[llvm] [LICM] Support hoisting of non-argmemonly readonly calls (PR #144497)

Mon Aug 18 23:08:54 PDT 2025

mikaelholmen wrote:

Hi @nikic 

I ran into a crash that I could bisect back to this patch.
```
opt -passes="function(interleaved-load-combine),cgscc(function-attrs),function(loop-mssa(licm))" bbi-109713.ll -S -o /dev/null -mtriple=hexagon
```
crashes in LICM with
```
opt: ../include/llvm/Support/Casting.h:578: decltype(auto) llvm::cast(From *) [To = llvm::MemoryUse, From = llvm::MemoryUseOrDef]: Assertion `isa<To>(Val) && "cast<Ty>() argument of incompatible type!"' failed.
PLEASE submit a bug report to https://github.com/llvm/llvm-project/issues/ and include the crash backtrace.
Stack dump:
0.	Program arguments: build-all/bin/opt -passes=function(interleaved-load-combine),cgscc(function-attrs),function(loop-mssa(licm)) bbi-109713.ll -S -o /dev/null -mtriple=hexagon
1.	Running pass "function(loop-mssa(licm<allowspeculation>))" on module "bbi-109713.ll"
2.	Running pass "loop-mssa(licm<allowspeculation>)" on function "f875"
 #0 0x0000559040539f46 llvm::sys::PrintStackTrace(llvm::raw_ostream&, int) (build-all/bin/opt+0x47eff46)
 #1 0x00005590405374d5 llvm::sys::RunSignalHandlers() (build-all/bin/opt+0x47ed4d5)
 #2 0x000055904053b0c9 SignalHandler(int, siginfo_t*, void*) Signals.cpp:0:0
 #3 0x00007f0fe5b55990 __restore_rt (/lib64/libpthread.so.0+0x12990)
 #4 0x00007f0fe34f552f raise (/lib64/libc.so.6+0x4e52f)
 #5 0x00007f0fe34c8e65 abort (/lib64/libc.so.6+0x21e65)
 #6 0x00007f0fe34c8d39 _nl_load_domain.cold.0 (/lib64/libc.so.6+0x21d39)
 #7 0x00007f0fe34ede86 (/lib64/libc.so.6+0x46e86)
 #8 0x0000559040f4c89e (build-all/bin/opt+0x520289e)
 #9 0x0000559040f45ace llvm::canSinkOrHoistInst(llvm::Instruction&, llvm::AAResults*, llvm::DominatorTree*, llvm::Loop*, llvm::MemorySSAUpdater&, bool, llvm::SinkAndHoistLICMFlags&, llvm::OptimizationRemarkEmitter*) (build-all/bin/opt+0x51fbace)
#10 0x0000559040f463d4 llvm::hoistRegion(llvm::DomTreeNodeBase<llvm::BasicBlock>*, llvm::AAResults*, llvm::LoopInfo*, llvm::DominatorTree*, llvm::AssumptionCache*, llvm::TargetLibraryInfo*, llvm::Loop*, llvm::MemorySSAUpdater&, llvm::ScalarEvolution*, llvm::ICFLoopSafetyInfo*, llvm::SinkAndHoistLICMFlags&, llvm::OptimizationRemarkEmitter*, bool, bool, bool) (build-all/bin/opt+0x51fc3d4)
#11 0x0000559040f40d55 (anonymous namespace)::LoopInvariantCodeMotion::runOnLoop(llvm::Loop*, llvm::AAResults*, llvm::LoopInfo*, llvm::DominatorTree*, llvm::AssumptionCache*, llvm::TargetLibraryInfo*, llvm::TargetTransformInfo*, llvm::ScalarEvolution*, llvm::MemorySSA*, llvm::OptimizationRemarkEmitter*, bool) LICM.cpp:0:0
#12 0x0000559040f4071e llvm::LICMPass::run(llvm::Loop&, llvm::AnalysisManager<llvm::Loop, llvm::LoopStandardAnalysisResults&>&, llvm::LoopStandardAnalysisResults&, llvm::LPMUpdater&) (build-all/bin/opt+0x51f671e)
#13 0x0000559041a01e4d llvm::detail::PassModel<llvm::Loop, llvm::LICMPass, llvm::AnalysisManager<llvm::Loop, llvm::LoopStandardAnalysisResults&>, llvm::LoopStandardAnalysisResults&, llvm::LPMUpdater&>::run(llvm::Loop&, llvm::AnalysisManager<llvm::Loop, llvm::LoopStandardAnalysisResults&>&, llvm::LoopStandardAnalysisResults&, llvm::LPMUpdater&) PassBuilderPipelines.cpp:0:0
#14 0x0000559041c99bbc std::optional<llvm::PreservedAnalyses> llvm::PassManager<llvm::Loop, llvm::AnalysisManager<llvm::Loop, llvm::LoopStandardAnalysisResults&>, llvm::LoopStandardAnalysisResults&, llvm::LPMUpdater&>::runSinglePass<llvm::Loop, std::unique_ptr<llvm::detail::PassConcept<llvm::Loop, llvm::AnalysisManager<llvm::Loop, llvm::LoopStandardAnalysisResults&>, llvm::LoopStandardAnalysisResults&, llvm::LPMUpdater&>, std::default_delete<llvm::detail::PassConcept<llvm::Loop, llvm::AnalysisManager<llvm::Loop, llvm::LoopStandardAnalysisResults&>, llvm::LoopStandardAnalysisResults&, llvm::LPMUpdater&>>>>(llvm::Loop&, std::unique_ptr<llvm::detail::PassConcept<llvm::Loop, llvm::AnalysisManager<llvm::Loop, llvm::LoopStandardAnalysisResults&>, llvm::LoopStandardAnalysisResults&, llvm::LPMUpdater&>, std::default_delete<llvm::detail::PassConcept<llvm::Loop, llvm::AnalysisManager<llvm::Loop, llvm::LoopStandardAnalysisResults&>, llvm::LoopStandardAnalysisResults&, llvm::LPMUpdater&>>>&, llvm::AnalysisManager<llvm::Loop, llvm::LoopStandardAnalysisResults&>&, llvm::LoopStandardAnalysisResults&, llvm::LPMUpdater&, llvm::PassInstrumentation&) (build-all/bin/opt+0x5f4fbbc)
#15 0x0000559041c997f3 llvm::PassManager<llvm::Loop, llvm::AnalysisManager<llvm::Loop, llvm::LoopStandardAnalysisResults&>, llvm::LoopStandardAnalysisResults&, llvm::LPMUpdater&>::runWithoutLoopNestPasses(llvm::Loop&, llvm::AnalysisManager<llvm::Loop, llvm::LoopStandardAnalysisResults&>&, llvm::LoopStandardAnalysisResults&, llvm::LPMUpdater&) (build-all/bin/opt+0x5f4f7f3)
#16 0x0000559041c98cf4 llvm::PassManager<llvm::Loop, llvm::AnalysisManager<llvm::Loop, llvm::LoopStandardAnalysisResults&>, llvm::LoopStandardAnalysisResults&, llvm::LPMUpdater&>::run(llvm::Loop&, llvm::AnalysisManager<llvm::Loop, llvm::LoopStandardAnalysisResults&>&, llvm::LoopStandardAnalysisResults&, llvm::LPMUpdater&) (build-all/bin/opt+0x5f4ecf4)
#17 0x00005590419ff8dd llvm::detail::PassModel<llvm::Loop, llvm::PassManager<llvm::Loop, llvm::AnalysisManager<llvm::Loop, llvm::LoopStandardAnalysisResults&>, llvm::LoopStandardAnalysisResults&, llvm::LPMUpdater&>, llvm::AnalysisManager<llvm::Loop, llvm::LoopStandardAnalysisResults&>, llvm::LoopStandardAnalysisResults&, llvm::LPMUpdater&>::run(llvm::Loop&, llvm::AnalysisManager<llvm::Loop, llvm::LoopStandardAnalysisResults&>&, llvm::LoopStandardAnalysisResults&, llvm::LPMUpdater&) PassBuilderPipelines.cpp:0:0
#18 0x0000559041c9ac01 llvm::FunctionToLoopPassAdaptor::run(llvm::Function&, llvm::AnalysisManager<llvm::Function>&) (build-all/bin/opt+0x5f50c01)
#19 0x0000559041a023cd llvm::detail::PassModel<llvm::Function, llvm::FunctionToLoopPassAdaptor, llvm::AnalysisManager<llvm::Function>>::run(llvm::Function&, llvm::AnalysisManager<llvm::Function>&) PassBuilderPipelines.cpp:0:0
#20 0x0000559040754215 llvm::PassManager<llvm::Function, llvm::AnalysisManager<llvm::Function>>::run(llvm::Function&, llvm::AnalysisManager<llvm::Function>&) (build-all/bin/opt+0x4a0a215)
#21 0x0000559041a0489d llvm::detail::PassModel<llvm::Function, llvm::PassManager<llvm::Function, llvm::AnalysisManager<llvm::Function>>, llvm::AnalysisManager<llvm::Function>>::run(llvm::Function&, llvm::AnalysisManager<llvm::Function>&) PassBuilderPipelines.cpp:0:0
#22 0x0000559040758dce llvm::ModuleToFunctionPassAdaptor::run(llvm::Module&, llvm::AnalysisManager<llvm::Module>&) (build-all/bin/opt+0x4a0edce)
#23 0x0000559041993f3d llvm::detail::PassModel<llvm::Module, llvm::ModuleToFunctionPassAdaptor, llvm::AnalysisManager<llvm::Module>>::run(llvm::Module&, llvm::AnalysisManager<llvm::Module>&) NewPMDriver.cpp:0:0
#24 0x0000559040752f05 llvm::PassManager<llvm::Module, llvm::AnalysisManager<llvm::Module>>::run(llvm::Module&, llvm::AnalysisManager<llvm::Module>&) (build-all/bin/opt+0x4a08f05)
#25 0x000055904198cd84 llvm::runPassPipeline(llvm::StringRef, llvm::Module&, llvm::TargetMachine*, llvm::TargetLibraryInfoImpl*, llvm::ToolOutputFile*, llvm::ToolOutputFile*, llvm::ToolOutputFile*, llvm::StringRef, llvm::ArrayRef<llvm::PassPlugin>, llvm::ArrayRef<std::function<void (llvm::PassBuilder&)>>, llvm::opt_tool::OutputKind, llvm::opt_tool::VerifierKind, bool, bool, bool, bool, bool, bool, bool, bool) (build-all/bin/opt+0x5c42d84)
#26 0x00005590404db738 optMain (build-all/bin/opt+0x4791738)
#27 0x00007f0fe34e17e5 __libc_start_main (/lib64/libc.so.6+0x3a7e5)
#28 0x00005590404d916e _start (build-all/bin/opt+0x478f16e)
Abort (core dumped)
```
It's the cast below that fails:
```
    if (Behavior.onlyReadsMemory()) {
      // If we can prove there are no writes to the memory read by the call, we
      // can hoist or sink.
      return !pointerInvalidatedByLoop(
          MSSA, cast<MemoryUse>(MSSA->getMemoryAccess(CI)), CurLoop, I, Flags,
          /*InvariantGroup=*/false);
    }
```
[bbi-109713.ll.gz](https://github.com/user-attachments/files/21849263/bbi-109713.ll.gz)


https://github.com/llvm/llvm-project/pull/144497