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120 lines
3.3 KiB
C++
120 lines
3.3 KiB
C++
//===-- Thumb2ITBlockPass.cpp - Insert Thumb IT blocks ----------*- C++ -*-===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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#define DEBUG_TYPE "thumb2-it"
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#include "ARM.h"
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#include "ARMMachineFunctionInfo.h"
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#include "Thumb2InstrInfo.h"
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#include "llvm/CodeGen/MachineInstr.h"
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#include "llvm/CodeGen/MachineInstrBuilder.h"
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#include "llvm/CodeGen/MachineFunctionPass.h"
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#include "llvm/ADT/Statistic.h"
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using namespace llvm;
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STATISTIC(NumITs, "Number of IT blocks inserted");
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namespace {
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struct Thumb2ITBlockPass : public MachineFunctionPass {
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static char ID;
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Thumb2ITBlockPass() : MachineFunctionPass(&ID) {}
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const Thumb2InstrInfo *TII;
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ARMFunctionInfo *AFI;
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virtual bool runOnMachineFunction(MachineFunction &Fn);
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virtual const char *getPassName() const {
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return "Thumb IT blocks insertion pass";
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}
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private:
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bool InsertITBlocks(MachineBasicBlock &MBB);
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};
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char Thumb2ITBlockPass::ID = 0;
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}
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static ARMCC::CondCodes getPredicate(const MachineInstr *MI, unsigned &PredReg){
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unsigned Opc = MI->getOpcode();
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if (Opc == ARM::tBcc || Opc == ARM::t2Bcc)
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return ARMCC::AL;
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return llvm::getInstrPredicate(MI, PredReg);
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}
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bool Thumb2ITBlockPass::InsertITBlocks(MachineBasicBlock &MBB) {
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bool Modified = false;
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MachineBasicBlock::iterator MBBI = MBB.begin(), E = MBB.end();
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while (MBBI != E) {
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MachineInstr *MI = &*MBBI;
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DebugLoc dl = MI->getDebugLoc();
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unsigned PredReg = 0;
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ARMCC::CondCodes CC = getPredicate(MI, PredReg);
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if (CC == ARMCC::AL) {
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++MBBI;
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continue;
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}
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// Insert an IT instruction.
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MachineInstrBuilder MIB = BuildMI(MBB, MBBI, dl, TII->get(ARM::t2IT))
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.addImm(CC);
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++MBBI;
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// Finalize IT mask.
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ARMCC::CondCodes OCC = ARMCC::getOppositeCondition(CC);
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unsigned Mask = 0, Pos = 3;
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// Branches, including tricky ones like LDM_RET, need to end an IT
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// block so check the instruction we just put in the block.
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while (MBBI != E && Pos &&
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(!MI->getDesc().isBranch() && !MI->getDesc().isReturn())) {
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MachineInstr *NMI = &*MBBI;
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MI = NMI;
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DebugLoc ndl = NMI->getDebugLoc();
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unsigned NPredReg = 0;
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ARMCC::CondCodes NCC = getPredicate(NMI, NPredReg);
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if (NCC == OCC) {
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Mask |= (1 << Pos);
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} else if (NCC != CC)
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break;
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--Pos;
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++MBBI;
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}
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Mask |= (1 << Pos);
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MIB.addImm(Mask);
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Modified = true;
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++NumITs;
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}
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return Modified;
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}
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bool Thumb2ITBlockPass::runOnMachineFunction(MachineFunction &Fn) {
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const TargetMachine &TM = Fn.getTarget();
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AFI = Fn.getInfo<ARMFunctionInfo>();
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TII = static_cast<const Thumb2InstrInfo*>(TM.getInstrInfo());
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if (!AFI->isThumbFunction())
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return false;
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bool Modified = false;
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for (MachineFunction::iterator MFI = Fn.begin(), E = Fn.end(); MFI != E;
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++MFI) {
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MachineBasicBlock &MBB = *MFI;
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Modified |= InsertITBlocks(MBB);
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}
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return Modified;
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}
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/// createThumb2ITBlockPass - Returns an instance of the Thumb2 IT blocks
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/// insertion pass.
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FunctionPass *llvm::createThumb2ITBlockPass() {
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return new Thumb2ITBlockPass();
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}
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