bjoernager/rust
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Add+Use mir::BinOp::Cmp

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This commit is contained in:
Scott McMurray 2023-03-05 20:19:41 -08:00
parent 744c664ba2
commit 3da115a93b
35 changed files with 521 additions and 119 deletions
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30
compiler/rustc_codegen_ssa/src/mir/rvalue.rs
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@ -7,6 +7,7 @@ use crate::common::{self, IntPredicate};
use crate::traits::*;
use crate::MemFlags;
use rustc_hir as hir;
use rustc_middle::mir;
use rustc_middle::mir::Operand;
use rustc_middle::ty::cast::{CastTy, IntTy};
@ -882,6 +883,35 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
bx.icmp(base::bin_op_to_icmp_predicate(op.to_hir_binop(), is_signed), lhs, rhs)
}
}
mir::BinOp::Cmp => {
use std::cmp::Ordering;
debug_assert!(!is_float);
let pred = |op| base::bin_op_to_icmp_predicate(op, is_signed);
if bx.cx().tcx().sess.opts.optimize == OptLevel::No {
// FIXME: This actually generates tighter assembly, and is a classic trick
// <https://graphics.stanford.edu/~seander/bithacks.html#CopyIntegerSign>
// However, as of 2023-11 it optimizes worse in things like derived
// `PartialOrd`, so only use it in debug for now. Once LLVM can handle it
// better (see <https://github.com/llvm/llvm-project/issues/73417>), it'll
// be worth trying it in optimized builds as well.
let is_gt = bx.icmp(pred(hir::BinOpKind::Gt), lhs, rhs);
let gtext = bx.zext(is_gt, bx.type_i8());
let is_lt = bx.icmp(pred(hir::BinOpKind::Lt), lhs, rhs);
let ltext = bx.zext(is_lt, bx.type_i8());
bx.unchecked_ssub(gtext, ltext)
} else {
// These operations are those expected by `tests/codegen/integer-cmp.rs`,
// from <https://github.com/rust-lang/rust/pull/63767>.
let is_lt = bx.icmp(pred(hir::BinOpKind::Lt), lhs, rhs);
let is_ne = bx.icmp(pred(hir::BinOpKind::Ne), lhs, rhs);
let ge = bx.select(
is_ne,
bx.cx().const_i8(Ordering::Greater as i8),
bx.cx().const_i8(Ordering::Equal as i8),
);
bx.select(is_lt, bx.cx().const_i8(Ordering::Less as i8), ge)
}
}
}
}

1
compiler/rustc_codegen_ssa/src/traits/consts.rs
View file

@ -19,6 +19,7 @@ pub trait ConstMethods<'tcx>: BackendTypes {
fn const_bool(&self, val: bool) -> Self::Value;
fn const_i16(&self, i: i16) -> Self::Value;
fn const_i32(&self, i: i32) -> Self::Value;
fn const_i8(&self, i: i8) -> Self::Value;
fn const_u32(&self, i: u32) -> Self::Value;
fn const_u64(&self, i: u64) -> Self::Value;
fn const_u128(&self, i: u128) -> Self::Value;