Encode int/float/bool/char patterns directly as ScalarInt

Author: oli-obk

compiler/rustc_mir_build/src/build/matches/simplify.rs

@@ -196,8 +196,8 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
                 Err(match_pair)
             }
 
-            PatKind::Range(PatRange { lo, hi, end }) => {
-                let (range, bias) = match *lo.ty.kind() {
+            PatKind::Range(PatRange { lo, hi, end, ty }) => {
+                let (range, bias) = match *ty.kind() {
                     ty::Char => {
                         (Some(('\u{0000}' as u128, '\u{10FFFF}' as u128, Size::from_bits(32))), 0)
                     }
@@ -215,18 +215,18 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
                     _ => (None, 0),
                 };
                 if let Some((min, max, sz)) = range {
-                    if let (Some(lo), Some(hi)) = (lo.val.try_to_bits(sz), hi.val.try_to_bits(sz)) {
-                        // We want to compare ranges numerically, but the order of the bitwise
-                        // representation of signed integers does not match their numeric order.
-                        // Thus, to correct the ordering, we need to shift the range of signed
-                        // integers to correct the comparison. This is achieved by XORing with a
-                        // bias (see pattern/_match.rs for another pertinent example of this
-                        // pattern).
-                        let (lo, hi) = (lo ^ bias, hi ^ bias);
-                        if lo <= min && (hi > max || hi == max && end == RangeEnd::Included) {
-                            // Irrefutable pattern match.
-                            return Ok(());
-                        }
+                    let lo = lo.assert_bits(sz);
+                    let hi = hi.assert_bits(sz);
+                    // We want to compare ranges numerically, but the order of the bitwise
+                    // representation of signed integers does not match their numeric order.
+                    // Thus, to correct the ordering, we need to shift the range of signed
+                    // integers to correct the comparison. This is achieved by XORing with a
+                    // bias (see pattern/_match.rs for another pertinent example of this
+                    // pattern).
+                    let (lo, hi) = (lo ^ bias, hi ^ bias);
+                    if lo <= min && (hi > max || hi == max && end == RangeEnd::Included) {
+                        // Irrefutable pattern match.
+                        return Ok(());
                     }
                 }
                 Err(match_pair)

compiler/rustc_mir_build/src/build/matches/test.rs

@@ -13,6 +13,7 @@ use crate::thir::*;
 use rustc_data_structures::fx::FxIndexMap;
 use rustc_hir::{LangItem, RangeEnd};
 use rustc_index::bit_set::BitSet;
+use rustc_middle::mir::interpret::ConstValue;
 use rustc_middle::mir::*;
 use rustc_middle::ty::subst::{GenericArg, Subst};
 use rustc_middle::ty::util::IntTypeExt;
@@ -58,8 +59,7 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
             },
 
             PatKind::Range(range) => {
-                assert_eq!(range.lo.ty, match_pair.pattern.ty);
-                assert_eq!(range.hi.ty, match_pair.pattern.ty);
+                assert_eq!(range.ty, match_pair.pattern.ty);
                 Test { span: match_pair.pattern.span, kind: TestKind::Range(range) }
             }
 
@@ -271,11 +271,13 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
                 }
             }
 
-            TestKind::Range(PatRange { ref lo, ref hi, ref end }) => {
+            TestKind::Range(PatRange { lo, hi, ref end, ty }) => {
                 let lower_bound_success = self.cfg.start_new_block();
                 let target_blocks = make_target_blocks(self);
 
                 // Test `val` by computing `lo <= val && val <= hi`, using primitive comparisons.
+                let lo = ty::Const::from_value(self.tcx, ConstValue::Scalar(lo.into()), ty);
+                let hi = ty::Const::from_value(self.tcx, ConstValue::Scalar(hi.into()), ty);
                 let lo = self.literal_operand(test.span, lo);
                 let hi = self.literal_operand(test.span, hi);
                 let val = Operand::Copy(place);
@@ -640,9 +642,17 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
 
                     let tcx = self.tcx;
 
-                    let test_ty = test.lo.ty;
-                    let lo = compare_const_vals(tcx, test.lo, pat.hi, self.param_env, test_ty)?;
-                    let hi = compare_const_vals(tcx, test.hi, pat.lo, self.param_env, test_ty)?;
+                    let test_ty = match_pair.pattern.ty;
+                    let test_lo =
+                        ty::Const::from_value(tcx, ConstValue::Scalar(test.lo.into()), test_ty);
+                    let test_hi =
+                        ty::Const::from_value(tcx, ConstValue::Scalar(test.hi.into()), test_ty);
+                    let pat_lo =
+                        ty::Const::from_value(tcx, ConstValue::Scalar(test.lo.into()), test_ty);
+                    let pat_hi =
+                        ty::Const::from_value(tcx, ConstValue::Scalar(test.hi.into()), test_ty);
+                    let lo = compare_const_vals(tcx, test_lo, pat_hi, self.param_env, test_ty)?;
+                    let hi = compare_const_vals(tcx, test_hi, pat_lo, self.param_env, test_ty)?;
 
                     match (test.end, pat.end, lo, hi) {
                         // pat < test
@@ -769,8 +779,10 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
 
         let tcx = self.tcx;
 
-        let a = compare_const_vals(tcx, range.lo, value, self.param_env, range.lo.ty)?;
-        let b = compare_const_vals(tcx, value, range.hi, self.param_env, range.lo.ty)?;
+        let lo = ty::Const::from_value(tcx, ConstValue::Scalar(range.lo.into()), value.ty);
+        let hi = ty::Const::from_value(tcx, ConstValue::Scalar(range.hi.into()), value.ty);
+        let a = compare_const_vals(tcx, lo, value, self.param_env, value.ty)?;
+        let b = compare_const_vals(tcx, value, hi, self.param_env, value.ty)?;
 
         match (b, range.end) {
             (Less, _) | (Equal, RangeEnd::Included) if a != Greater => Some(true),

compiler/rustc_mir_build/src/thir/pattern/deconstruct_pat.rs

@@ -54,9 +54,10 @@ use rustc_index::vec::Idx;
 
 use rustc_hir::def_id::DefId;
 use rustc_hir::{HirId, RangeEnd};
+use rustc_middle::mir::interpret::ConstValue;
 use rustc_middle::mir::Field;
 use rustc_middle::ty::layout::IntegerExt;
-use rustc_middle::ty::{self, Const, Ty, TyCtxt};
+use rustc_middle::ty::{self, Const, ScalarInt, Ty, TyCtxt};
 use rustc_session::lint;
 use rustc_span::{Span, DUMMY_SP};
 use rustc_target::abi::{Integer, Size, VariantIdx};
@@ -203,14 +204,18 @@ impl IntRange {
         let bias = IntRange::signed_bias(tcx, ty);
         let (lo, hi) = (lo ^ bias, hi ^ bias);
 
-        let env = ty::ParamEnv::empty().and(ty);
-        let lo_const = ty::Const::from_bits(tcx, lo, env);
-        let hi_const = ty::Const::from_bits(tcx, hi, env);
-
         let kind = if lo == hi {
-            PatKind::Constant { value: lo_const }
+            let ty = ty::ParamEnv::empty().and(ty);
+            PatKind::Constant { value: ty::Const::from_bits(tcx, lo, ty) }
         } else {
-            PatKind::Range(PatRange { lo: lo_const, hi: hi_const, end: RangeEnd::Included })
+            let param_env_and_ty = ty::ParamEnv::empty().and(ty);
+            let size = tcx.layout_of(param_env_and_ty).unwrap().size;
+            PatKind::Range(PatRange {
+                lo: ScalarInt::from_uint(lo, size),
+                hi: ScalarInt::from_uint(hi, size),
+                end: RangeEnd::Included,
+                ty,
+            })
         };
 
         Pat { ty, span: DUMMY_SP, kind: Box::new(kind) }
@@ -587,7 +592,7 @@ pub(super) enum Constructor<'tcx> {
     /// Ranges of integer literal values (`2`, `2..=5` or `2..5`).
     IntRange(IntRange),
     /// Ranges of floating-point literal values (`2.0..=5.2`).
-    FloatRange(&'tcx ty::Const<'tcx>, &'tcx ty::Const<'tcx>, RangeEnd),
+    FloatRange(ScalarInt, ScalarInt, RangeEnd),
     /// String literals. Strings are not quite the same as `&[u8]` so we treat them separately.
     Str(&'tcx ty::Const<'tcx>),
     /// Array and slice patterns.
@@ -650,7 +655,11 @@ impl<'tcx> Constructor<'tcx> {
                     IntRange(int_range)
                 } else {
                     match pat.ty.kind() {
-                        ty::Float(_) => FloatRange(value, value, RangeEnd::Included),
+                        ty::Float(_) => {
+                            let value =
+                                value.val.eval(cx.tcx, cx.param_env).try_to_scalar_int().unwrap();
+                            FloatRange(value, value, RangeEnd::Included)
+                        }
                         // In `expand_pattern`, we convert string literals to `&CONST` patterns with
                         // `CONST` a pattern of type `str`. In truth this contains a constant of type
                         // `&str`.
@@ -662,13 +671,13 @@ impl<'tcx> Constructor<'tcx> {
                     }
                 }
             }
-            &PatKind::Range(PatRange { lo, hi, end }) => {
-                let ty = lo.ty;
+            &PatKind::Range(PatRange { lo, hi, end, ty }) => {
+                let size = cx.tcx.layout_of(cx.param_env.and(ty)).unwrap().size;
                 if let Some(int_range) = IntRange::from_range(
                     cx.tcx,
-                    lo.eval_bits(cx.tcx, cx.param_env, lo.ty),
-                    hi.eval_bits(cx.tcx, cx.param_env, hi.ty),
-                    ty,
+                    lo.assert_bits(size),
+                    hi.assert_bits(size),
+                    pat.ty,
                     &end,
                 ) {
                     IntRange(int_range)
@@ -762,6 +771,26 @@ impl<'tcx> Constructor<'tcx> {
                 FloatRange(self_from, self_to, self_end),
                 FloatRange(other_from, other_to, other_end),
             ) => {
+                let self_to = ty::Const::from_value(
+                    pcx.cx.tcx,
+                    ConstValue::Scalar((*self_to).into()),
+                    pcx.ty,
+                );
+                let other_to = ty::Const::from_value(
+                    pcx.cx.tcx,
+                    ConstValue::Scalar((*other_to).into()),
+                    pcx.ty,
+                );
+                let self_from = ty::Const::from_value(
+                    pcx.cx.tcx,
+                    ConstValue::Scalar((*self_from).into()),
+                    pcx.ty,
+                );
+                let other_from = ty::Const::from_value(
+                    pcx.cx.tcx,
+                    ConstValue::Scalar((*other_from).into()),
+                    pcx.ty,
+                );
                 match (
                     compare_const_vals(pcx.cx.tcx, self_to, other_to, pcx.cx.param_env, pcx.ty),
                     compare_const_vals(pcx.cx.tcx, self_from, other_from, pcx.cx.param_env, pcx.ty),
@@ -1256,7 +1285,7 @@ impl<'p, 'tcx> Fields<'p, 'tcx> {
                 }
             },
             &Str(value) => PatKind::Constant { value },
-            &FloatRange(lo, hi, end) => PatKind::Range(PatRange { lo, hi, end }),
+            &FloatRange(lo, hi, end) => PatKind::Range(PatRange { lo, hi, end, ty: pcx.ty }),
             IntRange(range) => return range.to_pat(pcx.cx.tcx, pcx.ty),
             NonExhaustive => PatKind::Wild,
             Wildcard => return Pat::wildcard_from_ty(pcx.ty),

compiler/rustc_mir_build/src/thir/pattern/mod.rs

@@ -24,6 +24,7 @@ use rustc_middle::ty::{self, AdtDef, DefIdTree, Region, Ty, TyCtxt, UserType};
 use rustc_middle::ty::{
     CanonicalUserType, CanonicalUserTypeAnnotation, CanonicalUserTypeAnnotations,
 };
+use rustc_middle::ty::{ConstInt, ScalarInt};
 use rustc_span::{Span, Symbol, DUMMY_SP};
 use rustc_target::abi::VariantIdx;
 
@@ -196,8 +197,9 @@ pub enum PatKind<'tcx> {
 
 #[derive(Copy, Clone, Debug, PartialEq)]
 pub struct PatRange<'tcx> {
-    pub lo: &'tcx ty::Const<'tcx>,
-    pub hi: &'tcx ty::Const<'tcx>,
+    pub lo: ScalarInt,
+    pub hi: ScalarInt,
+    pub ty: Ty<'tcx>,
     pub end: RangeEnd,
 }
 
@@ -316,10 +318,12 @@ impl<'tcx> fmt::Display for Pat<'tcx> {
                 write!(f, "{}", subpattern)
             }
             PatKind::Constant { value } => write!(f, "{}", value),
-            PatKind::Range(PatRange { lo, hi, end }) => {
-                write!(f, "{}", lo)?;
+            PatKind::Range(PatRange { lo, hi, end, ty }) => {
+                let lo = ConstInt::new(lo, ty.is_signed(), ty.is_ptr_sized_integral());
+                let hi = ConstInt::new(hi, ty.is_signed(), ty.is_ptr_sized_integral());
+                write!(f, "{:?}", lo)?;
                 write!(f, "{}", end)?;
-                write!(f, "{}", hi)
+                write!(f, "{:?}", hi)
             }
             PatKind::Slice { ref prefix, ref slice, ref suffix }
             | PatKind::Array { ref prefix, ref slice, ref suffix } => {
@@ -447,10 +451,23 @@ impl<'a, 'tcx> PatCtxt<'a, 'tcx> {
         assert_eq!(lo.ty, ty);
         assert_eq!(hi.ty, ty);
         let cmp = compare_const_vals(self.tcx, lo, hi, self.param_env, ty);
+        let lo_const = lo;
+        let lo = lo
+            .val
+            .eval(self.tcx, self.param_env)
+            .try_to_scalar_int()
+            .expect("range patterns must be integral");
+        let hi = hi
+            .val
+            .eval(self.tcx, self.param_env)
+            .try_to_scalar_int()
+            .expect("range patterns must be integral");
         match (end, cmp) {
             // `x..y` where `x < y`.
             // Non-empty because the range includes at least `x`.
-            (RangeEnd::Excluded, Some(Ordering::Less)) => PatKind::Range(PatRange { lo, hi, end }),
+            (RangeEnd::Excluded, Some(Ordering::Less)) => {
+                PatKind::Range(PatRange { lo, hi, end, ty })
+            }
             // `x..y` where `x >= y`. The range is empty => error.
             (RangeEnd::Excluded, _) => {
                 struct_span_err!(
@@ -463,9 +480,11 @@ impl<'a, 'tcx> PatCtxt<'a, 'tcx> {
                 PatKind::Wild
             }
             // `x..=y` where `x == y`.
-            (RangeEnd::Included, Some(Ordering::Equal)) => PatKind::Constant { value: lo },
+            (RangeEnd::Included, Some(Ordering::Equal)) => PatKind::Constant { value: lo_const },
             // `x..=y` where `x < y`.
-            (RangeEnd::Included, Some(Ordering::Less)) => PatKind::Range(PatRange { lo, hi, end }),
+            (RangeEnd::Included, Some(Ordering::Less)) => {
+                PatKind::Range(PatRange { lo, hi, end, ty })
+            }
             // `x..=y` where `x > y` hence the range is empty => error.
             (RangeEnd::Included, _) => {
                 let mut err = struct_span_err!(

src/test/mir-opt/match_test.main.SimplifyCfg-initial.after.mir

@@ -28,43 +28,43 @@ fn main() -> () {
         StorageLive(_3);                 // scope 2 at $DIR/match_test.rs:12:5: 17:6
         FakeRead(ForMatchedPlace, _1);   // scope 2 at $DIR/match_test.rs:12:11: 12:12
         _6 = Le(const 0_i32, _1);        // scope 2 at $DIR/match_test.rs:13:9: 13:14
-        switchInt(move _6) -> [false: bb4, otherwise: bb1]; // scope 2 at $DIR/match_test.rs:13:9: 13:14
+        switchInt(move _6) -> [false: bb3, otherwise: bb1]; // scope 2 at $DIR/match_test.rs:13:9: 13:14
     }
 
     bb1: {
         _7 = Lt(_1, const 10_i32);       // scope 2 at $DIR/match_test.rs:13:9: 13:14
-        switchInt(move _7) -> [false: bb4, otherwise: bb2]; // scope 2 at $DIR/match_test.rs:13:9: 13:14
+        switchInt(move _7) -> [false: bb3, otherwise: bb2]; // scope 2 at $DIR/match_test.rs:13:9: 13:14
     }
 
     bb2: {
-        falseEdge -> [real: bb9, imaginary: bb6]; // scope 2 at $DIR/match_test.rs:13:9: 13:14
+        falseEdge -> [real: bb9, imaginary: bb5]; // scope 2 at $DIR/match_test.rs:13:9: 13:14
     }
 
     bb3: {
-        _3 = const 3_i32;                // scope 2 at $DIR/match_test.rs:16:14: 16:15
-        goto -> bb14;                    // scope 2 at $DIR/match_test.rs:12:5: 17:6
+        _4 = Le(const 10_i32, _1);       // scope 2 at $DIR/match_test.rs:14:9: 14:16
+        switchInt(move _4) -> [false: bb6, otherwise: bb4]; // scope 2 at $DIR/match_test.rs:14:9: 14:16
     }
 
     bb4: {
-        _4 = Le(const 10_i32, _1);       // scope 2 at $DIR/match_test.rs:14:9: 14:16
-        switchInt(move _4) -> [false: bb7, otherwise: bb5]; // scope 2 at $DIR/match_test.rs:14:9: 14:16
+        _5 = Le(_1, const 20_i32);       // scope 2 at $DIR/match_test.rs:14:9: 14:16
+        switchInt(move _5) -> [false: bb6, otherwise: bb5]; // scope 2 at $DIR/match_test.rs:14:9: 14:16
     }
 
     bb5: {
-        _5 = Le(_1, const 20_i32);       // scope 2 at $DIR/match_test.rs:14:9: 14:16
-        switchInt(move _5) -> [false: bb7, otherwise: bb6]; // scope 2 at $DIR/match_test.rs:14:9: 14:16
+        falseEdge -> [real: bb12, imaginary: bb7]; // scope 2 at $DIR/match_test.rs:14:9: 14:16
     }
 
     bb6: {
-        falseEdge -> [real: bb12, imaginary: bb8]; // scope 2 at $DIR/match_test.rs:14:9: 14:16
+        switchInt(_1) -> [-1_i32: bb7, otherwise: bb8]; // scope 2 at $DIR/match_test.rs:15:9: 15:11
     }
 
     bb7: {
-        switchInt(_1) -> [-1_i32: bb8, otherwise: bb3]; // scope 2 at $DIR/match_test.rs:15:9: 15:11
+        falseEdge -> [real: bb13, imaginary: bb8]; // scope 2 at $DIR/match_test.rs:15:9: 15:11
     }
 
     bb8: {
-        falseEdge -> [real: bb13, imaginary: bb3]; // scope 2 at $DIR/match_test.rs:15:9: 15:11
+        _3 = const 3_i32;                // scope 2 at $DIR/match_test.rs:16:14: 16:15
+        goto -> bb14;                    // scope 2 at $DIR/match_test.rs:12:5: 17:6
     }
 
     bb9: {
@@ -83,7 +83,7 @@ fn main() -> () {
 
     bb11: {
         StorageDead(_9);                 // scope 2 at $DIR/match_test.rs:13:23: 13:24
-        falseEdge -> [real: bb3, imaginary: bb6]; // scope 2 at $DIR/match_test.rs:13:18: 13:19
+        falseEdge -> [real: bb3, imaginary: bb5]; // scope 2 at $DIR/match_test.rs:13:18: 13:19
     }
 
     bb12: {

src/test/ui/consts/const-match-check.eval1.stderr

@@ -1,8 +1,8 @@
-error[E0005]: refutable pattern in local binding: `i32::MIN..=-1_i32` and `1_i32..=i32::MAX` not covered
+error[E0005]: refutable pattern in local binding: `i32::MIN..=-1` and `1..=i32::MAX` not covered
   --> $DIR/const-match-check.rs:25:15
    |
 LL |     A = { let 0 = 0; 0 },
-   |               ^ patterns `i32::MIN..=-1_i32` and `1_i32..=i32::MAX` not covered
+   |               ^ patterns `i32::MIN..=-1` and `1..=i32::MAX` not covered
    |
    = note: `let` bindings require an "irrefutable pattern", like a `struct` or an `enum` with only one variant
    = note: for more information, visit https://doc.rust-lang.org/book/ch18-02-refutability.html

src/test/ui/consts/const-match-check.eval2.stderr

@@ -1,8 +1,8 @@
-error[E0005]: refutable pattern in local binding: `i32::MIN..=-1_i32` and `1_i32..=i32::MAX` not covered
+error[E0005]: refutable pattern in local binding: `i32::MIN..=-1` and `1..=i32::MAX` not covered
   --> $DIR/const-match-check.rs:31:24
    |
 LL |     let x: [i32; { let 0 = 0; 0 }] = [];
-   |                        ^ patterns `i32::MIN..=-1_i32` and `1_i32..=i32::MAX` not covered
+   |                        ^ patterns `i32::MIN..=-1` and `1..=i32::MAX` not covered
    |
    = note: `let` bindings require an "irrefutable pattern", like a `struct` or an `enum` with only one variant
    = note: for more information, visit https://doc.rust-lang.org/book/ch18-02-refutability.html