diff options
-rw-r--r-- | llvm/include/llvm/Target/TargetInstrInfo.h | 8 | ||||
-rw-r--r-- | llvm/lib/CodeGen/MachineCSE.cpp | 5 | ||||
-rw-r--r-- | llvm/lib/Target/R600/SIInstrInfo.h | 2 |
3 files changed, 13 insertions, 2 deletions
diff --git a/llvm/include/llvm/Target/TargetInstrInfo.h b/llvm/include/llvm/Target/TargetInstrInfo.h index f9c1e523e5a..2b0a888fa77 100644 --- a/llvm/include/llvm/Target/TargetInstrInfo.h +++ b/llvm/include/llvm/Target/TargetInstrInfo.h @@ -1235,6 +1235,14 @@ public: return false; } + /// \brief Return the value to use for the MachineCSE's LookAheadLimit, + /// which is a heuristic used for CSE'ing phys reg defs. + virtual unsigned getMachineCSELookAheadLimit () const { + // The default lookahead is small to prevent unprofitable quadratic + // behavior. + return 5; + } + private: int CallFrameSetupOpcode, CallFrameDestroyOpcode; }; diff --git a/llvm/lib/CodeGen/MachineCSE.cpp b/llvm/lib/CodeGen/MachineCSE.cpp index f72d72a2e87..87aaaa0834c 100644 --- a/llvm/lib/CodeGen/MachineCSE.cpp +++ b/llvm/lib/CodeGen/MachineCSE.cpp @@ -48,7 +48,7 @@ namespace { MachineRegisterInfo *MRI; public: static char ID; // Pass identification - MachineCSE() : MachineFunctionPass(ID), LookAheadLimit(5), CurrVN(0) { + MachineCSE() : MachineFunctionPass(ID), LookAheadLimit(0), CurrVN(0) { initializeMachineCSEPass(*PassRegistry::getPassRegistry()); } @@ -69,7 +69,7 @@ namespace { } private: - const unsigned LookAheadLimit; + unsigned LookAheadLimit; typedef RecyclingAllocator<BumpPtrAllocator, ScopedHashTableVal<MachineInstr*, unsigned> > AllocatorTy; typedef ScopedHashTable<MachineInstr*, unsigned, @@ -716,5 +716,6 @@ bool MachineCSE::runOnMachineFunction(MachineFunction &MF) { MRI = &MF.getRegInfo(); AA = &getAnalysis<AliasAnalysis>(); DT = &getAnalysis<MachineDominatorTree>(); + LookAheadLimit = TII->getMachineCSELookAheadLimit(); return PerformCSE(DT->getRootNode()); } diff --git a/llvm/lib/Target/R600/SIInstrInfo.h b/llvm/lib/Target/R600/SIInstrInfo.h index 7e049dca7b1..f952c0f0853 100644 --- a/llvm/lib/Target/R600/SIInstrInfo.h +++ b/llvm/lib/Target/R600/SIInstrInfo.h @@ -142,6 +142,8 @@ public: bool FoldImmediate(MachineInstr *UseMI, MachineInstr *DefMI, unsigned Reg, MachineRegisterInfo *MRI) const final; + unsigned getMachineCSELookAheadLimit() const override { return 500; } + bool isSALU(uint16_t Opcode) const { return get(Opcode).TSFlags & SIInstrFlags::SALU; } |