1 files changed, 145 insertions, 0 deletions
diff --git a/tests/codegen-llvm/union-abi.rs b/tests/codegen-llvm/union-abi.rs
new file mode 100644
index 00000000000..28acc4de2f3
--- /dev/null
+++ b/tests/codegen-llvm/union-abi.rs
@@ -0,0 +1,145 @@
+//@ ignore-emscripten vectors passed directly
+//@ compile-flags: -Copt-level=3 -C no-prepopulate-passes
+// 32-bit x86 returns `f32` differently to avoid the x87 stack.
+// 32-bit systems will return 128bit values using a return area pointer.
+//@ revisions: x86-sse x86-nosse bit32 bit64
+//@[x86-sse] only-x86
+//@[x86-sse] only-rustc_abi-x86-sse2
+//@[x86-nosse] only-x86
+//@[x86-nosse] ignore-rustc_abi-x86-sse2
+//@[bit32] ignore-x86
+//@[bit32] only-32bit
+//@[bit64] ignore-x86
+//@[bit64] only-64bit
+
+// 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; 4]);
+
+#[derive(Copy, Clone)]
+pub union UnionI64x4 {
+    a: (),
+    b: i64x4,
+}
+
+// CHECK: define {{(dso_local )?}}void @test_UnionI64x4(ptr {{.*}} %_1)
+#[no_mangle]
+pub fn test_UnionI64x4(_: UnionI64x4) {
+    loop {}
+}
+
+pub union UnionI64x4_ {
+    a: i64x4,
+    b: (),
+    c: i64x4,
+    d: Unhab,
+    e: ((), ()),
+    f: UnionI64x4,
+}
+
+// CHECK: define {{(dso_local )?}}void @test_UnionI64x4_(ptr {{.*}} %_1)
+#[no_mangle]
+pub fn test_UnionI64x4_(_: UnionI64x4_) {
+    loop {}
+}
+
+pub union UnionI64x4I64 {
+    a: i64x4,
+    b: i64,
+}
+
+// CHECK: define {{(dso_local )?}}void @test_UnionI64x4I64(ptr {{.*}} %_1)
+#[no_mangle]
+pub fn test_UnionI64x4I64(_: UnionI64x4I64) {
+    loop {}
+}
+
+pub union UnionI64x4Tuple {
+    a: i64x4,
+    b: (i64, i64, i64, i64),
+}
+
+// CHECK: define {{(dso_local )?}}void @test_UnionI64x4Tuple(ptr {{.*}} %_1)
+#[no_mangle]
+pub fn test_UnionI64x4Tuple(_: UnionI64x4Tuple) {
+    loop {}
+}
+
+pub union UnionF32 {
+    a: f32,
+}
+
+// x86-sse: define {{(dso_local )?}}<4 x i8> @test_UnionF32(float %_1)
+// x86-nosse: define {{(dso_local )?}}i32 @test_UnionF32(float %_1)
+// bit32: define {{(dso_local )?}}float @test_UnionF32(float %_1)
+// bit64: define {{(dso_local )?}}float @test_UnionF32(float %_1)
+#[no_mangle]
+pub fn test_UnionF32(_: UnionF32) -> UnionF32 {
+    loop {}
+}
+
+pub union UnionF32F32 {
+    a: f32,
+    b: f32,
+}
+
+// x86-sse: define {{(dso_local )?}}<4 x i8> @test_UnionF32F32(float %_1)
+// x86-nosse: define {{(dso_local )?}}i32 @test_UnionF32F32(float %_1)
+// bit32: define {{(dso_local )?}}float @test_UnionF32F32(float %_1)
+// bit64: define {{(dso_local )?}}float @test_UnionF32F32(float %_1)
+#[no_mangle]
+pub fn test_UnionF32F32(_: UnionF32F32) -> UnionF32F32 {
+    loop {}
+}
+
+pub union UnionF32U32 {
+    a: f32,
+    b: u32,
+}
+
+// CHECK: define {{(dso_local )?}}i32 @test_UnionF32U32(i32{{( %0)?}})
+#[no_mangle]
+pub fn test_UnionF32U32(_: UnionF32U32) -> UnionF32U32 {
+    loop {}
+}
+
+pub union UnionU128 {
+    a: u128,
+}
+// x86-sse: define {{(dso_local )?}}void @test_UnionU128({{.*}}sret([16 x i8]){{.*}}, i128 %_1)
+// x86-nosse: define {{(dso_local )?}}void @test_UnionU128({{.*}}sret([16 x i8]){{.*}}, i128 %_1)
+// bit32: define {{(dso_local )?}}void @test_UnionU128({{.*}}sret([16 x i8]){{.*}}, i128 %_1)
+// bit64: define {{(dso_local )?}}i128 @test_UnionU128(i128 %_1)
+#[no_mangle]
+pub fn test_UnionU128(_: UnionU128) -> UnionU128 {
+    loop {}
+}
+
+#[repr(C)]
+pub union CUnionU128 {
+    a: u128,
+}
+// CHECK: define {{(dso_local )?}}void @test_CUnionU128(ptr {{.*}} %_1)
+#[no_mangle]
+pub fn test_CUnionU128(_: CUnionU128) {
+    loop {}
+}
+
+pub union UnionBool {
+    b: bool,
+}
+// CHECK: define {{(dso_local )?}}noundef zeroext i1 @test_UnionBool(i8{{.*}} %b)
+#[no_mangle]
+pub fn test_UnionBool(b: UnionBool) -> bool {
+    unsafe { b.b }
+}
+// CHECK: %_0 = trunc{{( nuw)?}} i8 %b to i1