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LSV: document hang reported in #37865 #102479

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Merged
merged 3 commits into from
Aug 9, 2024
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LSV: document hang reported in #37865 #102479

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a0d0666
LSV: document hang reported in #37865
artagnon Aug 8, 2024
8bbe6f2
LSV/test/pr37865: check assert message
artagnon Aug 8, 2024
d89bf1d
LSV/test/pr37865: fix thinko; include FileCheck
artagnon Aug 8, 2024
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2 changes: 2 additions & 0 deletions llvm/lib/Transforms/Vectorize/LoadStoreVectorizer.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -216,6 +216,8 @@ void reorder(Instruction *I) {
if (IM->getParent() != I->getParent())
continue;

assert(IM != I && "Unexpected cycle while re-ordering instructions");

if (!IM->comesBefore(I)) {
InstructionsToMove.insert(IM);
Worklist.push_back(IM);
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15 changes: 15 additions & 0 deletions llvm/test/Transforms/LoadStoreVectorizer/AArch64/pr37865.ll
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@@ -0,0 +1,15 @@
; REQUIRES: asserts
; RUN: not --crash opt -mtriple=aarch64 -passes=load-store-vectorizer \
; RUN: -disable-output %s 2>&1 | FileCheck %s

define i32 @load_cycle(ptr %x) {
; CHECK: Unexpected cycle while re-ordering instructions
entry:
%gep.x.1 = getelementptr inbounds [2 x i32], ptr %x, i32 0, i32 1
%load.x.1 = load i32, ptr %gep.x.1
%rem = urem i32 %load.x.1, 1
%gep.x.2 = getelementptr inbounds [2 x i32], ptr %x, i32 %rem, i32 0
Comment on lines +9 to +11
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I think this just failed to check that one of the vectorization pointer candidates actually depends on the other load, so these shouldn't be vectorization candidates

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Right, I figured that I have to fix the creation of the Chain.

%load.x.2 = load i32, ptr %gep.x.2
%ret = add i32 %load.x.2, %load.x.1
ret i32 %ret
}
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