c85501b9c1
Operand: 72 -> 24 B Statement: 192 -> 96 B Terminator: 256 -> 112 B librustc translation memory usage: 1795 -> 1669 MB next step would be interning lvalues, I suppose?
69 lines
2.5 KiB
Rust
69 lines
2.5 KiB
Rust
// Copyright 2016 The Rust Project Developers. See the COPYRIGHT
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// file at the top-level directory of this distribution and at
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// http://rust-lang.org/COPYRIGHT.
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//
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// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
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// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
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// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
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// option. This file may not be copied, modified, or distributed
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// except according to those terms.
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//! A pass that simplifies branches when their condition is known.
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use rustc::ty::TyCtxt;
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use rustc::middle::const_val::ConstVal;
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use rustc::mir::transform::{MirPass, MirSource};
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use rustc::mir::*;
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use std::borrow::Cow;
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pub struct SimplifyBranches { label: String }
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impl SimplifyBranches {
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pub fn new(label: &str) -> Self {
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SimplifyBranches { label: format!("SimplifyBranches-{}", label) }
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}
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}
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impl MirPass for SimplifyBranches {
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fn name<'a>(&'a self) -> Cow<'a, str> {
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Cow::Borrowed(&self.label)
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}
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fn run_pass<'a, 'tcx>(&self,
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_tcx: TyCtxt<'a, 'tcx, 'tcx>,
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_src: MirSource,
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mir: &mut Mir<'tcx>) {
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for block in mir.basic_blocks_mut() {
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let terminator = block.terminator_mut();
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terminator.kind = match terminator.kind {
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TerminatorKind::SwitchInt { discr: Operand::Constant(box Constant {
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literal: Literal::Value { ref value }, ..
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}), ref values, ref targets, .. } => {
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if let Some(ref constint) = value.to_const_int() {
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let (otherwise, targets) = targets.split_last().unwrap();
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let mut ret = TerminatorKind::Goto { target: *otherwise };
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for (v, t) in values.iter().zip(targets.iter()) {
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if v == constint {
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ret = TerminatorKind::Goto { target: *t };
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break;
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}
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}
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ret
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} else {
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continue
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}
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},
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TerminatorKind::Assert { target, cond: Operand::Constant(box Constant {
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literal: Literal::Value {
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value: ConstVal::Bool(cond)
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}, ..
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}), expected, .. } if cond == expected => {
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TerminatorKind::Goto { target: target }
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},
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_ => continue
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};
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}
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}
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}
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