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Rollup merge of #119052 - cjgillot:gvn-index-overflow, r=compiler-errors

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Avoid overflow in GVN constant indexing.

Fixes https://github.com/rust-lang/rust/issues/118992
Fixes https://github.com/rust-lang/rust/issues/119008
This commit is contained in:
Matthias Krüger 2023-12-17 21:30:00 +01:00 committed by GitHub
commit 39fe059a35
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GPG Key ID: 4AEE18F83AFDEB23
4 changed files with 229 additions and 5 deletions
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8
compiler/rustc_mir_transform/src/gvn.rs
View File

@ -644,12 +644,10 @@ fn simplify_place_projection(&mut self, place: &mut Place<'tcx>, location: Locat
{
if let Some(offset) = self.evaluated[idx].as_ref()
&& let Ok(offset) = self.ecx.read_target_usize(offset)
&& let Some(min_length) = offset.checked_add(1)
{
projection.to_mut()[i] = ProjectionElem::ConstantIndex {
offset,
min_length: offset + 1,
from_end: false,
};
projection.to_mut()[i] =
ProjectionElem::ConstantIndex { offset, min_length, from_end: false };
} else if let Some(new_idx) = self.try_as_local(idx, location) {
projection.to_mut()[i] = ProjectionElem::Index(new_idx);
self.reused_locals.insert(new_idx);

104
tests/mir-opt/gvn.constant_index_overflow.GVN.panic-abort.diff Normal file
View File

@ -0,0 +1,104 @@
- // MIR for `constant_index_overflow` before GVN
+ // MIR for `constant_index_overflow` after GVN
fn constant_index_overflow(_1: &[T]) -> () {
debug x => _1;
let mut _0: ();
let _2: usize;
let mut _4: bool;
let mut _5: usize;
let mut _6: usize;
let mut _7: &[T];
let _8: usize;
let mut _9: usize;
let mut _10: bool;
let _11: usize;
let mut _12: usize;
let mut _13: bool;
let mut _14: T;
scope 1 {
debug a => _2;
let _3: T;
scope 2 {
debug b => _3;
}
}
bb0: {
- StorageLive(_2);
- _2 = const _ as usize (IntToInt);
+ nop;
+ _2 = const usize::MAX;
StorageLive(_3);
StorageLive(_4);
StorageLive(_5);
- _5 = _2;
+ _5 = const usize::MAX;
StorageLive(_6);
StorageLive(_7);
_7 = &(*_1);
_6 = core::slice::<impl [T]>::len(move _7) -> [return: bb1, unwind unreachable];
}
bb1: {
StorageDead(_7);
- _4 = Lt(move _5, move _6);
+ _4 = Lt(const usize::MAX, move _6);
switchInt(move _4) -> [0: bb4, otherwise: bb2];
}
bb2: {
StorageDead(_6);
StorageDead(_5);
StorageLive(_8);
- _8 = _2;
+ _8 = const usize::MAX;
_9 = Len((*_1));
- _10 = Lt(_8, _9);
- assert(move _10, "index out of bounds: the length is {} but the index is {}", move _9, _8) -> [success: bb3, unwind unreachable];
+ _10 = Lt(const usize::MAX, _9);
+ assert(move _10, "index out of bounds: the length is {} but the index is {}", move _9, const usize::MAX) -> [success: bb3, unwind unreachable];
}
bb3: {
- _3 = (*_1)[_8];
+ _3 = (*_1)[_2];
StorageDead(_8);
goto -> bb6;
}
bb4: {
StorageDead(_6);
StorageDead(_5);
StorageLive(_11);
_11 = const 0_usize;
_12 = Len((*_1));
- _13 = Lt(_11, _12);
- assert(move _13, "index out of bounds: the length is {} but the index is {}", move _12, _11) -> [success: bb5, unwind unreachable];
+ _13 = Lt(const 0_usize, _12);
+ assert(move _13, "index out of bounds: the length is {} but the index is {}", move _12, const 0_usize) -> [success: bb5, unwind unreachable];
}
bb5: {
- _3 = (*_1)[_11];
+ _3 = (*_1)[0 of 1];
StorageDead(_11);
goto -> bb6;
}
bb6: {
StorageDead(_4);
StorageLive(_14);
_14 = _3;
_0 = opaque::<T>(move _14) -> [return: bb7, unwind unreachable];
}
bb7: {
StorageDead(_14);
StorageDead(_3);
- StorageDead(_2);
+ nop;
return;
}
}

104
tests/mir-opt/gvn.constant_index_overflow.GVN.panic-unwind.diff Normal file
View File

@ -0,0 +1,104 @@
- // MIR for `constant_index_overflow` before GVN
+ // MIR for `constant_index_overflow` after GVN
fn constant_index_overflow(_1: &[T]) -> () {
debug x => _1;
let mut _0: ();
let _2: usize;
let mut _4: bool;
let mut _5: usize;
let mut _6: usize;
let mut _7: &[T];
let _8: usize;
let mut _9: usize;
let mut _10: bool;
let _11: usize;
let mut _12: usize;
let mut _13: bool;
let mut _14: T;
scope 1 {
debug a => _2;
let _3: T;
scope 2 {
debug b => _3;
}
}
bb0: {
- StorageLive(_2);
- _2 = const _ as usize (IntToInt);
+ nop;
+ _2 = const usize::MAX;
StorageLive(_3);
StorageLive(_4);
StorageLive(_5);
- _5 = _2;
+ _5 = const usize::MAX;
StorageLive(_6);
StorageLive(_7);
_7 = &(*_1);
_6 = core::slice::<impl [T]>::len(move _7) -> [return: bb1, unwind continue];
}
bb1: {
StorageDead(_7);
- _4 = Lt(move _5, move _6);
+ _4 = Lt(const usize::MAX, move _6);
switchInt(move _4) -> [0: bb4, otherwise: bb2];
}
bb2: {
StorageDead(_6);
StorageDead(_5);
StorageLive(_8);
- _8 = _2;
+ _8 = const usize::MAX;
_9 = Len((*_1));
- _10 = Lt(_8, _9);
- assert(move _10, "index out of bounds: the length is {} but the index is {}", move _9, _8) -> [success: bb3, unwind continue];
+ _10 = Lt(const usize::MAX, _9);
+ assert(move _10, "index out of bounds: the length is {} but the index is {}", move _9, const usize::MAX) -> [success: bb3, unwind continue];
}
bb3: {
- _3 = (*_1)[_8];
+ _3 = (*_1)[_2];
StorageDead(_8);
goto -> bb6;
}
bb4: {
StorageDead(_6);
StorageDead(_5);
StorageLive(_11);
_11 = const 0_usize;
_12 = Len((*_1));
- _13 = Lt(_11, _12);
- assert(move _13, "index out of bounds: the length is {} but the index is {}", move _12, _11) -> [success: bb5, unwind continue];
+ _13 = Lt(const 0_usize, _12);
+ assert(move _13, "index out of bounds: the length is {} but the index is {}", move _12, const 0_usize) -> [success: bb5, unwind continue];
}
bb5: {
- _3 = (*_1)[_11];
+ _3 = (*_1)[0 of 1];
StorageDead(_11);
goto -> bb6;
}
bb6: {
StorageDead(_4);
StorageLive(_14);
_14 = _3;
_0 = opaque::<T>(move _14) -> [return: bb7, unwind continue];
}
bb7: {
StorageDead(_14);
StorageDead(_3);
- StorageDead(_2);
+ nop;
return;
}
}

18
tests/mir-opt/gvn.rs
View File

@ -609,6 +609,22 @@ fn indirect_static() {
})
}
/// Verify that having constant index `u64::MAX` does not yield to an overflow in rustc.
fn constant_index_overflow<T: Copy>(x: &[T]) {
// CHECK-LABEL: fn constant_index_overflow(
// CHECK: debug a => [[a:_.*]];
// CHECK: debug b => [[b:_.*]];
// CHECK: [[a]] = const usize::MAX;
// CHECK-NOT: = (*_1)[{{.*}} of 0];
// CHECK: [[b]] = (*_1)[[[a]]];
// CHECK-NOT: = (*_1)[{{.*}} of 0];
// CHECK: [[b]] = (*_1)[0 of 1];
// CHECK-NOT: = (*_1)[{{.*}} of 0];
let a = u64::MAX as usize;
let b = if a < x.len() { x[a] } else { x[0] };
opaque(b)
}
fn main() {
subexpression_elimination(2, 4, 5);
wrap_unwrap(5);
@ -627,6 +643,7 @@ fn main() {
repeat();
fn_pointers();
indirect_static();
constant_index_overflow(&[5, 3]);
}
#[inline(never)]
@ -653,3 +670,4 @@ fn identity<T>(x: T) -> T {
// EMIT_MIR gvn.repeat.GVN.diff
// EMIT_MIR gvn.fn_pointers.GVN.diff
// EMIT_MIR gvn.indirect_static.GVN.diff
// EMIT_MIR gvn.constant_index_overflow.GVN.diff