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-rw-r--r--contrib/llvm/lib/CodeGen/ProcessImplicitDefs.cpp301
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diff --git a/contrib/llvm/lib/CodeGen/ProcessImplicitDefs.cpp b/contrib/llvm/lib/CodeGen/ProcessImplicitDefs.cpp
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+//===---------------------- ProcessImplicitDefs.cpp -----------------------===//
+//
+// The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#define DEBUG_TYPE "processimplicitdefs"
+
+#include "llvm/CodeGen/ProcessImplicitDefs.h"
+
+#include "llvm/ADT/DepthFirstIterator.h"
+#include "llvm/ADT/SmallSet.h"
+#include "llvm/Analysis/AliasAnalysis.h"
+#include "llvm/CodeGen/LiveVariables.h"
+#include "llvm/CodeGen/MachineInstr.h"
+#include "llvm/CodeGen/MachineRegisterInfo.h"
+#include "llvm/CodeGen/Passes.h"
+#include "llvm/Support/Debug.h"
+#include "llvm/Target/TargetInstrInfo.h"
+#include "llvm/Target/TargetRegisterInfo.h"
+
+
+using namespace llvm;
+
+char ProcessImplicitDefs::ID = 0;
+INITIALIZE_PASS_BEGIN(ProcessImplicitDefs, "processimpdefs",
+ "Process Implicit Definitions", false, false)
+INITIALIZE_PASS_DEPENDENCY(LiveVariables)
+INITIALIZE_PASS_END(ProcessImplicitDefs, "processimpdefs",
+ "Process Implicit Definitions", false, false)
+
+void ProcessImplicitDefs::getAnalysisUsage(AnalysisUsage &AU) const {
+ AU.setPreservesCFG();
+ AU.addPreserved<AliasAnalysis>();
+ AU.addPreserved<LiveVariables>();
+ AU.addRequired<LiveVariables>();
+ AU.addPreservedID(MachineLoopInfoID);
+ AU.addPreservedID(MachineDominatorsID);
+ AU.addPreservedID(TwoAddressInstructionPassID);
+ AU.addPreservedID(PHIEliminationID);
+ MachineFunctionPass::getAnalysisUsage(AU);
+}
+
+bool
+ProcessImplicitDefs::CanTurnIntoImplicitDef(MachineInstr *MI,
+ unsigned Reg, unsigned OpIdx,
+ SmallSet<unsigned, 8> &ImpDefRegs) {
+ switch(OpIdx) {
+ case 1:
+ return MI->isCopy() && (MI->getOperand(0).getSubReg() == 0 ||
+ ImpDefRegs.count(MI->getOperand(0).getReg()));
+ case 2:
+ return MI->isSubregToReg() && (MI->getOperand(0).getSubReg() == 0 ||
+ ImpDefRegs.count(MI->getOperand(0).getReg()));
+ default: return false;
+ }
+}
+
+static bool isUndefCopy(MachineInstr *MI, unsigned Reg,
+ SmallSet<unsigned, 8> &ImpDefRegs) {
+ if (MI->isCopy()) {
+ MachineOperand &MO0 = MI->getOperand(0);
+ MachineOperand &MO1 = MI->getOperand(1);
+ if (MO1.getReg() != Reg)
+ return false;
+ if (!MO0.getSubReg() || ImpDefRegs.count(MO0.getReg()))
+ return true;
+ return false;
+ }
+ return false;
+}
+
+/// processImplicitDefs - Process IMPLICIT_DEF instructions and make sure
+/// there is one implicit_def for each use. Add isUndef marker to
+/// implicit_def defs and their uses.
+bool ProcessImplicitDefs::runOnMachineFunction(MachineFunction &fn) {
+
+ DEBUG(dbgs() << "********** PROCESS IMPLICIT DEFS **********\n"
+ << "********** Function: "
+ << ((Value*)fn.getFunction())->getName() << '\n');
+
+ bool Changed = false;
+
+ TII = fn.getTarget().getInstrInfo();
+ TRI = fn.getTarget().getRegisterInfo();
+ MRI = &fn.getRegInfo();
+ LV = &getAnalysis<LiveVariables>();
+
+ SmallSet<unsigned, 8> ImpDefRegs;
+ SmallVector<MachineInstr*, 8> ImpDefMIs;
+ SmallVector<MachineInstr*, 4> RUses;
+ SmallPtrSet<MachineBasicBlock*,16> Visited;
+ SmallPtrSet<MachineInstr*, 8> ModInsts;
+
+ MachineBasicBlock *Entry = fn.begin();
+ for (df_ext_iterator<MachineBasicBlock*, SmallPtrSet<MachineBasicBlock*,16> >
+ DFI = df_ext_begin(Entry, Visited), E = df_ext_end(Entry, Visited);
+ DFI != E; ++DFI) {
+ MachineBasicBlock *MBB = *DFI;
+ for (MachineBasicBlock::iterator I = MBB->begin(), E = MBB->end();
+ I != E; ) {
+ MachineInstr *MI = &*I;
+ ++I;
+ if (MI->isImplicitDef()) {
+ if (MI->getOperand(0).getSubReg())
+ continue;
+ unsigned Reg = MI->getOperand(0).getReg();
+ ImpDefRegs.insert(Reg);
+ if (TargetRegisterInfo::isPhysicalRegister(Reg)) {
+ for (const unsigned *SS = TRI->getSubRegisters(Reg); *SS; ++SS)
+ ImpDefRegs.insert(*SS);
+ }
+ ImpDefMIs.push_back(MI);
+ continue;
+ }
+
+ // Eliminate %reg1032:sub<def> = COPY undef.
+ if (MI->isCopy() && MI->getOperand(0).getSubReg()) {
+ MachineOperand &MO = MI->getOperand(1);
+ if (MO.isUndef() || ImpDefRegs.count(MO.getReg())) {
+ if (MO.isKill()) {
+ LiveVariables::VarInfo& vi = LV->getVarInfo(MO.getReg());
+ vi.removeKill(MI);
+ }
+ unsigned Reg = MI->getOperand(0).getReg();
+ MI->eraseFromParent();
+ Changed = true;
+
+ // A REG_SEQUENCE may have been expanded into partial definitions.
+ // If this was the last one, mark Reg as implicitly defined.
+ if (TargetRegisterInfo::isVirtualRegister(Reg) && MRI->def_empty(Reg))
+ ImpDefRegs.insert(Reg);
+ continue;
+ }
+ }
+
+ bool ChangedToImpDef = false;
+ for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) {
+ MachineOperand& MO = MI->getOperand(i);
+ if (!MO.isReg() || (MO.isDef() && !MO.getSubReg()) || MO.isUndef())
+ continue;
+ unsigned Reg = MO.getReg();
+ if (!Reg)
+ continue;
+ if (!ImpDefRegs.count(Reg))
+ continue;
+ // Use is a copy, just turn it into an implicit_def.
+ if (CanTurnIntoImplicitDef(MI, Reg, i, ImpDefRegs)) {
+ bool isKill = MO.isKill();
+ MI->setDesc(TII->get(TargetOpcode::IMPLICIT_DEF));
+ for (int j = MI->getNumOperands() - 1, ee = 0; j > ee; --j)
+ MI->RemoveOperand(j);
+ if (isKill) {
+ ImpDefRegs.erase(Reg);
+ LiveVariables::VarInfo& vi = LV->getVarInfo(Reg);
+ vi.removeKill(MI);
+ }
+ ChangedToImpDef = true;
+ Changed = true;
+ break;
+ }
+
+ Changed = true;
+ MO.setIsUndef();
+ // This is a partial register redef of an implicit def.
+ // Make sure the whole register is defined by the instruction.
+ if (MO.isDef()) {
+ MI->addRegisterDefined(Reg);
+ continue;
+ }
+ if (MO.isKill() || MI->isRegTiedToDefOperand(i)) {
+ // Make sure other uses of
+ for (unsigned j = i+1; j != e; ++j) {
+ MachineOperand &MOJ = MI->getOperand(j);
+ if (MOJ.isReg() && MOJ.isUse() && MOJ.getReg() == Reg)
+ MOJ.setIsUndef();
+ }
+ ImpDefRegs.erase(Reg);
+ }
+ }
+
+ if (ChangedToImpDef) {
+ // Backtrack to process this new implicit_def.
+ --I;
+ } else {
+ for (unsigned i = 0; i != MI->getNumOperands(); ++i) {
+ MachineOperand& MO = MI->getOperand(i);
+ if (!MO.isReg() || !MO.isDef())
+ continue;
+ ImpDefRegs.erase(MO.getReg());
+ }
+ }
+ }
+
+ // Any outstanding liveout implicit_def's?
+ for (unsigned i = 0, e = ImpDefMIs.size(); i != e; ++i) {
+ MachineInstr *MI = ImpDefMIs[i];
+ unsigned Reg = MI->getOperand(0).getReg();
+ if (TargetRegisterInfo::isPhysicalRegister(Reg) ||
+ !ImpDefRegs.count(Reg)) {
+ // Delete all "local" implicit_def's. That include those which define
+ // physical registers since they cannot be liveout.
+ MI->eraseFromParent();
+ Changed = true;
+ continue;
+ }
+
+ // If there are multiple defs of the same register and at least one
+ // is not an implicit_def, do not insert implicit_def's before the
+ // uses.
+ bool Skip = false;
+ SmallVector<MachineInstr*, 4> DeadImpDefs;
+ for (MachineRegisterInfo::def_iterator DI = MRI->def_begin(Reg),
+ DE = MRI->def_end(); DI != DE; ++DI) {
+ MachineInstr *DeadImpDef = &*DI;
+ if (!DeadImpDef->isImplicitDef()) {
+ Skip = true;
+ break;
+ }
+ DeadImpDefs.push_back(DeadImpDef);
+ }
+ if (Skip)
+ continue;
+
+ // The only implicit_def which we want to keep are those that are live
+ // out of its block.
+ for (unsigned j = 0, ee = DeadImpDefs.size(); j != ee; ++j)
+ DeadImpDefs[j]->eraseFromParent();
+ Changed = true;
+
+ // Process each use instruction once.
+ for (MachineRegisterInfo::use_iterator UI = MRI->use_begin(Reg),
+ UE = MRI->use_end(); UI != UE; ++UI) {
+ if (UI.getOperand().isUndef())
+ continue;
+ MachineInstr *RMI = &*UI;
+ if (ModInsts.insert(RMI))
+ RUses.push_back(RMI);
+ }
+
+ for (unsigned i = 0, e = RUses.size(); i != e; ++i) {
+ MachineInstr *RMI = RUses[i];
+
+ // Turn a copy use into an implicit_def.
+ if (isUndefCopy(RMI, Reg, ImpDefRegs)) {
+ RMI->setDesc(TII->get(TargetOpcode::IMPLICIT_DEF));
+
+ bool isKill = false;
+ SmallVector<unsigned, 4> Ops;
+ for (unsigned j = 0, ee = RMI->getNumOperands(); j != ee; ++j) {
+ MachineOperand &RRMO = RMI->getOperand(j);
+ if (RRMO.isReg() && RRMO.getReg() == Reg) {
+ Ops.push_back(j);
+ if (RRMO.isKill())
+ isKill = true;
+ }
+ }
+ // Leave the other operands along.
+ for (unsigned j = 0, ee = Ops.size(); j != ee; ++j) {
+ unsigned OpIdx = Ops[j];
+ RMI->RemoveOperand(OpIdx-j);
+ }
+
+ // Update LiveVariables varinfo if the instruction is a kill.
+ if (isKill) {
+ LiveVariables::VarInfo& vi = LV->getVarInfo(Reg);
+ vi.removeKill(RMI);
+ }
+ continue;
+ }
+
+ // Replace Reg with a new vreg that's marked implicit.
+ const TargetRegisterClass* RC = MRI->getRegClass(Reg);
+ unsigned NewVReg = MRI->createVirtualRegister(RC);
+ bool isKill = true;
+ for (unsigned j = 0, ee = RMI->getNumOperands(); j != ee; ++j) {
+ MachineOperand &RRMO = RMI->getOperand(j);
+ if (RRMO.isReg() && RRMO.getReg() == Reg) {
+ RRMO.setReg(NewVReg);
+ RRMO.setIsUndef();
+ if (isKill) {
+ // Only the first operand of NewVReg is marked kill.
+ RRMO.setIsKill();
+ isKill = false;
+ }
+ }
+ }
+ }
+ RUses.clear();
+ ModInsts.clear();
+ }
+ ImpDefRegs.clear();
+ ImpDefMIs.clear();
+ }
+
+ return Changed;
+}
+
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