rust/src/librustc_trans/basic_block.rs
James Miller 02cb1d4ef1 Delete obviously-unreachable blocks
Some blocks won't be translated at all because they aren't reachable at
the LLVM level, these need to be dealt with because they lack a
terminator and therefore trigger an LLVM assertion.

Other blocks aren't reachable because of codegen-time optimistions, for
example not dropping types that don't need it, often resulting in blocks
with no predecessors. We'll clean those up as well.
2016-03-30 13:00:02 +13:00

59 lines
1.7 KiB
Rust

// Copyright 2013 The Rust Project Developers. See the COPYRIGHT
// file at the top-level directory of this distribution and at
// http://rust-lang.org/COPYRIGHT.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.
use llvm;
use llvm::BasicBlockRef;
use value::{Users, Value};
use std::iter::{Filter, Map};
#[derive(Copy, Clone)]
pub struct BasicBlock(pub BasicBlockRef);
pub type Preds = Map<Filter<Users, fn(&Value) -> bool>, fn(Value) -> BasicBlock>;
/// Wrapper for LLVM BasicBlockRef
impl BasicBlock {
pub fn get(&self) -> BasicBlockRef {
let BasicBlock(v) = *self; v
}
pub fn as_value(self) -> Value {
unsafe {
Value(llvm::LLVMBasicBlockAsValue(self.get()))
}
}
pub fn pred_iter(self) -> Preds {
fn is_a_terminator_inst(user: &Value) -> bool { user.is_a_terminator_inst() }
let is_a_terminator_inst: fn(&Value) -> bool = is_a_terminator_inst;
fn get_parent(user: Value) -> BasicBlock { user.get_parent().unwrap() }
let get_parent: fn(Value) -> BasicBlock = get_parent;
self.as_value().user_iter()
.filter(is_a_terminator_inst)
.map(get_parent)
}
pub fn get_single_predecessor(self) -> Option<BasicBlock> {
let mut iter = self.pred_iter();
match (iter.next(), iter.next()) {
(Some(first), None) => Some(first),
_ => None
}
}
pub fn delete(self) {
unsafe {
llvm::LLVMDeleteBasicBlock(self.0);
}
}
}