ABI checks: add support for tier2 arches

See #131800 for the data collection behind this change.

Also adds a test that exercise the "empty list of features" path.

Author: veluca93

compiler/rustc_monomorphize/messages.ftl

@@ -7,6 +7,13 @@ monomorphize_abi_error_disabled_vector_type_def =
   .label = function defined here
   .help = consider enabling it globally (`-C target-feature=+{$required_feature}`) or locally (`#[target_feature(enable="{$required_feature}")]`)
 
+monomorphize_abi_error_unsupported_vector_type_call =
+  this function call uses a SIMD vector type that is not currently supported with the chosen ABI
+  .label = function called here
+monomorphize_abi_error_unsupported_vector_type_def =
+  this function definition uses a SIMD vector type that is not currently supported with the chosen ABI
+  .label = function defined here
+
 monomorphize_couldnt_dump_mono_stats =
     unexpected error occurred while dumping monomorphization stats: {$error}
 

compiler/rustc_monomorphize/src/collector/abi_check.rs

@@ -12,7 +12,10 @@ use rustc_span::{DUMMY_SP, Span, Symbol};
 use rustc_target::abi::call::{FnAbi, PassMode};
 use rustc_target::abi::{BackendRepr, RegKind};
 
-use crate::errors::{AbiErrorDisabledVectorTypeCall, AbiErrorDisabledVectorTypeDef};
+use crate::errors::{
+    AbiErrorDisabledVectorTypeCall, AbiErrorDisabledVectorTypeDef,
+    AbiErrorUnsupportedVectorTypeCall, AbiErrorUnsupportedVectorTypeDef,
+};
 
 fn uses_vector_registers(mode: &PassMode, repr: &BackendRepr) -> bool {
     match mode {
@@ -25,11 +28,15 @@ fn uses_vector_registers(mode: &PassMode, repr: &BackendRepr) -> bool {
     }
 }
 
+/// Checks whether a certain function ABI is compatible with the target features currently enabled
+/// for a certain function.
+/// If not, `emit_err` is called, with `Some(feature)` if a certain feature should be enabled and
+/// with `None` if no feature is known that would make the ABI compatible.
 fn do_check_abi<'tcx>(
     tcx: TyCtxt<'tcx>,
     abi: &FnAbi<'tcx, Ty<'tcx>>,
     target_feature_def: DefId,
-    mut emit_err: impl FnMut(&'static str),
+    mut emit_err: impl FnMut(Option<&'static str>),
 ) {
     let Some(feature_def) = tcx.sess.target.features_for_correct_vector_abi() else {
         return;
@@ -42,15 +49,15 @@ fn do_check_abi<'tcx>(
             let feature = match feature_def.iter().find(|(bits, _)| size.bits() <= *bits) {
                 Some((_, feature)) => feature,
                 None => {
-                    emit_err("<no available feature for this size>");
+                    emit_err(None);
                     continue;
                 }
             };
             let feature_sym = Symbol::intern(feature);
             if !tcx.sess.unstable_target_features.contains(&feature_sym)
                 && !codegen_attrs.target_features.iter().any(|x| x.name == feature_sym)
             {
-                emit_err(feature);
+                emit_err(Some(&feature));
             }
         }
     }
@@ -67,12 +74,21 @@ fn check_instance_abi<'tcx>(tcx: TyCtxt<'tcx>, instance: Instance<'tcx>) {
     };
     do_check_abi(tcx, abi, instance.def_id(), |required_feature| {
         let span = tcx.def_span(instance.def_id());
-        tcx.emit_node_span_lint(
-            ABI_UNSUPPORTED_VECTOR_TYPES,
-            CRATE_HIR_ID,
-            span,
-            AbiErrorDisabledVectorTypeDef { span, required_feature },
-        );
+        if let Some(required_feature) = required_feature {
+            tcx.emit_node_span_lint(
+                ABI_UNSUPPORTED_VECTOR_TYPES,
+                CRATE_HIR_ID,
+                span,
+                AbiErrorDisabledVectorTypeDef { span, required_feature },
+            );
+        } else {
+            tcx.emit_node_span_lint(
+                ABI_UNSUPPORTED_VECTOR_TYPES,
+                CRATE_HIR_ID,
+                span,
+                AbiErrorUnsupportedVectorTypeDef { span },
+            );
+        }
     })
 }
 
@@ -111,12 +127,21 @@ fn check_call_site_abi<'tcx>(
         return;
     };
     do_check_abi(tcx, callee_abi, caller.def_id(), |required_feature| {
-        tcx.emit_node_span_lint(
-            ABI_UNSUPPORTED_VECTOR_TYPES,
-            CRATE_HIR_ID,
-            span,
-            AbiErrorDisabledVectorTypeCall { span, required_feature },
-        );
+        if let Some(required_feature) = required_feature {
+            tcx.emit_node_span_lint(
+                ABI_UNSUPPORTED_VECTOR_TYPES,
+                CRATE_HIR_ID,
+                span,
+                AbiErrorDisabledVectorTypeCall { span, required_feature },
+            );
+        } else {
+            tcx.emit_node_span_lint(
+                ABI_UNSUPPORTED_VECTOR_TYPES,
+                CRATE_HIR_ID,
+                span,
+                AbiErrorUnsupportedVectorTypeCall { span },
+            );
+        }
     });
 }
 

compiler/rustc_monomorphize/src/errors.rs

@@ -110,3 +110,17 @@ pub(crate) struct AbiErrorDisabledVectorTypeCall<'a> {
     pub span: Span,
     pub required_feature: &'a str,
 }
+
+#[derive(LintDiagnostic)]
+#[diag(monomorphize_abi_error_unsupported_vector_type_def)]
+pub(crate) struct AbiErrorUnsupportedVectorTypeDef {
+    #[label]
+    pub span: Span,
+}
+
+#[derive(LintDiagnostic)]
+#[diag(monomorphize_abi_error_unsupported_vector_type_call)]
+pub(crate) struct AbiErrorUnsupportedVectorTypeCall {
+    #[label]
+    pub span: Span,
+}

compiler/rustc_target/src/target_features.rs

@@ -582,6 +582,14 @@ pub fn all_rust_features() -> impl Iterator<Item = (&'static str, Stability)> {
 const X86_FEATURES_FOR_CORRECT_VECTOR_ABI: &'static [(u64, &'static str)] =
     &[(128, "sse"), (256, "avx"), (512, "avx512f")];
 const AARCH64_FEATURES_FOR_CORRECT_VECTOR_ABI: &'static [(u64, &'static str)] = &[(128, "neon")];
+const ARM_FEATURES_FOR_CORRECT_VECTOR_ABI: &'static [(u64, &'static str)] = &[(128, "neon")];
+const POWERPC_FEATURES_FOR_CORRECT_VECTOR_ABI: &'static [(u64, &'static str)] = &[(128, "altivec")];
+const WASM_FEATURES_FOR_CORRECT_VECTOR_ABI: &'static [(u64, &'static str)] = &[(128, "simd128")];
+const S390X_FEATURES_FOR_CORRECT_VECTOR_ABI: &'static [(u64, &'static str)] = &[(128, "vector")];
+// Always warn on RISCV and SPARC, as the necessary target features cannot be enabled in Rust at
+// the moment.
+const RISCV_FEATURES_FOR_CORRECT_VECTOR_ABI: &'static [(u64, &'static str)] = &[];
+const SPARC_FEATURES_FOR_CORRECT_VECTOR_ABI: &'static [(u64, &'static str)] = &[];
 
 impl super::spec::Target {
     pub fn rust_target_features(&self) -> &'static [(&'static str, Stability, ImpliedFeatures)] {
@@ -606,9 +614,19 @@ impl super::spec::Target {
     // Returns None if we do not support ABI checks on the given target yet.
     pub fn features_for_correct_vector_abi(&self) -> Option<&'static [(u64, &'static str)]> {
         match &*self.arch {
+            // Tier 1
             "x86" | "x86_64" => Some(X86_FEATURES_FOR_CORRECT_VECTOR_ABI),
             "aarch64" => Some(AARCH64_FEATURES_FOR_CORRECT_VECTOR_ABI),
-            // FIXME: add support for non-tier1 architectures
+            // Tier 2
+            "arm64ec" => Some(AARCH64_FEATURES_FOR_CORRECT_VECTOR_ABI),
+            "arm" => Some(ARM_FEATURES_FOR_CORRECT_VECTOR_ABI),
+            "powerpc" | "powerpc64" => Some(POWERPC_FEATURES_FOR_CORRECT_VECTOR_ABI),
+            "loongarch64" => Some(&[]), // on-stack ABI, so we complain about all by-val vectors
+            "riscv32" | "riscv64" => Some(RISCV_FEATURES_FOR_CORRECT_VECTOR_ABI),
+            "wasm32" | "wasm64" => Some(WASM_FEATURES_FOR_CORRECT_VECTOR_ABI),
+            "s390x" => Some(S390X_FEATURES_FOR_CORRECT_VECTOR_ABI),
+            "sparc" | "sparc64" => Some(SPARC_FEATURES_FOR_CORRECT_VECTOR_ABI),
+            // FIXME: add support for non-tier2 architectures
             _ => None,
         }
     }

tests/ui/simd-abi-checks-empty-list.rs

@@ -0,0 +1,19 @@
+//@ needs-llvm-components: sparc
+//@ compile-flags: --target=sparc-unknown-none-elf --crate-type=rlib
+//@ build-pass
+//@ ignore-pass (test emits codegen-time warnings)
+#![no_core]
+#![feature(no_core, lang_items, repr_simd)]
+#![allow(improper_ctypes_definitions)]
+#[lang = "sized"]
+trait Sized {}
+
+#[lang = "copy"]
+trait Copy {}
+
+#[repr(simd)]
+pub struct SimdVec([i32; 4]);
+
+pub extern "C" fn pass_by_vec(_: SimdVec) {}
+//~^ this function definition uses a SIMD vector type that is not currently supported with the chosen ABI
+//~| WARNING this was previously accepted by the compiler

tests/ui/simd-abi-checks-empty-list.stderr

@@ -0,0 +1,12 @@
+warning: this function definition uses a SIMD vector type that is not currently supported with the chosen ABI
+  --> $DIR/simd-abi-checks-empty-list.rs:17:1
+   |
+LL | pub extern "C" fn pass_by_vec(_: SimdVec) {}
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ function defined here
+   |
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+   = note: for more information, see issue #116558 <https://github.com/rust-lang/rust/issues/116558>
+   = note: `#[warn(abi_unsupported_vector_types)]` on by default
+
+warning: 1 warning emitted
+