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

Sun Mar 23 04:35:39 PDT 2025

llvm-ci wrote:

LLVM Buildbot has detected a new failure on builder `llvm-x86_64-debian-dylib` running on `gribozavr4` while building `llvm` at step 5 "build-unified-tree".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/60/builds/22845

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

```
Step 5 (build-unified-tree) failure: build (failure)
...
20.171 [4069/96/3072] Building RISCVGenDAGISel.inc...
20.211 [4068/96/3073] Building CXX object lib/CodeGen/CMakeFiles/LLVMCodeGen.dir/ModuloSchedule.cpp.o
20.282 [4067/96/3074] Building CXX object lib/CodeGen/CMakeFiles/LLVMCodeGen.dir/MachineBlockPlacement.cpp.o
20.400 [4066/96/3075] Building CXX object lib/CodeGen/CMakeFiles/LLVMCodeGen.dir/TargetRegisterInfo.cpp.o
20.514 [4065/96/3076] Building AMDGPUGenSearchableTables.inc...
20.529 [4064/96/3077] Building CXX object lib/CodeGen/CMakeFiles/LLVMCodeGen.dir/MachineOutliner.cpp.o
20.558 [4063/96/3078] Building CXX object lib/Target/AArch64/CMakeFiles/LLVMAArch64CodeGen.dir/SMEABIPass.cpp.o
20.562 [4062/96/3079] Building CXX object lib/Object/CMakeFiles/LLVMObject.dir/IRSymtab.cpp.o
20.604 [4061/96/3080] Building CXX object lib/Target/AArch64/CMakeFiles/LLVMAArch64CodeGen.dir/SVEIntrinsicOpts.cpp.o
20.851 [4060/96/3081] Building CXX object lib/CodeGen/CMakeFiles/LLVMCodeGen.dir/TargetInstrInfo.cpp.o
FAILED: lib/CodeGen/CMakeFiles/LLVMCodeGen.dir/TargetInstrInfo.cpp.o 
CCACHE_CPP2=yes CCACHE_HASHDIR=yes /usr/bin/ccache /usr/bin/clang++ -DGTEST_HAS_RTTI=0 -DLLVM_EXPORTS -D_DEBUG -D_GLIBCXX_ASSERTIONS -D_GNU_SOURCE -D__STDC_CONSTANT_MACROS -D__STDC_FORMAT_MACROS -D__STDC_LIMIT_MACROS -I/b/1/llvm-x86_64-debian-dylib/build/lib/CodeGen -I/b/1/llvm-x86_64-debian-dylib/llvm-project/llvm/lib/CodeGen -I/b/1/llvm-x86_64-debian-dylib/build/include -I/b/1/llvm-x86_64-debian-dylib/llvm-project/llvm/include -fPIC -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  -fno-exceptions -funwind-tables -fno-rtti -UNDEBUG -std=c++17 -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 /b/1/llvm-x86_64-debian-dylib/llvm-project/llvm/lib/CodeGen/TargetInstrInfo.cpp
/b/1/llvm-x86_64-debian-dylib/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<llvm::Register, [...]>'
                            InstIdxForVirtReg, Root.getOperand(0).getReg());
                            ^~~~~~~~~~~~~~~~~
/b/1/llvm-x86_64-debian-dylib/llvm-project/llvm/lib/CodeGen/TargetInstrInfo.cpp:1021:35: note: passing argument to parameter 'InstrIdxForVirtReg' here
    DenseMap<unsigned, unsigned> &InstrIdxForVirtReg,
                                  ^
1 error generated.
21.096 [4060/95/3082] Building CXX object lib/CodeGen/CMakeFiles/LLVMCodeGen.dir/VLIWMachineScheduler.cpp.o
21.329 [4060/94/3083] Building CXX object lib/CodeGen/CMakeFiles/LLVMCodeGen.dir/ShrinkWrap.cpp.o
21.358 [4060/93/3084] Building CXX object lib/CodeGen/SelectionDAG/CMakeFiles/LLVMSelectionDAG.dir/ResourcePriorityQueue.cpp.o
21.423 [4060/92/3085] Building CXX object lib/CodeGen/CMakeFiles/LLVMCodeGen.dir/MachineBasicBlock.cpp.o
22.130 [4060/91/3086] Building CXX object lib/CodeGen/CMakeFiles/LLVMCodeGen.dir/LiveDebugVariables.cpp.o
22.223 [4060/90/3087] Building CXX object lib/CodeGen/CMakeFiles/LLVMCodeGen.dir/ScheduleDAGInstrs.cpp.o
22.551 [4060/89/3088] Building CXX object lib/CodeGen/SelectionDAG/CMakeFiles/LLVMSelectionDAG.dir/ScheduleDAGFast.cpp.o
22.552 [4060/88/3089] Building CXX object lib/CodeGen/CMakeFiles/LLVMCodeGen.dir/RegisterCoalescer.cpp.o
22.817 [4060/87/3090] Building CXX object lib/CodeGen/CMakeFiles/LLVMCodeGen.dir/SplitKit.cpp.o
23.067 [4060/86/3091] Building CXX object lib/CodeGen/SelectionDAG/CMakeFiles/LLVMSelectionDAG.dir/InstrEmitter.cpp.o
23.074 [4060/85/3092] Building CXX object lib/CodeGen/SelectionDAG/CMakeFiles/LLVMSelectionDAG.dir/ScheduleDAGRRList.cpp.o
23.134 [4060/84/3093] Building CXX object lib/CodeGen/GlobalISel/CMakeFiles/LLVMGlobalISel.dir/MachineIRBuilder.cpp.o
23.322 [4060/83/3094] Building CXX object lib/Target/AArch64/CMakeFiles/LLVMAArch64CodeGen.dir/AArch64AdvSIMDScalarPass.cpp.o
23.448 [4060/82/3095] Building CXX object lib/CodeGen/CMakeFiles/LLVMCodeGen.dir/MachineSink.cpp.o
23.480 [4060/81/3096] Building CXX object lib/CodeGen/SelectionDAG/CMakeFiles/LLVMSelectionDAG.dir/FunctionLoweringInfo.cpp.o
23.630 [4060/80/3097] Building CXX object lib/CodeGen/CMakeFiles/LLVMCodeGen.dir/MIRPrinter.cpp.o
24.015 [4060/79/3098] Building CXX object lib/CodeGen/CMakeFiles/LLVMCodeGen.dir/TwoAddressInstructionPass.cpp.o
24.017 [4060/78/3099] Building CXX object lib/CodeGen/SelectionDAG/CMakeFiles/LLVMSelectionDAG.dir/FastISel.cpp.o
24.155 [4060/77/3100] Building CXX object lib/Target/AArch64/CMakeFiles/LLVMAArch64CodeGen.dir/AArch64ConditionOptimizer.cpp.o
24.190 [4060/76/3101] Building CXX object lib/CodeGen/SelectionDAG/CMakeFiles/LLVMSelectionDAG.dir/SelectionDAGDumper.cpp.o
24.395 [4060/75/3102] Building CXX object lib/CodeGen/SelectionDAG/CMakeFiles/LLVMSelectionDAG.dir/ScheduleDAGSDNodes.cpp.o
24.418 [4060/74/3103] Building CXX object lib/CodeGen/GlobalISel/CMakeFiles/LLVMGlobalISel.dir/Utils.cpp.o
24.666 [4060/73/3104] Building CXX object lib/CodeGen/CMakeFiles/LLVMCodeGen.dir/WindowScheduler.cpp.o
24.687 [4060/72/3105] Building CXX object lib/Target/AArch64/CMakeFiles/LLVMAArch64CodeGen.dir/AArch64ConditionalCompares.cpp.o
24.843 [4060/71/3106] Building CXX object lib/Target/AArch64/CMakeFiles/LLVMAArch64CodeGen.dir/GISel/AArch64PostSelectOptimize.cpp.o
25.108 [4060/70/3107] Building CXX object lib/Target/AArch64/CMakeFiles/LLVMAArch64CodeGen.dir/AArch64MIPeepholeOpt.cpp.o
25.351 [4060/69/3108] Building CXX object lib/CodeGen/CMakeFiles/LLVMCodeGen.dir/MachineScheduler.cpp.o
25.518 [4060/68/3109] Building CXX object lib/MC/MCParser/CMakeFiles/LLVMMCParser.dir/AsmParser.cpp.o
25.600 [4060/67/3110] Building CXX object lib/Target/AArch64/CMakeFiles/LLVMAArch64CodeGen.dir/AArch64CallingConvention.cpp.o
25.701 [4060/66/3111] Building CXX object lib/Target/ARM/CMakeFiles/LLVMARMCodeGen.dir/A15SDOptimizer.cpp.o

```

</details>

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