Forward the ABI of the non-zero sized fields of an union if they have the same ABI

This is supposed to fix the performence regression of using MaybeUninit in
https://github.com/rust-lang/rust/pull/54668

1 files changed, 80 insertions, 0 deletions

diff --git a/src/test/codegen/union-abi.rs b/src/test/codegen/union-abi.rs
new file mode 100644
index 00000000000..0fa06fa777b
--- /dev/null
+++ b/src/test/codegen/union-abi.rs
@@ -0,0 +1,80 @@
+// Copyright 2017 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+// compile-flags: -C no-prepopulate-passes
+
+// This test that using union forward the abi of the inner type, as
+// discussed in #54668
+
+#![crate_type="lib"]
+#![feature(repr_simd)]
+
+#[derive(Copy, Clone)]
+pub enum Unhab {}
+
+#[repr(simd)]
+#[derive(Copy, Clone)]
+pub struct i64x4(i64, i64, i64, i64);
+
+#[derive(Copy, Clone)]
+pub union UnionI64x4{ a:(), b: i64x4 }
+
+// CHECK: define <4 x i64> @test_UnionI64x4(<4 x i64> %arg0)
+#[no_mangle]
+pub extern fn test_UnionI64x4(_: UnionI64x4) -> UnionI64x4 { loop {} }
+
+pub union UnionI64x4_{ a: i64x4, b: (), c:i64x4, d: Unhab, e: ((),()), f: UnionI64x4 }
+
+// CHECK: define <4 x i64> @test_UnionI64x4_(<4 x i64> %arg0)
+#[no_mangle]
+pub extern fn test_UnionI64x4_(_: UnionI64x4_) -> UnionI64x4_ { loop {} }
+
+pub union UnionI64x4I64{ a: i64x4, b: i64 }
+
+// CHECK: define void @test_UnionI64x4I64(%UnionI64x4I64* {{.*}} %arg0)
+#[no_mangle]
+pub fn test_UnionI64x4I64(_: UnionI64x4I64) { loop {} }
+
+pub union UnionI64x4Tuple{ a: i64x4, b: (i64, i64, i64, i64) }
+
+// CHECK: define void @test_UnionI64x4Tuple(%UnionI64x4Tuple* {{.*}} %arg0)
+#[no_mangle]
+pub fn test_UnionI64x4Tuple(_: UnionI64x4Tuple) { loop {} }
+
+
+pub union UnionF32{a:f32}
+
+// CHECK: define float @test_UnionF32(float %arg0)
+#[no_mangle]
+pub extern fn test_UnionF32(_: UnionF32) -> UnionF32 { loop {} }
+
+pub union UnionF32F32{a:f32, b:f32}
+
+// CHECK: define float @test_UnionF32F32(float %arg0)
+#[no_mangle]
+pub extern fn test_UnionF32F32(_: UnionF32F32) -> UnionF32F32 { loop {} }
+
+pub union UnionF32U32{a:f32, b:u32}
+
+// CHECK: define i32 @test_UnionF32U32(i32)
+#[no_mangle]
+pub extern fn test_UnionF32U32(_: UnionF32U32) -> UnionF32U32 { loop {} }
+
+pub union UnionU128{a:u128}
+// CHECK: define i128 @test_UnionU128(i128 %arg0)
+#[no_mangle]
+pub fn test_UnionU128(_: UnionU128) -> UnionU128 { loop {} }
+
+#[repr(C)]
+pub union CUnionU128{a:u128}
+// CHECK: define void @test_CUnionU128(%CUnionU128* {{.*}} %arg0)
+#[no_mangle]
+pub fn test_CUnionU128(_: CUnionU128) { loop {} }
+