Auto merge of #137436 - matthiaskrgr:rollup-mqir082, r=matthiaskrgr

Rollup of 7 pull requests

Successful merges:

 - #135501 (Inject `compiler_builtins` during postprocessing and ensure it is made private)
 - #136543 (intrinsics: unify rint, roundeven, nearbyint in a single round_ties_even intrinsic)
 - #137121 (stabilize `(const_)ptr_sub_ptr`)
 - #137180 (Give `global_asm` a fake body to store typeck results, represent `sym fn` as a hir expr to fix `sym fn` operands with lifetimes)
 - #137256 (compiler: untangle SIMD alignment assumptions)
 - #137383 (stabilize `unsigned_is_multiple_of`)
 - #137415 (Remove invalid suggestion of into_iter for extern macro)

r? `@ghost`
`@rustbot` modify labels: rollup

Author: bors

compiler/rustc_abi/src/callconv/reg.rs

@@ -57,7 +57,7 @@ impl Reg {
                 128 => dl.f128_align.abi,
                 _ => panic!("unsupported float: {self:?}"),
             },
-            RegKind::Vector => dl.vector_align(self.size).abi,
+            RegKind::Vector => dl.llvmlike_vector_align(self.size).abi,
         }
     }
 }

compiler/rustc_abi/src/layout.rs

@@ -310,10 +310,10 @@ impl<Cx: HasDataLayout> LayoutCalculator<Cx> {
         let mut align = if repr.pack.is_some() { dl.i8_align } else { dl.aggregate_align };
         let mut max_repr_align = repr.align;
 
-        // If all the non-ZST fields have the same ABI and union ABI optimizations aren't
-        // disabled, we can use that common ABI for the union as a whole.
+        // If all the non-ZST fields have the same repr and union repr optimizations aren't
+        // disabled, we can use that common repr for the union as a whole.
         struct AbiMismatch;
-        let mut common_non_zst_abi_and_align = if repr.inhibits_union_abi_opt() {
+        let mut common_non_zst_repr_and_align = if repr.inhibits_union_abi_opt() {
             // Can't optimize
             Err(AbiMismatch)
         } else {
@@ -337,14 +337,14 @@ impl<Cx: HasDataLayout> LayoutCalculator<Cx> {
                 continue;
             }
 
-            if let Ok(common) = common_non_zst_abi_and_align {
+            if let Ok(common) = common_non_zst_repr_and_align {
                 // Discard valid range information and allow undef
                 let field_abi = field.backend_repr.to_union();
 
                 if let Some((common_abi, common_align)) = common {
                     if common_abi != field_abi {
                         // Different fields have different ABI: disable opt
-                        common_non_zst_abi_and_align = Err(AbiMismatch);
+                        common_non_zst_repr_and_align = Err(AbiMismatch);
                     } else {
                         // Fields with the same non-Aggregate ABI should also
                         // have the same alignment
@@ -357,7 +357,7 @@ impl<Cx: HasDataLayout> LayoutCalculator<Cx> {
                     }
                 } else {
                     // First non-ZST field: record its ABI and alignment
-                    common_non_zst_abi_and_align = Ok(Some((field_abi, field.align.abi)));
+                    common_non_zst_repr_and_align = Ok(Some((field_abi, field.align.abi)));
                 }
             }
         }
@@ -376,16 +376,25 @@ impl<Cx: HasDataLayout> LayoutCalculator<Cx> {
 
         // If all non-ZST fields have the same ABI, we may forward that ABI
         // for the union as a whole, unless otherwise inhibited.
-        let abi = match common_non_zst_abi_and_align {
+        let backend_repr = match common_non_zst_repr_and_align {
             Err(AbiMismatch) | Ok(None) => BackendRepr::Memory { sized: true },
-            Ok(Some((abi, _))) => {
-                if abi.inherent_align(dl).map(|a| a.abi) != Some(align.abi) {
-                    // Mismatched alignment (e.g. union is #[repr(packed)]): disable opt
+            Ok(Some((repr, _))) => match repr {
+                // Mismatched alignment (e.g. union is #[repr(packed)]): disable opt
+                BackendRepr::Scalar(_) | BackendRepr::ScalarPair(_, _)
+                    if repr.scalar_align(dl).unwrap() != align.abi =>
+                {
                     BackendRepr::Memory { sized: true }
-                } else {
-                    abi
                 }
-            }
+                // Vectors require at least element alignment, else disable the opt
+                BackendRepr::Vector { element, count: _ } if element.align(dl).abi > align.abi => {
+                    BackendRepr::Memory { sized: true }
+                }
+                // the alignment tests passed and we can use this
+                BackendRepr::Scalar(..)
+                | BackendRepr::ScalarPair(..)
+                | BackendRepr::Vector { .. }
+                | BackendRepr::Memory { .. } => repr,
+            },
         };
 
         let Some(union_field_count) = NonZeroUsize::new(only_variant.len()) else {
@@ -400,7 +409,7 @@ impl<Cx: HasDataLayout> LayoutCalculator<Cx> {
         Ok(LayoutData {
             variants: Variants::Single { index: only_variant_idx },
             fields: FieldsShape::Union(union_field_count),
-            backend_repr: abi,
+            backend_repr,
             largest_niche: None,
             uninhabited: false,
             align,

compiler/rustc_abi/src/lib.rs

@@ -408,16 +408,21 @@ impl TargetDataLayout {
         }
     }
 
+    /// psABI-mandated alignment for a vector type, if any
     #[inline]
-    pub fn vector_align(&self, vec_size: Size) -> AbiAndPrefAlign {
-        for &(size, align) in &self.vector_align {
-            if size == vec_size {
-                return align;
-            }
-        }
-        // Default to natural alignment, which is what LLVM does.
-        // That is, use the size, rounded up to a power of 2.
-        AbiAndPrefAlign::new(Align::from_bytes(vec_size.bytes().next_power_of_two()).unwrap())
+    fn cabi_vector_align(&self, vec_size: Size) -> Option<AbiAndPrefAlign> {
+        self.vector_align
+            .iter()
+            .find(|(size, _align)| *size == vec_size)
+            .map(|(_size, align)| *align)
+    }
+
+    /// an alignment resembling the one LLVM would pick for a vector
+    #[inline]
+    pub fn llvmlike_vector_align(&self, vec_size: Size) -> AbiAndPrefAlign {
+        self.cabi_vector_align(vec_size).unwrap_or(AbiAndPrefAlign::new(
+            Align::from_bytes(vec_size.bytes().next_power_of_two()).unwrap(),
+        ))
     }
 }
 
@@ -810,20 +815,19 @@ impl Align {
         self.bits().try_into().unwrap()
     }
 
-    /// Computes the best alignment possible for the given offset
-    /// (the largest power of two that the offset is a multiple of).
+    /// Obtain the greatest factor of `size` that is an alignment
+    /// (the largest power of two the Size is a multiple of).
     ///
-    /// N.B., for an offset of `0`, this happens to return `2^64`.
+    /// Note that all numbers are factors of 0
     #[inline]
-    pub fn max_for_offset(offset: Size) -> Align {
-        Align { pow2: offset.bytes().trailing_zeros() as u8 }
+    pub fn max_aligned_factor(size: Size) -> Align {
+        Align { pow2: size.bytes().trailing_zeros() as u8 }
     }
 
-    /// Lower the alignment, if necessary, such that the given offset
-    /// is aligned to it (the offset is a multiple of the alignment).
+    /// Reduces Align to an aligned factor of `size`.
     #[inline]
-    pub fn restrict_for_offset(self, offset: Size) -> Align {
-        self.min(Align::max_for_offset(offset))
+    pub fn restrict_for_offset(self, size: Size) -> Align {
+        self.min(Align::max_aligned_factor(size))
     }
 }
 
@@ -1455,37 +1459,38 @@ impl BackendRepr {
         matches!(*self, BackendRepr::Scalar(s) if s.is_bool())
     }
 
-    /// Returns the fixed alignment of this ABI, if any is mandated.
-    pub fn inherent_align<C: HasDataLayout>(&self, cx: &C) -> Option<AbiAndPrefAlign> {
-        Some(match *self {
-            BackendRepr::Scalar(s) => s.align(cx),
-            BackendRepr::ScalarPair(s1, s2) => s1.align(cx).max(s2.align(cx)),
-            BackendRepr::Vector { element, count } => {
-                cx.data_layout().vector_align(element.size(cx) * count)
-            }
-            BackendRepr::Memory { .. } => return None,
-        })
+    /// The psABI alignment for a `Scalar` or `ScalarPair`
+    ///
+    /// `None` for other variants.
+    pub fn scalar_align<C: HasDataLayout>(&self, cx: &C) -> Option<Align> {
+        match *self {
+            BackendRepr::Scalar(s) => Some(s.align(cx).abi),
+            BackendRepr::ScalarPair(s1, s2) => Some(s1.align(cx).max(s2.align(cx)).abi),
+            // The align of a Vector can vary in surprising ways
+            BackendRepr::Vector { .. } | BackendRepr::Memory { .. } => None,
+        }
     }
 
-    /// Returns the fixed size of this ABI, if any is mandated.
-    pub fn inherent_size<C: HasDataLayout>(&self, cx: &C) -> Option<Size> {
-        Some(match *self {
-            BackendRepr::Scalar(s) => {
-                // No padding in scalars.
-                s.size(cx)
-            }
+    /// The psABI size for a `Scalar` or `ScalarPair`
+    ///
+    /// `None` for other variants
+    pub fn scalar_size<C: HasDataLayout>(&self, cx: &C) -> Option<Size> {
+        match *self {
+            // No padding in scalars.
+            BackendRepr::Scalar(s) => Some(s.size(cx)),
+            // May have some padding between the pair.
             BackendRepr::ScalarPair(s1, s2) => {
-                // May have some padding between the pair.
                 let field2_offset = s1.size(cx).align_to(s2.align(cx).abi);
-                (field2_offset + s2.size(cx)).align_to(self.inherent_align(cx)?.abi)
+                let size = (field2_offset + s2.size(cx)).align_to(
+                    self.scalar_align(cx)
+                        // We absolutely must have an answer here or everything is FUBAR.
+                        .unwrap(),
+                );
+                Some(size)
             }
-            BackendRepr::Vector { element, count } => {
-                // No padding in vectors, except possibly for trailing padding
-                // to make the size a multiple of align (e.g. for vectors of size 3).
-                (element.size(cx) * count).align_to(self.inherent_align(cx)?.abi)
-            }
-            BackendRepr::Memory { .. } => return None,
-        })
+            // The size of a Vector can vary in surprising ways
+            BackendRepr::Vector { .. } | BackendRepr::Memory { .. } => None,
+        }
     }
 
     /// Discard validity range information and allow undef.

compiler/rustc_ast_lowering/src/asm.rs

@@ -1,13 +1,12 @@
 use std::collections::hash_map::Entry;
 use std::fmt::Write;
 
-use rustc_ast::ptr::P;
 use rustc_ast::*;
 use rustc_data_structures::fx::{FxHashMap, FxHashSet, FxIndexMap};
 use rustc_hir as hir;
 use rustc_hir::def::{DefKind, Res};
 use rustc_session::parse::feature_err;
-use rustc_span::{Span, kw, sym};
+use rustc_span::{Span, sym};
 use rustc_target::asm;
 
 use super::LoweringContext;
@@ -230,20 +229,7 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
                                 tokens: None,
                             };
 
-                            // Wrap the expression in an AnonConst.
-                            let parent_def_id = self.current_hir_id_owner.def_id;
-                            let node_id = self.next_node_id();
-                            self.create_def(
-                                parent_def_id,
-                                node_id,
-                                kw::Empty,
-                                DefKind::AnonConst,
-                                *op_sp,
-                            );
-                            let anon_const = AnonConst { id: node_id, value: P(expr) };
-                            hir::InlineAsmOperand::SymFn {
-                                anon_const: self.lower_anon_const_to_anon_const(&anon_const),
-                            }
+                            hir::InlineAsmOperand::SymFn { expr: self.lower_expr(&expr) }
                         }
                     }
                     InlineAsmOperand::Label { block } => {

compiler/rustc_ast_lowering/src/item.rs

@@ -251,7 +251,12 @@ impl<'hir> LoweringContext<'_, 'hir> {
                     .arena
                     .alloc_from_iter(fm.items.iter().map(|x| self.lower_foreign_item_ref(x))),
             },
-            ItemKind::GlobalAsm(asm) => hir::ItemKind::GlobalAsm(self.lower_inline_asm(span, asm)),
+            ItemKind::GlobalAsm(asm) => {
+                let asm = self.lower_inline_asm(span, asm);
+                let fake_body =
+                    self.lower_body(|this| (&[], this.expr(span, hir::ExprKind::InlineAsm(asm))));
+                hir::ItemKind::GlobalAsm { asm, fake_body }
+            }
             ItemKind::TyAlias(box TyAlias { generics, where_clauses, ty, .. }) => {
                 // We lower
                 //

compiler/rustc_borrowck/src/universal_regions.rs

@@ -126,6 +126,11 @@ pub(crate) enum DefiningTy<'tcx> {
     /// The MIR represents an inline const. The signature has no inputs and a
     /// single return value found via `InlineConstArgs::ty`.
     InlineConst(DefId, GenericArgsRef<'tcx>),
+
+    // Fake body for a global asm. Not particularly useful or interesting,
+    // but we need it so we can properly store the typeck results of the asm
+    // operands, which aren't associated with a body otherwise.
+    GlobalAsm(DefId),
 }
 
 impl<'tcx> DefiningTy<'tcx> {
@@ -138,9 +143,10 @@ impl<'tcx> DefiningTy<'tcx> {
             DefiningTy::Closure(_, args) => args.as_closure().upvar_tys(),
             DefiningTy::CoroutineClosure(_, args) => args.as_coroutine_closure().upvar_tys(),
             DefiningTy::Coroutine(_, args) => args.as_coroutine().upvar_tys(),
-            DefiningTy::FnDef(..) | DefiningTy::Const(..) | DefiningTy::InlineConst(..) => {
-                ty::List::empty()
-            }
+            DefiningTy::FnDef(..)
+            | DefiningTy::Const(..)
+            | DefiningTy::InlineConst(..)
+            | DefiningTy::GlobalAsm(_) => ty::List::empty(),
         }
     }
 
@@ -152,7 +158,10 @@ impl<'tcx> DefiningTy<'tcx> {
             DefiningTy::Closure(..)
             | DefiningTy::CoroutineClosure(..)
             | DefiningTy::Coroutine(..) => 1,
-            DefiningTy::FnDef(..) | DefiningTy::Const(..) | DefiningTy::InlineConst(..) => 0,
+            DefiningTy::FnDef(..)
+            | DefiningTy::Const(..)
+            | DefiningTy::InlineConst(..)
+            | DefiningTy::GlobalAsm(_) => 0,
         }
     }
 
@@ -171,7 +180,8 @@ impl<'tcx> DefiningTy<'tcx> {
             | DefiningTy::Coroutine(def_id, ..)
             | DefiningTy::FnDef(def_id, ..)
             | DefiningTy::Const(def_id, ..)
-            | DefiningTy::InlineConst(def_id, ..) => def_id,
+            | DefiningTy::InlineConst(def_id, ..)
+            | DefiningTy::GlobalAsm(def_id) => def_id,
         }
     }
 }
@@ -411,6 +421,7 @@ impl<'tcx> UniversalRegions<'tcx> {
                     tcx.def_path_str_with_args(def_id, args),
                 ));
             }
+            DefiningTy::GlobalAsm(_) => unreachable!(),
         }
     }
 
@@ -633,6 +644,8 @@ impl<'cx, 'tcx> UniversalRegionsBuilder<'cx, 'tcx> {
                     DefiningTy::InlineConst(self.mir_def.to_def_id(), args)
                 }
             }
+
+            BodyOwnerKind::GlobalAsm => DefiningTy::GlobalAsm(self.mir_def.to_def_id()),
         }
     }
 
@@ -666,6 +679,8 @@ impl<'cx, 'tcx> UniversalRegionsBuilder<'cx, 'tcx> {
             }
 
             DefiningTy::FnDef(_, args) | DefiningTy::Const(_, args) => args,
+
+            DefiningTy::GlobalAsm(_) => ty::List::empty(),
         };
 
         let global_mapping = iter::once((tcx.lifetimes.re_static, fr_static));
@@ -802,6 +817,10 @@ impl<'cx, 'tcx> UniversalRegionsBuilder<'cx, 'tcx> {
                 let ty = args.as_inline_const().ty();
                 ty::Binder::dummy(tcx.mk_type_list(&[ty]))
             }
+
+            DefiningTy::GlobalAsm(def_id) => {
+                ty::Binder::dummy(tcx.mk_type_list(&[tcx.type_of(def_id).instantiate_identity()]))
+            }
         };
 
         // FIXME(#129952): We probably want a more principled approach here.