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

LLVM Continuous Integration via llvm-commits llvm-commits at lists.llvm.org
Sun Mar 23 04:52:34 PDT 2025 

llvm-ci wrote:

LLVM Buildbot has detected a new failure on builder `ppc64le-lld-multistage-test` running on `ppc64le-lld-multistage-test` while building `llvm` at step 6 "build-stage1-unified-tree".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/168/builds/10064

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

```
Step 6 (build-stage1-unified-tree) failure: build (failure)
...
28.370 [148/600/280] Building CXX object lib/Target/ARM/CMakeFiles/LLVMARMCodeGen.dir/ARMBranchTargets.cpp.o
28.438 [148/599/281] Building CXX object lib/Target/AMDGPU/CMakeFiles/LLVMAMDGPUCodeGen.dir/R600ClauseMergePass.cpp.o
28.475 [148/598/282] Building CXX object lib/CodeGen/CMakeFiles/LLVMCodeGen.dir/MachineDebugify.cpp.o
28.494 [148/597/283] Building CXX object lib/Target/SystemZ/CMakeFiles/LLVMSystemZCodeGen.dir/SystemZSelectionDAGInfo.cpp.o
28.502 [148/596/284] Building CXX object lib/Target/Mips/CMakeFiles/LLVMMipsCodeGen.dir/MipsMachineFunction.cpp.o
28.515 [148/595/285] Building CXX object lib/Target/Hexagon/CMakeFiles/LLVMHexagonCodeGen.dir/HexagonCopyToCombine.cpp.o
28.684 [148/594/286] Building CXX object lib/Target/PowerPC/CMakeFiles/LLVMPowerPCCodeGen.dir/PPCHazardRecognizers.cpp.o
28.725 [148/593/287] Building CXX object lib/Target/WebAssembly/CMakeFiles/LLVMWebAssemblyCodeGen.dir/WebAssemblyRuntimeLibcallSignatures.cpp.o
28.906 [148/592/288] Building CXX object lib/Target/NVPTX/CMakeFiles/LLVMNVPTXCodeGen.dir/NVPTXReplaceImageHandles.cpp.o
28.911 [148/591/289] Building CXX object lib/CodeGen/CMakeFiles/LLVMCodeGen.dir/TargetInstrInfo.cpp.o
FAILED: lib/CodeGen/CMakeFiles/LLVMCodeGen.dir/TargetInstrInfo.cpp.o 
ccache /usr/lib64/ccache/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 -I/home/buildbots/llvm-external-buildbots/workers/ppc64le-lld-multistage-test/ppc64le-lld-multistage-test/build/stage1/lib/CodeGen -I/home/buildbots/llvm-external-buildbots/workers/ppc64le-lld-multistage-test/ppc64le-lld-multistage-test/llvm-project/llvm/lib/CodeGen -I/home/buildbots/llvm-external-buildbots/workers/ppc64le-lld-multistage-test/ppc64le-lld-multistage-test/build/stage1/include -I/home/buildbots/llvm-external-buildbots/workers/ppc64le-lld-multistage-test/ppc64le-lld-multistage-test/llvm-project/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-class-memaccess -Wno-noexcept-type -Wdelete-non-virtual-dtor -Wno-comment -Wno-misleading-indentation -fdiagnostics-color -ffunction-sections -fdata-sections -O3 -DNDEBUG -std=c++17  -fno-exceptions -funwind-tables -fno-rtti -UNDEBUG -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/buildbots/llvm-external-buildbots/workers/ppc64le-lld-multistage-test/ppc64le-lld-multistage-test/llvm-project/llvm/lib/CodeGen/TargetInstrInfo.cpp
In file included from /usr/include/c++/8/cassert:44,
                 from /home/buildbots/llvm-external-buildbots/workers/ppc64le-lld-multistage-test/ppc64le-lld-multistage-test/llvm-project/llvm/include/llvm/ADT/IntrusiveRefCntPtr.h:64,
                 from /home/buildbots/llvm-external-buildbots/workers/ppc64le-lld-multistage-test/ppc64le-lld-multistage-test/llvm-project/llvm/include/llvm/Support/PGOOptions.h:17,
                 from /home/buildbots/llvm-external-buildbots/workers/ppc64le-lld-multistage-test/ppc64le-lld-multistage-test/llvm-project/llvm/include/llvm/Target/TargetMachine.h:24,
                 from /home/buildbots/llvm-external-buildbots/workers/ppc64le-lld-multistage-test/ppc64le-lld-multistage-test/llvm-project/llvm/lib/CodeGen/TargetInstrInfo.cpp:38:
/home/buildbots/llvm-external-buildbots/workers/ppc64le-lld-multistage-test/ppc64le-lld-multistage-test/llvm-project/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/buildbots/llvm-external-buildbots/workers/ppc64le-lld-multistage-test/ppc64le-lld-multistage-test/llvm-project/llvm/lib/CodeGen/TargetInstrInfo.cpp:1487:46: warning: comparison of unsigned expression >= 0 is always true [-Wtype-limits]
         assert(IndexedReg.index() - MaxWidth >= 0);
                ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~
/home/buildbots/llvm-external-buildbots/workers/ppc64le-lld-multistage-test/ppc64le-lld-multistage-test/llvm-project/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/buildbots/llvm-external-buildbots/workers/ppc64le-lld-multistage-test/ppc64le-lld-multistage-test/llvm-project/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/buildbots/llvm-external-buildbots/workers/ppc64le-lld-multistage-test/ppc64le-lld-multistage-test/llvm-project/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>&’
28.932 [148/590/290] Building CXX object lib/Target/AMDGPU/CMakeFiles/LLVMAMDGPUCodeGen.dir/GCNCreateVOPD.cpp.o
28.946 [148/589/291] Building CXX object lib/Target/AVR/CMakeFiles/LLVMAVRCodeGen.dir/AVRExpandPseudoInsts.cpp.o
28.966 [148/588/292] Building CXX object lib/Target/Hexagon/CMakeFiles/LLVMHexagonCodeGen.dir/HexagonHardwareLoops.cpp.o
29.009 [148/587/293] Building CXX object lib/CodeGen/CMakeFiles/LLVMCodeGen.dir/Analysis.cpp.o
29.035 [148/586/294] Building CXX object lib/Target/PowerPC/CMakeFiles/LLVMPowerPCCodeGen.dir/PPCCTRLoops.cpp.o
29.107 [148/585/295] Building CXX object lib/CodeGen/CMakeFiles/LLVMCodeGen.dir/RegAllocFast.cpp.o
29.111 [148/584/296] Building CXX object lib/Target/Hexagon/CMakeFiles/LLVMHexagonCodeGen.dir/HexagonLoadStoreWidening.cpp.o
29.116 [148/583/297] Building CXX object lib/Target/Mips/CMakeFiles/LLVMMipsCodeGen.dir/MipsRegisterInfo.cpp.o
29.130 [148/582/298] Building CXX object lib/Target/LoongArch/CMakeFiles/LLVMLoongArchCodeGen.dir/LoongArchExpandAtomicPseudoInsts.cpp.o
29.159 [148/581/299] Linking CXX executable tools/clang/unittests/Serialization/SerializationTests
29.187 [148/580/300] Building CXX object lib/Target/SystemZ/CMakeFiles/LLVMSystemZCodeGen.dir/SystemZHazardRecognizer.cpp.o
29.192 [148/579/301] Building CXX object lib/Target/PowerPC/CMakeFiles/LLVMPowerPCCodeGen.dir/PPCBranchSelector.cpp.o
29.205 [148/578/302] Building CXX object lib/Target/Sparc/CMakeFiles/LLVMSparcCodeGen.dir/SparcInstrInfo.cpp.o
29.208 [148/577/303] Building CXX object lib/Target/SystemZ/CMakeFiles/LLVMSystemZCodeGen.dir/SystemZElimCompare.cpp.o
29.212 [148/576/304] Building CXX object lib/Target/Mips/CMakeFiles/LLVMMipsCodeGen.dir/Mips16FrameLowering.cpp.o
29.240 [148/575/305] Building CXX object lib/CodeGen/CMakeFiles/LLVMCodeGen.dir/IfConversion.cpp.o
29.255 [148/574/306] Building CXX object lib/Target/AArch64/CMakeFiles/LLVMAArch64CodeGen.dir/AArch64MacroFusion.cpp.o
29.258 [148/573/307] Building CXX object lib/CodeGen/CMakeFiles/LLVMCodeGen.dir/CFIInstrInserter.cpp.o
29.261 [148/572/308] Building CXX object lib/Target/WebAssembly/CMakeFiles/LLVMWebAssemblyCodeGen.dir/WebAssemblyUtilities.cpp.o
29.295 [148/571/309] Linking CXX executable tools/clang/unittests/Sema/SemaTests
29.352 [148/570/310] Building CXX object lib/Target/XCore/CMakeFiles/LLVMXCoreCodeGen.dir/XCoreFrameLowering.cpp.o

```

</details>

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

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