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[const-prop] Don't const-prop into terminators unless mir-opt-level >= 2

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This commit is contained in:
Wesley Wiser 2019-05-11 12:33:10 -04:00
parent 2baab0eaaa
commit ec853ba026
1 changed files with 19 additions and 10 deletions
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29
src/librustc_mir/transform/const_prop.rs
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@ -546,6 +546,10 @@ impl<'a, 'mir, 'tcx> ConstPropagator<'a, 'mir, 'tcx> {
}
}
}
fn should_const_prop(&self) -> bool {
self.tcx.sess.opts.debugging_opts.mir_opt_level >= 2
}
}
fn type_size_of<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
@ -639,7 +643,7 @@ impl<'b, 'a, 'tcx> MutVisitor<'tcx> for ConstPropagator<'b, 'a, 'tcx> {
assert!(self.places[local].is_none());
self.places[local] = Some(value);
if self.tcx.sess.opts.debugging_opts.mir_opt_level >= 2 {
if self.should_const_prop() {
self.replace_with_const(rval, value, statement.source_info.span);
}
}
@ -726,20 +730,25 @@ impl<'b, 'a, 'tcx> MutVisitor<'tcx> for ConstPropagator<'b, 'a, 'tcx> {
&msg,
);
} else {
if let ScalarMaybeUndef::Scalar(scalar) = value_const {
*cond = self.operand_from_scalar(
scalar,
self.tcx.types.bool,
source_info.span,
);
if self.should_const_prop() {
if let ScalarMaybeUndef::Scalar(scalar) = value_const {
*cond = self.operand_from_scalar(
scalar,
self.tcx.types.bool,
source_info.span,
);
}
}
}
}
},
TerminatorKind::SwitchInt { ref mut discr, switch_ty, .. } => {
if let Some(value) = self.eval_operand(&discr, source_info) {
if let ScalarMaybeUndef::Scalar(scalar) = self.ecx.read_scalar(value).unwrap() {
*discr = self.operand_from_scalar(scalar, switch_ty, source_info.span);
if self.should_const_prop() {
if let Some(value) = self.eval_operand(&discr, source_info) {
if let ScalarMaybeUndef::Scalar(scalar) =
self.ecx.read_scalar(value).unwrap() {
*discr = self.operand_from_scalar(scalar, switch_ty, source_info.span);
}
}
}
},