forked from OSchip/llvm-project
121 lines
3.8 KiB
C++
121 lines
3.8 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 (MCID.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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if (ITBlockSize && MI != ITBlockMIs[ITBlockSize-1])
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return Hazard;
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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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// Skip over one non-VFP / NEON instruction.
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if (!LastMCID.isBarrier() &&
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// On A9, AGU and NEON/FPU are muxed.
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!(STI.isCortexA9() && (LastMCID.mayLoad() || LastMCID.mayStore())) &&
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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 = llvm::prior(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, TRI))) {
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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 = 0;
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FpMLxStalls = 0;
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ITBlockSize = 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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unsigned Opcode = MI->getOpcode();
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if (ITBlockSize) {
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--ITBlockSize;
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} else if (Opcode == ARM::t2IT) {
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unsigned Mask = MI->getOperand(1).getImm();
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unsigned NumTZ = CountTrailingZeros_32(Mask);
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assert(NumTZ <= 3 && "Invalid IT mask!");
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ITBlockSize = 4 - NumTZ;
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MachineBasicBlock::iterator I = MI;
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for (unsigned i = 0; i < ITBlockSize; ++i) {
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// Advance to the next instruction, skipping any dbg_value instructions.
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do {
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++I;
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} while (I->isDebugValue());
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ITBlockMIs[ITBlockSize-1-i] = &*I;
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}
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}
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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 = 0;
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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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