From 7ff99155c39edd73ebf1c6adfa023b1048fee9a4 Mon Sep 17 00:00:00 2001
From: rdivacky <rdivacky@FreeBSD.org>
Date: Wed, 4 Nov 2009 14:58:56 +0000
Subject: Update LLVM to r86025.
---
lib/CodeGen/ProcessImplicitDefs.cpp | 231 ++++++++++++++++++++++++++++++++++++
1 file changed, 231 insertions(+)
create mode 100644 lib/CodeGen/ProcessImplicitDefs.cpp
(limited to 'lib/CodeGen/ProcessImplicitDefs.cpp')
diff --git a/lib/CodeGen/ProcessImplicitDefs.cpp b/lib/CodeGen/ProcessImplicitDefs.cpp
new file mode 100644
index 0000000..48567a0
--- /dev/null
+++ b/lib/CodeGen/ProcessImplicitDefs.cpp
@@ -0,0 +1,231 @@
+//===---------------------- 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;
+static RegisterPass<ProcessImplicitDefs> X("processimpdefs",
+ "Process Implicit Definitions.");
+
+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,
+ const TargetInstrInfo *tii_) {
+ unsigned SrcReg, DstReg, SrcSubReg, DstSubReg;
+ if (tii_->isMoveInstr(*MI, SrcReg, DstReg, SrcSubReg, DstSubReg) &&
+ Reg == SrcReg)
+ return true;
+
+ if (OpIdx == 2 && MI->getOpcode() == TargetInstrInfo::SUBREG_TO_REG)
+ return true;
+ if (OpIdx == 1 && MI->getOpcode() == TargetInstrInfo::EXTRACT_SUBREG)
+ return true;
+ 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(errs() << "********** PROCESS IMPLICIT DEFS **********\n"
+ << "********** Function: "
+ << ((Value*)fn.getFunction())->getName() << '\n');
+
+ bool Changed = false;
+
+ const TargetInstrInfo *tii_ = fn.getTarget().getInstrInfo();
+ const TargetRegisterInfo *tri_ = fn.getTarget().getRegisterInfo();
+ MachineRegisterInfo *mri_ = &fn.getRegInfo();
+
+ LiveVariables *lv_ = &getAnalysis<LiveVariables>();
+
+ SmallSet<unsigned, 8> ImpDefRegs;
+ SmallVector<MachineInstr*, 8> ImpDefMIs;
+ MachineBasicBlock *Entry = fn.begin();
+ SmallPtrSet<MachineBasicBlock*,16> Visited;
+
+ 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->getOpcode() == TargetInstrInfo::IMPLICIT_DEF) {
+ 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;
+ }
+
+ if (MI->getOpcode() == TargetInstrInfo::INSERT_SUBREG) {
+ MachineOperand &MO = MI->getOperand(2);
+ if (ImpDefRegs.count(MO.getReg())) {
+ // %reg1032<def> = INSERT_SUBREG %reg1032, undef, 2
+ // This is an identity copy, eliminate it now.
+ if (MO.isKill()) {
+ LiveVariables::VarInfo& vi = lv_->getVarInfo(MO.getReg());
+ vi.removeKill(MI);
+ }
+ MI->eraseFromParent();
+ Changed = true;
+ continue;
+ }
+ }
+
+ bool ChangedToImpDef = false;
+ for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) {
+ MachineOperand& MO = MI->getOperand(i);
+ if (!MO.isReg() || !MO.isUse() || 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, tii_)) {
+ bool isKill = MO.isKill();
+ MI->setDesc(tii_->get(TargetInstrInfo::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();
+ 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;
+ for (MachineRegisterInfo::def_iterator DI = mri_->def_begin(Reg),
+ DE = mri_->def_end(); DI != DE; ++DI) {
+ if (DI->getOpcode() != TargetInstrInfo::IMPLICIT_DEF) {
+ Skip = true;
+ break;
+ }
+ }
+ if (Skip)
+ continue;
+
+ // The only implicit_def which we want to keep are those that are live
+ // out of its block.
+ MI->eraseFromParent();
+ Changed = true;
+
+ for (MachineRegisterInfo::use_iterator UI = mri_->use_begin(Reg),
+ UE = mri_->use_end(); UI != UE; ) {
+ MachineOperand &RMO = UI.getOperand();
+ MachineInstr *RMI = &*UI;
+ ++UI;
+ MachineBasicBlock *RMBB = RMI->getParent();
+ if (RMBB == MBB)
+ continue;
+
+ // Turn a copy use into an implicit_def.
+ unsigned SrcReg, DstReg, SrcSubReg, DstSubReg;
+ if (tii_->isMoveInstr(*RMI, SrcReg, DstReg, SrcSubReg, DstSubReg) &&
+ Reg == SrcReg) {
+ RMI->setDesc(tii_->get(TargetInstrInfo::IMPLICIT_DEF));
+ for (int j = RMI->getNumOperands() - 1, ee = 0; j > ee; --j)
+ RMI->RemoveOperand(j);
+ continue;
+ }
+
+ const TargetRegisterClass* RC = mri_->getRegClass(Reg);
+ unsigned NewVReg = mri_->createVirtualRegister(RC);
+ RMO.setReg(NewVReg);
+ RMO.setIsUndef();
+ RMO.setIsKill();
+ }
+ }
+ ImpDefRegs.clear();
+ ImpDefMIs.clear();
+ }
+
+ return Changed;
+}
+
--
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