diff options
| -rw-r--r-- | compiler/rustc_mir_build/src/thir/pattern/deconstruct_pat.rs | 193 |
1 files changed, 102 insertions, 91 deletions
diff --git a/compiler/rustc_mir_build/src/thir/pattern/deconstruct_pat.rs b/compiler/rustc_mir_build/src/thir/pattern/deconstruct_pat.rs index 7c1ae4ad3cf..8344ddb2a69 100644 --- a/compiler/rustc_mir_build/src/thir/pattern/deconstruct_pat.rs +++ b/compiler/rustc_mir_build/src/thir/pattern/deconstruct_pat.rs @@ -61,7 +61,7 @@ use rustc_middle::ty::layout::IntegerExt; use rustc_middle::ty::{self, Ty, TyCtxt, VariantDef}; use rustc_session::lint; use rustc_span::{Span, DUMMY_SP}; -use rustc_target::abi::{FieldIdx, Integer, Size, VariantIdx, FIRST_VARIANT}; +use rustc_target::abi::{FieldIdx, Integer, Primitive, Size, VariantIdx, FIRST_VARIANT}; use self::Constructor::*; use self::SliceKind::*; @@ -86,6 +86,35 @@ fn expand_or_pat<'p, 'tcx>(pat: &'p Pat<'tcx>) -> Vec<&'p Pat<'tcx>> { pats } +/// Evaluate an int constant, with a faster branch for a common case. +#[inline] +fn fast_try_eval_bits<'tcx>( + tcx: TyCtxt<'tcx>, + param_env: ty::ParamEnv<'tcx>, + value: &mir::Const<'tcx>, +) -> Option<u128> { + let int = match value { + // If the constant is already evaluated, we shortcut here. + mir::Const::Ty(c) if let ty::ConstKind::Value(valtree) = c.kind() => { + valtree.unwrap_leaf() + }, + // This is a more general form of the previous case. + _ => { + value.try_eval_scalar_int(tcx, param_env)? + }, + }; + let size = match value.ty().kind() { + ty::Bool => Size::from_bytes(1), + ty::Char => Size::from_bytes(4), + ty::Int(ity) => Integer::from_int_ty(&tcx, *ity).size(), + ty::Uint(uty) => Integer::from_uint_ty(&tcx, *uty).size(), + ty::Float(ty::FloatTy::F32) => Primitive::F32.size(&tcx), + ty::Float(ty::FloatTy::F64) => Primitive::F64.size(&tcx), + _ => return None, + }; + int.to_bits(size).ok() +} + /// An inclusive interval, used for precise integer exhaustiveness checking. /// `IntRange`s always store a contiguous range. This means that values are /// encoded such that `0` encodes the minimum value for the integer, @@ -116,37 +145,12 @@ impl IntRange { } #[inline] - fn integral_size_and_signed_bias(tcx: TyCtxt<'_>, ty: Ty<'_>) -> Option<(Size, u128)> { - match *ty.kind() { - ty::Bool => Some((Size::from_bytes(1), 0)), - ty::Char => Some((Size::from_bytes(4), 0)), - ty::Int(ity) => { - let size = Integer::from_int_ty(&tcx, ity).size(); - Some((size, 1u128 << (size.bits() as u128 - 1))) - } - ty::Uint(uty) => Some((Integer::from_uint_ty(&tcx, uty).size(), 0)), - _ => None, - } - } - - #[inline] - fn from_constant<'tcx>( - tcx: TyCtxt<'tcx>, - param_env: ty::ParamEnv<'tcx>, - value: mir::Const<'tcx>, - ) -> Option<IntRange> { - let ty = value.ty(); - let (target_size, bias) = Self::integral_size_and_signed_bias(tcx, ty)?; - let val = match value { - mir::Const::Ty(c) if let ty::ConstKind::Value(valtree) = c.kind() => { - valtree.unwrap_leaf().to_bits(target_size).ok() - }, - // This is a more general form of the previous case. - _ => value.try_eval_bits(tcx, param_env), - }?; - - let val = val ^ bias; - Some(IntRange { range: val..=val }) + fn from_bits<'tcx>(tcx: TyCtxt<'tcx>, ty: Ty<'tcx>, bits: u128) -> IntRange { + let bias = IntRange::signed_bias(tcx, ty); + // Perform a shift if the underlying types are signed, + // which makes the interval arithmetic simpler. + let val = bits ^ bias; + IntRange { range: val..=val } } #[inline] @@ -155,20 +159,18 @@ impl IntRange { lo: u128, hi: u128, ty: Ty<'tcx>, - end: &RangeEnd, - ) -> Option<IntRange> { - Self::is_integral(ty).then(|| { - // Perform a shift if the underlying types are signed, - // which makes the interval arithmetic simpler. - let bias = IntRange::signed_bias(tcx, ty); - let (lo, hi) = (lo ^ bias, hi ^ bias); - let offset = (*end == RangeEnd::Excluded) as u128; - if lo > hi || (lo == hi && *end == RangeEnd::Excluded) { - // This should have been caught earlier by E0030. - bug!("malformed range pattern: {}..={}", lo, (hi - offset)); - } - IntRange { range: lo..=(hi - offset) } - }) + end: RangeEnd, + ) -> IntRange { + // Perform a shift if the underlying types are signed, + // which makes the interval arithmetic simpler. + let bias = IntRange::signed_bias(tcx, ty); + let (lo, hi) = (lo ^ bias, hi ^ bias); + let offset = (end == RangeEnd::Excluded) as u128; + if lo > hi || (lo == hi && end == RangeEnd::Excluded) { + // This should have been caught earlier by E0030. + bug!("malformed range pattern: {}..={}", lo, (hi - offset)); + } + IntRange { range: lo..=(hi - offset) } } // The return value of `signed_bias` should be XORed with an endpoint to encode/decode it. @@ -894,7 +896,7 @@ impl<'tcx> SplitWildcard<'tcx> { let make_range = |start, end| { IntRange( // `unwrap()` is ok because we know the type is an integer. - IntRange::from_range(cx.tcx, start, end, pcx.ty, &RangeEnd::Included).unwrap(), + IntRange::from_range(cx.tcx, start, end, pcx.ty, RangeEnd::Included), ) }; // This determines the set of all possible constructors for the type `pcx.ty`. For numbers, @@ -1342,57 +1344,66 @@ impl<'p, 'tcx> DeconstructedPat<'p, 'tcx> { } } PatKind::Constant { value } => { - if let Some(int_range) = IntRange::from_constant(cx.tcx, cx.param_env, *value) { - ctor = IntRange(int_range); - fields = Fields::empty(); - } else { - match pat.ty.kind() { - ty::Float(float_ty) => { - let bits = value.eval_bits(cx.tcx, cx.param_env); - use rustc_apfloat::Float; - ctor = match float_ty { - ty::FloatTy::F32 => { - let value = rustc_apfloat::ieee::Single::from_bits(bits); - F32Range(value, value, RangeEnd::Included) - } - ty::FloatTy::F64 => { - let value = rustc_apfloat::ieee::Double::from_bits(bits); - F64Range(value, value, RangeEnd::Included) - } - }; - fields = Fields::empty(); - } - ty::Ref(_, t, _) if t.is_str() => { - // We want a `&str` constant to behave like a `Deref` pattern, to be compatible - // with other `Deref` patterns. This could have been done in `const_to_pat`, - // but that causes issues with the rest of the matching code. - // So here, the constructor for a `"foo"` pattern is `&` (represented by - // `Single`), and has one field. That field has constructor `Str(value)` and no - // fields. - // Note: `t` is `str`, not `&str`. - let subpattern = - DeconstructedPat::new(Str(*value), Fields::empty(), *t, pat.span); - ctor = Single; - fields = Fields::singleton(cx, subpattern) - } - // All constants that can be structurally matched have already been expanded - // into the corresponding `Pat`s by `const_to_pat`. Constants that remain are - // opaque. - _ => { - ctor = Opaque; - fields = Fields::empty(); - } + match pat.ty.kind() { + ty::Bool | ty::Char | ty::Int(_) | ty::Uint(_) => { + ctor = match fast_try_eval_bits(cx.tcx, cx.param_env, value) { + Some(bits) => IntRange(IntRange::from_bits(cx.tcx, pat.ty, bits)), + None => Opaque, + }; + fields = Fields::empty(); + } + ty::Float(ty::FloatTy::F32) => { + ctor = match fast_try_eval_bits(cx.tcx, cx.param_env, value) { + Some(bits) => { + use rustc_apfloat::Float; + let value = rustc_apfloat::ieee::Single::from_bits(bits); + F32Range(value, value, RangeEnd::Included) + } + None => Opaque, + }; + fields = Fields::empty(); + } + ty::Float(ty::FloatTy::F64) => { + ctor = match fast_try_eval_bits(cx.tcx, cx.param_env, value) { + Some(bits) => { + use rustc_apfloat::Float; + let value = rustc_apfloat::ieee::Double::from_bits(bits); + F64Range(value, value, RangeEnd::Included) + } + None => Opaque, + }; + fields = Fields::empty(); + } + ty::Ref(_, t, _) if t.is_str() => { + // We want a `&str` constant to behave like a `Deref` pattern, to be compatible + // with other `Deref` patterns. This could have been done in `const_to_pat`, + // but that causes issues with the rest of the matching code. + // So here, the constructor for a `"foo"` pattern is `&` (represented by + // `Single`), and has one field. That field has constructor `Str(value)` and no + // fields. + // Note: `t` is `str`, not `&str`. + let subpattern = + DeconstructedPat::new(Str(*value), Fields::empty(), *t, pat.span); + ctor = Single; + fields = Fields::singleton(cx, subpattern) + } + // All constants that can be structurally matched have already been expanded + // into the corresponding `Pat`s by `const_to_pat`. Constants that remain are + // opaque. + _ => { + ctor = Opaque; + fields = Fields::empty(); } } } - &PatKind::Range(box PatRange { lo, hi, end }) => { + PatKind::Range(box PatRange { lo, hi, end }) => { use rustc_apfloat::Float; let ty = lo.ty(); - let lo = lo.eval_bits(cx.tcx, cx.param_env); - let hi = hi.eval_bits(cx.tcx, cx.param_env); + let lo = fast_try_eval_bits(cx.tcx, cx.param_env, lo).unwrap(); + let hi = fast_try_eval_bits(cx.tcx, cx.param_env, hi).unwrap(); ctor = match ty.kind() { ty::Char | ty::Int(_) | ty::Uint(_) => { - IntRange(IntRange::from_range(cx.tcx, lo, hi, ty, &end).unwrap()) + IntRange(IntRange::from_range(cx.tcx, lo, hi, ty, *end)) } ty::Float(ty::FloatTy::F32) => { let lo = rustc_apfloat::ieee::Single::from_bits(lo); |