diff options
| -rw-r--r-- | src/librustc_mir/transform/match_branches.rs | 28 |
1 files changed, 15 insertions, 13 deletions
diff --git a/src/librustc_mir/transform/match_branches.rs b/src/librustc_mir/transform/match_branches.rs index 5fab46f029f..07dec23429b 100644 --- a/src/librustc_mir/transform/match_branches.rs +++ b/src/librustc_mir/transform/match_branches.rs @@ -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); + } + } } } } |