65 lines · cpp
1//===- ReduceRegisterUses.cpp - Specialized Delta Pass --------------------===//2//3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.4// See https://llvm.org/LICENSE.txt for license information.5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception6//7//===----------------------------------------------------------------------===//8//9// This file implements a function which calls the Generic Delta pass in order10// to reduce uninteresting register uses from the MachineFunction.11//12//===----------------------------------------------------------------------===//13 14#include "ReduceRegisterUses.h"15#include "llvm/CodeGen/MachineFunction.h"16#include "llvm/CodeGen/MachineModuleInfo.h"17#include "llvm/CodeGen/MachineRegisterInfo.h"18 19using namespace llvm;20 21static void removeUsesFromFunction(Oracle &O, MachineFunction &MF) {22 MachineRegisterInfo &MRI = MF.getRegInfo();23 24 for (MachineBasicBlock &MBB : MF) {25 for (MachineInstr &MI : MBB) {26 // Generic instructions are not supposed to have undef operands.27 if (isPreISelGenericOpcode(MI.getOpcode()))28 continue;29 30 int NumOperands = MI.getNumOperands();31 int NumRequiredOps = MI.getNumExplicitOperands() +32 MI.getDesc().implicit_defs().size() +33 MI.getDesc().implicit_uses().size();34 35 for (int I = NumOperands - 1; I >= 0; --I) {36 MachineOperand &MO = MI.getOperand(I);37 if (!MO.isReg() || !MO.readsReg())38 continue;39 40 Register Reg = MO.getReg();41 if (Reg.isPhysical() && MRI.isReserved(Reg))42 continue;43 44 if (O.shouldKeep())45 continue;46 47 // Remove implicit operands. If the register is part of the fixed48 // operand list, set to undef.49 if (I >= NumRequiredOps)50 MI.removeOperand(I);51 else52 MO.setIsUndef();53 }54 }55 }56}57 58void llvm::reduceRegisterUsesMIRDeltaPass(Oracle &O,59 ReducerWorkItem &WorkItem) {60 for (const Function &F : WorkItem.getModule()) {61 if (auto *MF = WorkItem.MMI->getMachineFunction(F))62 removeUsesFromFunction(O, *MF);63 }64}65