies.
+                src_to_copies.retain(|_, copies| {
+                    copies.retain(|copy| available_copies.contains(copy));
+                    !copies.is_empty()
+                });
+                dest_to_copies.retain(|_, copies| {
+                    copies.retain(|copy| available_copies.contains(copy));
+                    !copies.is_empty()
+                });
             }
             ReferredSymbols::Incomplete(_) => {
                 // The only safe thing we can do is to clear all information.

test/src/e2e_vm_tests/test_programs/should_pass/language/references/mutability_of_references_memcpy_bug/Forc.lock

@@ -0,0 +1,13 @@
+[[package]]
+name = "core"
+source = "path+from-root-1F6D5E67DD060824"
+
+[[package]]
+name = "mutability_of_references_memcpy_bug"
+source = "member"
+dependencies = ["std"]
+
+[[package]]
+name = "std"
+source = "path+from-root-1F6D5E67DD060824"
+dependencies = ["core"]

test/src/e2e_vm_tests/test_programs/should_pass/language/references/mutability_of_references_memcpy_bug/Forc.toml

@@ -0,0 +1,8 @@
+[project]
+authors = ["Fuel Labs <[email protected]>"]
+entry = "main.sw"
+license = "Apache-2.0"
+name = "mutability_of_references_memcpy_bug"
+
+[dependencies]
+std = { path = "../../../../../reduced_std_libs/sway-lib-std-assert" }

test/src/e2e_vm_tests/test_programs/should_pass/language/references/mutability_of_references_memcpy_bug/src/lib.sw

@@ -0,0 +1,19 @@
+library;
+
+#[inline(never)]
+pub fn unit(b: u256) -> u256 {
+    b
+}
+
+#[inline(never)]
+pub fn weird(_b: u256) {
+    let mut b = _b; // b = _b = 2
+
+    log(b);
+
+    let mut b_tmp = b; // b_tmp = b = 2
+
+    b = 0x03u256; // b = a = 1
+
+    assert(unit(b_tmp) == 0x02u256);
+}

test/src/e2e_vm_tests/test_programs/should_pass/language/references/mutability_of_references_memcpy_bug/src/main.sw

@@ -0,0 +1,27 @@
+contract;
+
+pub mod lib;
+
+use ::lib::weird;
+
+abi MyContract {
+    fn test_function(b: u256) -> u256;
+}
+
+impl MyContract for Contract {
+
+    fn test_function(_b: u256) -> u256 {
+        weird(_b);
+        0x00u256
+    }
+}
+
+
+
+#[test]
+fn test() {
+    let caller = abi(MyContract, CONTRACT_ID);
+    let b = 0x02u256;
+
+    let _ = caller.test_function(b);
+}

test/src/e2e_vm_tests/test_programs/should_pass/language/references/mutability_of_references_memcpy_bug/test.toml

@@ -0,0 +1,3 @@
+category = "unit_tests_pass"
+validate_abi = false
+expected_warnings = 0