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Revert "LSV: forbid load-cycles when vectorizing; fix bug (#104815)" (#106245)
This reverts commit c46b41a. Multiple tests time out, either due to performance hit (see comment) or a cycle.
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-98
lines changed

2 files changed

+5
-98
lines changed

llvm/lib/Transforms/Vectorize/LoadStoreVectorizer.cpp

Lines changed: 1 addition & 23 deletions
Original file line numberDiff line numberDiff line change
@@ -998,32 +998,10 @@ bool Vectorizer::isSafeToMove(
998998
LLVM_DEBUG(dbgs() << "LSV: isSafeToMove(" << *ChainElem << " -> "
999999
<< *ChainBegin << ")\n");
10001000

1001-
assert(isa<LoadInst>(ChainElem) == IsLoadChain &&
1002-
isa<LoadInst>(ChainBegin) == IsLoadChain);
1003-
1001+
assert(isa<LoadInst>(ChainElem) == IsLoadChain);
10041002
if (ChainElem == ChainBegin)
10051003
return true;
10061004

1007-
if constexpr (IsLoadChain) {
1008-
// If ChainElem depends on ChainBegin, they're not safe to reorder.
1009-
SmallVector<Instruction *, 8> Worklist;
1010-
Worklist.emplace_back(ChainElem);
1011-
while (!Worklist.empty()) {
1012-
Instruction *I = Worklist.pop_back_val();
1013-
for (Use &O : I->operands()) {
1014-
if (isa<PHINode>(O))
1015-
continue;
1016-
if (auto *J = dyn_cast<Instruction>(O)) {
1017-
if (J == ChainBegin) {
1018-
LLVM_DEBUG(dbgs() << "LSV: dependent loads; not safe to reorder\n");
1019-
return false;
1020-
}
1021-
Worklist.emplace_back(J);
1022-
}
1023-
}
1024-
}
1025-
}
1026-
10271005
// Invariant loads can always be reordered; by definition they are not
10281006
// clobbered by stores.
10291007
if (isInvariantLoad(ChainElem))
Lines changed: 4 additions & 75 deletions
Original file line numberDiff line numberDiff line change
@@ -1,22 +1,9 @@
1-
; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --version 5
2-
; RUN: opt -mtriple=aarch64 -passes=load-store-vectorizer -S %s | FileCheck %s
3-
4-
; LSV was attempting to vectorize this earlier, but crashed while re-ordering
5-
; instructions due to the load-load cycle. Now, the candidate loads are no
6-
; longer considered safe for reordering.
1+
; REQUIRES: asserts
2+
; RUN: not --crash opt -mtriple=aarch64 -passes=load-store-vectorizer \
3+
; RUN: -disable-output %s 2>&1 | FileCheck %s
74

85
define i32 @load_cycle(ptr %x) {
9-
; CHECK-LABEL: define i32 @load_cycle(
10-
; CHECK-SAME: ptr [[X:%.*]]) {
11-
; CHECK-NEXT: [[ENTRY:.*:]]
12-
; CHECK-NEXT: [[GEP_X_1:%.*]] = getelementptr inbounds [2 x i32], ptr [[X]], i32 0, i32 1
13-
; CHECK-NEXT: [[LOAD_X_1:%.*]] = load i32, ptr [[GEP_X_1]], align 4
14-
; CHECK-NEXT: [[REM:%.*]] = urem i32 [[LOAD_X_1]], 1
15-
; CHECK-NEXT: [[GEP_X_2:%.*]] = getelementptr inbounds [2 x i32], ptr [[X]], i32 [[REM]], i32 0
16-
; CHECK-NEXT: [[LOAD_X_2:%.*]] = load i32, ptr [[GEP_X_2]], align 4
17-
; CHECK-NEXT: [[RET:%.*]] = add i32 [[LOAD_X_2]], [[LOAD_X_1]]
18-
; CHECK-NEXT: ret i32 [[RET]]
19-
;
6+
; CHECK: Unexpected cycle while re-ordering instructions
207
entry:
218
%gep.x.1 = getelementptr inbounds [2 x i32], ptr %x, i32 0, i32 1
229
%load.x.1 = load i32, ptr %gep.x.1
@@ -26,61 +13,3 @@ entry:
2613
%ret = add i32 %load.x.2, %load.x.1
2714
ret i32 %ret
2815
}
29-
30-
define i32 @load_cycle2(ptr %x, i32 %y) {
31-
; CHECK-LABEL: define i32 @load_cycle2(
32-
; CHECK-SAME: ptr [[X:%.*]], i32 [[Y:%.*]]) {
33-
; CHECK-NEXT: [[ENTRY:.*:]]
34-
; CHECK-NEXT: [[GEP_X_1:%.*]] = getelementptr inbounds [2 x i32], ptr [[X]], i32 [[Y]], i32 1
35-
; CHECK-NEXT: [[LOAD_X_1:%.*]] = load i32, ptr [[GEP_X_1]], align 4
36-
; CHECK-NEXT: [[MUL:%.*]] = mul i32 [[LOAD_X_1]], 2
37-
; CHECK-NEXT: [[ADD:%.*]] = add i32 [[Y]], [[MUL]]
38-
; CHECK-NEXT: [[SUB_1:%.*]] = sub i32 [[ADD]], [[LOAD_X_1]]
39-
; CHECK-NEXT: [[SUB_2:%.*]] = sub i32 [[SUB_1]], [[LOAD_X_1]]
40-
; CHECK-NEXT: [[GEP_X_2:%.*]] = getelementptr inbounds [2 x i32], ptr [[X]], i32 [[SUB_2]], i32 0
41-
; CHECK-NEXT: [[LOAD_X_2:%.*]] = load i32, ptr [[GEP_X_2]], align 4
42-
; CHECK-NEXT: [[RET:%.*]] = add i32 [[LOAD_X_2]], [[LOAD_X_1]]
43-
; CHECK-NEXT: ret i32 [[RET]]
44-
;
45-
entry:
46-
%gep.x.1 = getelementptr inbounds [2 x i32], ptr %x, i32 %y, i32 1
47-
%load.x.1 = load i32, ptr %gep.x.1
48-
%mul = mul i32 %load.x.1, 2
49-
%add = add i32 %y, %mul
50-
%sub.1 = sub i32 %add, %load.x.1
51-
%sub.2 = sub i32 %sub.1, %load.x.1
52-
%gep.x.2 = getelementptr inbounds [2 x i32], ptr %x, i32 %sub.2, i32 0
53-
%load.x.2 = load i32, ptr %gep.x.2
54-
%ret = add i32 %load.x.2, %load.x.1
55-
ret i32 %ret
56-
}
57-
58-
@global.1 = global i32 0
59-
@global.2 = global [1 x [3 x i32]] zeroinitializer
60-
61-
define i16 @load_cycle3() {
62-
; CHECK-LABEL: define i16 @load_cycle3() {
63-
; CHECK-NEXT: [[ENTRY:.*:]]
64-
; CHECK-NEXT: [[LOAD_1:%.*]] = load i32, ptr @global.1, align 4
65-
; CHECK-NEXT: [[UREM_1:%.*]] = urem i32 [[LOAD_1]], 1
66-
; CHECK-NEXT: [[GEP_1:%.*]] = getelementptr inbounds [1 x [3 x i32]], ptr @global.2, i32 0, i32 [[UREM_1]]
67-
; CHECK-NEXT: [[GEP_2:%.*]] = getelementptr inbounds [3 x i32], ptr [[GEP_1]], i32 0, i32 2
68-
; CHECK-NEXT: [[LOAD_2:%.*]] = load i32, ptr [[GEP_2]], align 4
69-
; CHECK-NEXT: [[UREM_2:%.*]] = urem i32 [[LOAD_2]], 1
70-
; CHECK-NEXT: [[GEP_3:%.*]] = getelementptr inbounds [1 x [3 x i32]], ptr @global.2, i32 0, i32 [[UREM_2]]
71-
; CHECK-NEXT: [[GEP_4:%.*]] = getelementptr inbounds [3 x i32], ptr [[GEP_3]], i32 0, i32 1
72-
; CHECK-NEXT: [[LOAD_3:%.*]] = load i32, ptr [[GEP_4]], align 4
73-
; CHECK-NEXT: ret i16 0
74-
;
75-
entry:
76-
%load.1 = load i32, ptr @global.1
77-
%urem.1 = urem i32 %load.1, 1
78-
%gep.1 = getelementptr inbounds [1 x [3 x i32]], ptr @global.2, i32 0, i32 %urem.1
79-
%gep.2 = getelementptr inbounds [3 x i32], ptr %gep.1, i32 0, i32 2
80-
%load.2 = load i32, ptr %gep.2
81-
%urem.2 = urem i32 %load.2, 1
82-
%gep.3 = getelementptr inbounds [1 x [3 x i32]], ptr @global.2, i32 0, i32 %urem.2
83-
%gep.4 = getelementptr inbounds [3 x i32], ptr %gep.3, i32 0, i32 1
84-
%load.3 = load i32, ptr %gep.4
85-
ret i16 0
86-
}

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