work around the wasm32-unknown-unknown ABI being broken

Author: folkertdev

compiler/rustc_codegen_ssa/src/mir/naked_asm.rs

@@ -308,8 +308,14 @@ fn wasm_functype<'tcx>(tcx: TyCtxt<'tcx>, fn_abi: &FnAbi<'tcx, Ty<'tcx>>) -> Str
         other => bug!("wasm pointer size cannot be {other} bits"),
     };
 
-    let hidden_return =
-        matches!(fn_abi.ret.mode, PassMode::Indirect { .. } | PassMode::Pair { .. });
+    // FIXME: remove this once the wasm32-unknown-unknown ABI is fixed
+    if let PassMode::Pair { .. } = fn_abi.ret.mode {
+        bug!(
+            "cannot return a pair (the wasm32-unknown-unknown ABI is broken, see https://github.com/rust-lang/rust/issues/115666"
+        );
+    }
+
+    let hidden_return = matches!(fn_abi.ret.mode, PassMode::Indirect { .. });
 
     signature.push('(');
 
@@ -346,6 +352,12 @@ fn wasm_type<'tcx>(signature: &mut String, arg_abi: &ArgAbi<'_, Ty<'tcx>>, ptr_t
             let direct_type = match arg_abi.layout.backend_repr {
                 BackendRepr::Scalar(scalar) => wasm_primitive(scalar.primitive(), ptr_type),
                 BackendRepr::Vector { .. } => "v128",
+                BackendRepr::Memory { .. } => {
+                    // FIXME: remove this branch once the wasm32-unknown-unknown ABI is fixed
+                    bug!(
+                        "cannot use memory args (the wasm32-unknown-unknown ABI is broken, see https://github.com/rust-lang/rust/issues/115666"
+                    );
+                }
                 other => unreachable!("unexpected BackendRepr: {:?}", other),
             };
 

tests/assembly/wasm32-naked-fn.rs

@@ -1,10 +1,10 @@
-//@ revisions: wasm32-unknown wasm64-unknown wasm32-wasip1
+// FIXME: add wasm32-unknown when the wasm32-unknown-unknown ABI is fixed
+// see https://github.com/rust-lang/rust/issues/115666
+//@ revisions: wasm64-unknown wasm32-wasip1
 //@ add-core-stubs
 //@ assembly-output: emit-asm
-//@ [wasm32-unknown] compile-flags: --target wasm32-unknown-unknown
 //@ [wasm64-unknown] compile-flags: --target wasm64-unknown-unknown
 //@ [wasm32-wasip1] compile-flags: --target wasm32-wasip1
-//@ [wasm32-unknown] needs-llvm-components: webassembly
 //@ [wasm64-unknown] needs-llvm-components: webassembly
 //@ [wasm32-wasip1] needs-llvm-components: webassembly
 
@@ -98,7 +98,7 @@ unsafe extern "C" fn fn_i64_i64(num: i64) -> i64 {
 }
 
 // CHECK-LABEL: fn_i128_i128:
-// wasm32-unknown,wasm32-wasip1: .functype fn_i128_i128 (i32, i64, i64) -> ()
+// wasm32-wasip1: .functype fn_i128_i128 (i32, i64, i64) -> ()
 // wasm64-unknown: .functype fn_i128_i128 (i64, i64, i64) -> ()
 #[allow(improper_ctypes_definitions)]
 #[no_mangle]
@@ -115,7 +115,7 @@ unsafe extern "C" fn fn_i128_i128(num: i128) -> i128 {
 }
 
 // CHECK-LABEL: fn_f128_f128:
-// wasm32-unknown,wasm32-wasip1: .functype fn_f128_f128 (i32, i64, i64) -> ()
+// wasm32-wasip1: .functype fn_f128_f128 (i32, i64, i64) -> ()
 // wasm64-unknown: .functype fn_f128_f128 (i64, i64, i64) -> ()
 #[no_mangle]
 #[naked]
@@ -138,18 +138,19 @@ struct Compound {
 
 // CHECK-LABEL: fn_compound_compound:
 // wasm32-wasip1: .functype fn_compound_compound (i32, i32) -> ()
-// wasm32-unknown: .functype fn_compound_compound (i32, i32, i64) -> ()
 // wasm64-unknown: .functype fn_compound_compound (i64, i64) -> ()
 #[no_mangle]
 #[naked]
 unsafe extern "C" fn fn_compound_compound(_: Compound) -> Compound {
-    // this is the wasm32-unknown-unknown assembly
+    // this is the wasm32-wasip1 assembly
     naked_asm!(
         "local.get       0",
-        "local.get       2",
+        "local.get       1",
+        "i64.load        8",
         "i64.store       8",
         "local.get       0",
         "local.get       1",
+        "i32.load16_u    0",
         "i32.store16     0",
     )
 }