Auto merge of #60237 - saleemjaffer:issue-56166-miri-fntype-arg-passing, r=eddyb

Move pointee_info_at from rustc_codegen_llvm to rustc_target.

Makes progress towards #56166.

This is a continuation of https://github.com/rust-lang/rust/pull/57150.

@oli-obk Should I close the older PR?

4 files changed, 20 insertions, 135 deletions

diff --git a/src/librustc_codegen_llvm/abi.rs b/src/librustc_codegen_llvm/abi.rs
index 2c4a1ded97f..70d184240fc 100644
--- a/src/librustc_codegen_llvm/abi.rs
+++ b/src/librustc_codegen_llvm/abi.rs
@@ -2,8 +2,8 @@ use crate::llvm::{self, AttributePlace};
 use crate::builder::Builder;
 use crate::context::CodegenCx;
 use crate::type_::Type;
-use crate::type_of::{LayoutLlvmExt, PointerKind};
 use crate::value::Value;
+use crate::type_of::{LayoutLlvmExt};
 use rustc_codegen_ssa::MemFlags;
 use rustc_codegen_ssa::mir::place::PlaceRef;
 use rustc_codegen_ssa::mir::operand::OperandValue;
@@ -13,7 +13,7 @@ use rustc_codegen_ssa::traits::*;
 
 use rustc_target::abi::{HasDataLayout, LayoutOf, Size, TyLayout, Abi as LayoutAbi};
 use rustc::ty::{self, Ty, Instance};
-use rustc::ty::layout;
+use rustc::ty::layout::{self, PointerKind};
 
 use libc::c_uint;
 
diff --git a/src/librustc_codegen_llvm/builder.rs b/src/librustc_codegen_llvm/builder.rs
index 123fda1e215..bc2bb97a19e 100644
--- a/src/librustc_codegen_llvm/builder.rs
+++ b/src/librustc_codegen_llvm/builder.rs
@@ -66,6 +66,12 @@ impl ty::layout::HasTyCtxt<'tcx> for Builder<'_, '_, 'tcx> {
     }
 }
 
+impl ty::layout::HasParamEnv<'tcx> for Builder<'_, '_, 'tcx> {
+    fn param_env(&self) -> ty::ParamEnv<'tcx> {
+        self.cx.param_env()
+    }
+}
+
 impl ty::layout::LayoutOf for Builder<'_, '_, 'tcx> {
     type Ty = Ty<'tcx>;
     type TyLayout = TyLayout<'tcx>;
diff --git a/src/librustc_codegen_llvm/context.rs b/src/librustc_codegen_llvm/context.rs
index f6956bd5736..7bf8f705ea8 100644
--- a/src/librustc_codegen_llvm/context.rs
+++ b/src/librustc_codegen_llvm/context.rs
@@ -8,7 +8,6 @@ use rustc::hir;
 
 use crate::monomorphize::partitioning::CodegenUnit;
 use crate::type_::Type;
-use crate::type_of::PointeeInfo;
 use rustc_codegen_ssa::traits::*;
 
 use rustc_data_structures::base_n;
@@ -16,7 +15,9 @@ use rustc_data_structures::small_c_str::SmallCStr;
 use rustc::mir::mono::Stats;
 use rustc::session::config::{self, DebugInfo};
 use rustc::session::Session;
-use rustc::ty::layout::{LayoutError, LayoutOf, Size, TyLayout, VariantIdx};
+use rustc::ty::layout::{
+    LayoutError, LayoutOf, PointeeInfo, Size, TyLayout, VariantIdx, HasParamEnv
+};
 use rustc::ty::{self, Ty, TyCtxt};
 use rustc::util::nodemap::FxHashMap;
 use rustc_target::spec::{HasTargetSpec, Target};
@@ -862,3 +863,9 @@ impl LayoutOf for CodegenCx<'ll, 'tcx> {
             })
     }
 }
+
+impl<'tcx, 'll> HasParamEnv<'tcx> for CodegenCx<'ll, 'tcx> {
+    fn param_env(&self) -> ty::ParamEnv<'tcx> {
+        ty::ParamEnv::reveal_all()
+    }
+}
diff --git a/src/librustc_codegen_llvm/type_of.rs b/src/librustc_codegen_llvm/type_of.rs
index cbcc457fda9..ff25ed92566 100644
--- a/src/librustc_codegen_llvm/type_of.rs
+++ b/src/librustc_codegen_llvm/type_of.rs
@@ -1,10 +1,9 @@
 use crate::abi::{FnType, FnTypeExt};
 use crate::common::*;
 use crate::type_::Type;
-use rustc::hir;
 use rustc::ty::{self, Ty, TypeFoldable};
-use rustc::ty::layout::{self, Align, LayoutOf, Size, TyLayout};
-use rustc_target::abi::FloatTy;
+use rustc::ty::layout::{self, Align, LayoutOf, PointeeInfo, Size, TyLayout};
+use rustc_target::abi::{FloatTy, TyLayoutMethods};
 use rustc_mir::monomorphize::item::DefPathBasedNames;
 use rustc_codegen_ssa::traits::*;
 
@@ -174,28 +173,6 @@ impl<'a, 'tcx> CodegenCx<'a, 'tcx> {
     }
 }
 
-#[derive(Copy, Clone, PartialEq, Eq)]
-pub enum PointerKind {
-    /// Most general case, we know no restrictions to tell LLVM.
-    Shared,
-
-    /// `&T` where `T` contains no `UnsafeCell`, is `noalias` and `readonly`.
-    Frozen,
-
-    /// `&mut T`, when we know `noalias` is safe for LLVM.
-    UniqueBorrowed,
-
-    /// `Box<T>`, unlike `UniqueBorrowed`, it also has `noalias` on returns.
-    UniqueOwned
-}
-
-#[derive(Copy, Clone)]
-pub struct PointeeInfo {
-    pub size: Size,
-    pub align: Align,
-    pub safe: Option<PointerKind>,
-}
-
 pub trait LayoutLlvmExt<'tcx> {
     fn is_llvm_immediate(&self) -> bool;
     fn is_llvm_scalar_pair<'a>(&self) -> bool;
@@ -406,112 +383,7 @@ impl<'tcx> LayoutLlvmExt<'tcx> for TyLayout<'tcx> {
             return pointee;
         }
 
-        let mut result = None;
-        match self.ty.sty {
-            ty::RawPtr(mt) if offset.bytes() == 0 => {
-                let (size, align) = cx.size_and_align_of(mt.ty);
-                result = Some(PointeeInfo {
-                    size,
-                    align,
-                    safe: None
-                });
-            }
-
-            ty::Ref(_, ty, mt) if offset.bytes() == 0 => {
-                let (size, align) = cx.size_and_align_of(ty);
-
-                let kind = match mt {
-                    hir::MutImmutable => if cx.type_is_freeze(ty) {
-                        PointerKind::Frozen
-                    } else {
-                        PointerKind::Shared
-                    },
-                    hir::MutMutable => {
-                        // Previously we would only emit noalias annotations for LLVM >= 6 or in
-                        // panic=abort mode. That was deemed right, as prior versions had many bugs
-                        // in conjunction with unwinding, but later versions didn’t seem to have
-                        // said issues. See issue #31681.
-                        //
-                        // Alas, later on we encountered a case where noalias would generate wrong
-                        // code altogether even with recent versions of LLVM in *safe* code with no
-                        // unwinding involved. See #54462.
-                        //
-                        // For now, do not enable mutable_noalias by default at all, while the
-                        // issue is being figured out.
-                        let mutable_noalias = cx.tcx.sess.opts.debugging_opts.mutable_noalias
-                            .unwrap_or(false);
-                        if mutable_noalias {
-                            PointerKind::UniqueBorrowed
-                        } else {
-                            PointerKind::Shared
-                        }
-                    }
-                };
-
-                result = Some(PointeeInfo {
-                    size,
-                    align,
-                    safe: Some(kind)
-                });
-            }
-
-            _ => {
-                let mut data_variant = match self.variants {
-                    // Within the discriminant field, only the niche itself is
-                    // always initialized, so we only check for a pointer at its
-                    // offset.
-                    //
-                    // If the niche is a pointer, it's either valid (according
-                    // to its type), or null (which the niche field's scalar
-                    // validity range encodes).  This allows using
-                    // `dereferenceable_or_null` for e.g., `Option<&T>`, and
-                    // this will continue to work as long as we don't start
-                    // using more niches than just null (e.g., the first page of
-                    // the address space, or unaligned pointers).
-                    layout::Variants::Multiple {
-                        discr_kind: layout::DiscriminantKind::Niche {
-                            dataful_variant,
-                            ..
-                        },
-                        discr_index,
-                        ..
-                    } if self.fields.offset(discr_index) == offset =>
-                        Some(self.for_variant(cx, dataful_variant)),
-                    _ => Some(*self),
-                };
-
-                if let Some(variant) = data_variant {
-                    // We're not interested in any unions.
-                    if let layout::FieldPlacement::Union(_) = variant.fields {
-                        data_variant = None;
-                    }
-                }
-
-                if let Some(variant) = data_variant {
-                    let ptr_end = offset + layout::Pointer.size(cx);
-                    for i in 0..variant.fields.count() {
-                        let field_start = variant.fields.offset(i);
-                        if field_start <= offset {
-                            let field = variant.field(cx, i);
-                            if ptr_end <= field_start + field.size {
-                                // We found the right field, look inside it.
-                                result = field.pointee_info_at(cx, offset - field_start);
-                                break;
-                            }
-                        }
-                    }
-                }
-
-                // FIXME(eddyb) This should be for `ptr::Unique<T>`, not `Box<T>`.
-                if let Some(ref mut pointee) = result {
-                    if let ty::Adt(def, _) = self.ty.sty {
-                        if def.is_box() && offset.bytes() == 0 {
-                            pointee.safe = Some(PointerKind::UniqueOwned);
-                        }
-                    }
-                }
-            }
-        }
+        let result = Ty::pointee_info_at(*self, cx, offset);
 
         cx.pointee_infos.borrow_mut().insert((self.ty, offset), result);
         result