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

Sun Mar 23 04:32:17 PDT 2025

llvm-ci wrote:

LLVM Buildbot has detected a new failure on builder `ppc64le-mlir-rhel-clang` running on `ppc64le-mlir-rhel-test` while building `llvm` at step 5 "build-check-mlir-build-only".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/129/builds/17419

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

```
Step 5 (build-check-mlir-build-only) failure: build (failure)
...
34.699 [54/96/4048] Building CXX object lib/CodeGen/CMakeFiles/LLVMCodeGen.dir/MachineRegisterInfo.cpp.o
34.784 [54/95/4049] Building CXX object lib/CodeGen/CMakeFiles/LLVMCodeGen.dir/ScheduleDAG.cpp.o
35.052 [54/94/4050] Building CXX object lib/CodeGen/CMakeFiles/LLVMCodeGen.dir/StackSlotColoring.cpp.o
35.097 [54/93/4051] Building CXX object lib/CodeGen/CMakeFiles/LLVMCodeGen.dir/AggressiveAntiDepBreaker.cpp.o
35.222 [54/92/4052] Building CXX object lib/CodeGen/CMakeFiles/LLVMCodeGen.dir/EarlyIfConversion.cpp.o
35.250 [54/91/4053] Building CXX object lib/CodeGen/CMakeFiles/LLVMCodeGen.dir/MachineLateInstrsCleanup.cpp.o
35.524 [54/90/4054] Building CXX object lib/CodeGen/CMakeFiles/LLVMCodeGen.dir/TargetRegisterInfo.cpp.o
35.662 [54/89/4055] Building CXX object lib/CodeGen/CMakeFiles/LLVMCodeGen.dir/TailDuplicator.cpp.o
35.740 [54/88/4056] Building CXX object lib/CodeGen/CMakeFiles/LLVMCodeGen.dir/MachineCombiner.cpp.o
36.078 [54/87/4057] Building CXX object lib/CodeGen/CMakeFiles/LLVMCodeGen.dir/TargetInstrInfo.cpp.o
FAILED: lib/CodeGen/CMakeFiles/LLVMCodeGen.dir/TargetInstrInfo.cpp.o 
ccache /home/buildbots/llvm-external-buildbots/clang.19.1.7/bin/clang++ -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-mlir-rhel-test/ppc64le-mlir-rhel-clang-build/build/lib/CodeGen -I/home/buildbots/llvm-external-buildbots/workers/ppc64le-mlir-rhel-test/ppc64le-mlir-rhel-clang-build/llvm-project/llvm/lib/CodeGen -I/home/buildbots/llvm-external-buildbots/workers/ppc64le-mlir-rhel-test/ppc64le-mlir-rhel-clang-build/build/include -I/home/buildbots/llvm-external-buildbots/workers/ppc64le-mlir-rhel-test/ppc64le-mlir-rhel-clang-build/llvm-project/llvm/include -fPIC -fno-semantic-interposition -fvisibility-inlines-hidden -Werror=date-time -Werror=unguarded-availability-new -Wall -Wextra -Wno-unused-parameter -Wwrite-strings -Wcast-qual -Wmissing-field-initializers -pedantic -Wno-long-long -Wc++98-compat-extra-semi -Wimplicit-fallthrough -Wcovered-switch-default -Wno-noexcept-type -Wnon-virtual-dtor -Wdelete-non-virtual-dtor -Wsuggest-override -Wstring-conversion -Wmisleading-indentation -Wctad-maybe-unsupported -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-mlir-rhel-test/ppc64le-mlir-rhel-clang-build/llvm-project/llvm/lib/CodeGen/TargetInstrInfo.cpp
/home/buildbots/llvm-external-buildbots/workers/ppc64le-mlir-rhel-test/ppc64le-mlir-rhel-clang-build/llvm-project/llvm/lib/CodeGen/TargetInstrInfo.cpp:1514:29: error: non-const lvalue reference to type 'DenseMap<unsigned int, [...]>' cannot bind to a value of unrelated type 'DenseMap<Register, [...]>'
 1514 |                             InstIdxForVirtReg, Root.getOperand(0).getReg());
      |                             ^~~~~~~~~~~~~~~~~
/home/buildbots/llvm-external-buildbots/workers/ppc64le-mlir-rhel-test/ppc64le-mlir-rhel-clang-build/llvm-project/llvm/lib/CodeGen/TargetInstrInfo.cpp:1021:35: note: passing argument to parameter 'InstrIdxForVirtReg' here
 1021 |     DenseMap<unsigned, unsigned> &InstrIdxForVirtReg,
      |                                   ^
1 error generated.
36.285 [54/86/4058] Building CXX object lib/CodeGen/CMakeFiles/LLVMCodeGen.dir/MachineInstr.cpp.o
36.505 [54/85/4059] Building CXX object lib/CodeGen/CMakeFiles/LLVMCodeGen.dir/VLIWMachineScheduler.cpp.o
36.559 [54/84/4060] Building CXX object lib/CodeGen/SelectionDAG/CMakeFiles/LLVMSelectionDAG.dir/ResourcePriorityQueue.cpp.o
36.864 [54/83/4061] Building CXX object lib/CodeGen/SelectionDAG/CMakeFiles/LLVMSelectionDAG.dir/ScheduleDAGFast.cpp.o
37.232 [54/82/4062] Building CXX object lib/CodeGen/CMakeFiles/LLVMCodeGen.dir/MacroFusion.cpp.o
37.415 [54/81/4063] Building CXX object lib/Target/PowerPC/CMakeFiles/LLVMPowerPCCodeGen.dir/PPCHazardRecognizers.cpp.o
37.475 [54/80/4064] Building CXX object lib/CodeGen/CMakeFiles/LLVMCodeGen.dir/KCFI.cpp.o
37.814 [54/79/4065] Building CXX object lib/CodeGen/SelectionDAG/CMakeFiles/LLVMSelectionDAG.dir/SelectionDAGDumper.cpp.o
37.912 [54/78/4066] Building CXX object lib/CodeGen/CMakeFiles/LLVMCodeGen.dir/MIRPrinter.cpp.o
38.147 [54/77/4067] Building CXX object lib/CodeGen/CMakeFiles/LLVMCodeGen.dir/MachineCycleAnalysis.cpp.o
38.243 [54/76/4068] Building CXX object lib/Target/PowerPC/CMakeFiles/LLVMPowerPCCodeGen.dir/PPCBranchSelector.cpp.o
38.286 [54/75/4069] Building CXX object lib/CodeGen/CMakeFiles/LLVMCodeGen.dir/IfConversion.cpp.o
38.351 [54/74/4070] Building CXX object lib/CodeGen/CMakeFiles/LLVMCodeGen.dir/MachineFunctionSplitter.cpp.o
38.393 [54/73/4071] Building CXX object lib/CodeGen/CMakeFiles/LLVMCodeGen.dir/RegAllocFast.cpp.o
38.506 [54/72/4072] Building CXX object lib/Target/PowerPC/CMakeFiles/LLVMPowerPCCodeGen.dir/PPCTOCRegDeps.cpp.o
38.514 [54/71/4073] Building CXX object lib/CodeGen/CMakeFiles/LLVMCodeGen.dir/MachineOperand.cpp.o
38.699 [54/70/4074] Building CXX object lib/CodeGen/CMakeFiles/LLVMCodeGen.dir/MachineCSE.cpp.o
38.708 [54/69/4075] Building CXX object lib/CodeGen/CMakeFiles/LLVMCodeGen.dir/BranchFolding.cpp.o
38.901 [54/68/4076] Building CXX object lib/CodeGen/CMakeFiles/LLVMCodeGen.dir/ShrinkWrap.cpp.o
38.923 [54/67/4077] Building CXX object lib/CodeGen/CMakeFiles/LLVMCodeGen.dir/MachineUniformityAnalysis.cpp.o
39.040 [54/66/4078] Building CXX object lib/Target/PowerPC/CMakeFiles/LLVMPowerPCCodeGen.dir/PPCVSXCopy.cpp.o
39.356 [54/65/4079] Building CXX object lib/CodeGen/CMakeFiles/LLVMCodeGen.dir/InlineSpiller.cpp.o
39.378 [54/64/4080] Building CXX object lib/CodeGen/CMakeFiles/LLVMCodeGen.dir/MachineCopyPropagation.cpp.o
39.402 [54/63/4081] Building CXX object lib/CodeGen/CMakeFiles/LLVMCodeGen.dir/TwoAddressInstructionPass.cpp.o
39.404 [54/62/4082] Building CXX object lib/CodeGen/CMakeFiles/LLVMCodeGen.dir/PrologEpilogInserter.cpp.o
39.526 [54/61/4083] Building CXX object lib/Target/PowerPC/AsmParser/CMakeFiles/LLVMPowerPCAsmParser.dir/PPCAsmParser.cpp.o
39.631 [54/60/4084] Building CXX object lib/Target/PowerPC/CMakeFiles/LLVMPowerPCCodeGen.dir/PPCLoopInstrFormPrep.cpp.o
40.056 [54/59/4085] Building CXX object lib/Target/PowerPC/CMakeFiles/LLVMPowerPCCodeGen.dir/PPCLowerMASSVEntries.cpp.o
40.101 [54/58/4086] Building CXX object lib/Target/PowerPC/CMakeFiles/LLVMPowerPCCodeGen.dir/PPCGenScalarMASSEntries.cpp.o
40.142 [54/57/4087] Building CXX object lib/CodeGen/CMakeFiles/LLVMCodeGen.dir/RDFGraph.cpp.o

```

</details>

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