[llvm] [AArch64][MachineCombiner] Reassociate long chains of accumulation instructions into a tree to increase ILP (PR #126060)

Sun Mar 23 04:33:15 PDT 2025

llvm-ci wrote:

LLVM Buildbot has detected a new failure on builder `openmp-offload-sles-build-only` running on `rocm-worker-hw-04-sles` while building `llvm` at step 5 "compile-openmp".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/140/builds/19616

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

```
Step 5 (compile-openmp) failure: build (failure)
...
     for (const auto &[GUID, TypeIdPair] : make_range(TidIter))
                                       ^
In file included from /home/botworker/bbot/builds/openmp-offload-sles-build/llvm.src/llvm/include/llvm/Analysis/CtxProfAnalysis.h:17:0,
                 from /home/botworker/bbot/builds/openmp-offload-sles-build/llvm.src/llvm/include/llvm/Transforms/Utils/CallPromotionUtils.h:17,
                 from /home/botworker/bbot/builds/openmp-offload-sles-build/llvm.src/llvm/lib/Transforms/IPO/MemProfContextDisambiguation.cpp:44:
/home/botworker/bbot/builds/openmp-offload-sles-build/llvm.src/llvm/include/llvm/ProfileData/PGOCtxProfReader.h: In member function ‘void llvm::PGOCtxProfContext::ingestAllContexts(uint32_t, llvm::PGOCtxProfContext::CallTargetMapTy&&)’:
/home/botworker/bbot/builds/openmp-offload-sles-build/llvm.src/llvm/include/llvm/ProfileData/PGOCtxProfReader.h:152:22: warning: unused variable ‘_’ [-Wunused-variable]
     auto [_, Inserted] = callsites().try_emplace(CSId, std::move(Other));
                      ^
20.897 [4777/32/2348] Building CXX object lib/CodeGen/CMakeFiles/LLVMCodeGen.dir/TargetInstrInfo.cpp.o
FAILED: lib/CodeGen/CMakeFiles/LLVMCodeGen.dir/TargetInstrInfo.cpp.o 
ccache /usr/bin/c++ -DGTEST_HAS_RTTI=0 -D_DEBUG -D_GLIBCXX_ASSERTIONS -D_GNU_SOURCE -D__STDC_CONSTANT_MACROS -D__STDC_FORMAT_MACROS -D__STDC_LIMIT_MACROS -Ilib/CodeGen -I/home/botworker/bbot/builds/openmp-offload-sles-build/llvm.src/llvm/lib/CodeGen -Iinclude -I/home/botworker/bbot/builds/openmp-offload-sles-build/llvm.src/llvm/include -fPIC -fno-semantic-interposition -fvisibility-inlines-hidden -Werror=date-time -Wall -Wextra -Wno-unused-parameter -Wwrite-strings -Wcast-qual -Wno-missing-field-initializers -pedantic -Wno-long-long -Wimplicit-fallthrough -Wno-uninitialized -Wno-nonnull -Wno-noexcept-type -Wdelete-non-virtual-dtor -Wno-comment -Wno-misleading-indentation -fdiagnostics-color -ffunction-sections -fdata-sections -O3 -DNDEBUG  -fno-exceptions -funwind-tables -fno-rtti -UNDEBUG -std=c++1z -MD -MT lib/CodeGen/CMakeFiles/LLVMCodeGen.dir/TargetInstrInfo.cpp.o -MF lib/CodeGen/CMakeFiles/LLVMCodeGen.dir/TargetInstrInfo.cpp.o.d -o lib/CodeGen/CMakeFiles/LLVMCodeGen.dir/TargetInstrInfo.cpp.o -c /home/botworker/bbot/builds/openmp-offload-sles-build/llvm.src/llvm/lib/CodeGen/TargetInstrInfo.cpp
In file included from /home/botworker/bbot/builds/openmp-offload-sles-build/llvm.src/llvm/include/llvm/CodeGen/MachineScheduler.h:87:0,
                 from /home/botworker/bbot/builds/openmp-offload-sles-build/llvm.src/llvm/lib/CodeGen/TargetInstrInfo.cpp:22:
/home/botworker/bbot/builds/openmp-offload-sles-build/llvm.src/llvm/include/llvm/CodeGen/ScheduleDAG.h:308:40: warning: ‘llvm::SUnit::SchedulingPref’ is too small to hold all values of ‘enum llvm::Sched::Preference’
     Sched::Preference SchedulingPref : 4; ///< Scheduling preference.
                                        ^
In file included from /usr/include/c++/7/cassert:44:0,
                 from /home/botworker/bbot/builds/openmp-offload-sles-build/llvm.src/llvm/include/llvm/ADT/IntrusiveRefCntPtr.h:64,
                 from /home/botworker/bbot/builds/openmp-offload-sles-build/llvm.src/llvm/include/llvm/Support/PGOOptions.h:17,
                 from /home/botworker/bbot/builds/openmp-offload-sles-build/llvm.src/llvm/include/llvm/Target/TargetMachine.h:24,
                 from /home/botworker/bbot/builds/openmp-offload-sles-build/llvm.src/llvm/lib/CodeGen/TargetInstrInfo.cpp:38:
/home/botworker/bbot/builds/openmp-offload-sles-build/llvm.src/llvm/lib/CodeGen/TargetInstrInfo.cpp: In member function ‘virtual void llvm::TargetInstrInfo::genAlternativeCodeSequence(llvm::MachineInstr&, unsigned int, llvm::SmallVectorImpl<llvm::MachineInstr*>&, llvm::SmallVectorImpl<llvm::MachineInstr*>&, llvm::DenseMap<llvm::Register, unsigned int>&) const’:
/home/botworker/bbot/builds/openmp-offload-sles-build/llvm.src/llvm/lib/CodeGen/TargetInstrInfo.cpp:1487:46: warning: comparison of unsigned expression >= 0 is always true [-Wtype-limits]
         assert(IndexedReg.index() - MaxWidth >= 0);
                ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~
/home/botworker/bbot/builds/openmp-offload-sles-build/llvm.src/llvm/lib/CodeGen/TargetInstrInfo.cpp:1514:75: error: no matching function for call to ‘llvm::TargetInstrInfo::reduceAccumulatorTree(llvm::SmallVector<llvm::Register, 8>&, llvm::SmallVectorImpl<llvm::MachineInstr*>&, llvm::MachineFunction&, llvm::MachineInstr&, llvm::MachineRegisterInfo&, llvm::DenseMap<llvm::Register, unsigned int>&, llvm::Register) const’
                             InstIdxForVirtReg, Root.getOperand(0).getReg());
                                                                           ^
/home/botworker/bbot/builds/openmp-offload-sles-build/llvm.src/llvm/lib/CodeGen/TargetInstrInfo.cpp:1017:6: note: candidate: void llvm::TargetInstrInfo::reduceAccumulatorTree(llvm::SmallVectorImpl<llvm::Register>&, llvm::SmallVectorImpl<llvm::MachineInstr*>&, llvm::MachineFunction&, llvm::MachineInstr&, llvm::MachineRegisterInfo&, llvm::DenseMap<unsigned int, unsigned int>&, llvm::Register) const
 void TargetInstrInfo::reduceAccumulatorTree(
      ^~~~~~~~~~~~~~~
/home/botworker/bbot/builds/openmp-offload-sles-build/llvm.src/llvm/lib/CodeGen/TargetInstrInfo.cpp:1017:6: note:   no known conversion for argument 6 from ‘llvm::DenseMap<llvm::Register, unsigned int>’ to ‘llvm::DenseMap<unsigned int, unsigned int>&’
20.897 [4777/31/2349] Building CXX object lib/Transforms/IPO/CMakeFiles/LLVMipo.dir/ModuleInliner.cpp.o
In file included from /home/botworker/bbot/builds/openmp-offload-sles-build/llvm.src/llvm/include/llvm/Analysis/CtxProfAnalysis.h:17:0,
                 from /home/botworker/bbot/builds/openmp-offload-sles-build/llvm.src/llvm/lib/Transforms/IPO/ModuleInliner.cpp:23:
/home/botworker/bbot/builds/openmp-offload-sles-build/llvm.src/llvm/include/llvm/ProfileData/PGOCtxProfReader.h: In member function ‘void llvm::PGOCtxProfContext::ingestAllContexts(uint32_t, llvm::PGOCtxProfContext::CallTargetMapTy&&)’:
/home/botworker/bbot/builds/openmp-offload-sles-build/llvm.src/llvm/include/llvm/ProfileData/PGOCtxProfReader.h:152:22: warning: unused variable ‘_’ [-Wunused-variable]
     auto [_, Inserted] = callsites().try_emplace(CSId, std::move(Other));
                      ^
20.901 [4777/30/2350] Building CXX object lib/Transforms/IPO/CMakeFiles/LLVMipo.dir/SampleContextTracker.cpp.o
20.901 [4777/29/2351] Building CXX object lib/Transforms/IPO/CMakeFiles/LLVMipo.dir/OpenMPOpt.cpp.o
20.903 [4777/28/2352] Building CXX object lib/Transforms/IPO/CMakeFiles/LLVMipo.dir/PartialInlining.cpp.o
20.907 [4777/27/2353] Building CXX object lib/Transforms/IPO/CMakeFiles/LLVMipo.dir/SampleProfileMatcher.cpp.o
20.908 [4777/26/2354] Building CXX object lib/Transforms/IPO/CMakeFiles/LLVMipo.dir/SampleProfile.cpp.o
In file included from /usr/include/c++/7/cassert:44:0,
                 from /home/botworker/bbot/builds/openmp-offload-sles-build/llvm.src/llvm/include/llvm/ProfileData/InstrProf.h:39,
                 from /home/botworker/bbot/builds/openmp-offload-sles-build/llvm.src/llvm/lib/Transforms/IPO/SampleProfile.cpp:61:
/home/botworker/bbot/builds/openmp-offload-sles-build/llvm.src/llvm/include/llvm/ProfileData/InstrProf.h: In member function ‘llvm::ArrayRef<llvm::InstrProfValueSiteRecord> llvm::InstrProfRecord::getValueSitesForKind(uint32_t) const’:

```

</details>

https://github.com/llvm/llvm-project/pull/126060