[PATCH] D92071: [PowerPC] support register pressure reduction in machine combiner.

[Theodore Popp via Phabricator via llvm-commits]

tpopp added a comment.

I'm going to roll this back as it's causing build bot failures (in progress example here: http://45.33.8.238/win/31506/). Sanitizers show the following issues:

  ==9097==WARNING: MemorySanitizer: use-of-uninitialized-value
      #0 0x5628a1bd3d10 in llvm::PPCInstrInfo::getFMAPatterns(llvm::MachineInstr&, llvm::SmallVectorImpl<llvm::MachineCombinerPattern>&, bool) const third_party/llvm/llvm-project/llvm/lib/Target/PowerPC/PPCInstrIn
  fo.cpp:474:27                                                                                            
      #1 0x5628a1bd7e6c in llvm::PPCInstrInfo::getMachineCombinerPatterns(llvm::MachineInstr&, llvm::SmallVectorImpl<llvm::MachineCombinerPattern>&, bool) const third_party/llvm/llvm-project/llvm/lib/Target/PowerP
  C/PPCInstrInfo.cpp:751:7                            
      #2 0x5628a3291840 in combineInstructions third_party/llvm/llvm-project/llvm/lib/CodeGen/MachineCombiner.cpp:593:15
      #3 0x5628a3291840 in (anonymous namespace)::MachineCombiner::runOnMachineFunction(llvm::MachineFunction&) third_party/llvm/llvm-project/llvm/lib/CodeGen/MachineCombiner.cpp:736:16                            
      #4 0x5628a32f91a2 in llvm::MachineFunctionPass::runOnFunction(llvm::Function&) third_party/llvm/llvm-project/llvm/lib/CodeGen/MachineFunctionPass.cpp:72:13                                                    
      #5 0x5628a5e0dce7 in llvm::FPPassManager::runOnFunction(llvm::Function&) third_party/llvm/llvm-project/llvm/lib/IR/LegacyPassManager.cpp:1439:27                                                               
      #6 0x5628a5e22f60 in llvm::FPPassManager::runOnModule(llvm::Module&) third_party/llvm/llvm-project/llvm/lib/IR/LegacyPassManager.cpp:1485:16                                                                   
      #7 0x5628a5e0f1d5 in runOnModule third_party/llvm/llvm-project/llvm/lib/IR/LegacyPassManager.cpp:1554:27
      #8 0x5628a5e0f1d5 in llvm::legacy::PassManagerImpl::run(llvm::Module&) third_party/llvm/llvm-project/llvm/lib/IR/LegacyPassManager.cpp:541:44                                                                  
      #9 0x56289f8dcb66 in compileModule(char**, llvm::LLVMContext&) third_party/llvm/llvm-project/llvm/tools/llc/llc.cpp:658:8

and

  ==1709==ERROR: AddressSanitizer: stack-use-after-scope on address 0x7f155364a060 at pc 0x555a067755c4 bp 0x7fff9b909050 sp 0x7fff9b909048
  READ of size 8 at 0x7f155364a060 thread T0
      #0 0x555a067755c3 in operator[] third_party/crosstool/v18/stable/toolchain/bin/../include/c++/v1/vector:1550:18
      #1 0x555a067755c3 in llvm::PPCInstrInfo::shouldReduceRegisterPressure(llvm::MachineBasicBlock*, llvm::RegisterClassInfo*) const third_party/llvm/llvm-project/llvm/lib/Target/PowerPC/PPCInstrInfo.cpp:655:10
      #2 0x555a07df5618 in combineInstructions third_party/llvm/llvm-project/llvm/lib/CodeGen/MachineCombiner.cpp:561:12
      #3 0x555a07df5618 in (anonymous namespace)::MachineCombiner::runOnMachineFunction(llvm::MachineFunction&) third_party/llvm/llvm-project/llvm/lib/CodeGen/MachineCombiner.cpp:736:16
      #4 0x555a07e54479 in llvm::MachineFunctionPass::runOnFunction(llvm::Function&) third_party/llvm/llvm-project/llvm/lib/CodeGen/MachineFunctionPass.cpp:72:13
      #5 0x555a0b360710 in llvm::FPPassManager::runOnFunction(llvm::Function&) third_party/llvm/llvm-project/llvm/lib/IR/LegacyPassManager.cpp:1439:27
      #6 0x555a0b374470 in llvm::FPPassManager::runOnModule(llvm::Module&) third_party/llvm/llvm-project/llvm/lib/IR/LegacyPassManager.cpp:1485:16
      #7 0x555a0b3616e0 in runOnModule third_party/llvm/llvm-project/llvm/lib/IR/LegacyPassManager.cpp:1554:27
      #8 0x555a0b3616e0 in llvm::legacy::PassManagerImpl::run(llvm::Module&) third_party/llvm/llvm-project/llvm/lib/IR/LegacyPassManager.cpp:541:44
      #9 0x555a0461db8b in compileModule(char**, llvm::LLVMContext&) third_party/llvm/llvm-project/llvm/tools/llc/llc.cpp:658:8
      #10 0x555a046183bf in main third_party/llvm/llvm-project/llvm/tools/llc/llc.cpp:363:22               
                                                      
  Address 0x7f155364a060 is located in stack of thread T0 at offset 96 in frame                                                                                                                                      
      #0 0x555a067742ff in llvm::PPCInstrInfo::shouldReduceRegisterPressure(llvm::MachineBasicBlock*, llvm::RegisterClassInfo*) const third_party/llvm/llvm-project/llvm/lib/Target/PowerPC/PPCInstrInfo.cpp:598
                                                      
    This frame has 7 object(s):                                                                            
      [32, 40) '__x.i.i'                                                                                                                                                                                             
      [64, 72) 'retval.i.i'                                                                                                                                                                                          
      [96, 424) 'Pressure.i' (line 624) <== Memory access at offset 96 is inside this variable                                                                                                                       
      [496, 848) 'RPTracker.i' (line 625)                                                                                                                                                                            
      [912, 920) 'MII.i' (line 631)                                                                                                                                                                                  
      [944, 952) 'MIE.i' (line 631)                                                                                                                                                                                  
      [976, 1408) 'RegOpers.i' (line 637)                                                                                                                                                                            
  HINT: this may be a false positive if your program uses some custom stack unwind mechanism, swapcontext or vfork                                                                                                   
        (longjmp and C++ exceptions *are* supported)                                                                                           


Repository:
  rG LLVM Github Monorepo

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  https://reviews.llvm.org/D92071/new/

https://reviews.llvm.org/D92071