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 rust-lang/rust#145967 by including spans in layout errors for all ADTs.

r? ``@RalfJung``

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

2 files changed, 22 insertions, 17 deletions

diff --git a/compiler/rustc_ty_utils/src/errors.rs b/compiler/rustc_ty_utils/src/errors.rs
index 0298e7e0e95..f92c405242c 100644
--- a/compiler/rustc_ty_utils/src/errors.rs
+++ b/compiler/rustc_ty_utils/src/errors.rs
@@ -79,19 +79,6 @@ pub(crate) struct UnexpectedFnPtrAssociatedItem {
 }
 
 #[derive(Diagnostic)]
-#[diag(ty_utils_zero_length_simd_type)]
-pub(crate) struct ZeroLengthSimdType<'tcx> {
-    pub ty: Ty<'tcx>,
-}
-
-#[derive(Diagnostic)]
-#[diag(ty_utils_oversized_simd_type)]
-pub(crate) struct OversizedSimdType<'tcx> {
-    pub ty: Ty<'tcx>,
-    pub max_lanes: u64,
-}
-
-#[derive(Diagnostic)]
 #[diag(ty_utils_non_primitive_simd_type)]
 pub(crate) struct NonPrimitiveSimdType<'tcx> {
     pub ty: Ty<'tcx>,
diff --git a/compiler/rustc_ty_utils/src/layout.rs b/compiler/rustc_ty_utils/src/layout.rs
index c4cb43011ad..f59bc2117d5 100644
--- a/compiler/rustc_ty_utils/src/layout.rs
+++ b/compiler/rustc_ty_utils/src/layout.rs
@@ -7,12 +7,14 @@ use rustc_abi::{
     VariantIdx, Variants, WrappingRange,
 };
 use rustc_hashes::Hash64;
+use rustc_hir::attrs::AttributeKind;
+use rustc_hir::find_attr;
 use rustc_index::IndexVec;
 use rustc_middle::bug;
 use rustc_middle::query::Providers;
 use rustc_middle::traits::ObligationCause;
 use rustc_middle::ty::layout::{
-    FloatExt, HasTyCtxt, IntegerExt, LayoutCx, LayoutError, LayoutOf, TyAndLayout,
+    FloatExt, HasTyCtxt, IntegerExt, LayoutCx, LayoutError, LayoutOf, SimdLayoutError, TyAndLayout,
 };
 use rustc_middle::ty::print::with_no_trimmed_paths;
 use rustc_middle::ty::{
@@ -23,7 +25,7 @@ use rustc_span::{Symbol, sym};
 use tracing::{debug, instrument};
 use {rustc_abi as abi, rustc_hir as hir};
 
-use crate::errors::{NonPrimitiveSimdType, OversizedSimdType, ZeroLengthSimdType};
+use crate::errors::NonPrimitiveSimdType;
 
 mod invariant;
 
@@ -121,11 +123,11 @@ fn map_error<'tcx>(
         }
         LayoutCalculatorError::ZeroLengthSimdType => {
             // Can't be caught in typeck if the array length is generic.
-            cx.tcx().dcx().emit_fatal(ZeroLengthSimdType { ty })
+            LayoutError::InvalidSimd { ty, kind: SimdLayoutError::ZeroLength }
         }
         LayoutCalculatorError::OversizedSimdType { max_lanes } => {
             // Can't be caught in typeck if the array length is generic.
-            cx.tcx().dcx().emit_fatal(OversizedSimdType { ty, max_lanes })
+            LayoutError::InvalidSimd { ty, kind: SimdLayoutError::TooManyLanes(max_lanes) }
         }
         LayoutCalculatorError::NonPrimitiveSimdType(field) => {
             // This error isn't caught in typeck, e.g., if
@@ -563,6 +565,22 @@ fn layout_of_uncached<'tcx>(
 
             let e_ly = cx.layout_of(e_ty)?;
 
+            // Check for the rustc_simd_monomorphize_lane_limit attribute and check the lane limit
+            if let Some(limit) = find_attr!(
+                tcx.get_all_attrs(def.did()),
+                AttributeKind::RustcSimdMonomorphizeLaneLimit(limit) => limit
+            ) {
+                if !limit.value_within_limit(e_len as usize) {
+                    return Err(map_error(
+                        &cx,
+                        ty,
+                        rustc_abi::LayoutCalculatorError::OversizedSimdType {
+                            max_lanes: limit.0 as u64,
+                        },
+                    ));
+                }
+            }
+
             map_layout(cx.calc.simd_type(e_ly, e_len, def.repr().packed()))?
         }