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Update to pick Eq or Ne

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This commit is contained in:
kadmin 2020-08-12 08:28:14 +00:00
parent bce5eb0c08
commit f51422b474
1 changed files with 15 additions and 13 deletions
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28
src/librustc_mir/transform/match_branches.rs
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@ -52,11 +52,8 @@ impl<'tcx> MirPass<'tcx> for MatchBranchSimplification {
if let Some(f_c) = f_c.literal.try_eval_bool(tcx, param_env) {
// This should also be a bool because it's writing to the same place
let s_c = s_c.literal.try_eval_bool(tcx, param_env).unwrap();
// Check that only const assignments of opposite bool values are
// permitted.
if f_c != s_c {
continue
}
assert_ne!(f_c, s_c, "Unexpected match would've compared eq earlier");
continue;
}
continue 'outer;
}
@ -70,14 +67,19 @@ impl<'tcx> MirPass<'tcx> for MatchBranchSimplification {
bbs[bb_idx].terminator_mut().kind = TerminatorKind::Goto { target: first };
for s in bbs[first].statements.iter_mut() {
if let StatementKind::Assign(box (_, ref mut rhs)) = s.kind {
let size = tcx.layout_of(param_env.and(switch_ty)).unwrap().size;
let const_cmp = Operand::const_from_scalar(
tcx,
switch_ty,
crate::interpret::Scalar::from_uint(val, size),
rustc_span::DUMMY_SP,
);
*rhs = Rvalue::BinaryOp(BinOp::Eq, Operand::Move(discr), const_cmp);
if let Rvalue::Use(Operand::Constant(c)) = rhs {
let size = tcx.layout_of(param_env.and(switch_ty)).unwrap().size;
let const_cmp = Operand::const_from_scalar(
tcx,
switch_ty,
crate::interpret::Scalar::from_uint(val, size),
rustc_span::DUMMY_SP,
);
if let Some(c) = c.literal.try_eval_bool(tcx, param_env) {
let op = if c { BinOp::Eq } else { BinOp::Ne };
*rhs = Rvalue::BinaryOp(op, Operand::Move(discr), const_cmp);
}
}
}
}
}