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scottmcmscottmcm
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Replace NormalizeArrayLen with GVN
GVN is actually on in release, and covers all the same things (or more), with `LowerSliceLen` changed to produce `PtrMetadata`.
1 parent 4a7b6c0 commit b611b6b

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30 files changed

+138
-218
lines changed

30 files changed

+138
-218
lines changed

‎compiler/rustc_mir_transform/src/lib.rs

-4
Original file line numberDiff line numberDiff line change
@@ -88,7 +88,6 @@ mod lower_slice_len;
8888
mod match_branches;
8989
mod mentioned_items;
9090
mod multiple_return_terminators;
91-
mod normalize_array_len;
9291
mod nrvo;
9392
mod prettify;
9493
mod promote_consts;
@@ -581,9 +580,6 @@ fn run_optimization_passes<'tcx>(tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>) {
581580
&o1(simplify::SimplifyCfg::AfterUnreachableEnumBranching),
582581
// Inlining may have introduced a lot of redundant code and a large move pattern.
583582
// Now, we need to shrink the generated MIR.
584-
585-
// Has to run after `slice::len` lowering
586-
&normalize_array_len::NormalizeArrayLen,
587583
&ref_prop::ReferencePropagation,
588584
&sroa::ScalarReplacementOfAggregates,
589585
&match_branches::MatchBranchSimplification,

‎compiler/rustc_mir_transform/src/lower_slice_len.rs

+8-16
Original file line numberDiff line numberDiff line change
@@ -1,10 +1,9 @@
1-
//! This pass lowers calls to core::slice::len to just Len op.
1+
//! This pass lowers calls to core::slice::len to just PtrMetadata op.
22
//! It should run before inlining!
33
44
use rustc_hir::def_id::DefId;
5-
use rustc_index::IndexSlice;
65
use rustc_middle::mir::*;
7-
use rustc_middle::ty::{self, TyCtxt};
6+
use rustc_middle::ty::TyCtxt;
87

98
pub struct LowerSliceLenCalls;
109

@@ -29,16 +28,11 @@ pub fn lower_slice_len_calls<'tcx>(tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>) {
2928
let basic_blocks = body.basic_blocks.as_mut_preserves_cfg();
3029
for block in basic_blocks {
3130
// lower `<[_]>::len` calls
32-
lower_slice_len_call(tcx, block, &body.local_decls, slice_len_fn_item_def_id);
31+
lower_slice_len_call(block, slice_len_fn_item_def_id);
3332
}
3433
}
3534

36-
fn lower_slice_len_call<'tcx>(
37-
tcx: TyCtxt<'tcx>,
38-
block: &mut BasicBlockData<'tcx>,
39-
local_decls: &IndexSlice<Local, LocalDecl<'tcx>>,
40-
slice_len_fn_item_def_id: DefId,
41-
) {
35+
fn lower_slice_len_call<'tcx>(block: &mut BasicBlockData<'tcx>, slice_len_fn_item_def_id: DefId) {
4236
let terminator = block.terminator();
4337
if let TerminatorKind::Call {
4438
func,
@@ -50,19 +44,17 @@ fn lower_slice_len_call<'tcx>(
5044
} = &terminator.kind
5145
// some heuristics for fast rejection
5246
&& let [arg] = &args[..]
53-
&& let Some(arg) = arg.node.place()
54-
&& let ty::FnDef(fn_def_id, _) = func.ty(local_decls, tcx).kind()
55-
&& *fn_def_id == slice_len_fn_item_def_id
47+
&& let Some((fn_def_id, _)) = func.const_fn_def()
48+
&& fn_def_id == slice_len_fn_item_def_id
5649
{
5750
// perform modifications from something like:
5851
// _5 = core::slice::<impl [u8]>::len(move _6) -> bb1
5952
// into:
60-
// _5 = Len(*_6)
53+
// _5 = PtrMetadata(move _6)
6154
// goto bb1
6255

6356
// make new RValue for Len
64-
let deref_arg = tcx.mk_place_deref(arg);
65-
let r_value = Rvalue::Len(deref_arg);
57+
let r_value = Rvalue::UnaryOp(UnOp::PtrMetadata, arg.node.clone());
6658
let len_statement_kind = StatementKind::Assign(Box::new((*destination, r_value)));
6759
let add_statement =
6860
Statement { kind: len_statement_kind, source_info: terminator.source_info };

‎compiler/rustc_mir_transform/src/normalize_array_len.rs

-103
This file was deleted.

‎tests/mir-opt/issue_76432.rs

-1
Original file line numberDiff line numberDiff line change
@@ -1,6 +1,5 @@
11
// skip-filecheck
22
// EMIT_MIR_FOR_EACH_PANIC_STRATEGY
3-
//@ compile-flags: -Zmir-enable-passes=-NormalizeArrayLen
43
// Check that we do not insert StorageDead at each target if StorageDead was never seen
54

65
use std::fmt::Debug;

‎tests/mir-opt/lower_array_len.array_bound.NormalizeArrayLen.panic-abort.diff ‎tests/mir-opt/lower_array_len.array_bound.GVN.panic-abort.diff

+13-8
Original file line numberDiff line numberDiff line change
@@ -1,5 +1,5 @@
1-
- // MIR for `array_bound` before NormalizeArrayLen
2-
+ // MIR for `array_bound` after NormalizeArrayLen
1+
- // MIR for `array_bound` before GVN
2+
+ // MIR for `array_bound` after GVN
33

44
fn array_bound(_1: usize, _2: &[u8; N]) -> u8 {
55
debug index => _1;
@@ -24,14 +24,15 @@
2424
_7 = &(*_2);
2525
_6 = move _7 as &[u8] (PointerCoercion(Unsize));
2626
StorageDead(_7);
27-
- _5 = Len((*_6));
27+
- _5 = PtrMetadata(move _6);
2828
+ _5 = const N;
2929
goto -> bb1;
3030
}
3131

3232
bb1: {
3333
StorageDead(_6);
34-
_3 = Lt(move _4, move _5);
34+
- _3 = Lt(move _4, move _5);
35+
+ _3 = Lt(_1, move _5);
3536
switchInt(move _3) -> [0: bb4, otherwise: bb2];
3637
}
3738

@@ -40,13 +41,17 @@
4041
StorageDead(_4);
4142
StorageLive(_8);
4243
_8 = _1;
43-
_9 = Len((*_2));
44-
_10 = Lt(_8, _9);
45-
assert(move _10, "index out of bounds: the length is {} but the index is {}", move _9, _8) -> [success: bb3, unwind unreachable];
44+
- _9 = Len((*_2));
45+
- _10 = Lt(_8, _9);
46+
- assert(move _10, "index out of bounds: the length is {} but the index is {}", move _9, _8) -> [success: bb3, unwind unreachable];
47+
+ _9 = const N;
48+
+ _10 = Lt(_1, const N);
49+
+ assert(move _10, "index out of bounds: the length is {} but the index is {}", const N, _1) -> [success: bb3, unwind unreachable];
4650
}
4751

4852
bb3: {
49-
_0 = (*_2)[_8];
53+
- _0 = (*_2)[_8];
54+
+ _0 = (*_2)[_1];
5055
StorageDead(_8);
5156
goto -> bb5;
5257
}

‎tests/mir-opt/lower_array_len.array_bound.NormalizeArrayLen.panic-unwind.diff ‎tests/mir-opt/lower_array_len.array_bound.GVN.panic-unwind.diff

+13-8
Original file line numberDiff line numberDiff line change
@@ -1,5 +1,5 @@
1-
- // MIR for `array_bound` before NormalizeArrayLen
2-
+ // MIR for `array_bound` after NormalizeArrayLen
1+
- // MIR for `array_bound` before GVN
2+
+ // MIR for `array_bound` after GVN
33

44
fn array_bound(_1: usize, _2: &[u8; N]) -> u8 {
55
debug index => _1;
@@ -24,14 +24,15 @@
2424
_7 = &(*_2);
2525
_6 = move _7 as &[u8] (PointerCoercion(Unsize));
2626
StorageDead(_7);
27-
- _5 = Len((*_6));
27+
- _5 = PtrMetadata(move _6);
2828
+ _5 = const N;
2929
goto -> bb1;
3030
}
3131

3232
bb1: {
3333
StorageDead(_6);
34-
_3 = Lt(move _4, move _5);
34+
- _3 = Lt(move _4, move _5);
35+
+ _3 = Lt(_1, move _5);
3536
switchInt(move _3) -> [0: bb4, otherwise: bb2];
3637
}
3738

@@ -40,13 +41,17 @@
4041
StorageDead(_4);
4142
StorageLive(_8);
4243
_8 = _1;
43-
_9 = Len((*_2));
44-
_10 = Lt(_8, _9);
45-
assert(move _10, "index out of bounds: the length is {} but the index is {}", move _9, _8) -> [success: bb3, unwind continue];
44+
- _9 = Len((*_2));
45+
- _10 = Lt(_8, _9);
46+
- assert(move _10, "index out of bounds: the length is {} but the index is {}", move _9, _8) -> [success: bb3, unwind continue];
47+
+ _9 = const N;
48+
+ _10 = Lt(_1, const N);
49+
+ assert(move _10, "index out of bounds: the length is {} but the index is {}", const N, _1) -> [success: bb3, unwind continue];
4650
}
4751

4852
bb3: {
49-
_0 = (*_2)[_8];
53+
- _0 = (*_2)[_8];
54+
+ _0 = (*_2)[_1];
5055
StorageDead(_8);
5156
goto -> bb5;
5257
}

‎tests/mir-opt/lower_array_len.array_bound_mut.NormalizeArrayLen.panic-abort.diff ‎tests/mir-opt/lower_array_len.array_bound_mut.GVN.panic-abort.diff

+21-12
Original file line numberDiff line numberDiff line change
@@ -1,5 +1,5 @@
1-
- // MIR for `array_bound_mut` before NormalizeArrayLen
2-
+ // MIR for `array_bound_mut` after NormalizeArrayLen
1+
- // MIR for `array_bound_mut` before GVN
2+
+ // MIR for `array_bound_mut` after GVN
33

44
fn array_bound_mut(_1: usize, _2: &mut [u8; N]) -> u8 {
55
debug index => _1;
@@ -27,14 +27,15 @@
2727
_7 = &(*_2);
2828
_6 = move _7 as &[u8] (PointerCoercion(Unsize));
2929
StorageDead(_7);
30-
- _5 = Len((*_6));
30+
- _5 = PtrMetadata(move _6);
3131
+ _5 = const N;
3232
goto -> bb1;
3333
}
3434

3535
bb1: {
3636
StorageDead(_6);
37-
_3 = Lt(move _4, move _5);
37+
- _3 = Lt(move _4, move _5);
38+
+ _3 = Lt(_1, move _5);
3839
switchInt(move _3) -> [0: bb4, otherwise: bb2];
3940
}
4041

@@ -43,13 +44,17 @@
4344
StorageDead(_4);
4445
StorageLive(_8);
4546
_8 = _1;
46-
_9 = Len((*_2));
47-
_10 = Lt(_8, _9);
48-
assert(move _10, "index out of bounds: the length is {} but the index is {}", move _9, _8) -> [success: bb3, unwind unreachable];
47+
- _9 = Len((*_2));
48+
- _10 = Lt(_8, _9);
49+
- assert(move _10, "index out of bounds: the length is {} but the index is {}", move _9, _8) -> [success: bb3, unwind unreachable];
50+
+ _9 = const N;
51+
+ _10 = Lt(_1, const N);
52+
+ assert(move _10, "index out of bounds: the length is {} but the index is {}", const N, _1) -> [success: bb3, unwind unreachable];
4953
}
5054

5155
bb3: {
52-
_0 = (*_2)[_8];
56+
- _0 = (*_2)[_8];
57+
+ _0 = (*_2)[_1];
5358
StorageDead(_8);
5459
goto -> bb6;
5560
}
@@ -59,13 +64,17 @@
5964
StorageDead(_4);
6065
StorageLive(_11);
6166
_11 = const 0_usize;
62-
_12 = Len((*_2));
63-
_13 = Lt(_11, _12);
64-
assert(move _13, "index out of bounds: the length is {} but the index is {}", move _12, _11) -> [success: bb5, unwind unreachable];
67+
- _12 = Len((*_2));
68+
- _13 = Lt(_11, _12);
69+
- assert(move _13, "index out of bounds: the length is {} but the index is {}", move _12, _11) -> [success: bb5, unwind unreachable];
70+
+ _12 = const N;
71+
+ _13 = Lt(const 0_usize, const N);
72+
+ assert(move _13, "index out of bounds: the length is {} but the index is {}", const N, const 0_usize) -> [success: bb5, unwind unreachable];
6573
}
6674

6775
bb5: {
68-
(*_2)[_11] = const 42_u8;
76+
- (*_2)[_11] = const 42_u8;
77+
+ (*_2)[0 of 1] = const 42_u8;
6978
StorageDead(_11);
7079
_0 = const 42_u8;
7180
goto -> bb6;

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