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Transform large arrays into Repeat expressions when possible.

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This commit is contained in:
Camille GILLOT 2023-09-23 16:23:37 +00:00
parent 80a5e8522d
commit dbf9ea30dd
4 changed files with 151 additions and 1 deletions
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14
compiler/rustc_mir_transform/src/gvn.rs
View File

@ -795,6 +795,20 @@ fn simplify_aggregate(
.collect();
let fields = fields?;
if let AggregateTy::Array = ty && fields.len() > 4 {
let first = fields[0];
if fields.iter().all(|&v| v == first) {
let len = ty::Const::from_target_usize(self.tcx, fields.len().try_into().unwrap());
if let Some(const_) = self.try_as_constant(first) {
*rvalue = Rvalue::Repeat(Operand::Constant(Box::new(const_)), len);
} else if let Some(local) = self.try_as_local(first, location) {
*rvalue = Rvalue::Repeat(Operand::Copy(local.into()), len);
self.reused_locals.insert(local);
}
return Some(Value::Repeat(first, len));
}
}
let value = Value::Aggregate(ty, variant_index, fields);
Some(value)
}

67
tests/mir-opt/gvn.aggregates.GVN.panic-abort.diff
View File

@ -8,6 +8,16 @@
let mut _4: [u16; 0];
let mut _6: ();
let mut _8: ();
let mut _11: i32;
let mut _12: i32;
let mut _13: i32;
let mut _14: i32;
let mut _15: i32;
let mut _16: i32;
let mut _17: i32;
let mut _18: i32;
let mut _19: i32;
let mut _20: i32;
scope 1 {
debug a_array => _1;
let _3: S<[u16; 0]>;
@ -19,6 +29,14 @@
let _7: S<()>;
scope 4 {
debug b_tuple => _7;
let _9: i32;
scope 5 {
debug val => _9;
let _10: [i32; 10];
scope 6 {
debug array => _10;
}
}
}
}
}
@ -55,7 +73,56 @@
+ _8 = const ();
+ _7 = const S::<()>(());
StorageDead(_8);
- StorageLive(_9);
+ nop;
_9 = const 5_i32;
StorageLive(_10);
StorageLive(_11);
- _11 = _9;
+ _11 = const 5_i32;
StorageLive(_12);
- _12 = _9;
+ _12 = const 5_i32;
StorageLive(_13);
- _13 = _9;
+ _13 = const 5_i32;
StorageLive(_14);
- _14 = _9;
+ _14 = const 5_i32;
StorageLive(_15);
- _15 = _9;
+ _15 = const 5_i32;
StorageLive(_16);
- _16 = _9;
+ _16 = const 5_i32;
StorageLive(_17);
- _17 = _9;
+ _17 = const 5_i32;
StorageLive(_18);
- _18 = _9;
+ _18 = const 5_i32;
StorageLive(_19);
- _19 = _9;
+ _19 = const 5_i32;
StorageLive(_20);
- _20 = _9;
- _10 = [move _11, move _12, move _13, move _14, move _15, move _16, move _17, move _18, move _19, move _20];
+ _20 = const 5_i32;
+ _10 = [const 5_i32; 10];
StorageDead(_20);
StorageDead(_19);
StorageDead(_18);
StorageDead(_17);
StorageDead(_16);
StorageDead(_15);
StorageDead(_14);
StorageDead(_13);
StorageDead(_12);
StorageDead(_11);
_0 = const ();
StorageDead(_10);
- StorageDead(_9);
+ nop;
StorageDead(_7);
StorageDead(_5);
StorageDead(_3);

67
tests/mir-opt/gvn.aggregates.GVN.panic-unwind.diff
View File

@ -8,6 +8,16 @@
let mut _4: [u16; 0];
let mut _6: ();
let mut _8: ();
let mut _11: i32;
let mut _12: i32;
let mut _13: i32;
let mut _14: i32;
let mut _15: i32;
let mut _16: i32;
let mut _17: i32;
let mut _18: i32;
let mut _19: i32;
let mut _20: i32;
scope 1 {
debug a_array => _1;
let _3: S<[u16; 0]>;
@ -19,6 +29,14 @@
let _7: S<()>;
scope 4 {
debug b_tuple => _7;
let _9: i32;
scope 5 {
debug val => _9;
let _10: [i32; 10];
scope 6 {
debug array => _10;
}
}
}
}
}
@ -55,7 +73,56 @@
+ _8 = const ();
+ _7 = const S::<()>(());
StorageDead(_8);
- StorageLive(_9);
+ nop;
_9 = const 5_i32;
StorageLive(_10);
StorageLive(_11);
- _11 = _9;
+ _11 = const 5_i32;
StorageLive(_12);
- _12 = _9;
+ _12 = const 5_i32;
StorageLive(_13);
- _13 = _9;
+ _13 = const 5_i32;
StorageLive(_14);
- _14 = _9;
+ _14 = const 5_i32;
StorageLive(_15);
- _15 = _9;
+ _15 = const 5_i32;
StorageLive(_16);
- _16 = _9;
+ _16 = const 5_i32;
StorageLive(_17);
- _17 = _9;
+ _17 = const 5_i32;
StorageLive(_18);
- _18 = _9;
+ _18 = const 5_i32;
StorageLive(_19);
- _19 = _9;
+ _19 = const 5_i32;
StorageLive(_20);
- _20 = _9;
- _10 = [move _11, move _12, move _13, move _14, move _15, move _16, move _17, move _18, move _19, move _20];
+ _20 = const 5_i32;
+ _10 = [const 5_i32; 10];
StorageDead(_20);
StorageDead(_19);
StorageDead(_18);
StorageDead(_17);
StorageDead(_16);
StorageDead(_15);
StorageDead(_14);
StorageDead(_13);
StorageDead(_12);
StorageDead(_11);
_0 = const ();
StorageDead(_10);
- StorageDead(_9);
+ nop;
StorageDead(_7);
StorageDead(_5);
StorageDead(_3);

4
tests/mir-opt/gvn.rs
View File

@ -61,7 +61,6 @@ fn subexpression_elimination(x: u64, y: u64, mut z: u64) {
let e = &z;
opaque(*e + x);
opaque(*e + x);
}
fn wrap_unwrap<T: Copy>(x: T) -> T {
@ -237,6 +236,9 @@ fn aggregates() {
let a_tuple: S<()> = S(());
let b_tuple: S<()> = S(()); // But this can be with `a_tuple`.
let val = 5;
let array = [val, val, val, val, val, val, val, val, val, val];
}
fn main() {