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Simplify bit inspection of a constant

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This commit is contained in:
Oliver Scherer 2018-12-13 11:15:18 +01:00
parent 37a0df3e9d
commit 17db209d4b
1 changed files with 10 additions and 14 deletions
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24
src/librustc_mir/transform/simplify_branches.rs
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@ -1,6 +1,6 @@
//! A pass that simplifies branches when their condition is known.
use rustc::ty::{self, TyCtxt, ParamEnv};
use rustc::ty::{TyCtxt, ParamEnv};
use rustc::mir::*;
use transform::{MirPass, MirSource};
@ -30,21 +30,17 @@ impl MirPass for SimplifyBranches {
discr: Operand::Constant(ref c), switch_ty, ref values, ref targets, ..
} => {
let switch_ty = ParamEnv::empty().and(switch_ty);
if let ty::LazyConst::Evaluated(c) = c.literal {
let c = c.assert_bits(tcx, switch_ty);
if let Some(constant) = c {
let (otherwise, targets) = targets.split_last().unwrap();
let mut ret = TerminatorKind::Goto { target: *otherwise };
for (&v, t) in values.iter().zip(targets.iter()) {
if v == constant {
ret = TerminatorKind::Goto { target: *t };
break;
}
let constant = c.literal.map_evaluated(|c| c.assert_bits(tcx, switch_ty));
if let Some(constant) = constant {
let (otherwise, targets) = targets.split_last().unwrap();
let mut ret = TerminatorKind::Goto { target: *otherwise };
for (&v, t) in values.iter().zip(targets.iter()) {
if v == constant {
ret = TerminatorKind::Goto { target: *t };
break;
}
ret
} else {
continue
}
ret
} else {
continue
}