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Expand match over binops.

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This commit is contained in:
Camille GILLOT 2024-01-08 22:54:05 +00:00
parent 166fe54eba
commit 0cc2102c4a
1 changed files with 18 additions and 15 deletions
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33
compiler/rustc_mir_transform/src/gvn.rs
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@ -966,12 +966,13 @@ impl<'body, 'tcx> VnState<'body, 'tcx> {
}
};
// Represent the values as `Ok(bits)` or `Err(VnIndex)`.
let a = as_bits(lhs).ok_or(lhs);
let b = as_bits(rhs).ok_or(rhs);
// Represent the values as `Left(bits)` or `Right(VnIndex)`.
use Either::{Left, Right};
let a = as_bits(lhs).map_or(Right(lhs), Left);
let b = as_bits(rhs).map_or(Right(rhs), Left);
let result = match (op, a, b) {
// Neutral elements.
(BinOp::Add | BinOp::BitOr | BinOp::BitXor, Ok(0), Err(p))
(BinOp::Add | BinOp::BitOr | BinOp::BitXor, Left(0), Right(p))
| (
BinOp::Add
| BinOp::BitOr
@ -980,28 +981,28 @@ impl<'body, 'tcx> VnState<'body, 'tcx> {
| BinOp::Offset
| BinOp::Shl
| BinOp::Shr,
Err(p),
Ok(0),
Right(p),
Left(0),
)
| (BinOp::Mul, Ok(1), Err(p))
| (BinOp::Mul | BinOp::Div, Err(p), Ok(1)) => p,
| (BinOp::Mul, Left(1), Right(p))
| (BinOp::Mul | BinOp::Div, Right(p), Left(1)) => p,
// Attempt to simplify `x & ALL_ONES` to `x`, with `ALL_ONES` depending on type size.
(BinOp::BitAnd, Err(p), Ok(ones)) | (BinOp::BitAnd, Ok(ones), Err(p))
(BinOp::BitAnd, Right(p), Left(ones)) | (BinOp::BitAnd, Left(ones), Right(p))
if ones == layout.size.truncate(u128::MAX)
|| (layout.ty.is_bool() && ones == 1) =>
{
p
}
// Absorbing elements.
(BinOp::Mul | BinOp::BitAnd, _, Ok(0))
| (BinOp::Rem, _, Ok(1))
(BinOp::Mul | BinOp::BitAnd, _, Left(0))
| (BinOp::Rem, _, Left(1))
| (
BinOp::Mul | BinOp::Div | BinOp::Rem | BinOp::BitAnd | BinOp::Shl | BinOp::Shr,
Ok(0),
Left(0),
_,
) => self.insert_scalar(Scalar::from_uint(0u128, layout.size), lhs_ty),
// Attempt to simplify `x | ALL_ONES` to `ALL_ONES`.
(BinOp::BitOr, _, Ok(ones)) | (BinOp::BitOr, Ok(ones), _)
(BinOp::BitOr, _, Left(ones)) | (BinOp::BitOr, Left(ones), _)
if ones == layout.size.truncate(u128::MAX)
|| (layout.ty.is_bool() && ones == 1) =>
{
@ -1015,8 +1016,10 @@ impl<'body, 'tcx> VnState<'body, 'tcx> {
// - if both operands can be computed as bits, just compare the bits;
// - if we proved that both operands have the same value, we can insert true/false;
// - otherwise, do nothing, as we do not try to prove inequality.
(BinOp::Eq, a, b) if (a.is_ok() && b.is_ok()) || a == b => self.insert_bool(a == b),
(BinOp::Ne, a, b) if (a.is_ok() && b.is_ok()) || a == b => self.insert_bool(a != b),
(BinOp::Eq, Left(a), Left(b)) => self.insert_bool(a == b),
(BinOp::Eq, a, b) if a == b => self.insert_bool(true),
(BinOp::Ne, Left(a), Left(b)) => self.insert_bool(a != b),
(BinOp::Ne, a, b) if a == b => self.insert_bool(false),
_ => return None,
};