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GVN: Use a VnIndex in Address projection. #144477

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GVN: Use a VnIndex in Address projection. #144477

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50c72b7
Make Value Copy by arena-allocating vectors.
cjgillot Jul 2, 2025
f092b9b
Use a VnIndex in Address projection.
cjgillot Jul 1, 2025
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322 changes: 191 additions & 131 deletions compiler/rustc_mir_transform/src/gvn.rs
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3 changes: 2 additions & 1 deletion tests/mir-opt/gvn.dereference_indexing.GVN.panic-abort.diff
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Original file line number Diff line number Diff line change
Expand Up @@ -43,7 +43,8 @@
+ nop;
StorageLive(_8);
StorageLive(_9);
_9 = copy (*_3);
- _9 = copy (*_3);
+ _9 = copy _1[_4];
_8 = opaque::<u8>(move _9) -> [return: bb2, unwind unreachable];
}

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3 changes: 2 additions & 1 deletion tests/mir-opt/gvn.dereference_indexing.GVN.panic-unwind.diff
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Expand Up @@ -43,7 +43,8 @@
+ nop;
StorageLive(_8);
StorageLive(_9);
_9 = copy (*_3);
- _9 = copy (*_3);
+ _9 = copy _1[_4];
_8 = opaque::<u8>(move _9) -> [return: bb2, unwind continue];
}

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4 changes: 2 additions & 2 deletions tests/mir-opt/gvn.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -1065,8 +1065,8 @@ fn dereference_indexing(array: [u8; 2], index: usize) {
&array[i]
};

// CHECK-NOT: [{{.*}}]
// CHECK: [[tmp:_.*]] = copy (*[[a]]);
// CHECK-NOT: StorageDead([[i]]);
// CHECK: [[tmp:_.*]] = copy _1[[[i]]];
// CHECK: opaque::<u8>(move [[tmp]])
opaque(*a);
}
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15 changes: 15 additions & 0 deletions tests/mir-opt/gvn_repeat.index_place.GVN.diff
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Original file line number Diff line number Diff line change
@@ -0,0 +1,15 @@
- // MIR for `index_place` before GVN
+ // MIR for `index_place` after GVN

fn index_place(_1: usize, _2: usize, _3: [i32; 5]) -> i32 {
let mut _0: i32;
let mut _4: &i32;

bb0: {
_4 = &_3[_1];
_1 = copy _2;
_0 = copy (*_4);
return;
}
}

3 changes: 1 addition & 2 deletions tests/mir-opt/gvn_repeat.repeat_local.GVN.diff
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Expand Up @@ -10,8 +10,7 @@
_4 = [copy _3; 5];
_5 = &_4[_1];
_1 = copy _2;
- _0 = copy (*_5);
+ _0 = copy _3;
_0 = copy (*_5);
return;
}
}
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21 changes: 20 additions & 1 deletion tests/mir-opt/gvn_repeat.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -6,6 +6,23 @@

use std::intrinsics::mir::*;

// EMIT_MIR gvn_repeat.index_place.GVN.diff
#[custom_mir(dialect = "runtime")]
pub fn index_place(mut idx1: usize, idx2: usize, array: [i32; 5]) -> i32 {
// CHECK-LABEL: fn index_place(
// CHECK: let mut [[ELEM:.*]]: &i32;
// CHECK: _0 = copy (*[[ELEM]])
mir! {
let elem;
{
elem = &array[idx1];
idx1 = idx2;
RET = *elem;
Return()
}
}
}

// EMIT_MIR gvn_repeat.repeat_place.GVN.diff
#[custom_mir(dialect = "runtime")]
pub fn repeat_place(mut idx1: usize, idx2: usize, val: &i32) -> i32 {
Expand All @@ -29,7 +46,8 @@ pub fn repeat_place(mut idx1: usize, idx2: usize, val: &i32) -> i32 {
#[custom_mir(dialect = "runtime")]
pub fn repeat_local(mut idx1: usize, idx2: usize, val: i32) -> i32 {
// CHECK-LABEL: fn repeat_local(
// CHECK: _0 = copy _3
// CHECK: let mut [[ELEM:.*]]: &i32;
// CHECK: _0 = copy (*[[ELEM]]);
mir! {
let array;
let elem;
Expand All @@ -44,6 +62,7 @@ pub fn repeat_local(mut idx1: usize, idx2: usize, val: i32) -> i32 {
}

fn main() {
assert_eq!(index_place(0, 5, [0; 5]), 0);
assert_eq!(repeat_place(0, 5, &0), 0);
assert_eq!(repeat_local(0, 5, 0), 0);
}
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