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Auto merge of #112238 - scottmcm:mir-add-unchecked, r=cjgillot

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Promote unchecked integer math to MIR `BinOp`s

So slice indexing by a range gets down to one basic block, for example.

r? cjgillot
This commit is contained in:
bors 2023-06-19 17:14:21 +00:00
commit 4051305389
40 changed files with 546 additions and 358 deletions
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13
compiler/rustc_middle/src/mir/syntax.rs
View file

@ -1267,10 +1267,16 @@ pub enum UnOp {
pub enum BinOp {
/// The `+` operator (addition)
Add,
/// Like `Add`, but with UB on overflow. (Integers only.)
AddUnchecked,
/// The `-` operator (subtraction)
Sub,
/// Like `Sub`, but with UB on overflow. (Integers only.)
SubUnchecked,
/// The `*` operator (multiplication)
Mul,
/// Like `Mul`, but with UB on overflow. (Integers only.)
MulUnchecked,
/// The `/` operator (division)
///
/// For integer types, division by zero is UB, as is `MIN / -1` for signed.
@ -1296,10 +1302,17 @@ pub enum BinOp {
///
/// The offset is truncated to the size of the first operand before shifting.
Shl,
/// Like `Shl`, but is UB if the RHS >= LHS::BITS
ShlUnchecked,
/// The `>>` operator (shift right)
///
/// The offset is truncated to the size of the first operand before shifting.
///
/// This is an arithmetic shift if the LHS is signed
/// and a logical shift if the LHS is unsigned.
Shr,
/// Like `Shl`, but is UB if the RHS >= LHS::BITS
ShrUnchecked,
/// The `==` operator (equality)
Eq,
/// The `<` operator (less than)

18
compiler/rustc_middle/src/mir/tcx.rs
View file

@ -235,8 +235,11 @@ impl<'tcx> BinOp {
// FIXME: handle SIMD correctly
match self {
&BinOp::Add
| &BinOp::AddUnchecked
| &BinOp::Sub
| &BinOp::SubUnchecked
| &BinOp::Mul
| &BinOp::MulUnchecked
| &BinOp::Div
| &BinOp::Rem
| &BinOp::BitXor
@ -246,7 +249,11 @@ impl<'tcx> BinOp {
assert_eq!(lhs_ty, rhs_ty);
lhs_ty
}
&BinOp::Shl | &BinOp::Shr | &BinOp::Offset => {
&BinOp::Shl
| &BinOp::ShlUnchecked
| &BinOp::Shr
| &BinOp::ShrUnchecked
| &BinOp::Offset => {
lhs_ty // lhs_ty can be != rhs_ty
}
&BinOp::Eq | &BinOp::Lt | &BinOp::Le | &BinOp::Ne | &BinOp::Ge | &BinOp::Gt => {
@ -293,7 +300,14 @@ impl BinOp {
BinOp::Gt => hir::BinOpKind::Gt,
BinOp::Le => hir::BinOpKind::Le,
BinOp::Ge => hir::BinOpKind::Ge,
BinOp::Offset => unreachable!(),
BinOp::AddUnchecked
| BinOp::SubUnchecked
| BinOp::MulUnchecked
| BinOp::ShlUnchecked
| BinOp::ShrUnchecked
| BinOp::Offset => {
unreachable!()
}
}
}
}