Auto merge of #88308 - eddyb:cooked-layouts, r=nagisa

Morph `layout_raw` query into `layout_of`.

Before this PR, `LayoutCx::layout_of` wrapped the `layout_raw` query, to:
* normalize the type, before attempting to compute the layout
* pass the layout to `record_layout_for_printing`, for `-Zprint-type-sizes`

Moving those two responsibilities into the query may reduce overhead (due to cached calls skipping those steps), but I want to do a perf run to know.

One of the changes I had to make was changing the return type of the query, to be able to both get out the type produced by normalizing inside the query *and* to match the signature of the old `TyCtxt::layout_of`. This change may be worse, perf-wise, so that's another reason I want to check.

r? `@nagisa` cc `@oli-obk`

Author: bors

compiler/rustc_middle/src/query/mod.rs

@@ -1100,10 +1100,12 @@ rustc_queries! {
         cache_on_disk_if { false }
     }
 
-    query layout_raw(
-        env: ty::ParamEnvAnd<'tcx, Ty<'tcx>>
-    ) -> Result<&'tcx rustc_target::abi::Layout, ty::layout::LayoutError<'tcx>> {
-        desc { "computing layout of `{}`", env.value }
+    /// Computes the layout of a type. Note that this implicitly
+    /// executes in "reveal all" mode, and will normalize the input type.
+    query layout_of(
+        key: ty::ParamEnvAnd<'tcx, Ty<'tcx>>
+    ) -> Result<ty::layout::TyAndLayout<'tcx>, ty::layout::LayoutError<'tcx>> {
+        desc { "computing layout of `{}`", key.value }
     }
 
     query dylib_dependency_formats(_: CrateNum)

compiler/rustc_middle/src/ty/layout.rs

@@ -205,10 +205,10 @@ impl<'tcx> fmt::Display for LayoutError<'tcx> {
     }
 }
 
-fn layout_raw<'tcx>(
+fn layout_of<'tcx>(
     tcx: TyCtxt<'tcx>,
     query: ty::ParamEnvAnd<'tcx, Ty<'tcx>>,
-) -> Result<&'tcx Layout, LayoutError<'tcx>> {
+) -> Result<TyAndLayout<'tcx>, LayoutError<'tcx>> {
     ty::tls::with_related_context(tcx, move |icx| {
         let (param_env, ty) = query.into_parts();
 
@@ -220,21 +220,33 @@ fn layout_raw<'tcx>(
         let icx = ty::tls::ImplicitCtxt { layout_depth: icx.layout_depth + 1, ..icx.clone() };
 
         ty::tls::enter_context(&icx, |_| {
+            let param_env = param_env.with_reveal_all_normalized(tcx);
+            let unnormalized_ty = ty;
+            let ty = tcx.normalize_erasing_regions(param_env, ty);
+            if ty != unnormalized_ty {
+                // Ensure this layout is also cached for the normalized type.
+                return tcx.layout_of(param_env.and(ty));
+            }
+
             let cx = LayoutCx { tcx, param_env };
-            let layout = cx.layout_raw_uncached(ty);
+
+            let layout = cx.layout_of_uncached(ty)?;
+            let layout = TyAndLayout { ty, layout };
+
+            cx.record_layout_for_printing(layout);
+
             // Type-level uninhabitedness should always imply ABI uninhabitedness.
-            if let Ok(layout) = layout {
-                if tcx.conservative_is_privately_uninhabited(param_env.and(ty)) {
-                    assert!(layout.abi.is_uninhabited());
-                }
+            if tcx.conservative_is_privately_uninhabited(param_env.and(ty)) {
+                assert!(layout.abi.is_uninhabited());
             }
-            layout
+
+            Ok(layout)
         })
     })
 }
 
 pub fn provide(providers: &mut ty::query::Providers) {
-    *providers = ty::query::Providers { layout_raw, ..*providers };
+    *providers = ty::query::Providers { layout_of, ..*providers };
 }
 
 pub struct LayoutCx<'tcx, C> {
@@ -492,7 +504,7 @@ impl<'tcx> LayoutCx<'tcx, TyCtxt<'tcx>> {
         })
     }
 
-    fn layout_raw_uncached(&self, ty: Ty<'tcx>) -> Result<&'tcx Layout, LayoutError<'tcx>> {
+    fn layout_of_uncached(&self, ty: Ty<'tcx>) -> Result<&'tcx Layout, LayoutError<'tcx>> {
         let tcx = self.tcx;
         let param_env = self.param_env;
         let dl = self.data_layout();
@@ -889,7 +901,9 @@ impl<'tcx> LayoutCx<'tcx, TyCtxt<'tcx>> {
                 let present_first = match present_first {
                     Some(present_first) => present_first,
                     // Uninhabited because it has no variants, or only absent ones.
-                    None if def.is_enum() => return tcx.layout_raw(param_env.and(tcx.types.never)),
+                    None if def.is_enum() => {
+                        return Ok(tcx.layout_of(param_env.and(tcx.types.never))?.layout);
+                    }
                     // If it's a struct, still compute a layout so that we can still compute the
                     // field offsets.
                     None => VariantIdx::new(0),
@@ -1368,11 +1382,9 @@ impl<'tcx> LayoutCx<'tcx, TyCtxt<'tcx>> {
 
             // Types with no meaningful known layout.
             ty::Projection(_) | ty::Opaque(..) => {
-                let normalized = tcx.normalize_erasing_regions(param_env, ty);
-                if ty == normalized {
-                    return Err(LayoutError::Unknown(ty));
-                }
-                tcx.layout_raw(param_env.and(normalized))?
+                // NOTE(eddyb) `layout_of` query should've normalized these away,
+                // if that was possible, so there's no reason to try again here.
+                return Err(LayoutError::Unknown(ty));
             }
 
             ty::Placeholder(..) | ty::GeneratorWitness(..) | ty::Infer(_) => {
@@ -1712,7 +1724,7 @@ impl<'tcx> LayoutCx<'tcx, TyCtxt<'tcx>> {
         Ok(layout)
     }
 
-    /// This is invoked by the `layout_raw` query to record the final
+    /// This is invoked by the `layout_of` query to record the final
     /// layout of each type.
     #[inline(always)]
     fn record_layout_for_printing(&self, layout: TyAndLayout<'tcx>) {
@@ -2040,22 +2052,9 @@ impl<'tcx> LayoutOf for LayoutCx<'tcx, TyCtxt<'tcx>> {
     type TyAndLayout = Result<TyAndLayout<'tcx>, LayoutError<'tcx>>;
 
     /// Computes the layout of a type. Note that this implicitly
-    /// executes in "reveal all" mode.
+    /// executes in "reveal all" mode, and will normalize the input type.
     fn layout_of(&self, ty: Ty<'tcx>) -> Self::TyAndLayout {
-        let param_env = self.param_env.with_reveal_all_normalized(self.tcx);
-        let ty = self.tcx.normalize_erasing_regions(param_env, ty);
-        let layout = self.tcx.layout_raw(param_env.and(ty))?;
-        let layout = TyAndLayout { ty, layout };
-
-        // N.B., this recording is normally disabled; when enabled, it
-        // can however trigger recursive invocations of `layout_of`.
-        // Therefore, we execute it *after* the main query has
-        // completed, to avoid problems around recursive structures
-        // and the like. (Admittedly, I wasn't able to reproduce a problem
-        // here, but it seems like the right thing to do. -nmatsakis)
-        self.record_layout_for_printing(layout);
-
-        Ok(layout)
+        self.tcx.layout_of(self.param_env.and(ty))
     }
 }
 
@@ -2064,50 +2063,9 @@ impl LayoutOf for LayoutCx<'tcx, ty::query::TyCtxtAt<'tcx>> {
     type TyAndLayout = Result<TyAndLayout<'tcx>, LayoutError<'tcx>>;
 
     /// Computes the layout of a type. Note that this implicitly
-    /// executes in "reveal all" mode.
+    /// executes in "reveal all" mode, and will normalize the input type.
     fn layout_of(&self, ty: Ty<'tcx>) -> Self::TyAndLayout {
-        let param_env = self.param_env.with_reveal_all_normalized(*self.tcx);
-        let ty = self.tcx.normalize_erasing_regions(param_env, ty);
-        let layout = self.tcx.layout_raw(param_env.and(ty))?;
-        let layout = TyAndLayout { ty, layout };
-
-        // N.B., this recording is normally disabled; when enabled, it
-        // can however trigger recursive invocations of `layout_of`.
-        // Therefore, we execute it *after* the main query has
-        // completed, to avoid problems around recursive structures
-        // and the like. (Admittedly, I wasn't able to reproduce a problem
-        // here, but it seems like the right thing to do. -nmatsakis)
-        let cx = LayoutCx { tcx: *self.tcx, param_env: self.param_env };
-        cx.record_layout_for_printing(layout);
-
-        Ok(layout)
-    }
-}
-
-// Helper (inherent) `layout_of` methods to avoid pushing `LayoutCx` to users.
-impl TyCtxt<'tcx> {
-    /// Computes the layout of a type. Note that this implicitly
-    /// executes in "reveal all" mode.
-    #[inline]
-    pub fn layout_of(
-        self,
-        param_env_and_ty: ty::ParamEnvAnd<'tcx, Ty<'tcx>>,
-    ) -> Result<TyAndLayout<'tcx>, LayoutError<'tcx>> {
-        let cx = LayoutCx { tcx: self, param_env: param_env_and_ty.param_env };
-        cx.layout_of(param_env_and_ty.value)
-    }
-}
-
-impl ty::query::TyCtxtAt<'tcx> {
-    /// Computes the layout of a type. Note that this implicitly
-    /// executes in "reveal all" mode.
-    #[inline]
-    pub fn layout_of(
-        self,
-        param_env_and_ty: ty::ParamEnvAnd<'tcx, Ty<'tcx>>,
-    ) -> Result<TyAndLayout<'tcx>, LayoutError<'tcx>> {
-        let cx = LayoutCx { tcx: self.at(self.span), param_env: param_env_and_ty.param_env };
-        cx.layout_of(param_env_and_ty.value)
+        self.tcx.layout_of(self.param_env.and(ty))
     }
 }
 

compiler/rustc_mir/src/util/alignment.rs

@@ -24,7 +24,7 @@ where
     };
 
     let ty = place.ty(local_decls, tcx).ty;
-    match tcx.layout_raw(param_env.and(ty)) {
+    match tcx.layout_of(param_env.and(ty)) {
         Ok(layout) if layout.align.abi <= pack => {
             // If the packed alignment is greater or equal to the field alignment, the type won't be
             // further disaligned.

compiler/rustc_target/src/abi/mod.rs

@@ -1139,7 +1139,7 @@ impl Layout {
 /// to that obtained from `layout_of(ty)`, as we need to produce
 /// layouts for which Rust types do not exist, such as enum variants
 /// or synthetic fields of enums (i.e., discriminants) and fat pointers.
-#[derive(Copy, Clone, Debug, PartialEq, Eq, Hash)]
+#[derive(Copy, Clone, Debug, PartialEq, Eq, Hash, HashStable_Generic)]
 pub struct TyAndLayout<'a, Ty> {
     pub ty: Ty,
     pub layout: &'a Layout,

compiler/rustc_typeck/src/check/upvar.rs

@@ -1481,7 +1481,7 @@ fn restrict_repr_packed_field_ref_capture<'tcx>(
         match p.kind {
             ProjectionKind::Field(..) => match ty.kind() {
                 ty::Adt(def, _) if def.repr.packed() => {
-                    match tcx.layout_raw(param_env.and(p.ty)) {
+                    match tcx.layout_of(param_env.and(p.ty)) {
                         Ok(layout) if layout.align.abi.bytes() == 1 => {
                             // if the alignment is 1, the type can't be further
                             // disaligned.

src/test/ui/consts/const-size_of-cycle.stderr

@@ -15,6 +15,7 @@ note: ...which requires const-evaluating + checking `Foo::bytes::{constant#0}`..
 LL |     bytes: [u8; std::mem::size_of::<Foo>()]
    |                 ^^^^^^^^^^^^^^^^^^^^^^^^^^
    = note: ...which requires computing layout of `Foo`...
+   = note: ...which requires computing layout of `[u8; _]`...
    = note: ...which requires normalizing `[u8; _]`...
    = note: ...which again requires simplifying constant for the type system `Foo::bytes::{constant#0}`, completing the cycle
 note: cycle used when checking that `Foo` is well-formed

src/test/ui/consts/issue-44415.stderr

@@ -15,6 +15,7 @@ note: ...which requires const-evaluating + checking `Foo::bytes::{constant#0}`..
 LL |     bytes: [u8; unsafe { intrinsics::size_of::<Foo>() }],
    |                 ^^^^^^
    = note: ...which requires computing layout of `Foo`...
+   = note: ...which requires computing layout of `[u8; _]`...
    = note: ...which requires normalizing `[u8; _]`...
    = note: ...which again requires simplifying constant for the type system `Foo::bytes::{constant#0}`, completing the cycle
 note: cycle used when checking that `Foo` is well-formed

src/test/ui/recursion/issue-26548-recursion-via-normalize.rs

@@ -1,6 +1,8 @@
-//~ ERROR cycle detected when computing layout of
-//~| NOTE ...which requires computing layout of
-//~| NOTE ...which again requires computing layout of
+//~ ERROR cycle detected when computing layout of `S`
+//~| NOTE ...which requires computing layout of `std::option::Option<<S as Mirror>::It>`...
+//~| NOTE ...which requires computing layout of `std::option::Option<S>`...
+//~| NOTE ...which again requires computing layout of `S`, completing the cycle
+//~| NOTE cycle used when computing layout of `std::option::Option<S>`
 
 // build-fail
 
@@ -13,6 +15,5 @@ impl<T: ?Sized> Mirror for T {
 struct S(Option<<S as Mirror>::It>);
 
 fn main() {
-    //~^ NOTE cycle used when optimizing MIR for `main`
     let _s = S(None);
 }

src/test/ui/recursion/issue-26548-recursion-via-normalize.stderr

@@ -1,12 +1,9 @@
-error[E0391]: cycle detected when computing layout of `std::option::Option<S>`
+error[E0391]: cycle detected when computing layout of `S`
    |
-   = note: ...which requires computing layout of `S`...
-   = note: ...which again requires computing layout of `std::option::Option<S>`, completing the cycle
-note: cycle used when optimizing MIR for `main`
-  --> $DIR/issue-26548-recursion-via-normalize.rs:15:1
-   |
-LL | fn main() {
-   | ^^^^^^^^^
+   = note: ...which requires computing layout of `std::option::Option<<S as Mirror>::It>`...
+   = note: ...which requires computing layout of `std::option::Option<S>`...
+   = note: ...which again requires computing layout of `S`, completing the cycle
+   = note: cycle used when computing layout of `std::option::Option<S>`
 
 error: aborting due to previous error