implement valtrees as the type-system representation for constant values

5 files changed, 169 insertions, 93 deletions

diff --git a/compiler/rustc_mir_build/src/build/expr/as_constant.rs b/compiler/rustc_mir_build/src/build/expr/as_constant.rs
index a87134d1f52..3d6e50f0c06 100644
--- a/compiler/rustc_mir_build/src/build/expr/as_constant.rs
+++ b/compiler/rustc_mir_build/src/build/expr/as_constant.rs
@@ -1,12 +1,16 @@
 //! See docs in build/expr/mod.rs
 
-use crate::build::{lit_to_mir_constant, Builder};
+use crate::build::{parse_float_into_constval, Builder};
+use rustc_ast as ast;
 use rustc_hir::def_id::DefId;
-use rustc_middle::mir::interpret::{ConstValue, LitToConstError, LitToConstInput, Scalar};
+use rustc_middle::mir::interpret::{
+    Allocation, ConstValue, LitToConstError, LitToConstInput, Scalar,
+};
 use rustc_middle::mir::*;
 use rustc_middle::thir::*;
 use rustc_middle::ty::subst::SubstsRef;
 use rustc_middle::ty::{self, CanonicalUserTypeAnnotation, Ty, TyCtxt};
+use rustc_target::abi::Size;
 
 impl<'a, 'tcx> Builder<'a, 'tcx> {
     /// Compile `expr`, yielding a compile-time constant. Assumes that
@@ -84,3 +88,54 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
         }
     }
 }
+
+#[instrument(skip(tcx, lit_input))]
+pub(crate) fn lit_to_mir_constant<'tcx>(
+    tcx: TyCtxt<'tcx>,
+    lit_input: LitToConstInput<'tcx>,
+) -> Result<ConstantKind<'tcx>, LitToConstError> {
+    let LitToConstInput { lit, ty, neg } = lit_input;
+    let trunc = |n| {
+        let param_ty = ty::ParamEnv::reveal_all().and(ty);
+        let width = tcx.layout_of(param_ty).map_err(|_| LitToConstError::Reported)?.size;
+        trace!("trunc {} with size {} and shift {}", n, width.bits(), 128 - width.bits());
+        let result = width.truncate(n);
+        trace!("trunc result: {}", result);
+        Ok(ConstValue::Scalar(Scalar::from_uint(result, width)))
+    };
+
+    let value = match (lit, &ty.kind()) {
+        (ast::LitKind::Str(s, _), ty::Ref(_, inner_ty, _)) if inner_ty.is_str() => {
+            let s = s.as_str();
+            let allocation = Allocation::from_bytes_byte_aligned_immutable(s.as_bytes());
+            let allocation = tcx.intern_const_alloc(allocation);
+            ConstValue::Slice { data: allocation, start: 0, end: s.len() }
+        }
+        (ast::LitKind::ByteStr(data), ty::Ref(_, inner_ty, _))
+            if matches!(inner_ty.kind(), ty::Slice(_)) =>
+        {
+            let allocation = Allocation::from_bytes_byte_aligned_immutable(data as &[u8]);
+            let allocation = tcx.intern_const_alloc(allocation);
+            ConstValue::Slice { data: allocation, start: 0, end: data.len() }
+        }
+        (ast::LitKind::ByteStr(data), ty::Ref(_, inner_ty, _)) if inner_ty.is_array() => {
+            let id = tcx.allocate_bytes(data);
+            ConstValue::Scalar(Scalar::from_pointer(id.into(), &tcx))
+        }
+        (ast::LitKind::Byte(n), ty::Uint(ty::UintTy::U8)) => {
+            ConstValue::Scalar(Scalar::from_uint(*n, Size::from_bytes(1)))
+        }
+        (ast::LitKind::Int(n, _), ty::Uint(_)) | (ast::LitKind::Int(n, _), ty::Int(_)) => {
+            trunc(if neg { (*n as i128).overflowing_neg().0 as u128 } else { *n })?
+        }
+        (ast::LitKind::Float(n, _), ty::Float(fty)) => {
+            parse_float_into_constval(*n, *fty, neg).ok_or(LitToConstError::Reported)?
+        }
+        (ast::LitKind::Bool(b), ty::Bool) => ConstValue::Scalar(Scalar::from_bool(*b)),
+        (ast::LitKind::Char(c), ty::Char) => ConstValue::Scalar(Scalar::from_char(*c)),
+        (ast::LitKind::Err(_), _) => return Err(LitToConstError::Reported),
+        _ => return Err(LitToConstError::TypeError),
+    };
+
+    Ok(ConstantKind::Val(value, ty))
+}
diff --git a/compiler/rustc_mir_build/src/build/mod.rs b/compiler/rustc_mir_build/src/build/mod.rs
index 793066e43c3..51f7aa642c8 100644
--- a/compiler/rustc_mir_build/src/build/mod.rs
+++ b/compiler/rustc_mir_build/src/build/mod.rs
@@ -1,7 +1,7 @@
 use crate::build;
 use crate::build::expr::as_place::PlaceBuilder;
 use crate::build::scope::DropKind;
-use crate::thir::constant::parse_float;
+use crate::thir::constant::parse_float_into_scalar;
 use crate::thir::pattern::pat_from_hir;
 use rustc_ast as ast;
 use rustc_data_structures::fx::FxHashMap;
@@ -14,14 +14,16 @@ use rustc_index::vec::{Idx, IndexVec};
 use rustc_infer::infer::{InferCtxt, TyCtxtInferExt};
 use rustc_middle::hir::place::PlaceBase as HirPlaceBase;
 use rustc_middle::middle::region;
-use rustc_middle::mir::interpret::Allocation;
-use rustc_middle::mir::interpret::{ConstValue, LitToConstError, LitToConstInput, Scalar};
+use rustc_middle::mir::interpret::{
+    Allocation, ConstValue, LitToConstError, LitToConstInput, Scalar,
+};
 use rustc_middle::mir::*;
 use rustc_middle::thir::{BindingMode, Expr, ExprId, LintLevel, LocalVarId, PatKind, Thir};
 use rustc_middle::ty::subst::Subst;
 use rustc_middle::ty::{self, Ty, TyCtxt, TypeFoldable, TypeckResults};
 use rustc_span::symbol::sym;
 use rustc_span::Span;
+use rustc_span::Symbol;
 use rustc_target::abi::Size;
 use rustc_target::spec::abi::Abi;
 
@@ -266,57 +268,6 @@ fn mir_build(tcx: TyCtxt<'_>, def: ty::WithOptConstParam<LocalDefId>) -> Body<'_
     })
 }
 
-#[instrument(skip(tcx, lit_input))]
-pub(crate) fn lit_to_mir_constant<'tcx>(
-    tcx: TyCtxt<'tcx>,
-    lit_input: LitToConstInput<'tcx>,
-) -> Result<ConstantKind<'tcx>, LitToConstError> {
-    let LitToConstInput { lit, ty, neg } = lit_input;
-    let trunc = |n| {
-        let param_ty = ty::ParamEnv::reveal_all().and(ty);
-        let width = tcx.layout_of(param_ty).map_err(|_| LitToConstError::Reported)?.size;
-        trace!("trunc {} with size {} and shift {}", n, width.bits(), 128 - width.bits());
-        let result = width.truncate(n);
-        trace!("trunc result: {}", result);
-        Ok(ConstValue::Scalar(Scalar::from_uint(result, width)))
-    };
-
-    let value = match (lit, &ty.kind()) {
-        (ast::LitKind::Str(s, _), ty::Ref(_, inner_ty, _)) if inner_ty.is_str() => {
-            let s = s.as_str();
-            let allocation = Allocation::from_bytes_byte_aligned_immutable(s.as_bytes());
-            let allocation = tcx.intern_const_alloc(allocation);
-            ConstValue::Slice { data: allocation, start: 0, end: s.len() }
-        }
-        (ast::LitKind::ByteStr(data), ty::Ref(_, inner_ty, _))
-            if matches!(inner_ty.kind(), ty::Slice(_)) =>
-        {
-            let allocation = Allocation::from_bytes_byte_aligned_immutable(data as &[u8]);
-            let allocation = tcx.intern_const_alloc(allocation);
-            ConstValue::Slice { data: allocation, start: 0, end: data.len() }
-        }
-        (ast::LitKind::ByteStr(data), ty::Ref(_, inner_ty, _)) if inner_ty.is_array() => {
-            let id = tcx.allocate_bytes(data);
-            ConstValue::Scalar(Scalar::from_pointer(id.into(), &tcx))
-        }
-        (ast::LitKind::Byte(n), ty::Uint(ty::UintTy::U8)) => {
-            ConstValue::Scalar(Scalar::from_uint(*n, Size::from_bytes(1)))
-        }
-        (ast::LitKind::Int(n, _), ty::Uint(_)) | (ast::LitKind::Int(n, _), ty::Int(_)) => {
-            trunc(if neg { (*n as i128).overflowing_neg().0 as u128 } else { *n })?
-        }
-        (ast::LitKind::Float(n, _), ty::Float(fty)) => {
-            parse_float(*n, *fty, neg).ok_or(LitToConstError::Reported)?
-        }
-        (ast::LitKind::Bool(b), ty::Bool) => ConstValue::Scalar(Scalar::from_bool(*b)),
-        (ast::LitKind::Char(c), ty::Char) => ConstValue::Scalar(Scalar::from_char(*c)),
-        (ast::LitKind::Err(_), _) => return Err(LitToConstError::Reported),
-        _ => return Err(LitToConstError::TypeError),
-    };
-
-    Ok(ConstantKind::Val(value, ty))
-}
-
 ///////////////////////////////////////////////////////////////////////////
 // BuildMir -- walks a crate, looking for fn items and methods to build MIR from
 
@@ -1137,6 +1088,65 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
     }
 }
 
+fn parse_float_into_constval<'tcx>(
+    num: Symbol,
+    float_ty: ty::FloatTy,
+    neg: bool,
+) -> Option<ConstValue<'tcx>> {
+    parse_float_into_scalar(num, float_ty, neg).map(ConstValue::Scalar)
+}
+
+#[instrument(skip(tcx, lit_input))]
+pub(crate) fn lit_to_mir_constant<'tcx>(
+    tcx: TyCtxt<'tcx>,
+    lit_input: LitToConstInput<'tcx>,
+) -> Result<ConstantKind<'tcx>, LitToConstError> {
+    let LitToConstInput { lit, ty, neg } = lit_input;
+    let trunc = |n| {
+        let param_ty = ty::ParamEnv::reveal_all().and(ty);
+        let width = tcx.layout_of(param_ty).map_err(|_| LitToConstError::Reported)?.size;
+        trace!("trunc {} with size {} and shift {}", n, width.bits(), 128 - width.bits());
+        let result = width.truncate(n);
+        trace!("trunc result: {}", result);
+        Ok(ConstValue::Scalar(Scalar::from_uint(result, width)))
+    };
+
+    let value = match (lit, &ty.kind()) {
+        (ast::LitKind::Str(s, _), ty::Ref(_, inner_ty, _)) if inner_ty.is_str() => {
+            let s = s.as_str();
+            let allocation = Allocation::from_bytes_byte_aligned_immutable(s.as_bytes());
+            let allocation = tcx.intern_const_alloc(allocation);
+            ConstValue::Slice { data: allocation, start: 0, end: s.len() }
+        }
+        (ast::LitKind::ByteStr(data), ty::Ref(_, inner_ty, _))
+            if matches!(inner_ty.kind(), ty::Slice(_)) =>
+        {
+            let allocation = Allocation::from_bytes_byte_aligned_immutable(data as &[u8]);
+            let allocation = tcx.intern_const_alloc(allocation);
+            ConstValue::Slice { data: allocation, start: 0, end: data.len() }
+        }
+        (ast::LitKind::ByteStr(data), ty::Ref(_, inner_ty, _)) if inner_ty.is_array() => {
+            let id = tcx.allocate_bytes(data);
+            ConstValue::Scalar(Scalar::from_pointer(id.into(), &tcx))
+        }
+        (ast::LitKind::Byte(n), ty::Uint(ty::UintTy::U8)) => {
+            ConstValue::Scalar(Scalar::from_uint(*n, Size::from_bytes(1)))
+        }
+        (ast::LitKind::Int(n, _), ty::Uint(_)) | (ast::LitKind::Int(n, _), ty::Int(_)) => {
+            trunc(if neg { (*n as i128).overflowing_neg().0 as u128 } else { *n })?
+        }
+        (ast::LitKind::Float(n, _), ty::Float(fty)) => {
+            parse_float_into_constval(*n, *fty, neg).ok_or(LitToConstError::Reported)?
+        }
+        (ast::LitKind::Bool(b), ty::Bool) => ConstValue::Scalar(Scalar::from_bool(*b)),
+        (ast::LitKind::Char(c), ty::Char) => ConstValue::Scalar(Scalar::from_char(*c)),
+        (ast::LitKind::Err(_), _) => return Err(LitToConstError::Reported),
+        _ => return Err(LitToConstError::TypeError),
+    };
+
+    Ok(ConstantKind::Val(value, ty))
+}
+
 ///////////////////////////////////////////////////////////////////////////
 // Builder methods are broken up into modules, depending on what kind
 // of thing is being lowered. Note that they use the `unpack` macro
diff --git a/compiler/rustc_mir_build/src/thir/constant.rs b/compiler/rustc_mir_build/src/thir/constant.rs
index d82e6688633..cfb09ecedd6 100644
--- a/compiler/rustc_mir_build/src/thir/constant.rs
+++ b/compiler/rustc_mir_build/src/thir/constant.rs
@@ -1,13 +1,10 @@
+use rustc_apfloat::ieee::{Double, Single};
 use rustc_apfloat::Float;
 use rustc_ast as ast;
-use rustc_middle::mir::interpret::{
-    Allocation, ConstValue, LitToConstError, LitToConstInput, Scalar,
-};
-use rustc_middle::ty::{self, ParamEnv, TyCtxt};
+use rustc_middle::mir::interpret::{LitToConstError, LitToConstInput, Scalar};
+use rustc_middle::ty::{self, ParamEnv, ScalarInt, TyCtxt};
 use rustc_span::symbol::Symbol;
-use rustc_target::abi::Size;
 
-// FIXME Once valtrees are available, get rid of this function and the query
 pub(crate) fn lit_to_const<'tcx>(
     tcx: TyCtxt<'tcx>,
     lit_input: LitToConstInput<'tcx>,
@@ -20,58 +17,59 @@ pub(crate) fn lit_to_const<'tcx>(
         trace!("trunc {} with size {} and shift {}", n, width.bits(), 128 - width.bits());
         let result = width.truncate(n);
         trace!("trunc result: {}", result);
-        Ok(ConstValue::Scalar(Scalar::from_uint(result, width)))
+
+        Ok(ScalarInt::try_from_uint(result, width)
+            .unwrap_or_else(|| bug!("expected to create ScalarInt from uint {:?}", result)))
     };
 
-    let lit = match (lit, &ty.kind()) {
+    let valtree = match (lit, &ty.kind()) {
         (ast::LitKind::Str(s, _), ty::Ref(_, inner_ty, _)) if inner_ty.is_str() => {
-            let s = s.as_str();
-            let allocation = Allocation::from_bytes_byte_aligned_immutable(s.as_bytes());
-            let allocation = tcx.intern_const_alloc(allocation);
-            ConstValue::Slice { data: allocation, start: 0, end: s.len() }
+            let str_bytes = s.as_str().as_bytes();
+            ty::ValTree::from_raw_bytes(tcx, str_bytes)
         }
         (ast::LitKind::ByteStr(data), ty::Ref(_, inner_ty, _))
             if matches!(inner_ty.kind(), ty::Slice(_)) =>
         {
-            let allocation = Allocation::from_bytes_byte_aligned_immutable(data as &[u8]);
-            let allocation = tcx.intern_const_alloc(allocation);
-            ConstValue::Slice { data: allocation, start: 0, end: data.len() }
+            let bytes = data as &[u8];
+            ty::ValTree::from_raw_bytes(tcx, bytes)
         }
         (ast::LitKind::ByteStr(data), ty::Ref(_, inner_ty, _)) if inner_ty.is_array() => {
-            let id = tcx.allocate_bytes(data);
-            ConstValue::Scalar(Scalar::from_pointer(id.into(), &tcx))
+            let bytes = data as &[u8];
+            ty::ValTree::from_raw_bytes(tcx, bytes)
         }
         (ast::LitKind::Byte(n), ty::Uint(ty::UintTy::U8)) => {
-            ConstValue::Scalar(Scalar::from_uint(*n, Size::from_bytes(1)))
+            ty::ValTree::from_scalar_int((*n).into())
         }
         (ast::LitKind::Int(n, _), ty::Uint(_)) | (ast::LitKind::Int(n, _), ty::Int(_)) => {
-            trunc(if neg { (*n as i128).overflowing_neg().0 as u128 } else { *n })?
+            let scalar_int =
+                trunc(if neg { (*n as i128).overflowing_neg().0 as u128 } else { *n })?;
+            ty::ValTree::from_scalar_int(scalar_int)
         }
         (ast::LitKind::Float(n, _), ty::Float(fty)) => {
-            parse_float(*n, *fty, neg).ok_or(LitToConstError::Reported)?
+            parse_float_into_valtree(*n, *fty, neg).ok_or(LitToConstError::Reported)?
         }
-        (ast::LitKind::Bool(b), ty::Bool) => ConstValue::Scalar(Scalar::from_bool(*b)),
-        (ast::LitKind::Char(c), ty::Char) => ConstValue::Scalar(Scalar::from_char(*c)),
+        (ast::LitKind::Bool(b), ty::Bool) => ty::ValTree::from_scalar_int((*b).into()),
+        (ast::LitKind::Char(c), ty::Char) => ty::ValTree::from_scalar_int((*c).into()),
         (ast::LitKind::Err(_), _) => return Err(LitToConstError::Reported),
         _ => return Err(LitToConstError::TypeError),
     };
-    Ok(ty::Const::from_value(tcx, lit, ty))
+
+    Ok(ty::Const::from_value(tcx, valtree, ty))
 }
 
-// FIXME move this to rustc_mir_build::build
-pub(crate) fn parse_float<'tcx>(
+pub(crate) fn parse_float_into_scalar(
     num: Symbol,
-    fty: ty::FloatTy,
+    float_ty: ty::FloatTy,
     neg: bool,
-) -> Option<ConstValue<'tcx>> {
+) -> Option<Scalar> {
     let num = num.as_str();
-    use rustc_apfloat::ieee::{Double, Single};
-    let scalar = match fty {
+    match float_ty {
         ty::FloatTy::F32 => {
             let Ok(rust_f) = num.parse::<f32>() else { return None };
             let mut f = num.parse::<Single>().unwrap_or_else(|e| {
                 panic!("apfloat::ieee::Single failed to parse `{}`: {:?}", num, e)
             });
+
             assert!(
                 u128::from(rust_f.to_bits()) == f.to_bits(),
                 "apfloat::ieee::Single gave different result for `{}`: \
@@ -82,16 +80,19 @@ pub(crate) fn parse_float<'tcx>(
                 Single::from_bits(rust_f.to_bits().into()),
                 rust_f.to_bits()
             );
+
             if neg {
                 f = -f;
             }
-            Scalar::from_f32(f)
+
+            Some(Scalar::from_f32(f))
         }
         ty::FloatTy::F64 => {
             let Ok(rust_f) = num.parse::<f64>() else { return None };
             let mut f = num.parse::<Double>().unwrap_or_else(|e| {
                 panic!("apfloat::ieee::Double failed to parse `{}`: {:?}", num, e)
             });
+
             assert!(
                 u128::from(rust_f.to_bits()) == f.to_bits(),
                 "apfloat::ieee::Double gave different result for `{}`: \
@@ -102,12 +103,20 @@ pub(crate) fn parse_float<'tcx>(
                 Double::from_bits(rust_f.to_bits().into()),
                 rust_f.to_bits()
             );
+
             if neg {
                 f = -f;
             }
-            Scalar::from_f64(f)
+
+            Some(Scalar::from_f64(f))
         }
-    };
+    }
+}
 
-    Some(ConstValue::Scalar(scalar))
+fn parse_float_into_valtree<'tcx>(
+    num: Symbol,
+    float_ty: ty::FloatTy,
+    neg: bool,
+) -> Option<ty::ValTree<'tcx>> {
+    parse_float_into_scalar(num, float_ty, neg).map(|s| ty::ValTree::Leaf(s.try_to_int().unwrap()))
 }
diff --git a/compiler/rustc_mir_build/src/thir/pattern/const_to_pat.rs b/compiler/rustc_mir_build/src/thir/pattern/const_to_pat.rs
index f694e009ab9..b423c645447 100644
--- a/compiler/rustc_mir_build/src/thir/pattern/const_to_pat.rs
+++ b/compiler/rustc_mir_build/src/thir/pattern/const_to_pat.rs
@@ -371,6 +371,7 @@ impl<'a, 'tcx> ConstToPat<'a, 'tcx> {
             }
             ty::Adt(adt_def, substs) if adt_def.is_enum() => {
                 let destructured = tcx.destructure_mir_constant(param_env, cv);
+
                 PatKind::Variant {
                     adt_def: *adt_def,
                     substs,
@@ -502,7 +503,7 @@ impl<'a, 'tcx> ConstToPat<'a, 'tcx> {
                 // deref pattern.
                 _ => {
                     if !pointee_ty.is_sized(tcx.at(span), param_env) {
-                        // `tcx.deref_const()` below will ICE with an unsized type
+                        // `tcx.deref_mirconstant()` below will ICE with an unsized type
                         // (except slices, which are handled in a separate arm above).
                         let msg = format!("cannot use unsized non-slice type `{}` in constant patterns", pointee_ty);
                         if self.include_lint_checks {
diff --git a/compiler/rustc_mir_build/src/thir/pattern/mod.rs b/compiler/rustc_mir_build/src/thir/pattern/mod.rs
index 83175439b70..e28cb67217c 100644
--- a/compiler/rustc_mir_build/src/thir/pattern/mod.rs
+++ b/compiler/rustc_mir_build/src/thir/pattern/mod.rs
@@ -185,11 +185,11 @@ impl<'a, 'tcx> PatCtxt<'a, 'tcx> {
             }
             (Some(PatKind::Constant { value: lo }), None) => {
                 let hi = ty.numeric_max_val(self.tcx)?;
-                Some((*lo, hi.into()))
+                Some((*lo, mir::ConstantKind::from_const(hi, self.tcx)))
             }
             (None, Some(PatKind::Constant { value: hi })) => {
                 let lo = ty.numeric_min_val(self.tcx)?;
-                Some((lo.into(), *hi))
+                Some((mir::ConstantKind::from_const(lo, self.tcx), *hi))
             }
             _ => None,
         }
@@ -798,11 +798,12 @@ pub(crate) fn compare_const_vals<'tcx>(
     if let ty::Str = ty.kind() && let (
         Some(a_val @ ConstValue::Slice { .. }),
         Some(b_val @ ConstValue::Slice { .. }),
-    ) = (a.try_val(), b.try_val())
+    ) = (a.try_val(tcx), b.try_val(tcx))
     {
         let a_bytes = get_slice_bytes(&tcx, a_val);
         let b_bytes = get_slice_bytes(&tcx, b_val);
         return from_bool(a_bytes == b_bytes);
     }
+
     fallback()
 }