102 lines
3.4 KiB
C++
102 lines
3.4 KiB
C++
//===-- ARMHazardRecognizer.cpp - ARM postra hazard recognizer ------------===//
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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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#include "ARMHazardRecognizer.h"
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#include "ARMBaseInstrInfo.h"
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#include "ARMBaseRegisterInfo.h"
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#include "ARMSubtarget.h"
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#include "llvm/CodeGen/MachineInstr.h"
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#include "llvm/CodeGen/ScheduleDAG.h"
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#include "llvm/Target/TargetRegisterInfo.h"
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using namespace llvm;
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static bool hasRAWHazard(MachineInstr *DefMI, MachineInstr *MI,
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const TargetRegisterInfo &TRI) {
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// FIXME: Detect integer instructions properly.
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const MCInstrDesc &MCID = MI->getDesc();
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unsigned Domain = MCID.TSFlags & ARMII::DomainMask;
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if (MI->mayStore())
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return false;
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unsigned Opcode = MCID.getOpcode();
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if (Opcode == ARM::VMOVRS || Opcode == ARM::VMOVRRD)
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return false;
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if ((Domain & ARMII::DomainVFP) || (Domain & ARMII::DomainNEON))
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return MI->readsRegister(DefMI->getOperand(0).getReg(), &TRI);
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return false;
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}
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ScheduleHazardRecognizer::HazardType
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ARMHazardRecognizer::getHazardType(SUnit *SU, int Stalls) {
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assert(Stalls == 0 && "ARM hazards don't support scoreboard lookahead");
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MachineInstr *MI = SU->getInstr();
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if (!MI->isDebugValue()) {
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// Look for special VMLA / VMLS hazards. A VMUL / VADD / VSUB following
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// a VMLA / VMLS will cause 4 cycle stall.
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const MCInstrDesc &MCID = MI->getDesc();
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if (LastMI && (MCID.TSFlags & ARMII::DomainMask) != ARMII::DomainGeneral) {
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MachineInstr *DefMI = LastMI;
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const MCInstrDesc &LastMCID = LastMI->getDesc();
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const MachineFunction *MF = MI->getParent()->getParent();
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const ARMBaseInstrInfo &TII = *static_cast<const ARMBaseInstrInfo *>(
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MF->getSubtarget().getInstrInfo());
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// Skip over one non-VFP / NEON instruction.
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if (!LastMI->isBarrier() &&
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!(TII.getSubtarget().hasMuxedUnits() && LastMI->mayLoadOrStore()) &&
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(LastMCID.TSFlags & ARMII::DomainMask) == ARMII::DomainGeneral) {
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MachineBasicBlock::iterator I = LastMI;
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if (I != LastMI->getParent()->begin()) {
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I = std::prev(I);
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DefMI = &*I;
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}
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}
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if (TII.isFpMLxInstruction(DefMI->getOpcode()) &&
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(TII.canCauseFpMLxStall(MI->getOpcode()) ||
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hasRAWHazard(DefMI, MI, TII.getRegisterInfo()))) {
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// Try to schedule another instruction for the next 4 cycles.
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if (FpMLxStalls == 0)
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FpMLxStalls = 4;
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return Hazard;
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}
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}
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}
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return ScoreboardHazardRecognizer::getHazardType(SU, Stalls);
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}
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void ARMHazardRecognizer::Reset() {
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LastMI = nullptr;
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FpMLxStalls = 0;
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ScoreboardHazardRecognizer::Reset();
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}
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void ARMHazardRecognizer::EmitInstruction(SUnit *SU) {
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MachineInstr *MI = SU->getInstr();
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if (!MI->isDebugValue()) {
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LastMI = MI;
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FpMLxStalls = 0;
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}
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ScoreboardHazardRecognizer::EmitInstruction(SU);
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}
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void ARMHazardRecognizer::AdvanceCycle() {
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if (FpMLxStalls && --FpMLxStalls == 0)
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// Stalled for 4 cycles but still can't schedule any other instructions.
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LastMI = nullptr;
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ScoreboardHazardRecognizer::AdvanceCycle();
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}
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void ARMHazardRecognizer::RecedeCycle() {
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llvm_unreachable("reverse ARM hazard checking unsupported");
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}
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