2011-09-26 00:46:08 +08:00
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//===-- ExpandPostRAPseudos.cpp - Pseudo instruction expansion pass -------===//
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2007-07-26 16:18:32 +08:00
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//
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2019-01-19 16:50:56 +08:00
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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2007-07-26 16:18:32 +08:00
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//
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//===----------------------------------------------------------------------===//
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2008-09-25 07:44:12 +08:00
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//
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2011-09-26 00:46:08 +08:00
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// This file defines a pass that expands COPY and SUBREG_TO_REG pseudo
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// instructions after register allocation.
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2008-09-25 07:44:12 +08:00
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//
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//===----------------------------------------------------------------------===//
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2007-07-26 16:18:32 +08:00
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#include "llvm/CodeGen/MachineFunctionPass.h"
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#include "llvm/CodeGen/MachineInstr.h"
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2009-08-04 04:08:18 +08:00
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#include "llvm/CodeGen/MachineInstrBuilder.h"
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2007-12-31 12:13:23 +08:00
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#include "llvm/CodeGen/MachineRegisterInfo.h"
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2017-06-06 19:49:48 +08:00
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#include "llvm/CodeGen/Passes.h"
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2017-11-08 09:01:31 +08:00
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#include "llvm/CodeGen/TargetInstrInfo.h"
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2017-11-17 09:07:10 +08:00
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#include "llvm/CodeGen/TargetRegisterInfo.h"
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#include "llvm/CodeGen/TargetSubtargetInfo.h"
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2007-07-26 16:18:32 +08:00
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#include "llvm/Support/Debug.h"
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2009-07-25 08:23:56 +08:00
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#include "llvm/Support/raw_ostream.h"
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2014-08-05 05:25:23 +08:00
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2007-07-26 16:18:32 +08:00
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using namespace llvm;
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2014-04-22 10:02:50 +08:00
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#define DEBUG_TYPE "postrapseudos"
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2007-07-26 16:18:32 +08:00
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namespace {
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2011-09-26 00:46:08 +08:00
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struct ExpandPostRA : public MachineFunctionPass {
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private:
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const TargetRegisterInfo *TRI;
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const TargetInstrInfo *TII;
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2009-10-25 15:49:57 +08:00
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2011-09-26 00:46:08 +08:00
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public:
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static char ID; // Pass identification, replacement for typeid
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ExpandPostRA() : MachineFunctionPass(ID) {}
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2011-02-26 06:53:20 +08:00
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2014-03-07 17:26:03 +08:00
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void getAnalysisUsage(AnalysisUsage &AU) const override {
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2011-09-26 00:46:08 +08:00
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AU.setPreservesCFG();
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AU.addPreservedID(MachineLoopInfoID);
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AU.addPreservedID(MachineDominatorsID);
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MachineFunctionPass::getAnalysisUsage(AU);
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}
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2008-09-23 04:58:04 +08:00
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2011-09-26 00:46:08 +08:00
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/// runOnMachineFunction - pass entry point
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2014-03-07 17:26:03 +08:00
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bool runOnMachineFunction(MachineFunction&) override;
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2009-10-25 15:49:57 +08:00
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2011-09-26 00:46:08 +08:00
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private:
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bool LowerSubregToReg(MachineInstr *MI);
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bool LowerCopy(MachineInstr *MI);
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2008-12-19 06:14:08 +08:00
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2016-07-16 06:31:14 +08:00
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void TransferImplicitOperands(MachineInstr *MI);
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2011-09-26 00:46:08 +08:00
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};
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} // end anonymous namespace
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2007-07-26 16:18:32 +08:00
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2011-09-26 00:46:08 +08:00
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char ExpandPostRA::ID = 0;
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2012-02-09 05:23:13 +08:00
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char &llvm::ExpandPostRAPseudosID = ExpandPostRA::ID;
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2007-07-26 16:18:32 +08:00
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2017-05-26 05:26:32 +08:00
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INITIALIZE_PASS(ExpandPostRA, DEBUG_TYPE,
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2012-02-09 05:23:13 +08:00
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"Post-RA pseudo instruction expansion pass", false, false)
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2007-07-26 16:18:32 +08:00
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2016-07-16 06:31:14 +08:00
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/// TransferImplicitOperands - MI is a pseudo-instruction, and the lowered
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/// replacement instructions immediately precede it. Copy any implicit
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2010-06-30 02:42:49 +08:00
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/// operands from MI to the replacement instruction.
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2016-07-16 06:31:14 +08:00
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void ExpandPostRA::TransferImplicitOperands(MachineInstr *MI) {
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2010-06-30 02:42:49 +08:00
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MachineBasicBlock::iterator CopyMI = MI;
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--CopyMI;
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2016-07-16 06:31:14 +08:00
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for (const MachineOperand &MO : MI->implicit_operands())
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if (MO.isReg())
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CopyMI->addOperand(MO);
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2010-06-30 02:42:49 +08:00
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}
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2011-09-26 00:46:08 +08:00
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bool ExpandPostRA::LowerSubregToReg(MachineInstr *MI) {
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2007-08-07 00:33:56 +08:00
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MachineBasicBlock *MBB = MI->getParent();
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2008-10-03 23:45:36 +08:00
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assert((MI->getOperand(0).isReg() && MI->getOperand(0).isDef()) &&
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MI->getOperand(1).isImm() &&
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(MI->getOperand(2).isReg() && MI->getOperand(2).isUse()) &&
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MI->getOperand(3).isImm() && "Invalid subreg_to_reg");
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2010-06-23 06:11:07 +08:00
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2008-03-16 11:12:01 +08:00
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unsigned DstReg = MI->getOperand(0).getReg();
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unsigned InsReg = MI->getOperand(2).getReg();
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2010-06-23 06:11:07 +08:00
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assert(!MI->getOperand(2).getSubReg() && "SubIdx on physreg?");
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2009-03-23 15:19:58 +08:00
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unsigned SubIdx = MI->getOperand(3).getImm();
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2007-08-07 00:33:56 +08:00
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2008-03-16 11:12:01 +08:00
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assert(SubIdx != 0 && "Invalid index for insert_subreg");
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2009-10-25 15:49:57 +08:00
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unsigned DstSubReg = TRI->getSubReg(DstReg, SubIdx);
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2009-03-23 15:19:58 +08:00
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2008-02-11 02:45:23 +08:00
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assert(TargetRegisterInfo::isPhysicalRegister(DstReg) &&
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2007-08-07 00:33:56 +08:00
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"Insert destination must be in a physical register");
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2008-02-11 02:45:23 +08:00
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assert(TargetRegisterInfo::isPhysicalRegister(InsReg) &&
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2007-08-07 00:33:56 +08:00
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"Inserted value must be in a physical register");
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2018-05-14 20:53:11 +08:00
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LLVM_DEBUG(dbgs() << "subreg: CONVERTING: " << *MI);
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2008-03-16 11:12:01 +08:00
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2013-02-22 06:16:43 +08:00
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if (MI->allDefsAreDead()) {
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MI->setDesc(TII->get(TargetOpcode::KILL));
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2018-10-09 08:07:34 +08:00
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MI->RemoveOperand(3); // SubIdx
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MI->RemoveOperand(1); // Imm
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2018-05-14 20:53:11 +08:00
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LLVM_DEBUG(dbgs() << "subreg: replaced by: " << *MI);
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2013-02-22 06:16:43 +08:00
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return true;
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}
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2010-06-23 06:11:07 +08:00
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if (DstSubReg == InsReg) {
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2013-10-11 23:40:14 +08:00
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// No need to insert an identity copy instruction.
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2009-03-23 15:19:58 +08:00
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// Watch out for case like this:
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2017-12-07 18:40:31 +08:00
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// %rax = SUBREG_TO_REG 0, killed %eax, 3
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2017-11-29 01:15:09 +08:00
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// We must leave %rax live.
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2010-06-23 06:11:07 +08:00
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if (DstReg != InsReg) {
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MI->setDesc(TII->get(TargetOpcode::KILL));
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MI->RemoveOperand(3); // SubIdx
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MI->RemoveOperand(1); // Imm
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2018-05-14 20:53:11 +08:00
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LLVM_DEBUG(dbgs() << "subreg: replace by: " << *MI);
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2010-06-23 06:11:07 +08:00
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return true;
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}
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2018-05-14 20:53:11 +08:00
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LLVM_DEBUG(dbgs() << "subreg: eliminated!");
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2008-08-07 10:54:50 +08:00
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} else {
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2010-07-08 13:01:41 +08:00
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TII->copyPhysReg(*MBB, MI, MI->getDebugLoc(), DstSubReg, InsReg,
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MI->getOperand(2).isKill());
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2013-02-22 01:01:59 +08:00
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2012-07-28 04:19:49 +08:00
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// Implicitly define DstReg for subsequent uses.
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MachineBasicBlock::iterator CopyMI = MI;
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--CopyMI;
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CopyMI->addRegisterDefined(DstReg);
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2018-05-14 20:53:11 +08:00
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LLVM_DEBUG(dbgs() << "subreg: " << *CopyMI);
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2008-08-07 10:54:50 +08:00
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}
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2007-08-07 00:33:56 +08:00
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2018-05-14 20:53:11 +08:00
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LLVM_DEBUG(dbgs() << '\n');
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2008-07-18 07:49:46 +08:00
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MBB->erase(MI);
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2009-10-24 08:27:00 +08:00
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return true;
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2008-03-16 11:12:01 +08:00
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}
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2007-08-07 00:33:56 +08:00
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2011-09-26 00:46:08 +08:00
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bool ExpandPostRA::LowerCopy(MachineInstr *MI) {
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2013-02-22 06:16:43 +08:00
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if (MI->allDefsAreDead()) {
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2018-05-14 20:53:11 +08:00
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LLVM_DEBUG(dbgs() << "dead copy: " << *MI);
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2013-02-22 06:16:43 +08:00
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MI->setDesc(TII->get(TargetOpcode::KILL));
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2018-05-14 20:53:11 +08:00
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LLVM_DEBUG(dbgs() << "replaced by: " << *MI);
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2013-02-22 06:16:43 +08:00
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return true;
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}
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2010-07-03 06:29:50 +08:00
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MachineOperand &DstMO = MI->getOperand(0);
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MachineOperand &SrcMO = MI->getOperand(1);
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2017-05-12 14:32:03 +08:00
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bool IdentityCopy = (SrcMO.getReg() == DstMO.getReg());
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if (IdentityCopy || SrcMO.isUndef()) {
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2018-05-14 20:53:11 +08:00
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LLVM_DEBUG(dbgs() << (IdentityCopy ? "identity copy: " : "undef copy: ")
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<< *MI);
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2010-07-03 06:29:50 +08:00
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// No need to insert an identity copy instruction, but replace with a KILL
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// if liveness is changed.
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2013-02-22 06:16:43 +08:00
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if (SrcMO.isUndef() || MI->getNumOperands() > 2) {
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2010-07-03 06:29:50 +08:00
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// We must make sure the super-register gets killed. Replace the
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// instruction with KILL.
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MI->setDesc(TII->get(TargetOpcode::KILL));
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2018-05-14 20:53:11 +08:00
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LLVM_DEBUG(dbgs() << "replaced by: " << *MI);
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2010-07-03 06:29:50 +08:00
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return true;
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}
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// Vanilla identity copy.
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MI->eraseFromParent();
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return true;
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}
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2018-05-14 20:53:11 +08:00
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LLVM_DEBUG(dbgs() << "real copy: " << *MI);
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2010-07-08 13:01:41 +08:00
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TII->copyPhysReg(*MI->getParent(), MI, MI->getDebugLoc(),
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DstMO.getReg(), SrcMO.getReg(), SrcMO.isKill());
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2010-07-03 06:29:50 +08:00
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if (MI->getNumOperands() > 2)
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2016-07-16 06:31:14 +08:00
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TransferImplicitOperands(MI);
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2018-05-14 20:53:11 +08:00
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LLVM_DEBUG({
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2010-07-03 06:29:50 +08:00
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MachineBasicBlock::iterator dMI = MI;
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dbgs() << "replaced by: " << *(--dMI);
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});
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MI->eraseFromParent();
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return true;
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}
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2007-07-26 16:18:32 +08:00
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/// runOnMachineFunction - Reduce subregister inserts and extracts to register
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/// copies.
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///
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2011-09-26 00:46:08 +08:00
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bool ExpandPostRA::runOnMachineFunction(MachineFunction &MF) {
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2018-05-14 20:53:11 +08:00
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LLVM_DEBUG(dbgs() << "Machine Function\n"
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<< "********** EXPANDING POST-RA PSEUDO INSTRS **********\n"
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<< "********** Function: " << MF.getName() << '\n');
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2014-08-05 10:39:49 +08:00
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TRI = MF.getSubtarget().getRegisterInfo();
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TII = MF.getSubtarget().getInstrInfo();
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2007-07-26 16:18:32 +08:00
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2009-08-23 04:23:49 +08:00
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bool MadeChange = false;
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2007-07-26 16:18:32 +08:00
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for (MachineFunction::iterator mbbi = MF.begin(), mbbe = MF.end();
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mbbi != mbbe; ++mbbi) {
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for (MachineBasicBlock::iterator mi = mbbi->begin(), me = mbbi->end();
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2007-08-07 00:33:56 +08:00
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mi != me;) {
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2016-06-30 08:01:54 +08:00
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MachineInstr &MI = *mi;
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2011-09-26 03:21:35 +08:00
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// Advance iterator here because MI may be erased.
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++mi;
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2011-10-11 04:34:28 +08:00
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// Only expand pseudos.
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2016-06-30 08:01:54 +08:00
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if (!MI.isPseudo())
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2011-10-11 04:34:28 +08:00
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continue;
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// Give targets a chance to expand even standard pseudos.
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if (TII->expandPostRAPseudo(MI)) {
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MadeChange = true;
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continue;
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}
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// Expand standard pseudos.
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2016-06-30 08:01:54 +08:00
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switch (MI.getOpcode()) {
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2011-09-26 03:21:35 +08:00
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case TargetOpcode::SUBREG_TO_REG:
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2016-06-30 08:01:54 +08:00
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MadeChange |= LowerSubregToReg(&MI);
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2011-09-26 03:21:35 +08:00
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break;
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case TargetOpcode::COPY:
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2016-06-30 08:01:54 +08:00
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MadeChange |= LowerCopy(&MI);
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2011-09-26 03:21:35 +08:00
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break;
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case TargetOpcode::DBG_VALUE:
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continue;
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case TargetOpcode::INSERT_SUBREG:
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case TargetOpcode::EXTRACT_SUBREG:
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llvm_unreachable("Sub-register pseudos should have been eliminated.");
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2007-07-26 16:18:32 +08:00
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}
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}
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}
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return MadeChange;
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}
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