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implement valtrees as the type-system representation for constant values

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This commit is contained in:
b-naber 2022-02-16 10:56:01 +01:00
parent edab34ab2a
commit 705d818bd5
116 changed files with 1606 additions and 1032 deletions
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59
compiler/rustc_mir_build/src/build/expr/as_constant.rs
View file

@ -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))
}

118
compiler/rustc_mir_build/src/build/mod.rs
View file

@ -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

77
compiler/rustc_mir_build/src/thir/constant.rs
View file

@ -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(ConstValue::Scalar(scalar))
Some(Scalar::from_f64(f))
}
}
}
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()))
}

3
compiler/rustc_mir_build/src/thir/pattern/const_to_pat.rs
View file

@ -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 {

7
compiler/rustc_mir_build/src/thir/pattern/mod.rs
View file

@ -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()
}