diff options
Diffstat (limited to 'src/test/codegen/dst-vtable-align-nonzero.rs')
-rw-r--r-- | src/test/codegen/dst-vtable-align-nonzero.rs | 45 |
1 files changed, 45 insertions, 0 deletions
diff --git a/src/test/codegen/dst-vtable-align-nonzero.rs b/src/test/codegen/dst-vtable-align-nonzero.rs new file mode 100644 index 000000000..14c4c3f30 --- /dev/null +++ b/src/test/codegen/dst-vtable-align-nonzero.rs @@ -0,0 +1,45 @@ +// compile-flags: -O + +#![crate_type = "lib"] + +// This test checks that we annotate alignment loads from vtables with nonzero range metadata, +// and that this allows LLVM to eliminate redundant `align >= 1` checks. + +pub trait Trait { + fn f(&self); +} + +pub struct WrapperWithAlign1<T: ?Sized> { x: u8, y: T } + +pub struct WrapperWithAlign2<T: ?Sized> { x: u16, y: T } + +pub struct Struct<W: ?Sized> { + _field: i8, + dst: W, +} + +// CHECK-LABEL: @eliminates_runtime_check_when_align_1 +#[no_mangle] +pub fn eliminates_runtime_check_when_align_1( + x: &Struct<WrapperWithAlign1<dyn Trait>> +) -> &WrapperWithAlign1<dyn Trait> { + // CHECK: load [[USIZE:i[0-9]+]], {{.+}} !range [[RANGE_META:![0-9]+]] + // CHECK-NOT: llvm.umax + // CHECK-NOT: icmp + // CHECK-NOT: select + // CHECK: ret + &x.dst +} + +// CHECK-LABEL: @does_not_eliminate_runtime_check_when_align_2 +#[no_mangle] +pub fn does_not_eliminate_runtime_check_when_align_2( + x: &Struct<WrapperWithAlign2<dyn Trait>> +) -> &WrapperWithAlign2<dyn Trait> { + // CHECK: [[X0:%[0-9]+]] = load [[USIZE]], {{.+}} !range [[RANGE_META]] + // CHECK: {{icmp|llvm.umax}} + // CHECK: ret + &x.dst +} + +// CHECK: [[RANGE_META]] = !{[[USIZE]] 1, [[USIZE]] 0} |