*rvalue = Rvalue::Use(Operand::Constant(box constant));
}
- if let Some(operand) = self.optimizations.unneeded_not_equal.remove(&location) {
+ if let Some(operand) = self.optimizations.unneeded_equality_comparison.remove(&location) {
debug!("replacing {:?} with {:?}", rvalue, operand);
*rvalue = Rvalue::Use(operand);
}
OptimizationFinder { body, tcx, optimizations: OptimizationList::default() }
}
- fn find_operand_in_ne_false_pattern(
+ fn find_unneeded_equality_comparison(&mut self, rvalue: &Rvalue<'tcx>, location: Location) {
+ // find Ne(_place, false) or Ne(false, _place)
+ // or Eq(_place, true) or Eq(true, _place)
+ if let Rvalue::BinaryOp(op, l, r) = rvalue {
+ let const_to_find = if *op == BinOp::Ne {
+ false
+ } else if *op == BinOp::Eq {
+ true
+ } else {
+ return;
+ };
+ // (const, _place)
+ if let Some(o) = self.find_operand_in_equality_comparison_pattern(l, r, const_to_find) {
+ self.optimizations.unneeded_equality_comparison.insert(location, o.clone());
+ }
+ // (_place, const)
+ else if let Some(o) =
+ self.find_operand_in_equality_comparison_pattern(r, l, const_to_find)
+ {
+ self.optimizations.unneeded_equality_comparison.insert(location, o.clone());
+ }
+ }
+ }
+
+ fn find_operand_in_equality_comparison_pattern(
&self,
l: &Operand<'tcx>,
r: &'a Operand<'tcx>,
+ const_to_find: bool,
) -> Option<&'a Operand<'tcx>> {
let const_ = l.constant()?;
if const_.literal.ty == self.tcx.types.bool
- && const_.literal.val.try_to_bool() == Some(false)
+ && const_.literal.val.try_to_bool() == Some(const_to_find)
{
if r.place().is_some() {
return Some(r);
}
}
- // find Ne(_place, false) or Ne(false, _place)
- if let Rvalue::BinaryOp(BinOp::Ne, l, r) = rvalue {
- // (false, _place)
- if let Some(o) = self.find_operand_in_ne_false_pattern(l, r) {
- self.optimizations.unneeded_not_equal.insert(location, o.clone());
- }
- // (_place, false)
- else if let Some(o) = self.find_operand_in_ne_false_pattern(r, l) {
- self.optimizations.unneeded_not_equal.insert(location, o.clone());
- }
- }
+ self.find_unneeded_equality_comparison(rvalue, location);
self.super_rvalue(rvalue, location)
}
struct OptimizationList<'tcx> {
and_stars: FxHashSet<Location>,
arrays_lengths: FxHashMap<Location, Constant<'tcx>>,
- unneeded_not_equal: FxHashMap<Location, Operand<'tcx>>,
+ unneeded_equality_comparison: FxHashMap<Location, Operand<'tcx>>,
}
--- /dev/null
+- // MIR for `opt` before InstCombine
++ // MIR for `opt` after InstCombine
+
+ fn opt(_1: bool) -> i32 {
+ debug x => _1; // in scope 0 at $DIR/equal_true.rs:3:8: 3:9
+ let mut _0: i32; // return place in scope 0 at $DIR/equal_true.rs:3:20: 3:23
+ let mut _2: bool; // in scope 0 at $DIR/equal_true.rs:4:8: 4:17
+ let mut _3: bool; // in scope 0 at $DIR/equal_true.rs:4:8: 4:9
+
+ bb0: {
+ StorageLive(_2); // scope 0 at $DIR/equal_true.rs:4:8: 4:17
+ StorageLive(_3); // scope 0 at $DIR/equal_true.rs:4:8: 4:9
+ _3 = _1; // scope 0 at $DIR/equal_true.rs:4:8: 4:9
+- _2 = Eq(move _3, const true); // scope 0 at $DIR/equal_true.rs:4:8: 4:17
++ _2 = move _3; // scope 0 at $DIR/equal_true.rs:4:8: 4:17
+ StorageDead(_3); // scope 0 at $DIR/equal_true.rs:4:16: 4:17
+ switchInt(_2) -> [false: bb1, otherwise: bb2]; // scope 0 at $DIR/equal_true.rs:4:5: 4:34
+ }
+
+ bb1: {
+ _0 = const 1_i32; // scope 0 at $DIR/equal_true.rs:4:31: 4:32
+ goto -> bb3; // scope 0 at $DIR/equal_true.rs:4:5: 4:34
+ }
+
+ bb2: {
+ _0 = const 0_i32; // scope 0 at $DIR/equal_true.rs:4:20: 4:21
+ goto -> bb3; // scope 0 at $DIR/equal_true.rs:4:5: 4:34
+ }
+
+ bb3: {
+ StorageDead(_2); // scope 0 at $DIR/equal_true.rs:5:1: 5:2
+ return; // scope 0 at $DIR/equal_true.rs:5:2: 5:2
+ }
+ }
+