33use rustc_abi:: { BackendRepr , RegKind } ;
44use rustc_hir:: CRATE_HIR_ID ;
55use rustc_middle:: mir:: { self , traversal} ;
6- use rustc_middle:: ty:: { self , Instance , InstanceKind , Ty , TyCtxt } ;
7- use rustc_session:: lint:: builtin:: ABI_UNSUPPORTED_VECTOR_TYPES ;
6+ use rustc_middle:: ty:: layout:: LayoutCx ;
7+ use rustc_middle:: ty:: { self , Instance , InstanceKind , Ty , TyCtxt , TypingEnv } ;
8+ use rustc_session:: lint:: builtin:: { ABI_UNSUPPORTED_VECTOR_TYPES , WASM_C_ABI } ;
89use rustc_span:: def_id:: DefId ;
910use rustc_span:: { DUMMY_SP , Span , Symbol , sym} ;
10- use rustc_target:: callconv:: { Conv , FnAbi , PassMode } ;
11+ use rustc_target:: callconv:: { ArgAbi , Conv , FnAbi , PassMode } ;
12+ use rustc_target:: spec:: { HasWasmCAbiOpt , WasmCAbi } ;
1113
1214use crate :: errors;
1315
@@ -26,13 +28,15 @@ fn uses_vector_registers(mode: &PassMode, repr: &BackendRepr) -> bool {
2628/// for a certain function.
2729/// `is_call` indicates whether this is a call-site check or a definition-site check;
2830/// this is only relevant for the wording in the emitted error.
29- fn do_check_abi < ' tcx > (
31+ fn do_check_simd_vector_abi < ' tcx > (
3032 tcx : TyCtxt < ' tcx > ,
3133 abi : & FnAbi < ' tcx , Ty < ' tcx > > ,
3234 def_id : DefId ,
3335 is_call : bool ,
3436 span : impl Fn ( ) -> Span ,
3537) {
38+ // We check this on all functions, including those using the "Rust" ABI.
39+ // For the "Rust" ABI it would be a bug if the lint ever triggered, but better safe than sorry.
3640 let feature_def = tcx. sess . target . features_for_correct_vector_abi ( ) ;
3741 let codegen_attrs = tcx. codegen_fn_attrs ( def_id) ;
3842 let have_feature = |feat : Symbol | {
@@ -88,6 +92,61 @@ fn do_check_abi<'tcx>(
8892 }
8993}
9094
95+ /// Determines whether the given argument is passed the same way on the old and new wasm ABIs.
96+ fn wasm_abi_safe < ' tcx > ( tcx : TyCtxt < ' tcx > , arg : & ArgAbi < ' tcx , Ty < ' tcx > > ) -> bool {
97+ if matches ! ( arg. layout. backend_repr, BackendRepr :: Scalar ( _) ) {
98+ return true ;
99+ }
100+
101+ // This matches `unwrap_trivial_aggregate` in the wasm ABI logic.
102+ if arg. layout . is_aggregate ( ) {
103+ let cx = LayoutCx :: new ( tcx, TypingEnv :: fully_monomorphized ( ) ) ;
104+ if let Some ( unit) = arg. layout . homogeneous_aggregate ( & cx) . ok ( ) . and_then ( |ha| ha. unit ( ) ) {
105+ let size = arg. layout . size ;
106+ // Ensure there's just a single `unit` element in `arg`.
107+ if unit. size == size {
108+ return true ;
109+ }
110+ }
111+ }
112+
113+ false
114+ }
115+
116+ /// Warns against usage of `extern "C"` on wasm32-unknown-unknown that is affected by the
117+ /// ABI transition.
118+ fn do_check_wasm_abi < ' tcx > (
119+ tcx : TyCtxt < ' tcx > ,
120+ abi : & FnAbi < ' tcx , Ty < ' tcx > > ,
121+ is_call : bool ,
122+ span : impl Fn ( ) -> Span ,
123+ ) {
124+ // Only proceed for `extern "C" fn` on wasm32-unknown-unknown (same check as what `adjust_for_foreign_abi` uses to call `compute_wasm_abi_info`),
125+ // and only proceed if `wasm_c_abi_opt` indicates we should emit the lint.
126+ if !( tcx. sess . target . arch == "wasm32"
127+ && tcx. sess . target . os == "unknown"
128+ && tcx. wasm_c_abi_opt ( ) == WasmCAbi :: Legacy { with_lint : true }
129+ && abi. conv == Conv :: C )
130+ {
131+ return ;
132+ }
133+ // Warn against all types whose ABI will change. Return values are not affected by this change.
134+ for arg_abi in abi. args . iter ( ) {
135+ if wasm_abi_safe ( tcx, arg_abi) {
136+ continue ;
137+ }
138+ let span = span ( ) ;
139+ tcx. emit_node_span_lint (
140+ WASM_C_ABI ,
141+ CRATE_HIR_ID ,
142+ span,
143+ errors:: WasmCAbiTransition { ty : arg_abi. layout . ty , is_call } ,
144+ ) ;
145+ // Let's only warn once per function.
146+ break ;
147+ }
148+ }
149+
91150/// Checks that the ABI of a given instance of a function does not contain vector-passed arguments
92151/// or return values for which the corresponding target feature is not enabled.
93152fn check_instance_abi < ' tcx > ( tcx : TyCtxt < ' tcx > , instance : Instance < ' tcx > ) {
@@ -98,13 +157,10 @@ fn check_instance_abi<'tcx>(tcx: TyCtxt<'tcx>, instance: Instance<'tcx>) {
98157 // function.
99158 return ;
100159 } ;
101- do_check_abi (
102- tcx,
103- abi,
104- instance. def_id ( ) ,
105- /*is_call*/ false ,
106- || tcx. def_span ( instance. def_id ( ) ) ,
107- )
160+ do_check_simd_vector_abi ( tcx, abi, instance. def_id ( ) , /*is_call*/ false , || {
161+ tcx. def_span ( instance. def_id ( ) )
162+ } ) ;
163+ do_check_wasm_abi ( tcx, abi, /*is_call*/ false , || tcx. def_span ( instance. def_id ( ) ) ) ;
108164}
109165
110166/// Checks that a call expression does not try to pass a vector-passed argument which requires a
@@ -141,7 +197,8 @@ fn check_call_site_abi<'tcx>(
141197 // ABI failed to compute; this will not get through codegen.
142198 return ;
143199 } ;
144- do_check_abi ( tcx, callee_abi, caller. def_id ( ) , /*is_call*/ true , || span) ;
200+ do_check_simd_vector_abi ( tcx, callee_abi, caller. def_id ( ) , /*is_call*/ true , || span) ;
201+ do_check_wasm_abi ( tcx, callee_abi, /*is_call*/ true , || span) ;
145202}
146203
147204fn check_callees_abi < ' tcx > ( tcx : TyCtxt < ' tcx > , instance : Instance < ' tcx > , body : & mir:: Body < ' tcx > ) {
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