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mir_to_const improvements #11565

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merged 3 commits into from
Sep 28, 2023
Merged

mir_to_const improvements #11565

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84d6894
it's not Miri but MIR constants
RalfJung Sep 25, 2023
ce45221
simply some valtree-to-const conversion
RalfJung Sep 25, 2023
0f19857
mir_to_const: fix handling of float arrays
RalfJung Sep 25, 2023
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4 changes: 2 additions & 2 deletions clippy_lints/src/enum_clike.rs
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Original file line number Diff line number Diff line change
@@ -1,7 +1,7 @@
//! lint on C-like enums that are `repr(isize/usize)` and have values that
//! don't fit into an `i32`

use clippy_utils::consts::{miri_to_const, Constant};
use clippy_utils::consts::{mir_to_const, Constant};
use clippy_utils::diagnostics::span_lint;
use rustc_hir::{Item, ItemKind};
use rustc_lint::{LateContext, LateLintPass};
Expand Down Expand Up @@ -51,7 +51,7 @@ impl<'tcx> LateLintPass<'tcx> for UnportableVariant {
.const_eval_poly(def_id.to_def_id())
.ok()
.map(|val| rustc_middle::mir::Const::from_value(val, ty));
if let Some(Constant::Int(val)) = constant.and_then(|c| miri_to_const(cx, c)) {
if let Some(Constant::Int(val)) = constant.and_then(|c| mir_to_const(cx, c)) {
if let ty::Adt(adt, _) = ty.kind() {
if adt.is_enum() {
ty = adt.repr().discr_type().to_ty(cx.tcx);
Expand Down
6 changes: 3 additions & 3 deletions clippy_lints/src/matches/overlapping_arms.rs
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Original file line number Diff line number Diff line change
@@ -1,4 +1,4 @@
use clippy_utils::consts::{constant, constant_full_int, miri_to_const, FullInt};
use clippy_utils::consts::{constant, constant_full_int, mir_to_const, FullInt};
use clippy_utils::diagnostics::span_lint_and_note;
use core::cmp::Ordering;
use rustc_hir::{Arm, Expr, PatKind, RangeEnd};
Expand Down Expand Up @@ -37,14 +37,14 @@ fn all_ranges<'tcx>(cx: &LateContext<'tcx>, arms: &'tcx [Arm<'_>], ty: Ty<'tcx>)
Some(lhs) => constant(cx, cx.typeck_results(), lhs)?,
None => {
let min_val_const = ty.numeric_min_val(cx.tcx)?;
miri_to_const(cx, mir::Const::from_ty_const(min_val_const, cx.tcx))?
mir_to_const(cx, mir::Const::from_ty_const(min_val_const, cx.tcx))?
},
};
let rhs_const = match rhs {
Some(rhs) => constant(cx, cx.typeck_results(), rhs)?,
None => {
let max_val_const = ty.numeric_max_val(cx.tcx)?;
miri_to_const(cx, mir::Const::from_ty_const(max_val_const, cx.tcx))?
mir_to_const(cx, mir::Const::from_ty_const(max_val_const, cx.tcx))?
},
};
let lhs_val = lhs_const.int_value(cx, ty)?;
Expand Down
69 changes: 30 additions & 39 deletions clippy_utils/src/consts.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -9,11 +9,12 @@ use rustc_hir::def::{DefKind, Res};
use rustc_hir::{BinOp, BinOpKind, Block, ConstBlock, Expr, ExprKind, HirId, Item, ItemKind, Node, QPath, UnOp};
use rustc_lexer::tokenize;
use rustc_lint::LateContext;
use rustc_middle::mir::interpret::Scalar;
use rustc_middle::mir::interpret::{alloc_range, Scalar};
use rustc_middle::ty::{self, EarlyBinder, FloatTy, GenericArgsRef, List, ScalarInt, Ty, TyCtxt};
use rustc_middle::{bug, mir, span_bug};
use rustc_span::symbol::{Ident, Symbol};
use rustc_span::SyntaxContext;
use rustc_target::abi::Size;
use std::cmp::Ordering::{self, Equal};
use std::hash::{Hash, Hasher};
use std::iter;
Expand Down Expand Up @@ -403,7 +404,7 @@ impl<'a, 'tcx> ConstEvalLateContext<'a, 'tcx> {
&& adt_def.is_struct()
&& let Some(desired_field) = field_of_struct(*adt_def, self.lcx, *constant, field)
{
miri_to_const(self.lcx, desired_field)
mir_to_const(self.lcx, desired_field)
}
else {
result
Expand Down Expand Up @@ -483,7 +484,7 @@ impl<'a, 'tcx> ConstEvalLateContext<'a, 'tcx> {
.const_eval_resolve(self.param_env, mir::UnevaluatedConst::new(def_id, args), None)
.ok()
.map(|val| rustc_middle::mir::Const::from_value(val, ty))?;
let result = miri_to_const(self.lcx, result)?;
let result = mir_to_const(self.lcx, result)?;
self.source = ConstantSource::Constant;
Some(result)
},
Expand Down Expand Up @@ -655,10 +656,14 @@ impl<'a, 'tcx> ConstEvalLateContext<'a, 'tcx> {
}
}

pub fn miri_to_const<'tcx>(lcx: &LateContext<'tcx>, result: mir::Const<'tcx>) -> Option<Constant<'tcx>> {
pub fn mir_to_const<'tcx>(lcx: &LateContext<'tcx>, result: mir::Const<'tcx>) -> Option<Constant<'tcx>> {
use rustc_middle::mir::ConstValue;
match result {
mir::Const::Val(ConstValue::Scalar(Scalar::Int(int)), _) => match result.ty().kind() {
let mir::Const::Val(val, _) = result else {
// We only work on evaluated consts.
return None;
};
match (val, result.ty().kind()) {
(ConstValue::Scalar(Scalar::Int(int)), _) => match result.ty().kind() {
ty::Adt(adt_def, _) if adt_def.is_struct() => Some(Constant::Adt(result)),
ty::Bool => Some(Constant::Bool(int == ScalarInt::TRUE)),
ty::Uint(_) | ty::Int(_) => Some(Constant::Int(int.assert_bits(int.size()))),
Expand All @@ -671,42 +676,28 @@ pub fn miri_to_const<'tcx>(lcx: &LateContext<'tcx>, result: mir::Const<'tcx>) ->
ty::RawPtr(_) => Some(Constant::RawPtr(int.assert_bits(int.size()))),
_ => None,
},
mir::Const::Val(cv, _) if matches!(result.ty().kind(), ty::Ref(_, inner_ty, _) if matches!(inner_ty.kind(), ty::Str)) =>
{
let data = cv.try_get_slice_bytes_for_diagnostics(lcx.tcx)?;
(_, ty::Ref(_, inner_ty, _)) if matches!(inner_ty.kind(), ty::Str) => {
let data = val.try_get_slice_bytes_for_diagnostics(lcx.tcx)?;
String::from_utf8(data.to_owned()).ok().map(Constant::Str)
},
mir::Const::Val(ConstValue::Indirect { alloc_id, offset: _ }, _) => {
let alloc = lcx.tcx.global_alloc(alloc_id).unwrap_memory();
match result.ty().kind() {
ty::Adt(adt_def, _) if adt_def.is_struct() => Some(Constant::Adt(result)),
ty::Array(sub_type, len) => match sub_type.kind() {
ty::Float(FloatTy::F32) => match len.try_to_target_usize(lcx.tcx) {
Some(len) => alloc
.inner()
.inspect_with_uninit_and_ptr_outside_interpreter(0..(4 * usize::try_from(len).unwrap()))
.to_owned()
.array_chunks::<4>()
.map(|&chunk| Some(Constant::F32(f32::from_le_bytes(chunk))))
.collect::<Option<Vec<Constant<'tcx>>>>()
.map(Constant::Vec),
_ => None,
},
ty::Float(FloatTy::F64) => match len.try_to_target_usize(lcx.tcx) {
Some(len) => alloc
.inner()
.inspect_with_uninit_and_ptr_outside_interpreter(0..(8 * usize::try_from(len).unwrap()))
.to_owned()
.array_chunks::<8>()
.map(|&chunk| Some(Constant::F64(f64::from_le_bytes(chunk))))
.collect::<Option<Vec<Constant<'tcx>>>>()
.map(Constant::Vec),
_ => None,
},
_ => None,
},
_ => None,
(_, ty::Adt(adt_def, _)) if adt_def.is_struct() => Some(Constant::Adt(result)),
(ConstValue::Indirect { alloc_id, offset }, ty::Array(sub_type, len)) => {
let alloc = lcx.tcx.global_alloc(alloc_id).unwrap_memory().inner();
let len = len.try_to_target_usize(lcx.tcx)?;
let ty::Float(flt) = sub_type.kind() else {
return None;
};
let size = Size::from_bits(flt.bit_width());
let mut res = Vec::new();
for idx in 0..len {
let range = alloc_range(offset + size * idx, size);
let val = alloc.read_scalar(&lcx.tcx, range, /* read_provenance */ false).ok()?;
res.push(match flt {
FloatTy::F32 => Constant::F32(f32::from_bits(val.to_u32().ok()?)),
FloatTy::F64 => Constant::F64(f64::from_bits(val.to_u64().ok()?)),
});
}
Some(Constant::Vec(res))
},
_ => None,
}
Expand Down
10 changes: 3 additions & 7 deletions clippy_utils/src/lib.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -113,7 +113,7 @@ use rustc_span::{sym, Span};
use rustc_target::abi::Integer;
use visitors::Visitable;

use crate::consts::{constant, miri_to_const, Constant};
use crate::consts::{constant, mir_to_const, Constant};
use crate::higher::Range;
use crate::ty::{
adt_and_variant_of_res, can_partially_move_ty, expr_sig, is_copy, is_recursively_primitive_type,
Expand Down Expand Up @@ -1509,9 +1509,7 @@ pub fn is_range_full(cx: &LateContext<'_>, expr: &Expr<'_>, container_path: Opti
if let rustc_ty::Adt(_, subst) = ty.kind()
&& let bnd_ty = subst.type_at(0)
&& let Some(min_val) = bnd_ty.numeric_min_val(cx.tcx)
&& let const_val = cx.tcx.valtree_to_const_val((bnd_ty, min_val.to_valtree()))
&& let min_const_kind = Const::from_value(const_val, bnd_ty)
&& let Some(min_const) = miri_to_const(cx, min_const_kind)
&& let Some(min_const) = mir_to_const(cx, Const::from_ty_const(min_val, cx.tcx))
&& let Some(start_const) = constant(cx, cx.typeck_results(), start)
{
start_const == min_const
Expand All @@ -1525,9 +1523,7 @@ pub fn is_range_full(cx: &LateContext<'_>, expr: &Expr<'_>, container_path: Opti
if let rustc_ty::Adt(_, subst) = ty.kind()
&& let bnd_ty = subst.type_at(0)
&& let Some(max_val) = bnd_ty.numeric_max_val(cx.tcx)
&& let const_val = cx.tcx.valtree_to_const_val((bnd_ty, max_val.to_valtree()))
&& let max_const_kind = Const::from_value(const_val, bnd_ty)
&& let Some(max_const) = miri_to_const(cx, max_const_kind)
&& let Some(max_const) = mir_to_const(cx, Const::from_ty_const(max_val, cx.tcx))
&& let Some(end_const) = constant(cx, cx.typeck_results(), end)
{
end_const == max_const
Expand Down