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JumpThreading: Re-enable and fix Not ops on non-booleans

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This commit is contained in:
clubby789 2024-10-04 12:54:09 +00:00
parent 092a284ba0
commit 9f35fe47c7
6 changed files with 120 additions and 27 deletions
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29
compiler/rustc_mir_transform/src/jump_threading.rs
View file

@ -150,14 +150,6 @@ impl Condition {
fn matches(&self, value: ScalarInt) -> bool {
(self.value == value) == (self.polarity == Polarity::Eq)
}
fn inv(mut self) -> Self {
self.polarity = match self.polarity {
Polarity::Eq => Polarity::Ne,
Polarity::Ne => Polarity::Eq,
};
self
}
}
#[derive(Copy, Clone, Debug)]
@ -495,19 +487,20 @@ impl<'a, 'tcx> TOFinder<'a, 'tcx> {
}
}
}
// Transfer the conditions on the copy rhs, after inversing polarity.
// Transfer the conditions on the copy rhs, after inverting the value of the condition.
Rvalue::UnaryOp(UnOp::Not, Operand::Move(place) | Operand::Copy(place)) => {
if !place.ty(self.body, self.tcx).ty.is_bool() {
// Constructing the conditions by inverting the polarity
// of equality is only correct for bools. That is to say,
// `!a == b` is not `a != b` for integers greater than 1 bit.
return;
}
let layout = self.ecx.layout_of(place.ty(self.body, self.tcx).ty).unwrap();
let Some(conditions) = state.try_get_idx(lhs, &self.map) else { return };
let Some(place) = self.map.find(place.as_ref()) else { return };
// FIXME: I think This could be generalized to not bool if we
// actually perform a logical not on the condition's value.
let conds = conditions.map(self.arena, Condition::inv);
let conds = conditions.map(self.arena, |mut cond| {
cond.value = self
.ecx
.unary_op(UnOp::Not, &ImmTy::from_scalar_int(cond.value, layout))
.unwrap()
.to_scalar_int()
.unwrap();
cond
});
state.insert_value_idx(place, conds, &self.map);
}
// We expect `lhs ?= A`. We found `lhs = Eq(rhs, B)`.

6
tests/mir-opt/jump_threading.bitwise_not.JumpThreading.panic-abort.diff
View file

@ -3,7 +3,7 @@
fn bitwise_not() -> i32 {
let mut _0: i32;
let mut _1: i32;
let _1: i32;
let mut _2: bool;
let mut _3: i32;
let mut _4: i32;
@ -13,7 +13,6 @@
bb0: {
StorageLive(_1);
_1 = const 0_i32;
_1 = const 1_i32;
StorageLive(_2);
StorageLive(_3);
@ -22,7 +21,8 @@
_3 = Not(move _4);
StorageDead(_4);
_2 = Eq(move _3, const 0_i32);
switchInt(move _2) -> [0: bb2, otherwise: bb1];
- switchInt(move _2) -> [0: bb2, otherwise: bb1];
+ goto -> bb2;
}
bb1: {

6
tests/mir-opt/jump_threading.bitwise_not.JumpThreading.panic-unwind.diff
View file

@ -3,7 +3,7 @@
fn bitwise_not() -> i32 {
let mut _0: i32;
let mut _1: i32;
let _1: i32;
let mut _2: bool;
let mut _3: i32;
let mut _4: i32;
@ -13,7 +13,6 @@
bb0: {
StorageLive(_1);
_1 = const 0_i32;
_1 = const 1_i32;
StorageLive(_2);
StorageLive(_3);
@ -22,7 +21,8 @@
_3 = Not(move _4);
StorageDead(_4);
_2 = Eq(move _3, const 0_i32);
switchInt(move _2) -> [0: bb2, otherwise: bb1];
- switchInt(move _2) -> [0: bb2, otherwise: bb1];
+ goto -> bb2;
}
bb1: {

46
tests/mir-opt/jump_threading.logical_not.JumpThreading.panic-abort.diff Normal file
View file

@ -0,0 +1,46 @@
- // MIR for `logical_not` before JumpThreading
+ // MIR for `logical_not` after JumpThreading
fn logical_not() -> i32 {
let mut _0: i32;
let _1: bool;
let mut _2: bool;
let mut _3: bool;
let mut _4: bool;
scope 1 {
debug a => _1;
}
bb0: {
StorageLive(_1);
_1 = const false;
StorageLive(_2);
StorageLive(_3);
StorageLive(_4);
_4 = copy _1;
_3 = Not(move _4);
StorageDead(_4);
_2 = Eq(move _3, const true);
- switchInt(move _2) -> [0: bb2, otherwise: bb1];
+ goto -> bb1;
}
bb1: {
StorageDead(_3);
_0 = const 1_i32;
goto -> bb3;
}
bb2: {
StorageDead(_3);
_0 = const 0_i32;
goto -> bb3;
}
bb3: {
StorageDead(_2);
StorageDead(_1);
return;
}
}

46
tests/mir-opt/jump_threading.logical_not.JumpThreading.panic-unwind.diff Normal file
View file

@ -0,0 +1,46 @@
- // MIR for `logical_not` before JumpThreading
+ // MIR for `logical_not` after JumpThreading
fn logical_not() -> i32 {
let mut _0: i32;
let _1: bool;
let mut _2: bool;
let mut _3: bool;
let mut _4: bool;
scope 1 {
debug a => _1;
}
bb0: {
StorageLive(_1);
_1 = const false;
StorageLive(_2);
StorageLive(_3);
StorageLive(_4);
_4 = copy _1;
_3 = Not(move _4);
StorageDead(_4);
_2 = Eq(move _3, const true);
- switchInt(move _2) -> [0: bb2, otherwise: bb1];
+ goto -> bb1;
}
bb1: {
StorageDead(_3);
_0 = const 1_i32;
goto -> bb3;
}
bb2: {
StorageDead(_3);
_0 = const 0_i32;
goto -> bb3;
}
bb3: {
StorageDead(_2);
StorageDead(_1);
return;
}
}

14
tests/mir-opt/jump_threading.rs
View file

@ -532,14 +532,19 @@ fn floats() -> u32 {
pub fn bitwise_not() -> i32 {
// CHECK-LABEL: fn bitwise_not(
// CHECK: switchInt(
// Test for #131195, which was optimizing `!a == b` into `a != b`.
let mut a: i32 = 0;
a = 1;
let a = 1;
if !a == 0 { 1 } else { 0 }
}
pub fn logical_not() -> i32 {
// CHECK-LABEL: fn logical_not(
let a = false;
if !a == true { 1 } else { 0 }
}
fn main() {
// CHECK-LABEL: fn main(
too_complex(Ok(0));
@ -555,6 +560,8 @@ fn main() {
aggregate(7);
assume(7, false);
floats();
bitwise_not();
logical_not();
}
// EMIT_MIR jump_threading.too_complex.JumpThreading.diff
@ -572,3 +579,4 @@ fn main() {
// EMIT_MIR jump_threading.aggregate_copy.JumpThreading.diff
// EMIT_MIR jump_threading.floats.JumpThreading.diff
// EMIT_MIR jump_threading.bitwise_not.JumpThreading.diff
// EMIT_MIR jump_threading.logical_not.JumpThreading.diff