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Simplify Len.

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This commit is contained in:
Camille GILLOT 2023-03-20 20:15:59 +00:00
parent 5fc23ad8e6
commit 3c48243b6f
15 changed files with 96 additions and 52 deletions
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38
compiler/rustc_mir_transform/src/gvn.rs
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@ -776,10 +776,7 @@ impl<'body, 'tcx> VnState<'body, 'tcx> {
}
// Operations.
Rvalue::Len(ref mut place) => {
let place = self.simplify_place_value(place, location)?;
Value::Len(place)
}
Rvalue::Len(ref mut place) => return self.simplify_len(place, location),
Rvalue::Cast(kind, ref mut value, to) => {
let from = value.ty(self.local_decls, self.tcx);
let value = self.simplify_operand(value, location)?;
@ -1021,6 +1018,39 @@ impl<'body, 'tcx> VnState<'body, 'tcx> {
Some(result)
}
}
fn simplify_len(&mut self, place: &mut Place<'tcx>, location: Location) -> Option<VnIndex> {
// Trivial case: we are fetching a statically known length.
let place_ty = place.ty(self.local_decls, self.tcx).ty;
if let ty::Array(_, len) = place_ty.kind() {
return self.insert_constant(Const::from_ty_const(*len, self.tcx));
}
let mut inner = self.simplify_place_value(place, location)?;
// The length information is stored in the fat pointer.
// Reborrowing copies length information from one pointer to the other.
while let Value::Address { place: borrowed, .. } = self.get(inner)
&& let [PlaceElem::Deref] = borrowed.projection[..]
&& let Some(borrowed) = self.locals[borrowed.local]
{
inner = borrowed;
}
// We have an unsizing cast, which assigns the length to fat pointer metadata.
if let Value::Cast { kind, from, to, .. } = self.get(inner)
&& let CastKind::PointerCoercion(ty::adjustment::PointerCoercion::Unsize) = kind
&& let Some(from) = from.builtin_deref(true)
&& let ty::Array(_, len) = from.ty.kind()
&& let Some(to) = to.builtin_deref(true)
&& let ty::Slice(..) = to.ty.kind()
{
return self.insert_constant(Const::from_ty_const(*len, self.tcx));
}
// Fallback: a symbolic `Len`.
Some(self.insert(Value::Len(inner)))
}
}
fn op_to_prop_const<'tcx>(

7
tests/mir-opt/const_prop/array_index.main.GVN.32bit.panic-abort.diff
View File

@ -18,11 +18,12 @@
_2 = [const 0_u32, const 1_u32, const 2_u32, const 3_u32];
StorageLive(_3);
_3 = const 2_usize;
_4 = Len(_2);
- _4 = Len(_2);
- _5 = Lt(_3, _4);
- assert(move _5, "index out of bounds: the length is {} but the index is {}", move _4, _3) -> [success: bb1, unwind unreachable];
+ _5 = Lt(const 2_usize, _4);
+ assert(move _5, "index out of bounds: the length is {} but the index is {}", move _4, const 2_usize) -> [success: bb1, unwind unreachable];
+ _4 = const 4_usize;
+ _5 = const true;
+ assert(const true, "index out of bounds: the length is {} but the index is {}", const 4_usize, const 2_usize) -> [success: bb1, unwind unreachable];
}
bb1: {

7
tests/mir-opt/const_prop/array_index.main.GVN.32bit.panic-unwind.diff
View File

@ -18,11 +18,12 @@
_2 = [const 0_u32, const 1_u32, const 2_u32, const 3_u32];
StorageLive(_3);
_3 = const 2_usize;
_4 = Len(_2);
- _4 = Len(_2);
- _5 = Lt(_3, _4);
- assert(move _5, "index out of bounds: the length is {} but the index is {}", move _4, _3) -> [success: bb1, unwind continue];
+ _5 = Lt(const 2_usize, _4);
+ assert(move _5, "index out of bounds: the length is {} but the index is {}", move _4, const 2_usize) -> [success: bb1, unwind continue];
+ _4 = const 4_usize;
+ _5 = const true;
+ assert(const true, "index out of bounds: the length is {} but the index is {}", const 4_usize, const 2_usize) -> [success: bb1, unwind continue];
}
bb1: {

7
tests/mir-opt/const_prop/array_index.main.GVN.64bit.panic-abort.diff
View File

@ -18,11 +18,12 @@
_2 = [const 0_u32, const 1_u32, const 2_u32, const 3_u32];
StorageLive(_3);
_3 = const 2_usize;
_4 = Len(_2);
- _4 = Len(_2);
- _5 = Lt(_3, _4);
- assert(move _5, "index out of bounds: the length is {} but the index is {}", move _4, _3) -> [success: bb1, unwind unreachable];
+ _5 = Lt(const 2_usize, _4);
+ assert(move _5, "index out of bounds: the length is {} but the index is {}", move _4, const 2_usize) -> [success: bb1, unwind unreachable];
+ _4 = const 4_usize;
+ _5 = const true;
+ assert(const true, "index out of bounds: the length is {} but the index is {}", const 4_usize, const 2_usize) -> [success: bb1, unwind unreachable];
}
bb1: {

7
tests/mir-opt/const_prop/array_index.main.GVN.64bit.panic-unwind.diff
View File

@ -18,11 +18,12 @@
_2 = [const 0_u32, const 1_u32, const 2_u32, const 3_u32];
StorageLive(_3);
_3 = const 2_usize;
_4 = Len(_2);
- _4 = Len(_2);
- _5 = Lt(_3, _4);
- assert(move _5, "index out of bounds: the length is {} but the index is {}", move _4, _3) -> [success: bb1, unwind continue];
+ _5 = Lt(const 2_usize, _4);
+ assert(move _5, "index out of bounds: the length is {} but the index is {}", move _4, const 2_usize) -> [success: bb1, unwind continue];
+ _4 = const 4_usize;
+ _5 = const true;
+ assert(const true, "index out of bounds: the length is {} but the index is {}", const 4_usize, const 2_usize) -> [success: bb1, unwind continue];
}
bb1: {

7
tests/mir-opt/const_prop/large_array_index.main.GVN.32bit.panic-abort.diff
View File

@ -18,11 +18,12 @@
_2 = [const 0_u8; 5000];
StorageLive(_3);
_3 = const 2_usize;
_4 = Len(_2);
- _4 = Len(_2);
- _5 = Lt(_3, _4);
- assert(move _5, "index out of bounds: the length is {} but the index is {}", move _4, _3) -> [success: bb1, unwind unreachable];
+ _5 = Lt(const 2_usize, _4);
+ assert(move _5, "index out of bounds: the length is {} but the index is {}", move _4, const 2_usize) -> [success: bb1, unwind unreachable];
+ _4 = const 5000_usize;
+ _5 = const true;
+ assert(const true, "index out of bounds: the length is {} but the index is {}", const 5000_usize, const 2_usize) -> [success: bb1, unwind unreachable];
}
bb1: {

7
tests/mir-opt/const_prop/large_array_index.main.GVN.32bit.panic-unwind.diff
View File

@ -18,11 +18,12 @@
_2 = [const 0_u8; 5000];
StorageLive(_3);
_3 = const 2_usize;
_4 = Len(_2);
- _4 = Len(_2);
- _5 = Lt(_3, _4);
- assert(move _5, "index out of bounds: the length is {} but the index is {}", move _4, _3) -> [success: bb1, unwind continue];
+ _5 = Lt(const 2_usize, _4);
+ assert(move _5, "index out of bounds: the length is {} but the index is {}", move _4, const 2_usize) -> [success: bb1, unwind continue];
+ _4 = const 5000_usize;
+ _5 = const true;
+ assert(const true, "index out of bounds: the length is {} but the index is {}", const 5000_usize, const 2_usize) -> [success: bb1, unwind continue];
}
bb1: {

7
tests/mir-opt/const_prop/large_array_index.main.GVN.64bit.panic-abort.diff
View File

@ -18,11 +18,12 @@
_2 = [const 0_u8; 5000];
StorageLive(_3);
_3 = const 2_usize;
_4 = Len(_2);
- _4 = Len(_2);
- _5 = Lt(_3, _4);
- assert(move _5, "index out of bounds: the length is {} but the index is {}", move _4, _3) -> [success: bb1, unwind unreachable];
+ _5 = Lt(const 2_usize, _4);
+ assert(move _5, "index out of bounds: the length is {} but the index is {}", move _4, const 2_usize) -> [success: bb1, unwind unreachable];
+ _4 = const 5000_usize;
+ _5 = const true;
+ assert(const true, "index out of bounds: the length is {} but the index is {}", const 5000_usize, const 2_usize) -> [success: bb1, unwind unreachable];
}
bb1: {

7
tests/mir-opt/const_prop/large_array_index.main.GVN.64bit.panic-unwind.diff
View File

@ -18,11 +18,12 @@
_2 = [const 0_u8; 5000];
StorageLive(_3);
_3 = const 2_usize;
_4 = Len(_2);
- _4 = Len(_2);
- _5 = Lt(_3, _4);
- assert(move _5, "index out of bounds: the length is {} but the index is {}", move _4, _3) -> [success: bb1, unwind continue];
+ _5 = Lt(const 2_usize, _4);
+ assert(move _5, "index out of bounds: the length is {} but the index is {}", move _4, const 2_usize) -> [success: bb1, unwind continue];
+ _4 = const 5000_usize;
+ _5 = const true;
+ assert(const true, "index out of bounds: the length is {} but the index is {}", const 5000_usize, const 2_usize) -> [success: bb1, unwind continue];
}
bb1: {

7
tests/mir-opt/const_prop/repeat.main.GVN.32bit.panic-abort.diff
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@ -20,11 +20,12 @@
_3 = [const 42_u32; 8];
StorageLive(_4);
_4 = const 2_usize;
_5 = Len(_3);
- _5 = Len(_3);
- _6 = Lt(_4, _5);
- assert(move _6, "index out of bounds: the length is {} but the index is {}", move _5, _4) -> [success: bb1, unwind unreachable];
+ _6 = Lt(const 2_usize, _5);
+ assert(move _6, "index out of bounds: the length is {} but the index is {}", move _5, const 2_usize) -> [success: bb1, unwind unreachable];
+ _5 = const 8_usize;
+ _6 = const true;
+ assert(const true, "index out of bounds: the length is {} but the index is {}", const 8_usize, const 2_usize) -> [success: bb1, unwind unreachable];
}
bb1: {

7
tests/mir-opt/const_prop/repeat.main.GVN.32bit.panic-unwind.diff
View File

@ -20,11 +20,12 @@
_3 = [const 42_u32; 8];
StorageLive(_4);
_4 = const 2_usize;
_5 = Len(_3);
- _5 = Len(_3);
- _6 = Lt(_4, _5);
- assert(move _6, "index out of bounds: the length is {} but the index is {}", move _5, _4) -> [success: bb1, unwind continue];
+ _6 = Lt(const 2_usize, _5);
+ assert(move _6, "index out of bounds: the length is {} but the index is {}", move _5, const 2_usize) -> [success: bb1, unwind continue];
+ _5 = const 8_usize;
+ _6 = const true;
+ assert(const true, "index out of bounds: the length is {} but the index is {}", const 8_usize, const 2_usize) -> [success: bb1, unwind continue];
}
bb1: {

7
tests/mir-opt/const_prop/repeat.main.GVN.64bit.panic-abort.diff
View File

@ -20,11 +20,12 @@
_3 = [const 42_u32; 8];
StorageLive(_4);
_4 = const 2_usize;
_5 = Len(_3);
- _5 = Len(_3);
- _6 = Lt(_4, _5);
- assert(move _6, "index out of bounds: the length is {} but the index is {}", move _5, _4) -> [success: bb1, unwind unreachable];
+ _6 = Lt(const 2_usize, _5);
+ assert(move _6, "index out of bounds: the length is {} but the index is {}", move _5, const 2_usize) -> [success: bb1, unwind unreachable];
+ _5 = const 8_usize;
+ _6 = const true;
+ assert(const true, "index out of bounds: the length is {} but the index is {}", const 8_usize, const 2_usize) -> [success: bb1, unwind unreachable];
}
bb1: {

7
tests/mir-opt/const_prop/repeat.main.GVN.64bit.panic-unwind.diff
View File

@ -20,11 +20,12 @@
_3 = [const 42_u32; 8];
StorageLive(_4);
_4 = const 2_usize;
_5 = Len(_3);
- _5 = Len(_3);
- _6 = Lt(_4, _5);
- assert(move _6, "index out of bounds: the length is {} but the index is {}", move _5, _4) -> [success: bb1, unwind continue];
+ _6 = Lt(const 2_usize, _5);
+ assert(move _6, "index out of bounds: the length is {} but the index is {}", move _5, const 2_usize) -> [success: bb1, unwind continue];
+ _5 = const 8_usize;
+ _6 = const true;
+ assert(const true, "index out of bounds: the length is {} but the index is {}", const 8_usize, const 2_usize) -> [success: bb1, unwind continue];
}
bb1: {

13
tests/mir-opt/gvn.repeated_index.GVN.panic-abort.diff
View File

@ -32,11 +32,12 @@
StorageLive(_6);
StorageLive(_7);
_7 = const 0_usize;
_8 = Len(_3);
- _8 = Len(_3);
- _9 = Lt(_7, _8);
- assert(move _9, "index out of bounds: the length is {} but the index is {}", move _8, _7) -> [success: bb1, unwind unreachable];
+ _9 = Lt(const 0_usize, _8);
+ assert(move _9, "index out of bounds: the length is {} but the index is {}", _8, const 0_usize) -> [success: bb1, unwind unreachable];
+ _8 = const N;
+ _9 = Lt(const 0_usize, const N);
+ assert(move _9, "index out of bounds: the length is {} but the index is {}", const N, const 0_usize) -> [success: bb1, unwind unreachable];
}
bb1: {
@ -57,9 +58,9 @@
- _13 = Len(_3);
- _14 = Lt(_12, _13);
- assert(move _14, "index out of bounds: the length is {} but the index is {}", move _13, _12) -> [success: bb3, unwind unreachable];
+ _13 = _8;
+ _14 = Lt(_2, _8);
+ assert(move _14, "index out of bounds: the length is {} but the index is {}", _8, _2) -> [success: bb3, unwind unreachable];
+ _13 = const N;
+ _14 = Lt(_2, const N);
+ assert(move _14, "index out of bounds: the length is {} but the index is {}", const N, _2) -> [success: bb3, unwind unreachable];
}
bb3: {

13
tests/mir-opt/gvn.repeated_index.GVN.panic-unwind.diff
View File

@ -32,11 +32,12 @@
StorageLive(_6);
StorageLive(_7);
_7 = const 0_usize;
_8 = Len(_3);
- _8 = Len(_3);
- _9 = Lt(_7, _8);
- assert(move _9, "index out of bounds: the length is {} but the index is {}", move _8, _7) -> [success: bb1, unwind continue];
+ _9 = Lt(const 0_usize, _8);
+ assert(move _9, "index out of bounds: the length is {} but the index is {}", _8, const 0_usize) -> [success: bb1, unwind continue];
+ _8 = const N;
+ _9 = Lt(const 0_usize, const N);
+ assert(move _9, "index out of bounds: the length is {} but the index is {}", const N, const 0_usize) -> [success: bb1, unwind continue];
}
bb1: {
@ -57,9 +58,9 @@
- _13 = Len(_3);
- _14 = Lt(_12, _13);
- assert(move _14, "index out of bounds: the length is {} but the index is {}", move _13, _12) -> [success: bb3, unwind continue];
+ _13 = _8;
+ _14 = Lt(_2, _8);
+ assert(move _14, "index out of bounds: the length is {} but the index is {}", _8, _2) -> [success: bb3, unwind continue];
+ _13 = const N;
+ _14 = Lt(_2, const N);
+ assert(move _14, "index out of bounds: the length is {} but the index is {}", const N, _2) -> [success: bb3, unwind continue];
}
bb3: {