Add test for efficient codegen of manual eq implementations of a small struct

Author: clubby789

tests/assembly/manual-eq-efficient.rs

@@ -0,0 +1,25 @@
+// Regression test for #106269
+//@ revisions: WIN LIN
+//@ [WIN] only-windows
+//@ [LIN] only-linux
+//@ assembly-output: emit-asm
+//@ compile-flags: --crate-type=lib -O -C llvm-args=-x86-asm-syntax=intel
+//@ only-x86_64
+//@ ignore-sgx
+
+pub struct S {
+    a: u8,
+    b: u8,
+    c: u8,
+    d: u8,
+}
+
+// CHECK-LABEL: manual_eq:
+#[no_mangle]
+pub fn manual_eq(s1: &S, s2: &S) -> bool {
+    // CHECK: mov [[REG:[a-z0-9]+]], dword ptr [{{rdi|rcx}}]
+    // CHECK-NEXT: cmp [[REG]], dword ptr [{{rsi|rdx}}]
+    // CHECK-NEXT: sete al
+    // CHECK-NEXT: ret
+    s1.a == s2.a && s1.b == s2.b && s1.c == s2.c && s1.d == s2.d
+}