52 lines
1.8 KiB
Rust
52 lines
1.8 KiB
Rust
// Copyright 2015 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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use rustc::mir::repr::*;
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/// Update basic block ids in all terminators using the given replacements,
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/// useful e.g. after removal of several basic blocks to update all terminators
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/// in a single pass
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pub fn update_basic_block_ids(mir: &mut Mir, replacements: &[BasicBlock]) {
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for bb in mir.all_basic_blocks() {
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for target in mir.basic_block_data_mut(bb).terminator_mut().successors_mut() {
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*target = replacements[target.index()];
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}
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}
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}
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/// Mass removal of basic blocks to keep the ID-remapping cheap.
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pub fn retain_basic_blocks(mir: &mut Mir, keep: &[bool]) {
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let num_blocks = mir.basic_blocks.len();
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// Check that we have a usage flag for every block
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assert_eq!(num_blocks, keep.len());
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let first_dead = match keep.iter().position(|&k| !k) {
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None => return,
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Some(first_dead) => first_dead,
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};
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// `replacements` maps the old block ids to the new ones
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let mut replacements: Vec<_> = (0..num_blocks).map(BasicBlock::new).collect();
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let mut dead = 0;
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for i in first_dead..num_blocks {
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if keep[i] {
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replacements[i] = BasicBlock::new(i - dead);
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mir.basic_blocks.swap(i, i - dead);
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} else {
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dead += 1;
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}
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}
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mir.basic_blocks.truncate(num_blocks - dead);
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update_basic_block_ids(mir, &replacements);
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}
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