From a0d06664b3d149df8d33502586a0f55ce3f03b48 Mon Sep 17 00:00:00 2001 From: Ramkumar Ramachandra Date: Thu, 8 Aug 2024 15:23:52 +0100 Subject: [PATCH 1/3] LSV: document hang reported in #37865 LoadStoreVectorizer hangs on certain examples, when its reorder function goes into a cycle. Detect this cycle and explicitly forbid it, using an assert, and document the resulting crash in a test-case under AArch64. --- .../Transforms/Vectorize/LoadStoreVectorizer.cpp | 2 ++ .../LoadStoreVectorizer/AArch64/pr37865.ll | 13 +++++++++++++ 2 files changed, 15 insertions(+) create mode 100644 llvm/test/Transforms/LoadStoreVectorizer/AArch64/pr37865.ll diff --git a/llvm/lib/Transforms/Vectorize/LoadStoreVectorizer.cpp b/llvm/lib/Transforms/Vectorize/LoadStoreVectorizer.cpp index c91911ecad745..c35ea431296b7 100644 --- a/llvm/lib/Transforms/Vectorize/LoadStoreVectorizer.cpp +++ b/llvm/lib/Transforms/Vectorize/LoadStoreVectorizer.cpp @@ -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); diff --git a/llvm/test/Transforms/LoadStoreVectorizer/AArch64/pr37865.ll b/llvm/test/Transforms/LoadStoreVectorizer/AArch64/pr37865.ll new file mode 100644 index 0000000000000..d77c7256bfadb --- /dev/null +++ b/llvm/test/Transforms/LoadStoreVectorizer/AArch64/pr37865.ll @@ -0,0 +1,13 @@ +; REQUIRES: asserts +; RUN: not --crash opt -mtriple=aarch64 -passes=load-store-vectorizer -disable-output %s + +define i32 @load_cycle(ptr %x) { +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 + %load.x.2 = load i32, ptr %gep.x.2 + %ret = add i32 %load.x.2, %load.x.1 + ret i32 %ret +} From 8bbe6f2557bd2ee1dff71fdd32c4ca7bc844eada Mon Sep 17 00:00:00 2001 From: Ramkumar Ramachandra Date: Thu, 8 Aug 2024 18:25:31 +0100 Subject: [PATCH 2/3] LSV/test/pr37865: check assert message --- llvm/test/Transforms/LoadStoreVectorizer/AArch64/pr37865.ll | 1 + 1 file changed, 1 insertion(+) diff --git a/llvm/test/Transforms/LoadStoreVectorizer/AArch64/pr37865.ll b/llvm/test/Transforms/LoadStoreVectorizer/AArch64/pr37865.ll index d77c7256bfadb..8e5de719fe594 100644 --- a/llvm/test/Transforms/LoadStoreVectorizer/AArch64/pr37865.ll +++ b/llvm/test/Transforms/LoadStoreVectorizer/AArch64/pr37865.ll @@ -2,6 +2,7 @@ ; RUN: not --crash opt -mtriple=aarch64 -passes=load-store-vectorizer -disable-output %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 From d89bf1dfccfe77292669bb95b562bb61b0d6b501 Mon Sep 17 00:00:00 2001 From: Ramkumar Ramachandra Date: Thu, 8 Aug 2024 18:35:11 +0100 Subject: [PATCH 3/3] LSV/test/pr37865: fix thinko; include FileCheck --- llvm/test/Transforms/LoadStoreVectorizer/AArch64/pr37865.ll | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/llvm/test/Transforms/LoadStoreVectorizer/AArch64/pr37865.ll b/llvm/test/Transforms/LoadStoreVectorizer/AArch64/pr37865.ll index 8e5de719fe594..833e70814c291 100644 --- a/llvm/test/Transforms/LoadStoreVectorizer/AArch64/pr37865.ll +++ b/llvm/test/Transforms/LoadStoreVectorizer/AArch64/pr37865.ll @@ -1,5 +1,6 @@ ; REQUIRES: asserts -; RUN: not --crash opt -mtriple=aarch64 -passes=load-store-vectorizer -disable-output %s +; 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