Add regression test for bool indexing codegen

tests/assembly-llvm/indexing-with-bools-no-redundant-instructions.rs

@@ -0,0 +1,36 @@
+//@ assembly-output: emit-asm
+//@ only-x86_64
+//@ ignore-windows CHECK patterns use the SysV x86-64 calling convention
+//@ ignore-sgx Test incompatible with LVI mitigations
+//@ compile-flags: -Copt-level=3
+
+//! Regression test for https://github.com/rust-lang/rust/issues/123216.
+//! Indexing with a `bool` should not generate redundant `jmp` or `and`
+//! instructions.
+
+#![crate_type = "lib"]
+
+#[no_mangle]
+pub fn bool_index(a: u32, b: bool, c: bool, d: &mut [u128; 2]) {
+    // CHECK-LABEL: bool_index:
+    // CHECK: testl  %esi, %esi
+    // CHECK: je
+    // CHECK: xorb   %dl, %dil
+    // CHECK: orb    $1, (%rcx)
+    // CHECK-NOT: jmp
+    // CHECK-NOT: andb $1, %dil
+    // CHECK: movzbl %dil, %eax
+    // CHECK: andl   $1, %eax
+    // CHECK: shll   $4, %eax
+    // CHECK: orb    $1, (%rcx,%rax)
+    // CHECK: retq
+
+    let mut a = a & 1 != 0;
+
+    if b {
+        a ^= c;
+        d[0] |= 1;
+    }
+
+    d[a as usize] |= 1;
+}