Rollup merge of #146667 - calebzulawski:simd-mono-lane-limit, r=lcnr,RalfJung

Add an attribute to check the number of lanes in a SIMD vector after monomorphization

Allows std::simd to drop the `LaneCount<N>: SupportedLaneCount` trait and maintain good error messages.

Also, extends #145967 by including spans in layout errors for all ADTs.

r? ``@RalfJung``

cc ``@workingjubilee`` ``@programmerjake``

Author: Zalathar

compiler/rustc_attr_parsing/src/attributes/crate_level.rs

@@ -1,40 +1,4 @@
-use std::num::IntErrorKind;
-
-use rustc_hir::limit::Limit;
-
 use super::prelude::*;
-use crate::session_diagnostics::LimitInvalid;
-
-impl<S: Stage> AcceptContext<'_, '_, S> {
-    fn parse_limit_int(&self, nv: &NameValueParser) -> Option<Limit> {
-        let Some(limit) = nv.value_as_str() else {
-            self.expected_string_literal(nv.value_span, Some(nv.value_as_lit()));
-            return None;
-        };
-
-        let error_str = match limit.as_str().parse() {
-            Ok(i) => return Some(Limit::new(i)),
-            Err(e) => match e.kind() {
-                IntErrorKind::PosOverflow => "`limit` is too large",
-                IntErrorKind::Empty => "`limit` must be a non-negative integer",
-                IntErrorKind::InvalidDigit => "not a valid integer",
-                IntErrorKind::NegOverflow => {
-                    panic!(
-                        "`limit` should never negatively overflow since we're parsing into a usize and we'd get Empty instead"
-                    )
-                }
-                IntErrorKind::Zero => {
-                    panic!("zero is a valid `limit` so should have returned Ok() when parsing")
-                }
-                kind => panic!("unimplemented IntErrorKind variant: {:?}", kind),
-            },
-        };
-
-        self.emit_err(LimitInvalid { span: self.attr_span, value_span: nv.value_span, error_str });
-
-        None
-    }
-}
 
 pub(crate) struct CrateNameParser;
 

compiler/rustc_attr_parsing/src/attributes/rustc_internal.rs

@@ -49,3 +49,21 @@ impl<S: Stage> SingleAttributeParser<S> for RustcObjectLifetimeDefaultParser {
         Some(AttributeKind::RustcObjectLifetimeDefault)
     }
 }
+
+pub(crate) struct RustcSimdMonomorphizeLaneLimitParser;
+
+impl<S: Stage> SingleAttributeParser<S> for RustcSimdMonomorphizeLaneLimitParser {
+    const PATH: &[Symbol] = &[sym::rustc_simd_monomorphize_lane_limit];
+    const ATTRIBUTE_ORDER: AttributeOrder = AttributeOrder::KeepInnermost;
+    const ON_DUPLICATE: OnDuplicate<S> = OnDuplicate::Error;
+    const ALLOWED_TARGETS: AllowedTargets = AllowedTargets::AllowList(&[Allow(Target::Struct)]);
+    const TEMPLATE: AttributeTemplate = template!(NameValueStr: "N");
+
+    fn convert(cx: &mut AcceptContext<'_, '_, S>, args: &ArgParser<'_>) -> Option<AttributeKind> {
+        let ArgParser::NameValue(nv) = args else {
+            cx.expected_name_value(cx.attr_span, None);
+            return None;
+        };
+        Some(AttributeKind::RustcSimdMonomorphizeLaneLimit(cx.parse_limit_int(nv)?))
+    }
+}

compiler/rustc_attr_parsing/src/attributes/util.rs

@@ -1,11 +1,15 @@
+use std::num::IntErrorKind;
+
 use rustc_ast::LitKind;
 use rustc_ast::attr::AttributeExt;
 use rustc_feature::is_builtin_attr_name;
 use rustc_hir::RustcVersion;
+use rustc_hir::limit::Limit;
 use rustc_span::{Symbol, sym};
 
 use crate::context::{AcceptContext, Stage};
-use crate::parser::ArgParser;
+use crate::parser::{ArgParser, NameValueParser};
+use crate::session_diagnostics::LimitInvalid;
 
 /// Parse a rustc version number written inside string literal in an attribute,
 /// like appears in `since = "1.0.0"`. Suffixes like "-dev" and "-nightly" are
@@ -85,3 +89,34 @@ pub(crate) fn parse_single_integer<S: Stage>(
     };
     Some(num.0)
 }
+
+impl<S: Stage> AcceptContext<'_, '_, S> {
+    pub(crate) fn parse_limit_int(&self, nv: &NameValueParser) -> Option<Limit> {
+        let Some(limit) = nv.value_as_str() else {
+            self.expected_string_literal(nv.value_span, Some(nv.value_as_lit()));
+            return None;
+        };
+
+        let error_str = match limit.as_str().parse() {
+            Ok(i) => return Some(Limit::new(i)),
+            Err(e) => match e.kind() {
+                IntErrorKind::PosOverflow => "`limit` is too large",
+                IntErrorKind::Empty => "`limit` must be a non-negative integer",
+                IntErrorKind::InvalidDigit => "not a valid integer",
+                IntErrorKind::NegOverflow => {
+                    panic!(
+                        "`limit` should never negatively overflow since we're parsing into a usize and we'd get Empty instead"
+                    )
+                }
+                IntErrorKind::Zero => {
+                    panic!("zero is a valid `limit` so should have returned Ok() when parsing")
+                }
+                kind => panic!("unimplemented IntErrorKind variant: {:?}", kind),
+            },
+        };
+
+        self.emit_err(LimitInvalid { span: self.attr_span, value_span: nv.value_span, error_str });
+
+        None
+    }
+}

compiler/rustc_attr_parsing/src/context.rs

@@ -53,7 +53,7 @@ use crate::attributes::prototype::CustomMirParser;
 use crate::attributes::repr::{AlignParser, AlignStaticParser, ReprParser};
 use crate::attributes::rustc_internal::{
     RustcLayoutScalarValidRangeEnd, RustcLayoutScalarValidRangeStart,
-    RustcObjectLifetimeDefaultParser,
+    RustcObjectLifetimeDefaultParser, RustcSimdMonomorphizeLaneLimitParser,
 };
 use crate::attributes::semantics::MayDangleParser;
 use crate::attributes::stability::{
@@ -198,6 +198,7 @@ attribute_parsers!(
         Single<RustcLayoutScalarValidRangeEnd>,
         Single<RustcLayoutScalarValidRangeStart>,
         Single<RustcObjectLifetimeDefaultParser>,
+        Single<RustcSimdMonomorphizeLaneLimitParser>,
         Single<SanitizeParser>,
         Single<ShouldPanicParser>,
         Single<SkipDuringMethodDispatchParser>,

compiler/rustc_codegen_cranelift/src/common.rs

@@ -439,7 +439,10 @@ pub(crate) struct FullyMonomorphizedLayoutCx<'tcx>(pub(crate) TyCtxt<'tcx>);
 impl<'tcx> LayoutOfHelpers<'tcx> for FullyMonomorphizedLayoutCx<'tcx> {
     #[inline]
     fn handle_layout_err(&self, err: LayoutError<'tcx>, span: Span, ty: Ty<'tcx>) -> ! {
-        if let LayoutError::SizeOverflow(_) | LayoutError::ReferencesError(_) = err {
+        if let LayoutError::SizeOverflow(_)
+        | LayoutError::InvalidSimd { .. }
+        | LayoutError::ReferencesError(_) = err
+        {
             self.0.sess.dcx().span_fatal(span, err.to_string())
         } else {
             self.0
@@ -458,7 +461,9 @@ impl<'tcx> FnAbiOfHelpers<'tcx> for FullyMonomorphizedLayoutCx<'tcx> {
         span: Span,
         fn_abi_request: FnAbiRequest<'tcx>,
     ) -> ! {
-        if let FnAbiError::Layout(LayoutError::SizeOverflow(_)) = err {
+        if let FnAbiError::Layout(LayoutError::SizeOverflow(_) | LayoutError::InvalidSimd { .. }) =
+            err
+        {
             self.0.sess.dcx().emit_fatal(Spanned { span, node: err })
         } else {
             match fn_abi_request {

compiler/rustc_codegen_cranelift/src/global_asm.rs

@@ -42,7 +42,10 @@ impl<'tcx> AsmCodegenMethods<'tcx> for GlobalAsmContext<'_, 'tcx> {
 impl<'tcx> LayoutOfHelpers<'tcx> for GlobalAsmContext<'_, 'tcx> {
     #[inline]
     fn handle_layout_err(&self, err: LayoutError<'tcx>, span: Span, ty: Ty<'tcx>) -> ! {
-        if let LayoutError::SizeOverflow(_) | LayoutError::ReferencesError(_) = err {
+        if let LayoutError::SizeOverflow(_)
+        | LayoutError::InvalidSimd { .. }
+        | LayoutError::ReferencesError(_) = err
+        {
             self.tcx.sess.dcx().span_fatal(span, err.to_string())
         } else {
             self.tcx

compiler/rustc_codegen_gcc/src/context.rs

@@ -529,7 +529,10 @@ impl<'gcc, 'tcx> HasX86AbiOpt for CodegenCx<'gcc, 'tcx> {
 impl<'gcc, 'tcx> LayoutOfHelpers<'tcx> for CodegenCx<'gcc, 'tcx> {
     #[inline]
     fn handle_layout_err(&self, err: LayoutError<'tcx>, span: Span, ty: Ty<'tcx>) -> ! {
-        if let LayoutError::SizeOverflow(_) | LayoutError::ReferencesError(_) = err {
+        if let LayoutError::SizeOverflow(_)
+        | LayoutError::InvalidSimd { .. }
+        | LayoutError::ReferencesError(_) = err
+        {
             self.tcx.dcx().emit_fatal(respan(span, err.into_diagnostic()))
         } else {
             self.tcx.dcx().emit_fatal(ssa_errors::FailedToGetLayout { span, ty, err })
@@ -545,7 +548,9 @@ impl<'gcc, 'tcx> FnAbiOfHelpers<'tcx> for CodegenCx<'gcc, 'tcx> {
         span: Span,
         fn_abi_request: FnAbiRequest<'tcx>,
     ) -> ! {
-        if let FnAbiError::Layout(LayoutError::SizeOverflow(_)) = err {
+        if let FnAbiError::Layout(LayoutError::SizeOverflow(_) | LayoutError::InvalidSimd { .. }) =
+            err
+        {
             self.tcx.dcx().emit_fatal(respan(span, err))
         } else {
             match fn_abi_request {

compiler/rustc_codegen_llvm/src/context.rs

@@ -1044,7 +1044,10 @@ impl<'tcx, 'll> HasTypingEnv<'tcx> for CodegenCx<'ll, 'tcx> {
 impl<'tcx> LayoutOfHelpers<'tcx> for CodegenCx<'_, 'tcx> {
     #[inline]
     fn handle_layout_err(&self, err: LayoutError<'tcx>, span: Span, ty: Ty<'tcx>) -> ! {
-        if let LayoutError::SizeOverflow(_) | LayoutError::ReferencesError(_) = err {
+        if let LayoutError::SizeOverflow(_)
+        | LayoutError::ReferencesError(_)
+        | LayoutError::InvalidSimd { .. } = err
+        {
             self.tcx.dcx().emit_fatal(Spanned { span, node: err.into_diagnostic() })
         } else {
             self.tcx.dcx().emit_fatal(ssa_errors::FailedToGetLayout { span, ty, err })
@@ -1061,7 +1064,11 @@ impl<'tcx> FnAbiOfHelpers<'tcx> for CodegenCx<'_, 'tcx> {
         fn_abi_request: FnAbiRequest<'tcx>,
     ) -> ! {
         match err {
-            FnAbiError::Layout(LayoutError::SizeOverflow(_) | LayoutError::Cycle(_)) => {
+            FnAbiError::Layout(
+                LayoutError::SizeOverflow(_)
+                | LayoutError::Cycle(_)
+                | LayoutError::InvalidSimd { .. },
+            ) => {
                 self.tcx.dcx().emit_fatal(Spanned { span, node: err });
             }
             _ => match fn_abi_request {

compiler/rustc_codegen_llvm/src/debuginfo/metadata.rs

@@ -477,8 +477,8 @@ pub(crate) fn spanned_type_di_node<'ll, 'tcx>(
         ty::CoroutineClosure(..) => build_closure_env_di_node(cx, unique_type_id),
         ty::Coroutine(..) => enums::build_coroutine_di_node(cx, unique_type_id),
         ty::Adt(def, ..) => match def.adt_kind() {
-            AdtKind::Struct => build_struct_type_di_node(cx, unique_type_id),
-            AdtKind::Union => build_union_type_di_node(cx, unique_type_id),
+            AdtKind::Struct => build_struct_type_di_node(cx, unique_type_id, span),
+            AdtKind::Union => build_union_type_di_node(cx, unique_type_id, span),
             AdtKind::Enum => enums::build_enum_type_di_node(cx, unique_type_id, span),
         },
         ty::Tuple(_) => build_tuple_type_di_node(cx, unique_type_id),
@@ -1076,14 +1076,15 @@ fn visibility_di_flags<'ll, 'tcx>(
 fn build_struct_type_di_node<'ll, 'tcx>(
     cx: &CodegenCx<'ll, 'tcx>,
     unique_type_id: UniqueTypeId<'tcx>,
+    span: Span,
 ) -> DINodeCreationResult<'ll> {
     let struct_type = unique_type_id.expect_ty();
     let ty::Adt(adt_def, _) = struct_type.kind() else {
         bug!("build_struct_type_di_node() called with non-struct-type: {:?}", struct_type);
     };
     assert!(adt_def.is_struct());
     let containing_scope = get_namespace_for_item(cx, adt_def.did());
-    let struct_type_and_layout = cx.layout_of(struct_type);
+    let struct_type_and_layout = cx.spanned_layout_of(struct_type, span);
     let variant_def = adt_def.non_enum_variant();
     let def_location = if cx.sess().opts.unstable_opts.debug_info_type_line_numbers {
         Some(file_metadata_from_def_id(cx, Some(adt_def.did())))
@@ -1276,14 +1277,15 @@ fn build_closure_env_di_node<'ll, 'tcx>(
 fn build_union_type_di_node<'ll, 'tcx>(
     cx: &CodegenCx<'ll, 'tcx>,
     unique_type_id: UniqueTypeId<'tcx>,
+    span: Span,
 ) -> DINodeCreationResult<'ll> {
     let union_type = unique_type_id.expect_ty();
     let (union_def_id, variant_def) = match union_type.kind() {
         ty::Adt(def, _) => (def.did(), def.non_enum_variant()),
         _ => bug!("build_union_type_di_node on a non-ADT"),
     };
     let containing_scope = get_namespace_for_item(cx, union_def_id);
-    let union_ty_and_layout = cx.layout_of(union_type);
+    let union_ty_and_layout = cx.spanned_layout_of(union_type, span);
     let type_name = compute_debuginfo_type_name(cx.tcx, union_type, false);
     let def_location = if cx.sess().opts.unstable_opts.debug_info_type_line_numbers {
         Some(file_metadata_from_def_id(cx, Some(union_def_id)))

compiler/rustc_feature/src/builtin_attrs.rs

@@ -1211,6 +1211,12 @@ pub static BUILTIN_ATTRIBUTES: &[BuiltinAttribute] = &[
         "the `#[rustc_layout_scalar_valid_range_end]` attribute is just used to enable \
         niche optimizations in the standard library",
     ),
+    rustc_attr!(
+        rustc_simd_monomorphize_lane_limit, Normal, template!(NameValueStr: "N"), ErrorFollowing,
+        EncodeCrossCrate::Yes,
+        "the `#[rustc_simd_monomorphize_lane_limit]` attribute is just used by std::simd \
+        for better error messages",
+    ),
     rustc_attr!(
         rustc_nonnull_optimization_guaranteed, Normal, template!(Word), WarnFollowing,
         EncodeCrossCrate::Yes,