AMDGPU: Make SIFixVGPRCopies preserve everything

[arsenm]

Summary

All this does is add uses of reserved registers, which
aren't tracked by anything. Saves a loop info computation.

[arsenm]

c70cae6315f30edc910f0fa46cfa39bc25051652

llvm/lib/Target/AMDGPU/SIFixVGPRCopies.cpp

 public:
   static char ID;
 
 public:
   SIFixVGPRCopies() : MachineFunctionPass(ID) {
     initializeSIFixVGPRCopiesPass(*PassRegistry::getPassRegistry());
   }
 
+  void getAnalysisUsage(AnalysisUsage &AU) const override {
+    AU.setPreservesAll();
+    MachineFunctionPass::getAnalysisUsage(AU);
+  }
+
   bool runOnMachineFunction(MachineFunction &MF) override;
 
   StringRef getPassName() const override { return "SI Fix VGPR copies"; }
 };
 
 } // End anonymous namespace.
 
 INITIALIZE_PASS(SIFixVGPRCopies, DEBUG_TYPE, "SI Fix VGPR copies", false, false)

llvm/test/CodeGen/AMDGPU/llc-pipeline.ll

 ; GCN-O1-NEXT:        Stack Slot Coloring
 ; GCN-O1-NEXT:        Machine Copy Propagation Pass
 ; GCN-O1-NEXT:        Machine Loop Invariant Code Motion
 ; GCN-O1-NEXT:        SI Fix VGPR copies
 ; GCN-O1-NEXT:        SI optimize exec mask operations
 ; GCN-O1-NEXT:        Remove Redundant DEBUG_VALUE analysis
 ; GCN-O1-NEXT:        Fixup Statepoint Caller Saved
 ; GCN-O1-NEXT:        PostRA Machine Sink
-; GCN-O1-NEXT:        MachineDominator Tree Construction
-; GCN-O1-NEXT:        Machine Natural Loop Construction
 ; GCN-O1-NEXT:        Machine Block Frequency Analysis
+; GCN-O1-NEXT:        MachineDominator Tree Construction
 ; GCN-O1-NEXT:        MachinePostDominator Tree Construction
 ; GCN-O1-NEXT:        Lazy Machine Block Frequency Analysis
 ; GCN-O1-NEXT:        Machine Optimization Remark Emitter
 ; GCN-O1-NEXT:        Shrink Wrapping analysis
 ; GCN-O1-NEXT:        Prologue/Epilogue Insertion & Frame Finalization
 ; GCN-O1-NEXT:        Machine Late Instructions Cleanup Pass
 ; GCN-O1-NEXT:        Control Flow Optimizer
 ; GCN-O1-NEXT:        Lazy Machine Block Frequency Analysis

 ; GCN-O1-OPTS-NEXT:        Stack Slot Coloring
 ; GCN-O1-OPTS-NEXT:        Machine Copy Propagation Pass
 ; GCN-O1-OPTS-NEXT:        Machine Loop Invariant Code Motion
 ; GCN-O1-OPTS-NEXT:        SI Fix VGPR copies
 ; GCN-O1-OPTS-NEXT:        SI optimize exec mask operations
 ; GCN-O1-OPTS-NEXT:        Remove Redundant DEBUG_VALUE analysis
 ; GCN-O1-OPTS-NEXT:        Fixup Statepoint Caller Saved
 ; GCN-O1-OPTS-NEXT:        PostRA Machine Sink
-; GCN-O1-OPTS-NEXT:        MachineDominator Tree Construction
-; GCN-O1-OPTS-NEXT:        Machine Natural Loop Construction
 ; GCN-O1-OPTS-NEXT:        Machine Block Frequency Analysis
+; GCN-O1-OPTS-NEXT:        MachineDominator Tree Construction
 ; GCN-O1-OPTS-NEXT:        MachinePostDominator Tree Construction
 ; GCN-O1-OPTS-NEXT:        Lazy Machine Block Frequency Analysis
 ; GCN-O1-OPTS-NEXT:        Machine Optimization Remark Emitter
 ; GCN-O1-OPTS-NEXT:        Shrink Wrapping analysis
 ; GCN-O1-OPTS-NEXT:        Prologue/Epilogue Insertion & Frame Finalization
 ; GCN-O1-OPTS-NEXT:        Machine Late Instructions Cleanup Pass
 ; GCN-O1-OPTS-NEXT:        Control Flow Optimizer
 ; GCN-O1-OPTS-NEXT:        Lazy Machine Block Frequency Analysis

 ; GCN-O2-NEXT:        Stack Slot Coloring
 ; GCN-O2-NEXT:        Machine Copy Propagation Pass
 ; GCN-O2-NEXT:        Machine Loop Invariant Code Motion
 ; GCN-O2-NEXT:        SI Fix VGPR copies
 ; GCN-O2-NEXT:        SI optimize exec mask operations
 ; GCN-O2-NEXT:        Remove Redundant DEBUG_VALUE analysis
 ; GCN-O2-NEXT:        Fixup Statepoint Caller Saved
 ; GCN-O2-NEXT:        PostRA Machine Sink
-; GCN-O2-NEXT:        MachineDominator Tree Construction
-; GCN-O2-NEXT:        Machine Natural Loop Construction
 ; GCN-O2-NEXT:        Machine Block Frequency Analysis
+; GCN-O2-NEXT:        MachineDominator Tree Construction
 ; GCN-O2-NEXT:        MachinePostDominator Tree Construction
 ; GCN-O2-NEXT:        Lazy Machine Block Frequency Analysis
 ; GCN-O2-NEXT:        Machine Optimization Remark Emitter
 ; GCN-O2-NEXT:        Shrink Wrapping analysis
 ; GCN-O2-NEXT:        Prologue/Epilogue Insertion & Frame Finalization
 ; GCN-O2-NEXT:        Machine Late Instructions Cleanup Pass
 ; GCN-O2-NEXT:        Control Flow Optimizer
 ; GCN-O2-NEXT:        Lazy Machine Block Frequency Analysis

 ; GCN-O3-NEXT:        Stack Slot Coloring
 ; GCN-O3-NEXT:        Machine Copy Propagation Pass
 ; GCN-O3-NEXT:        Machine Loop Invariant Code Motion
 ; GCN-O3-NEXT:        SI Fix VGPR copies
 ; GCN-O3-NEXT:        SI optimize exec mask operations
 ; GCN-O3-NEXT:        Remove Redundant DEBUG_VALUE analysis
 ; GCN-O3-NEXT:        Fixup Statepoint Caller Saved
 ; GCN-O3-NEXT:        PostRA Machine Sink
-; GCN-O3-NEXT:        MachineDominator Tree Construction
-; GCN-O3-NEXT:        Machine Natural Loop Construction
 ; GCN-O3-NEXT:        Machine Block Frequency Analysis
+; GCN-O3-NEXT:        MachineDominator Tree Construction
 ; GCN-O3-NEXT:        MachinePostDominator Tree Construction
 ; GCN-O3-NEXT:        Lazy Machine Block Frequency Analysis
 ; GCN-O3-NEXT:        Machine Optimization Remark Emitter
 ; GCN-O3-NEXT:        Shrink Wrapping analysis
 ; GCN-O3-NEXT:        Prologue/Epilogue Insertion & Frame Finalization
 ; GCN-O3-NEXT:        Machine Late Instructions Cleanup Pass
 ; GCN-O3-NEXT:        Control Flow Optimizer
 ; GCN-O3-NEXT:        Lazy Machine Block Frequency Analysis