1 // compile-flags: -C opt-level=3
5 // #71602 reported a simple array comparison just generating a loop.
6 // This was originally fixed by ensuring it generates a single bcmp,
7 // but we now generate it as a load+icmp instead. `is_zero_slice` was
8 // tweaked to still test the case of comparison against a slice,
9 // and `is_zero_array` tests the new array-specific behaviour.
10 // The optimization was then extended to short slice-to-array comparisons,
11 // so the first test here now has a long slice to still get the bcmp.
13 // CHECK-LABEL: @is_zero_slice_long
15 pub fn is_zero_slice_long(data: &[u8; 456]) -> bool {
17 // CHECK-NEXT: %{{.+}} = getelementptr {{.+}}
18 // CHECK-NEXT: %[[BCMP:.+]] = tail call i32 @{{bcmp|memcmp}}({{.+}})
19 // CHECK-NEXT: %[[EQ:.+]] = icmp eq i32 %[[BCMP]], 0
20 // CHECK-NEXT: ret i1 %[[EQ]]
24 // CHECK-LABEL: @is_zero_slice_short
26 pub fn is_zero_slice_short(data: &[u8; 4]) -> bool {
28 // CHECK-NEXT: %[[PTR:.+]] = bitcast [4 x i8]* {{.+}} to i32*
29 // CHECK-NEXT: %[[LOAD:.+]] = load i32, i32* %[[PTR]], align 1
30 // CHECK-NEXT: %[[EQ:.+]] = icmp eq i32 %[[LOAD]], 0
31 // CHECK-NEXT: ret i1 %[[EQ]]
35 // CHECK-LABEL: @is_zero_array
37 pub fn is_zero_array(data: &[u8; 4]) -> bool {
39 // CHECK-NEXT: %[[PTR:.+]] = bitcast [4 x i8]* {{.+}} to i32*
40 // CHECK-NEXT: %[[LOAD:.+]] = load i32, i32* %[[PTR]], align 1
41 // CHECK-NEXT: %[[EQ:.+]] = icmp eq i32 %[[LOAD]], 0
42 // CHECK-NEXT: ret i1 %[[EQ]]