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Diffstat (limited to 'lib/CodeGen/OptimizeCmps.cpp')
-rw-r--r-- | lib/CodeGen/OptimizeCmps.cpp | 112 |
1 files changed, 0 insertions, 112 deletions
diff --git a/lib/CodeGen/OptimizeCmps.cpp b/lib/CodeGen/OptimizeCmps.cpp deleted file mode 100644 index 209c8b9504..0000000000 --- a/lib/CodeGen/OptimizeCmps.cpp +++ /dev/null @@ -1,112 +0,0 @@ -//===-- OptimizeCmps.cpp - Optimize comparison instrs ---------------------===// -// -// The LLVM Compiler Infrastructure -// -// This file is distributed under the University of Illinois Open Source -// License. See LICENSE.TXT for details. -// -//===----------------------------------------------------------------------===// -// -// This pass performs optimization of comparison instructions. For instance, in -// this code: -// -// sub r1, 1 -// cmp r1, 0 -// bz L1 -// -// If the "sub" instruction all ready sets (or could be modified to set) the -// same flag that the "cmp" instruction sets and that "bz" uses, then we can -// eliminate the "cmp" instruction. -// -//===----------------------------------------------------------------------===// - -#define DEBUG_TYPE "opt-compares" -#include "llvm/CodeGen/Passes.h" -#include "llvm/CodeGen/MachineFunctionPass.h" -#include "llvm/CodeGen/MachineInstrBuilder.h" -#include "llvm/CodeGen/MachineRegisterInfo.h" -#include "llvm/Target/TargetInstrInfo.h" -#include "llvm/Target/TargetRegisterInfo.h" -#include "llvm/Support/CommandLine.h" -#include "llvm/ADT/Statistic.h" -using namespace llvm; - -STATISTIC(NumEliminated, "Number of compares eliminated"); - -static cl::opt<bool> -EnableOptCmps("enable-optimize-cmps", cl::init(false), cl::Hidden); - -namespace { - class OptimizeCmps : public MachineFunctionPass { - const TargetMachine *TM; - const TargetInstrInfo *TII; - MachineRegisterInfo *MRI; - - bool OptimizeCmpInstr(MachineInstr *MI, MachineBasicBlock *MBB); - - public: - static char ID; // Pass identification - OptimizeCmps() : MachineFunctionPass(ID) {} - - virtual bool runOnMachineFunction(MachineFunction &MF); - - virtual void getAnalysisUsage(AnalysisUsage &AU) const { - AU.setPreservesCFG(); - MachineFunctionPass::getAnalysisUsage(AU); - } - }; -} - -char OptimizeCmps::ID = 0; -INITIALIZE_PASS(OptimizeCmps, "opt-cmps", - "Optimize comparison instrs", false, false); - -FunctionPass *llvm::createOptimizeCmpsPass() { return new OptimizeCmps(); } - -/// OptimizeCmpInstr - If the instruction is a compare and the previous -/// instruction it's comparing against all ready sets (or could be modified to -/// set) the same flag as the compare, then we can remove the comparison and use -/// the flag from the previous instruction. -bool OptimizeCmps::OptimizeCmpInstr(MachineInstr *MI, MachineBasicBlock *MBB) { - // If this instruction is a comparison against zero and isn't comparing a - // physical register, we can try to optimize it. - unsigned SrcReg; - int CmpValue; - if (!TII->AnalyzeCompare(MI, SrcReg, CmpValue) || - TargetRegisterInfo::isPhysicalRegister(SrcReg) || CmpValue != 0) - return false; - - MachineRegisterInfo::def_iterator DI = MRI->def_begin(SrcReg); - if (llvm::next(DI) != MRI->def_end()) - // Only support one definition. - return false; - - // Attempt to convert the defining instruction to set the "zero" flag. - if (TII->ConvertToSetZeroFlag(&*DI, MI)) { - ++NumEliminated; - return true; - } - - return false; -} - -bool OptimizeCmps::runOnMachineFunction(MachineFunction &MF) { - TM = &MF.getTarget(); - TII = TM->getInstrInfo(); - MRI = &MF.getRegInfo(); - - if (!EnableOptCmps) return false; - - bool Changed = false; - for (MachineFunction::iterator I = MF.begin(), E = MF.end(); I != E; ++I) { - MachineBasicBlock *MBB = &*I; - for (MachineBasicBlock::iterator - MII = MBB->begin(), ME = MBB->end(); MII != ME; ) { - MachineInstr *MI = &*MII++; - if (MI->getDesc().isCompare()) - Changed |= OptimizeCmpInstr(MI, MBB); - } - } - - return Changed; -} |