[llvm] [LoopVectorize] Add support for reverse loops in isDereferenceableAndAlignedInLoop (PR #96752)

[LLVM Continuous Integration via llvm-commits]

llvm-ci wrote:

LLVM Buildbot has detected a new failure on builder `sanitizer-aarch64-linux-bootstrap-ubsan` running on `sanitizer-buildbot9` while building `llvm` at step 2 "annotate".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/85/builds/4376

<details>
<summary>Here is the relevant piece of the build log for the reference</summary>

```
Step 2 (annotate) failure: 'python ../sanitizer_buildbot/sanitizers/zorg/buildbot/builders/sanitizers/buildbot_selector.py' (failure)
...
llvm-lit: /home/b/sanitizer-aarch64-linux-bootstrap-ubsan/build/llvm-project/llvm/utils/lit/lit/llvm/config.py:506: note: using lld-link: /home/b/sanitizer-aarch64-linux-bootstrap-ubsan/build/llvm_build_ubsan/bin/lld-link
llvm-lit: /home/b/sanitizer-aarch64-linux-bootstrap-ubsan/build/llvm-project/llvm/utils/lit/lit/llvm/config.py:506: note: using ld64.lld: /home/b/sanitizer-aarch64-linux-bootstrap-ubsan/build/llvm_build_ubsan/bin/ld64.lld
llvm-lit: /home/b/sanitizer-aarch64-linux-bootstrap-ubsan/build/llvm-project/llvm/utils/lit/lit/llvm/config.py:506: note: using wasm-ld: /home/b/sanitizer-aarch64-linux-bootstrap-ubsan/build/llvm_build_ubsan/bin/wasm-ld
llvm-lit: /home/b/sanitizer-aarch64-linux-bootstrap-ubsan/build/llvm-project/llvm/utils/lit/lit/llvm/config.py:506: note: using ld.lld: /home/b/sanitizer-aarch64-linux-bootstrap-ubsan/build/llvm_build_ubsan/bin/ld.lld
llvm-lit: /home/b/sanitizer-aarch64-linux-bootstrap-ubsan/build/llvm-project/llvm/utils/lit/lit/llvm/config.py:506: note: using lld-link: /home/b/sanitizer-aarch64-linux-bootstrap-ubsan/build/llvm_build_ubsan/bin/lld-link
llvm-lit: /home/b/sanitizer-aarch64-linux-bootstrap-ubsan/build/llvm-project/llvm/utils/lit/lit/llvm/config.py:506: note: using ld64.lld: /home/b/sanitizer-aarch64-linux-bootstrap-ubsan/build/llvm_build_ubsan/bin/ld64.lld
llvm-lit: /home/b/sanitizer-aarch64-linux-bootstrap-ubsan/build/llvm-project/llvm/utils/lit/lit/llvm/config.py:506: note: using wasm-ld: /home/b/sanitizer-aarch64-linux-bootstrap-ubsan/build/llvm_build_ubsan/bin/wasm-ld
llvm-lit: /home/b/sanitizer-aarch64-linux-bootstrap-ubsan/build/llvm-project/llvm/utils/lit/lit/main.py:72: note: The test suite configuration requested an individual test timeout of 0 seconds but a timeout of 900 seconds was requested on the command line. Forcing timeout to be 900 seconds.
-- Testing: 85839 tests, 72 workers --
Testing:  0.. 10.. 20.. 30.. 40.. 50.. 60.. 70.. 80.. 
FAIL: LLVM-Unit :: Analysis/./AnalysisTests/80/86 (77441 of 85839)
******************** TEST 'LLVM-Unit :: Analysis/./AnalysisTests/80/86' FAILED ********************
Script(shard):
--
GTEST_OUTPUT=json:/home/b/sanitizer-aarch64-linux-bootstrap-ubsan/build/llvm_build_ubsan/unittests/Analysis/./AnalysisTests-LLVM-Unit-1835745-80-86.json GTEST_SHUFFLE=0 GTEST_TOTAL_SHARDS=86 GTEST_SHARD_INDEX=80 /home/b/sanitizer-aarch64-linux-bootstrap-ubsan/build/llvm_build_ubsan/unittests/Analysis/./AnalysisTests
--

Note: This is test shard 81 of 86.
[==========] Running 7 tests from 7 test suites.
[----------] Global test environment set-up.
[----------] 1 test from CtxProfAnalysisTest
[ RUN      ] CtxProfAnalysisTest.GetBBIDTest
[       OK ] CtxProfAnalysisTest.GetBBIDTest (0 ms)
[----------] 1 test from CtxProfAnalysisTest (0 ms total)

[----------] 1 test from IRInstructionMapper
[ RUN      ] IRInstructionMapper.ExceptionHandlingExceptionCodeIllegal
[       OK ] IRInstructionMapper.ExceptionHandlingExceptionCodeIllegal (0 ms)
[----------] 1 test from IRInstructionMapper (0 ms total)

[----------] 1 test from LoadsTest
[ RUN      ] LoadsTest.IsDerefReadOnlyLoop
/home/b/sanitizer-aarch64-linux-bootstrap-ubsan/build/llvm-project/llvm/lib/Analysis/Loads.cpp:314:56: runtime error: reference binding to null pointer of type 'SmallVectorImpl<const SCEVPredicate *>'
    #0 0xc996fa29a9a8 in llvm::isDereferenceableAndAlignedInLoop(llvm::LoadInst*, llvm::Loop*, llvm::ScalarEvolution&, llvm::DominatorTree&, llvm::AssumptionCache*, llvm::SmallVectorImpl<llvm::SCEVPredicate const*>*) /home/b/sanitizer-aarch64-linux-bootstrap-ubsan/build/llvm-project/llvm/lib/Analysis/Loads.cpp:314:10
    #1 0xc996fa29ce00 in llvm::isDereferenceableReadOnlyLoop(llvm::Loop*, llvm::ScalarEvolution*, llvm::DominatorTree*, llvm::AssumptionCache*, llvm::SmallVectorImpl<llvm::SCEVPredicate const*>*) /home/b/sanitizer-aarch64-linux-bootstrap-ubsan/build/llvm-project/llvm/lib/Analysis/Loads.cpp:819:14
    #2 0xc996f9f77d30 in LoadsTest_IsDerefReadOnlyLoop_Test::TestBody()::$_0::operator()(llvm::Function*) const /home/b/sanitizer-aarch64-linux-bootstrap-ubsan/build/llvm-project/llvm/unittests/Analysis/LoadsTest.cpp:198:12
    #3 0xc996f9f7793c in LoadsTest_IsDerefReadOnlyLoop_Test::TestBody() /home/b/sanitizer-aarch64-linux-bootstrap-ubsan/build/llvm-project/llvm/unittests/Analysis/LoadsTest.cpp:201:3
    #4 0xc996fba8e444 in testing::Test::Run() /home/b/sanitizer-aarch64-linux-bootstrap-ubsan/build/llvm-project/third-party/unittest/googletest/src/gtest.cc:2687:5
    #5 0xc996fba8fc3c in testing::TestInfo::Run() /home/b/sanitizer-aarch64-linux-bootstrap-ubsan/build/llvm-project/third-party/unittest/googletest/src/gtest.cc:2836:11
    #6 0xc996fba90f90 in testing::TestSuite::Run() /home/b/sanitizer-aarch64-linux-bootstrap-ubsan/build/llvm-project/third-party/unittest/googletest/src/gtest.cc:3015:30
    #7 0xc996fbaa1aa0 in testing::internal::UnitTestImpl::RunAllTests() /home/b/sanitizer-aarch64-linux-bootstrap-ubsan/build/llvm-project/third-party/unittest/googletest/src/gtest.cc:5920:44
    #8 0xc996fbaa1058 in testing::UnitTest::Run() /home/b/sanitizer-aarch64-linux-bootstrap-ubsan/build/llvm-project/third-party/unittest/googletest/src/gtest.cc:5484:10
    #9 0xc996fba7304c in RUN_ALL_TESTS /home/b/sanitizer-aarch64-linux-bootstrap-ubsan/build/llvm-project/third-party/unittest/googletest/include/gtest/gtest.h:2317:73
    #10 0xc996fba7304c in main /home/b/sanitizer-aarch64-linux-bootstrap-ubsan/build/llvm-project/third-party/unittest/UnitTestMain/TestMain.cpp:55:10
    #11 0xe701662d84c0  (/lib/aarch64-linux-gnu/libc.so.6+0x284c0) (BuildId: 32fa4d6f3a8d5f430bdb7af2eb779470cd5ec7c2)
    #12 0xe701662d8594 in __libc_start_main (/lib/aarch64-linux-gnu/libc.so.6+0x28594) (BuildId: 32fa4d6f3a8d5f430bdb7af2eb779470cd5ec7c2)
    #13 0xc996f9e2a62c in _start (/home/b/sanitizer-aarch64-linux-bootstrap-ubsan/build/llvm_build_ubsan/unittests/Analysis/AnalysisTests+0x2aba62c)

SUMMARY: UndefinedBehaviorSanitizer: undefined-behavior /home/b/sanitizer-aarch64-linux-bootstrap-ubsan/build/llvm-project/llvm/lib/Analysis/Loads.cpp:314:56 
Step 11 (stage2/ubsan check) failure: stage2/ubsan check (failure)
...
llvm-lit: /home/b/sanitizer-aarch64-linux-bootstrap-ubsan/build/llvm-project/llvm/utils/lit/lit/llvm/config.py:506: note: using lld-link: /home/b/sanitizer-aarch64-linux-bootstrap-ubsan/build/llvm_build_ubsan/bin/lld-link
llvm-lit: /home/b/sanitizer-aarch64-linux-bootstrap-ubsan/build/llvm-project/llvm/utils/lit/lit/llvm/config.py:506: note: using ld64.lld: /home/b/sanitizer-aarch64-linux-bootstrap-ubsan/build/llvm_build_ubsan/bin/ld64.lld
llvm-lit: /home/b/sanitizer-aarch64-linux-bootstrap-ubsan/build/llvm-project/llvm/utils/lit/lit/llvm/config.py:506: note: using wasm-ld: /home/b/sanitizer-aarch64-linux-bootstrap-ubsan/build/llvm_build_ubsan/bin/wasm-ld
llvm-lit: /home/b/sanitizer-aarch64-linux-bootstrap-ubsan/build/llvm-project/llvm/utils/lit/lit/llvm/config.py:506: note: using ld.lld: /home/b/sanitizer-aarch64-linux-bootstrap-ubsan/build/llvm_build_ubsan/bin/ld.lld
llvm-lit: /home/b/sanitizer-aarch64-linux-bootstrap-ubsan/build/llvm-project/llvm/utils/lit/lit/llvm/config.py:506: note: using lld-link: /home/b/sanitizer-aarch64-linux-bootstrap-ubsan/build/llvm_build_ubsan/bin/lld-link
llvm-lit: /home/b/sanitizer-aarch64-linux-bootstrap-ubsan/build/llvm-project/llvm/utils/lit/lit/llvm/config.py:506: note: using ld64.lld: /home/b/sanitizer-aarch64-linux-bootstrap-ubsan/build/llvm_build_ubsan/bin/ld64.lld
llvm-lit: /home/b/sanitizer-aarch64-linux-bootstrap-ubsan/build/llvm-project/llvm/utils/lit/lit/llvm/config.py:506: note: using wasm-ld: /home/b/sanitizer-aarch64-linux-bootstrap-ubsan/build/llvm_build_ubsan/bin/wasm-ld
llvm-lit: /home/b/sanitizer-aarch64-linux-bootstrap-ubsan/build/llvm-project/llvm/utils/lit/lit/main.py:72: note: The test suite configuration requested an individual test timeout of 0 seconds but a timeout of 900 seconds was requested on the command line. Forcing timeout to be 900 seconds.
-- Testing: 85839 tests, 72 workers --
Testing:  0.. 10.. 20.. 30.. 40.. 50.. 60.. 70.. 80.. 
FAIL: LLVM-Unit :: Analysis/./AnalysisTests/80/86 (77441 of 85839)
******************** TEST 'LLVM-Unit :: Analysis/./AnalysisTests/80/86' FAILED ********************
Script(shard):
--
GTEST_OUTPUT=json:/home/b/sanitizer-aarch64-linux-bootstrap-ubsan/build/llvm_build_ubsan/unittests/Analysis/./AnalysisTests-LLVM-Unit-1835745-80-86.json GTEST_SHUFFLE=0 GTEST_TOTAL_SHARDS=86 GTEST_SHARD_INDEX=80 /home/b/sanitizer-aarch64-linux-bootstrap-ubsan/build/llvm_build_ubsan/unittests/Analysis/./AnalysisTests
--

Note: This is test shard 81 of 86.
[==========] Running 7 tests from 7 test suites.
[----------] Global test environment set-up.
[----------] 1 test from CtxProfAnalysisTest
[ RUN      ] CtxProfAnalysisTest.GetBBIDTest
[       OK ] CtxProfAnalysisTest.GetBBIDTest (0 ms)
[----------] 1 test from CtxProfAnalysisTest (0 ms total)

[----------] 1 test from IRInstructionMapper
[ RUN      ] IRInstructionMapper.ExceptionHandlingExceptionCodeIllegal
[       OK ] IRInstructionMapper.ExceptionHandlingExceptionCodeIllegal (0 ms)
[----------] 1 test from IRInstructionMapper (0 ms total)

[----------] 1 test from LoadsTest
[ RUN      ] LoadsTest.IsDerefReadOnlyLoop
/home/b/sanitizer-aarch64-linux-bootstrap-ubsan/build/llvm-project/llvm/lib/Analysis/Loads.cpp:314:56: runtime error: reference binding to null pointer of type 'SmallVectorImpl<const SCEVPredicate *>'
    #0 0xc996fa29a9a8 in llvm::isDereferenceableAndAlignedInLoop(llvm::LoadInst*, llvm::Loop*, llvm::ScalarEvolution&, llvm::DominatorTree&, llvm::AssumptionCache*, llvm::SmallVectorImpl<llvm::SCEVPredicate const*>*) /home/b/sanitizer-aarch64-linux-bootstrap-ubsan/build/llvm-project/llvm/lib/Analysis/Loads.cpp:314:10
    #1 0xc996fa29ce00 in llvm::isDereferenceableReadOnlyLoop(llvm::Loop*, llvm::ScalarEvolution*, llvm::DominatorTree*, llvm::AssumptionCache*, llvm::SmallVectorImpl<llvm::SCEVPredicate const*>*) /home/b/sanitizer-aarch64-linux-bootstrap-ubsan/build/llvm-project/llvm/lib/Analysis/Loads.cpp:819:14
    #2 0xc996f9f77d30 in LoadsTest_IsDerefReadOnlyLoop_Test::TestBody()::$_0::operator()(llvm::Function*) const /home/b/sanitizer-aarch64-linux-bootstrap-ubsan/build/llvm-project/llvm/unittests/Analysis/LoadsTest.cpp:198:12
    #3 0xc996f9f7793c in LoadsTest_IsDerefReadOnlyLoop_Test::TestBody() /home/b/sanitizer-aarch64-linux-bootstrap-ubsan/build/llvm-project/llvm/unittests/Analysis/LoadsTest.cpp:201:3
    #4 0xc996fba8e444 in testing::Test::Run() /home/b/sanitizer-aarch64-linux-bootstrap-ubsan/build/llvm-project/third-party/unittest/googletest/src/gtest.cc:2687:5
    #5 0xc996fba8fc3c in testing::TestInfo::Run() /home/b/sanitizer-aarch64-linux-bootstrap-ubsan/build/llvm-project/third-party/unittest/googletest/src/gtest.cc:2836:11
    #6 0xc996fba90f90 in testing::TestSuite::Run() /home/b/sanitizer-aarch64-linux-bootstrap-ubsan/build/llvm-project/third-party/unittest/googletest/src/gtest.cc:3015:30
    #7 0xc996fbaa1aa0 in testing::internal::UnitTestImpl::RunAllTests() /home/b/sanitizer-aarch64-linux-bootstrap-ubsan/build/llvm-project/third-party/unittest/googletest/src/gtest.cc:5920:44
    #8 0xc996fbaa1058 in testing::UnitTest::Run() /home/b/sanitizer-aarch64-linux-bootstrap-ubsan/build/llvm-project/third-party/unittest/googletest/src/gtest.cc:5484:10
    #9 0xc996fba7304c in RUN_ALL_TESTS /home/b/sanitizer-aarch64-linux-bootstrap-ubsan/build/llvm-project/third-party/unittest/googletest/include/gtest/gtest.h:2317:73
    #10 0xc996fba7304c in main /home/b/sanitizer-aarch64-linux-bootstrap-ubsan/build/llvm-project/third-party/unittest/UnitTestMain/TestMain.cpp:55:10
    #11 0xe701662d84c0  (/lib/aarch64-linux-gnu/libc.so.6+0x284c0) (BuildId: 32fa4d6f3a8d5f430bdb7af2eb779470cd5ec7c2)
    #12 0xe701662d8594 in __libc_start_main (/lib/aarch64-linux-gnu/libc.so.6+0x28594) (BuildId: 32fa4d6f3a8d5f430bdb7af2eb779470cd5ec7c2)
    #13 0xc996f9e2a62c in _start (/home/b/sanitizer-aarch64-linux-bootstrap-ubsan/build/llvm_build_ubsan/unittests/Analysis/AnalysisTests+0x2aba62c)

SUMMARY: UndefinedBehaviorSanitizer: undefined-behavior /home/b/sanitizer-aarch64-linux-bootstrap-ubsan/build/llvm-project/llvm/lib/Analysis/Loads.cpp:314:56 

```

</details>

https://github.com/llvm/llvm-project/pull/96752