Rollup merge of #154731 - maurer:array-abi-test, r=scottmcm

llvm: Fix array ABI test to not check equality implementation

LLVM has moved memcmp expansion in the pipeline, resulting in the bcmp call being expanded into loads and register comparisons, which breaks the test.

See llvm/llvm-project#77370

Based on history, I believe the test actually intended validate that these arrays were being passed as pointer arguments, which can be done more directly.

r? @durin42
cc @scottmcm (author of the test being modified)

@rustbot label llvm-main

Author: matthiaskrgr

tests/codegen-llvm/array-equality.rs

@@ -1,3 +1,6 @@
+//@ revisions: llvm-current llvm-next
+//@[llvm-current] ignore-llvm-version: 23-99
+//@[llvm-next] min-llvm-version: 23
 //@ compile-flags: -Copt-level=3 -Z merge-functions=disabled
 //@ only-x86_64
 #![crate_type = "lib"]
@@ -26,9 +29,18 @@ pub fn array_eq_ref(a: &[u16; 3], b: &[u16; 3]) -> bool {
 #[no_mangle]
 pub fn array_eq_value_still_passed_by_pointer(a: [u16; 9], b: [u16; 9]) -> bool {
     // CHECK-NEXT: start:
-    // CHECK: %[[CMP:.+]] = tail call i32 @{{bcmp|memcmp}}(ptr {{.*}} dereferenceable(18) %{{.+}}, ptr {{.*}} dereferenceable(18) %{{.+}}, i64 18)
-    // CHECK-NEXT: %[[EQ:.+]] = icmp eq i32 %[[CMP]], 0
-    // CHECK-NEXT: ret i1 %[[EQ]]
+    // CHECK-NOT: alloca
+    // llvm-current-NEXT: %[[CMP:.+]] = tail call i32 @{{bcmp|memcmp}}(ptr
+    // llvm-current-SAME: {{.*}} dereferenceable(18) %{{.+}}, ptr {{.*}} dereferenceable(18)
+    // llvm-current-SAME: %{{.+}}, i64 18)
+    // llvm-current-NEXT: %[[EQ:.+]] = icmp eq i32 %[[CMP]], 0
+    // llvm-current-NEXT: ret i1 %[[EQ]]
+    // CHECK-NOT: call
+    // New LLVM expands the bcmp earlier, so this becomes wide reads + icmp
+    // No allocas or calls, and at least one icmp
+    // llvm-next: icmp
+    // CHECK-NOT: alloca
+    // CHECK-NOT: call
     a == b
 }