Auto merge of #88242 - bonega:allocation_range, r=oli-obk

Use custom wrap-around type instead of RangeInclusive

Two reasons:

1. More memory is allocated than necessary for `valid_range` in `Scalar`. The range is not used as an iterator and `exhausted` is never used.
2. `contains`, `count` etc. methods in `RangeInclusive` are doing very unhelpful(and dangerous!) things when used as a wrap-around range. - In general this PR wants to limit potentially confusing methods, that have a low probability of working.

Doing a local perf run, every metric shows improvement except for instructions.
Max-rss seem to have a very consistent improvement.

Sorry - newbie here, probably doing something wrong.

8 files changed, 116 insertions, 82 deletions

diff --git a/compiler/rustc_codegen_llvm/src/builder.rs b/compiler/rustc_codegen_llvm/src/builder.rs
index 07e1b55afe5..13538683e05 100644
--- a/compiler/rustc_codegen_llvm/src/builder.rs
+++ b/compiler/rustc_codegen_llvm/src/builder.rs
@@ -462,7 +462,6 @@ impl BuilderMethods<'a, 'tcx> for Builder<'a, 'll, 'tcx> {
             load: &'ll Value,
             scalar: &abi::Scalar,
         ) {
-            let vr = scalar.valid_range.clone();
             match scalar.value {
                 abi::Int(..) => {
                     let range = scalar.valid_range_exclusive(bx);
@@ -470,7 +469,7 @@ impl BuilderMethods<'a, 'tcx> for Builder<'a, 'll, 'tcx> {
                         bx.range_metadata(load, range);
                     }
                 }
-                abi::Pointer if vr.start() < vr.end() && !vr.contains(&0) => {
+                abi::Pointer if !scalar.valid_range.contains_zero() => {
                     bx.nonnull_metadata(load);
                 }
                 _ => {}
diff --git a/compiler/rustc_codegen_llvm/src/consts.rs b/compiler/rustc_codegen_llvm/src/consts.rs
index e1baf95e1d9..ec92bd686d2 100644
--- a/compiler/rustc_codegen_llvm/src/consts.rs
+++ b/compiler/rustc_codegen_llvm/src/consts.rs
@@ -16,7 +16,9 @@ use rustc_middle::mir::interpret::{
 use rustc_middle::mir::mono::MonoItem;
 use rustc_middle::ty::{self, Instance, Ty};
 use rustc_middle::{bug, span_bug};
-use rustc_target::abi::{AddressSpace, Align, HasDataLayout, LayoutOf, Primitive, Scalar, Size};
+use rustc_target::abi::{
+    AddressSpace, Align, HasDataLayout, LayoutOf, Primitive, Scalar, Size, WrappingRange,
+};
 use tracing::debug;
 
 pub fn const_alloc_to_llvm(cx: &CodegenCx<'ll, '_>, alloc: &Allocation) -> &'ll Value {
@@ -59,7 +61,7 @@ pub fn const_alloc_to_llvm(cx: &CodegenCx<'ll, '_>, alloc: &Allocation) -> &'ll
                 Pointer::new(alloc_id, Size::from_bytes(ptr_offset)),
                 &cx.tcx,
             ),
-            &Scalar { value: Primitive::Pointer, valid_range: 0..=!0 },
+            &Scalar { value: Primitive::Pointer, valid_range: WrappingRange { start: 0, end: !0 } },
             cx.type_i8p_ext(address_space),
         ));
         next_offset = offset + pointer_size;
diff --git a/compiler/rustc_codegen_ssa/src/debuginfo/type_names.rs b/compiler/rustc_codegen_ssa/src/debuginfo/type_names.rs
index 81e905b1b5f..f0b32c96309 100644
--- a/compiler/rustc_codegen_ssa/src/debuginfo/type_names.rs
+++ b/compiler/rustc_codegen_ssa/src/debuginfo/type_names.rs
@@ -406,11 +406,11 @@ fn push_debuginfo_type_name<'tcx>(
             let dataful_discriminant_range =
                 &dataful_variant_layout.largest_niche.as_ref().unwrap().scalar.valid_range;
 
-            let min = dataful_discriminant_range.start();
-            let min = tag.value.size(&tcx).truncate(*min);
+            let min = dataful_discriminant_range.start;
+            let min = tag.value.size(&tcx).truncate(min);
 
-            let max = dataful_discriminant_range.end();
-            let max = tag.value.size(&tcx).truncate(*max);
+            let max = dataful_discriminant_range.end;
+            let max = tag.value.size(&tcx).truncate(max);
 
             let dataful_variant_name = def.variants[*dataful_variant].ident.as_str();
 
diff --git a/compiler/rustc_codegen_ssa/src/mir/rvalue.rs b/compiler/rustc_codegen_ssa/src/mir/rvalue.rs
index 65869483025..02e2db54e74 100644
--- a/compiler/rustc_codegen_ssa/src/mir/rvalue.rs
+++ b/compiler/rustc_codegen_ssa/src/mir/rvalue.rs
@@ -310,15 +310,15 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
 
                                 let er = scalar.valid_range_exclusive(bx.cx());
                                 if er.end != er.start
-                                    && scalar.valid_range.end() >= scalar.valid_range.start()
+                                    && scalar.valid_range.end >= scalar.valid_range.start
                                 {
                                     // We want `table[e as usize ± k]` to not
                                     // have bound checks, and this is the most
                                     // convenient place to put the `assume`s.
-                                    if *scalar.valid_range.start() > 0 {
+                                    if scalar.valid_range.start > 0 {
                                         let enum_value_lower_bound = bx
                                             .cx()
-                                            .const_uint_big(ll_t_in, *scalar.valid_range.start());
+                                            .const_uint_big(ll_t_in, scalar.valid_range.start);
                                         let cmp_start = bx.icmp(
                                             IntPredicate::IntUGE,
                                             llval,
@@ -328,7 +328,7 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
                                     }
 
                                     let enum_value_upper_bound =
-                                        bx.cx().const_uint_big(ll_t_in, *scalar.valid_range.end());
+                                        bx.cx().const_uint_big(ll_t_in, scalar.valid_range.end);
                                     let cmp_end = bx.icmp(
                                         IntPredicate::IntULE,
                                         llval,
diff --git a/compiler/rustc_lint/src/types.rs b/compiler/rustc_lint/src/types.rs
index ef8aee8f64e..829a2abef0d 100644
--- a/compiler/rustc_lint/src/types.rs
+++ b/compiler/rustc_lint/src/types.rs
@@ -795,7 +795,7 @@ crate fn repr_nullable_ptr<'tcx>(
         // Return the nullable type this Option-like enum can be safely represented with.
         let field_ty_abi = &cx.layout_of(field_ty).unwrap().abi;
         if let Abi::Scalar(field_ty_scalar) = field_ty_abi {
-            match (field_ty_scalar.valid_range.start(), field_ty_scalar.valid_range.end()) {
+            match (field_ty_scalar.valid_range.start, field_ty_scalar.valid_range.end) {
                 (0, _) => unreachable!("Non-null optimisation extended to a non-zero value."),
                 (1, _) => {
                     return Some(get_nullable_type(cx, field_ty).unwrap());
diff --git a/compiler/rustc_middle/src/ty/layout.rs b/compiler/rustc_middle/src/ty/layout.rs
index 80c99872dd7..0cbe57455a1 100644
--- a/compiler/rustc_middle/src/ty/layout.rs
+++ b/compiler/rustc_middle/src/ty/layout.rs
@@ -499,7 +499,7 @@ impl<'tcx> LayoutCx<'tcx, TyCtxt<'tcx>> {
         let scalar_unit = |value: Primitive| {
             let bits = value.size(dl).bits();
             assert!(bits <= 128);
-            Scalar { value, valid_range: 0..=(!0 >> (128 - bits)) }
+            Scalar { value, valid_range: WrappingRange { start: 0, end: (!0 >> (128 - bits)) } }
         };
         let scalar = |value: Primitive| tcx.intern_layout(Layout::scalar(self, scalar_unit(value)));
 
@@ -512,11 +512,14 @@ impl<'tcx> LayoutCx<'tcx, TyCtxt<'tcx>> {
             // Basic scalars.
             ty::Bool => tcx.intern_layout(Layout::scalar(
                 self,
-                Scalar { value: Int(I8, false), valid_range: 0..=1 },
+                Scalar { value: Int(I8, false), valid_range: WrappingRange { start: 0, end: 1 } },
             )),
             ty::Char => tcx.intern_layout(Layout::scalar(
                 self,
-                Scalar { value: Int(I32, false), valid_range: 0..=0x10FFFF },
+                Scalar {
+                    value: Int(I32, false),
+                    valid_range: WrappingRange { start: 0, end: 0x10FFFF },
+                },
             )),
             ty::Int(ity) => scalar(Int(Integer::from_int_ty(dl, ity), true)),
             ty::Uint(ity) => scalar(Int(Integer::from_uint_ty(dl, ity), false)),
@@ -526,7 +529,7 @@ impl<'tcx> LayoutCx<'tcx, TyCtxt<'tcx>> {
             }),
             ty::FnPtr(_) => {
                 let mut ptr = scalar_unit(Pointer);
-                ptr.valid_range = 1..=*ptr.valid_range.end();
+                ptr.valid_range = ptr.valid_range.with_start(1);
                 tcx.intern_layout(Layout::scalar(self, ptr))
             }
 
@@ -544,7 +547,7 @@ impl<'tcx> LayoutCx<'tcx, TyCtxt<'tcx>> {
             ty::Ref(_, pointee, _) | ty::RawPtr(ty::TypeAndMut { ty: pointee, .. }) => {
                 let mut data_ptr = scalar_unit(Pointer);
                 if !ty.is_unsafe_ptr() {
-                    data_ptr.valid_range = 1..=*data_ptr.valid_range.end();
+                    data_ptr.valid_range = data_ptr.valid_range.with_start(1);
                 }
 
                 let pointee = tcx.normalize_erasing_regions(param_env, pointee);
@@ -560,7 +563,7 @@ impl<'tcx> LayoutCx<'tcx, TyCtxt<'tcx>> {
                     ty::Slice(_) | ty::Str => scalar_unit(Int(dl.ptr_sized_integer(), false)),
                     ty::Dynamic(..) => {
                         let mut vtable = scalar_unit(Pointer);
-                        vtable.valid_range = 1..=*vtable.valid_range.end();
+                        vtable.valid_range = vtable.valid_range.with_start(1);
                         vtable
                     }
                     _ => return Err(LayoutError::Unknown(unsized_part)),
@@ -933,14 +936,14 @@ impl<'tcx> LayoutCx<'tcx, TyCtxt<'tcx>> {
                             if let Bound::Included(start) = start {
                                 // FIXME(eddyb) this might be incorrect - it doesn't
                                 // account for wrap-around (end < start) ranges.
-                                assert!(*scalar.valid_range.start() <= start);
-                                scalar.valid_range = start..=*scalar.valid_range.end();
+                                assert!(scalar.valid_range.start <= start);
+                                scalar.valid_range.start = start;
                             }
                             if let Bound::Included(end) = end {
                                 // FIXME(eddyb) this might be incorrect - it doesn't
                                 // account for wrap-around (end < start) ranges.
-                                assert!(*scalar.valid_range.end() >= end);
-                                scalar.valid_range = *scalar.valid_range.start()..=end;
+                                assert!(scalar.valid_range.end >= end);
+                                scalar.valid_range.end = end;
                             }
 
                             // Update `largest_niche` if we have introduced a larger niche.
@@ -1256,7 +1259,10 @@ impl<'tcx> LayoutCx<'tcx, TyCtxt<'tcx>> {
                 let tag_mask = !0u128 >> (128 - ity.size().bits());
                 let tag = Scalar {
                     value: Int(ity, signed),
-                    valid_range: (min as u128 & tag_mask)..=(max as u128 & tag_mask),
+                    valid_range: WrappingRange {
+                        start: (min as u128 & tag_mask),
+                        end: (max as u128 & tag_mask),
+                    },
                 };
                 let mut abi = Abi::Aggregate { sized: true };
                 if tag.value.size(dl) == size {
@@ -1535,7 +1541,10 @@ impl<'tcx> LayoutCx<'tcx, TyCtxt<'tcx>> {
         let max_discr = (info.variant_fields.len() - 1) as u128;
         let discr_int = Integer::fit_unsigned(max_discr);
         let discr_int_ty = discr_int.to_ty(tcx, false);
-        let tag = Scalar { value: Primitive::Int(discr_int, false), valid_range: 0..=max_discr };
+        let tag = Scalar {
+            value: Primitive::Int(discr_int, false),
+            valid_range: WrappingRange { start: 0, end: max_discr },
+        };
         let tag_layout = self.tcx.intern_layout(Layout::scalar(self, tag.clone()));
         let tag_layout = TyAndLayout { ty: discr_int_ty, layout: tag_layout };
 
@@ -2846,10 +2855,8 @@ where
                 return;
             }
 
-            if scalar.valid_range.start() < scalar.valid_range.end() {
-                if *scalar.valid_range.start() > 0 {
-                    attrs.set(ArgAttribute::NonNull);
-                }
+            if !scalar.valid_range.contains_zero() {
+                attrs.set(ArgAttribute::NonNull);
             }
 
             if let Some(pointee) = layout.pointee_info_at(cx, offset) {
diff --git a/compiler/rustc_mir/src/interpret/validity.rs b/compiler/rustc_mir/src/interpret/validity.rs
index b0cd6405eb9..2bb2f887257 100644
--- a/compiler/rustc_mir/src/interpret/validity.rs
+++ b/compiler/rustc_mir/src/interpret/validity.rs
@@ -7,7 +7,6 @@
 use std::convert::TryFrom;
 use std::fmt::Write;
 use std::num::NonZeroUsize;
-use std::ops::RangeInclusive;
 
 use rustc_data_structures::fx::FxHashSet;
 use rustc_hir as hir;
@@ -15,7 +14,9 @@ use rustc_middle::mir::interpret::InterpError;
 use rustc_middle::ty;
 use rustc_middle::ty::layout::TyAndLayout;
 use rustc_span::symbol::{sym, Symbol};
-use rustc_target::abi::{Abi, LayoutOf, Scalar as ScalarAbi, Size, VariantIdx, Variants};
+use rustc_target::abi::{
+    Abi, LayoutOf, Scalar as ScalarAbi, Size, VariantIdx, Variants, WrappingRange,
+};
 
 use std::hash::Hash;
 
@@ -181,22 +182,10 @@ fn write_path(out: &mut String, path: &[PathElem]) {
     }
 }
 
-// Test if a range that wraps at overflow contains `test`
-fn wrapping_range_contains(r: &RangeInclusive<u128>, test: u128) -> bool {
-    let (lo, hi) = r.clone().into_inner();
-    if lo > hi {
-        // Wrapped
-        (..=hi).contains(&test) || (lo..).contains(&test)
-    } else {
-        // Normal
-        r.contains(&test)
-    }
-}
-
 // Formats such that a sentence like "expected something {}" to mean
 // "expected something <in the given range>" makes sense.
-fn wrapping_range_format(r: &RangeInclusive<u128>, max_hi: u128) -> String {
-    let (lo, hi) = r.clone().into_inner();
+fn wrapping_range_format(r: WrappingRange, max_hi: u128) -> String {
+    let WrappingRange { start: lo, end: hi } = r;
     assert!(hi <= max_hi);
     if lo > hi {
         format!("less or equal to {}, or greater or equal to {}", hi, lo)
@@ -634,8 +623,8 @@ impl<'rt, 'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> ValidityVisitor<'rt, 'mir, '
         scalar_layout: &ScalarAbi,
     ) -> InterpResult<'tcx> {
         let value = self.read_scalar(op)?;
-        let valid_range = &scalar_layout.valid_range;
-        let (lo, hi) = valid_range.clone().into_inner();
+        let valid_range = scalar_layout.valid_range.clone();
+        let WrappingRange { start: lo, end: hi } = valid_range;
         // Determine the allowed range
         // `max_hi` is as big as the size fits
         let max_hi = u128::MAX >> (128 - op.layout.size.bits());
@@ -684,7 +673,7 @@ impl<'rt, 'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> ValidityVisitor<'rt, 'mir, '
             Ok(int) => int.assert_bits(op.layout.size),
         };
         // Now compare. This is slightly subtle because this is a special "wrap-around" range.
-        if wrapping_range_contains(&valid_range, bits) {
+        if valid_range.contains(bits) {
             Ok(())
         } else {
             throw_validation_failure!(self.path,
diff --git a/compiler/rustc_target/src/abi/mod.rs b/compiler/rustc_target/src/abi/mod.rs
index 8ef6e142cae..d206df46120 100644
--- a/compiler/rustc_target/src/abi/mod.rs
+++ b/compiler/rustc_target/src/abi/mod.rs
@@ -677,32 +677,80 @@ impl Primitive {
     }
 }
 
+/// Inclusive wrap-around range of valid values, that is, if
+/// start > end, it represents `start..=MAX`,
+/// followed by `0..=end`.
+///
+/// That is, for an i8 primitive, a range of `254..=2` means following
+/// sequence:
+///
+///    254 (-2), 255 (-1), 0, 1, 2
+///
+/// This is intended specifically to mirror LLVM’s `!range` metadata,
+/// semantics.
+#[derive(Clone, PartialEq, Eq, Hash)]
+#[derive(HashStable_Generic)]
+pub struct WrappingRange {
+    pub start: u128,
+    pub end: u128,
+}
+
+impl WrappingRange {
+    /// Returns `true` if `v` is contained in the range.
+    #[inline(always)]
+    pub fn contains(&self, v: u128) -> bool {
+        if self.start <= self.end {
+            self.start <= v && v <= self.end
+        } else {
+            self.start <= v || v <= self.end
+        }
+    }
+
+    /// Returns `true` if zero is contained in the range.
+    /// Equal to `range.contains(0)` but should be faster.
+    #[inline(always)]
+    pub fn contains_zero(&self) -> bool {
+        self.start > self.end || self.start == 0
+    }
+
+    /// Returns `self` with replaced `start`
+    #[inline(always)]
+    pub fn with_start(mut self, start: u128) -> Self {
+        self.start = start;
+        self
+    }
+
+    /// Returns `self` with replaced `end`
+    #[inline(always)]
+    pub fn with_end(mut self, end: u128) -> Self {
+        self.end = end;
+        self
+    }
+}
+
+impl fmt::Debug for WrappingRange {
+    fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
+        write!(fmt, "{}..={}", self.start, self.end)?;
+        Ok(())
+    }
+}
+
 /// Information about one scalar component of a Rust type.
 #[derive(Clone, PartialEq, Eq, Hash, Debug)]
 #[derive(HashStable_Generic)]
 pub struct Scalar {
     pub value: Primitive,
 
-    /// Inclusive wrap-around range of valid values, that is, if
-    /// start > end, it represents `start..=MAX`,
-    /// followed by `0..=end`.
-    ///
-    /// That is, for an i8 primitive, a range of `254..=2` means following
-    /// sequence:
-    ///
-    ///    254 (-2), 255 (-1), 0, 1, 2
-    ///
-    /// This is intended specifically to mirror LLVM’s `!range` metadata,
-    /// semantics.
     // FIXME(eddyb) always use the shortest range, e.g., by finding
     // the largest space between two consecutive valid values and
     // taking everything else as the (shortest) valid range.
-    pub valid_range: RangeInclusive<u128>,
+    pub valid_range: WrappingRange,
 }
 
 impl Scalar {
     pub fn is_bool(&self) -> bool {
-        matches!(self.value, Int(I8, false)) && self.valid_range == (0..=1)
+        matches!(self.value, Int(I8, false))
+            && matches!(self.valid_range, WrappingRange { start: 0, end: 1 })
     }
 
     /// Returns the valid range as a `x..y` range.
@@ -715,8 +763,8 @@ impl Scalar {
         let bits = self.value.size(cx).bits();
         assert!(bits <= 128);
         let mask = !0u128 >> (128 - bits);
-        let start = *self.valid_range.start();
-        let end = *self.valid_range.end();
+        let start = self.valid_range.start;
+        let end = self.valid_range.end;
         assert_eq!(start, start & mask);
         assert_eq!(end, end & mask);
         start..(end.wrapping_add(1) & mask)
@@ -971,14 +1019,14 @@ impl Niche {
         let max_value = !0u128 >> (128 - bits);
 
         // Find out how many values are outside the valid range.
-        let niche = v.end().wrapping_add(1)..*v.start();
+        let niche = v.end.wrapping_add(1)..v.start;
         niche.end.wrapping_sub(niche.start) & max_value
     }
 
     pub fn reserve<C: HasDataLayout>(&self, cx: &C, count: u128) -> Option<(u128, Scalar)> {
         assert!(count > 0);
 
-        let Scalar { value, valid_range: ref v } = self.scalar;
+        let Scalar { value, valid_range: v } = self.scalar.clone();
         let bits = value.size(cx).bits();
         assert!(bits <= 128);
         let max_value = !0u128 >> (128 - bits);
@@ -988,24 +1036,14 @@ impl Niche {
         }
 
         // Compute the range of invalid values being reserved.
-        let start = v.end().wrapping_add(1) & max_value;
-        let end = v.end().wrapping_add(count) & max_value;
-
-        // If the `end` of our range is inside the valid range,
-        // then we ran out of invalid values.
-        // FIXME(eddyb) abstract this with a wraparound range type.
-        let valid_range_contains = |x| {
-            if v.start() <= v.end() {
-                *v.start() <= x && x <= *v.end()
-            } else {
-                *v.start() <= x || x <= *v.end()
-            }
-        };
-        if valid_range_contains(end) {
+        let start = v.end.wrapping_add(1) & max_value;
+        let end = v.end.wrapping_add(count) & max_value;
+
+        if v.contains(end) {
             return None;
         }
 
-        Some((start, Scalar { value, valid_range: *v.start()..=end }))
+        Some((start, Scalar { value, valid_range: v.with_end(end) }))
     }
 }
 
@@ -1212,9 +1250,8 @@ impl<'a, Ty> TyAndLayout<'a, Ty> {
     {
         let scalar_allows_raw_init = move |s: &Scalar| -> bool {
             if zero {
-                let range = &s.valid_range;
                 // The range must contain 0.
-                range.contains(&0) || (*range.start() > *range.end()) // wrap-around allows 0
+                s.valid_range.contains_zero()
             } else {
                 // The range must include all values. `valid_range_exclusive` handles
                 // the wrap-around using target arithmetic; with wrap-around then the full