#include "ARMBaseRegisterInfo.h"
#include "ARMMachineFunctionInfo.h"
#include "MCTargetDesc/ARMAddressingModes.h"
+#include "llvm/Function.h"
#include "llvm/CodeGen/MachineFrameInfo.h"
#include "llvm/CodeGen/MachineFunction.h"
#include "llvm/CodeGen/MachineInstrBuilder.h"
#include "llvm/CodeGen/MachineRegisterInfo.h"
#include "llvm/CodeGen/RegisterScavenging.h"
#include "llvm/Target/TargetOptions.h"
+#include "llvm/Support/CommandLine.h"
using namespace llvm;
+cl::opt<bool>
+SpillAlignedNEONRegs("align-neon-spills", cl::Hidden,
+ cl::desc("Align ARM NEON spills in prolog and epilog"));
+
+static MachineBasicBlock::iterator
+skipAlignedDPRCS2Spills(MachineBasicBlock::iterator MI,
+ unsigned NumAlignedDPRCS2Regs);
+
/// hasFP - Return true if the specified function should have a dedicated frame
/// pointer register. This is true if the function has variable sized allocas
/// or if frame pointer elimination is disabled.
// belongs to which callee-save spill areas.
unsigned GPRCS1Size = 0, GPRCS2Size = 0, DPRCSSize = 0;
int FramePtrSpillFI = 0;
+ int D8SpillFI = 0;
// Allocate the vararg register save area. This is not counted in NumBytes.
if (VARegSaveSize)
}
break;
default:
- AFI->addDPRCalleeSavedAreaFrame(FI);
- DPRCSSize += 8;
+ // This is a DPR. Exclude the aligned DPRCS2 spills.
+ if (Reg == ARM::D8)
+ D8SpillFI = FI;
+ if (Reg < ARM::D8 || Reg >= ARM::D8 + AFI->getNumAlignedDPRCS2Regs()) {
+ AFI->addDPRCalleeSavedAreaFrame(FI);
+ DPRCSSize += 8;
+ }
}
}
MBBI++;
}
- NumBytes = DPRCSOffset;
+ // Move past the aligned DPRCS2 area.
+ if (AFI->getNumAlignedDPRCS2Regs() > 0) {
+ MBBI = skipAlignedDPRCS2Spills(MBBI, AFI->getNumAlignedDPRCS2Regs());
+ // The code inserted by emitAlignedDPRCS2Spills realigns the stack, and
+ // leaves the stack pointer pointing to the DPRCS2 area.
+ //
+ // Adjust NumBytes to represent the stack slots below the DPRCS2 area.
+ NumBytes += MFI->getObjectOffset(D8SpillFI);
+ } else
+ NumBytes = DPRCSOffset;
+
if (NumBytes) {
// Adjust SP after all the callee-save spills.
emitSPUpdate(isARM, MBB, MBBI, dl, TII, -NumBytes,
// If we need dynamic stack realignment, do it here. Be paranoid and make
// sure if we also have VLAs, we have a base pointer for frame access.
- if (RegInfo->needsStackRealignment(MF)) {
+ // If aligned NEON registers were sp[illed, the stack has already been
+ // realigned.
+ if (!AFI->getNumAlignedDPRCS2Regs() && RegInfo->needsStackRealignment(MF)) {
unsigned MaxAlign = MFI->getMaxAlignment();
assert (!AFI->isThumb1OnlyFunction());
if (!AFI->isThumbFunction()) {
unsigned StmOpc, unsigned StrOpc,
bool NoGap,
bool(*Func)(unsigned, bool),
+ unsigned NumAlignedDPRCS2Regs,
unsigned MIFlags) const {
MachineFunction &MF = *MBB.getParent();
const TargetInstrInfo &TII = *MF.getTarget().getInstrInfo();
unsigned Reg = CSI[i-1].getReg();
if (!(Func)(Reg, STI.isTargetDarwin())) continue;
+ // D-registers in the aligned area DPRCS2 are NOT spilled here.
+ if (Reg >= ARM::D8 && Reg < ARM::D8 + NumAlignedDPRCS2Regs)
+ continue;
+
// Add the callee-saved register as live-in unless it's LR and
// @llvm.returnaddress is called. If LR is returned for
// @llvm.returnaddress then it's already added to the function and
const std::vector<CalleeSavedInfo> &CSI,
unsigned LdmOpc, unsigned LdrOpc,
bool isVarArg, bool NoGap,
- bool(*Func)(unsigned, bool)) const {
+ bool(*Func)(unsigned, bool),
+ unsigned NumAlignedDPRCS2Regs) const {
MachineFunction &MF = *MBB.getParent();
const TargetInstrInfo &TII = *MF.getTarget().getInstrInfo();
ARMFunctionInfo *AFI = MF.getInfo<ARMFunctionInfo>();
unsigned Reg = CSI[i-1].getReg();
if (!(Func)(Reg, STI.isTargetDarwin())) continue;
+ // The aligned reloads from area DPRCS2 are not inserted here.
+ if (Reg >= ARM::D8 && Reg < ARM::D8 + NumAlignedDPRCS2Regs)
+ continue;
+
if (Reg == ARM::LR && !isTailCall && !isVarArg && STI.hasV5TOps()) {
Reg = ARM::PC;
LdmOpc = AFI->isThumbFunction() ? ARM::t2LDMIA_RET : ARM::LDMIA_RET;
}
}
+/// Emit aligned spill instructions for NumAlignedDPRCS2Regs D-registers
+/// starting from d8. It is assumed that the stack will be realigned before
+/// these instructions are executed.
+static void emitAlignedDPRCS2Spills(MachineBasicBlock &MBB,
+ MachineBasicBlock::iterator MI,
+ unsigned NumAlignedDPRCS2Regs,
+ const std::vector<CalleeSavedInfo> &CSI,
+ const TargetRegisterInfo *TRI) {
+ MachineFunction &MF = *MBB.getParent();
+ ARMFunctionInfo *AFI = MF.getInfo<ARMFunctionInfo>();
+ DebugLoc DL = MI->getDebugLoc();
+ const TargetInstrInfo &TII = *MF.getTarget().getInstrInfo();
+ MachineFrameInfo &MFI = *MF.getFrameInfo();
+
+ // Mark the D-register spill slots as properly aligned. Since MFI computes
+ // stack slot layout backwards, this can actually mean that the d-reg stack
+ // slot offsets can be wrong. The offset for d8 will always be correct.
+ for (unsigned i = 0, e = CSI.size(); i != e; ++i) {
+ unsigned DNum = CSI[i].getReg() - ARM::D8;
+ if (DNum >= 8)
+ continue;
+ int FI = CSI[i].getFrameIdx();
+ // The even-numbered registers will be 16-byte aligned, the odd-numbered
+ // registers will be 8-byte aligned.
+ MFI.setObjectAlignment(FI, DNum % 2 ? 8 : 16);
+
+ // The stack slot for D8 needs to be maximally aligned because this is
+ // actually the point where we align the stack pointer. MachineFrameInfo
+ // computes all offsets relative to the incoming stack pointer which is a
+ // bit weird when realigning the stack. Any extra padding for this
+ // over-alignment is not realized because the code inserted below adjusts
+ // the stack pointer by numregs * 8 before aligning the stack pointer.
+ if (DNum == 0)
+ MFI.setObjectAlignment(FI, MFI.getMaxAlignment());
+ }
+
+ // Move the stack pointer to the d8 spill slot, and align it at the same
+ // time. Leave the stack slot address in the scratch register r4.
+ //
+ // sub r4, sp, #numregs * 8
+ // bic r4, r4, #align - 1
+ // mov sp, r4
+ //
+ bool isThumb = AFI->isThumbFunction();
+ assert(!AFI->isThumb1OnlyFunction() && "Can't realign stack for thumb1");
+ AFI->setShouldRestoreSPFromFP(true);
+
+ // sub r4, sp, #numregs * 8
+ // The immediate is <= 64, so it doesn't need any special encoding.
+ unsigned Opc = isThumb ? ARM::t2SUBri : ARM::SUBri;
+ AddDefaultCC(AddDefaultPred(BuildMI(MBB, MI, DL, TII.get(Opc), ARM::R4)
+ .addReg(ARM::SP)
+ .addImm(8 * NumAlignedDPRCS2Regs)));
+
+ // bic r4, r4, #align-1
+ Opc = isThumb ? ARM::t2BICri : ARM::BICri;
+ unsigned MaxAlign = MF.getFrameInfo()->getMaxAlignment();
+ AddDefaultCC(AddDefaultPred(BuildMI(MBB, MI, DL, TII.get(Opc), ARM::R4)
+ .addReg(ARM::R4, RegState::Kill)
+ .addImm(MaxAlign - 1)));
+
+ // mov sp, r4
+ // The stack pointer must be adjusted before spilling anything, otherwise
+ // the stack slots could be clobbered by an interrupt handler.
+ // Leave r4 live, it is used below.
+ Opc = isThumb ? ARM::tMOVr : ARM::MOVr;
+ MachineInstrBuilder MIB = BuildMI(MBB, MI, DL, TII.get(Opc), ARM::SP)
+ .addReg(ARM::R4);
+ MIB = AddDefaultPred(MIB);
+ if (!isThumb)
+ AddDefaultCC(MIB);
+
+ // Now spill NumAlignedDPRCS2Regs registers starting from d8.
+ // r4 holds the stack slot address.
+ unsigned NextReg = ARM::D8;
+
+ // 16-byte aligned vst1.64 with 4 d-regs and address writeback.
+ // The writeback is only needed when emitting two vst1.64 instructions.
+ if (NumAlignedDPRCS2Regs >= 6) {
+ unsigned SupReg = TRI->getMatchingSuperReg(NextReg, ARM::dsub_0,
+ ARM::QQPRRegisterClass);
+ MBB.addLiveIn(SupReg);
+ AddDefaultPred(BuildMI(MBB, MI, DL, TII.get(ARM::VST1d64Qwb_fixed),
+ ARM::R4)
+ .addReg(ARM::R4, RegState::Kill).addImm(16)
+ .addReg(NextReg)
+ .addReg(SupReg, RegState::ImplicitKill));
+ NextReg += 4;
+ NumAlignedDPRCS2Regs -= 4;
+ }
+
+ // We won't modify r4 beyond this point. It currently points to the next
+ // register to be spilled.
+ unsigned R4BaseReg = NextReg;
+
+ // 16-byte aligned vst1.64 with 4 d-regs, no writeback.
+ if (NumAlignedDPRCS2Regs >= 4) {
+ unsigned SupReg = TRI->getMatchingSuperReg(NextReg, ARM::dsub_0,
+ ARM::QQPRRegisterClass);
+ MBB.addLiveIn(SupReg);
+ AddDefaultPred(BuildMI(MBB, MI, DL, TII.get(ARM::VST1d64Q))
+ .addReg(ARM::R4).addImm(16).addReg(NextReg)
+ .addReg(SupReg, RegState::ImplicitKill));
+ NextReg += 4;
+ NumAlignedDPRCS2Regs -= 4;
+ }
+
+ // 16-byte aligned vst1.64 with 2 d-regs.
+ if (NumAlignedDPRCS2Regs >= 2) {
+ unsigned SupReg = TRI->getMatchingSuperReg(NextReg, ARM::dsub_0,
+ ARM::QPRRegisterClass);
+ MBB.addLiveIn(SupReg);
+ AddDefaultPred(BuildMI(MBB, MI, DL, TII.get(ARM::VST1q64))
+ .addReg(ARM::R4).addImm(16).addReg(NextReg)
+ .addReg(SupReg, RegState::ImplicitKill));
+ NextReg += 2;
+ NumAlignedDPRCS2Regs -= 2;
+ }
+
+ // Finally, use a vanilla vstr.64 for the odd last register.
+ if (NumAlignedDPRCS2Regs) {
+ MBB.addLiveIn(NextReg);
+ // vstr.64 uses addrmode5 which has an offset scale of 4.
+ AddDefaultPred(BuildMI(MBB, MI, DL, TII.get(ARM::VSTRD))
+ .addReg(NextReg)
+ .addReg(ARM::R4).addImm((NextReg-R4BaseReg)*2));
+ }
+
+ // The last spill instruction inserted should kill the scratch register r4.
+ llvm::prior(MI)->addRegisterKilled(ARM::R4, TRI);
+}
+
+/// Skip past the code inserted by emitAlignedDPRCS2Spills, and return an
+/// iterator to the following instruction.
+static MachineBasicBlock::iterator
+skipAlignedDPRCS2Spills(MachineBasicBlock::iterator MI,
+ unsigned NumAlignedDPRCS2Regs) {
+ // sub r4, sp, #numregs * 8
+ // bic r4, r4, #align - 1
+ // mov sp, r4
+ ++MI; ++MI; ++MI;
+ assert(MI->mayStore() && "Expecting spill instruction");
+
+ // These switches all fall through.
+ switch(NumAlignedDPRCS2Regs) {
+ case 7:
+ ++MI;
+ assert(MI->mayStore() && "Expecting spill instruction");
+ default:
+ ++MI;
+ assert(MI->mayStore() && "Expecting spill instruction");
+ case 1:
+ case 2:
+ case 4:
+ assert(MI->killsRegister(ARM::R4) && "Missed kill flag");
+ ++MI;
+ }
+ return MI;
+}
+
+/// Emit aligned reload instructions for NumAlignedDPRCS2Regs D-registers
+/// starting from d8. These instructions are assumed to execute while the
+/// stack is still aligned, unlike the code inserted by emitPopInst.
+static void emitAlignedDPRCS2Restores(MachineBasicBlock &MBB,
+ MachineBasicBlock::iterator MI,
+ unsigned NumAlignedDPRCS2Regs,
+ const std::vector<CalleeSavedInfo> &CSI,
+ const TargetRegisterInfo *TRI) {
+ MachineFunction &MF = *MBB.getParent();
+ ARMFunctionInfo *AFI = MF.getInfo<ARMFunctionInfo>();
+ DebugLoc DL = MI->getDebugLoc();
+ const TargetInstrInfo &TII = *MF.getTarget().getInstrInfo();
+
+ // Find the frame index assigned to d8.
+ int D8SpillFI = 0;
+ for (unsigned i = 0, e = CSI.size(); i != e; ++i)
+ if (CSI[i].getReg() == ARM::D8) {
+ D8SpillFI = CSI[i].getFrameIdx();
+ break;
+ }
+
+ // Materialize the address of the d8 spill slot into the scratch register r4.
+ // This can be fairly complicated if the stack frame is large, so just use
+ // the normal frame index elimination mechanism to do it. This code runs as
+ // the initial part of the epilog where the stack and base pointers haven't
+ // been changed yet.
+ bool isThumb = AFI->isThumbFunction();
+ assert(!AFI->isThumb1OnlyFunction() && "Can't realign stack for thumb1");
+
+ unsigned Opc = isThumb ? ARM::t2ADDri : ARM::ADDri;
+ AddDefaultCC(AddDefaultPred(BuildMI(MBB, MI, DL, TII.get(Opc), ARM::R4)
+ .addFrameIndex(D8SpillFI).addImm(0)));
+
+ // Now restore NumAlignedDPRCS2Regs registers starting from d8.
+ unsigned NextReg = ARM::D8;
+
+ // 16-byte aligned vld1.64 with 4 d-regs and writeback.
+ if (NumAlignedDPRCS2Regs >= 6) {
+ unsigned SupReg = TRI->getMatchingSuperReg(NextReg, ARM::dsub_0,
+ ARM::QQPRRegisterClass);
+ AddDefaultPred(BuildMI(MBB, MI, DL, TII.get(ARM::VLD1d64Qwb_fixed), NextReg)
+ .addReg(ARM::R4, RegState::Define)
+ .addReg(ARM::R4, RegState::Kill).addImm(16)
+ .addReg(SupReg, RegState::ImplicitDefine));
+ NextReg += 4;
+ NumAlignedDPRCS2Regs -= 4;
+ }
+
+ // We won't modify r4 beyond this point. It currently points to the next
+ // register to be spilled.
+ unsigned R4BaseReg = NextReg;
+
+ // 16-byte aligned vld1.64 with 4 d-regs, no writeback.
+ if (NumAlignedDPRCS2Regs >= 4) {
+ unsigned SupReg = TRI->getMatchingSuperReg(NextReg, ARM::dsub_0,
+ ARM::QQPRRegisterClass);
+ AddDefaultPred(BuildMI(MBB, MI, DL, TII.get(ARM::VLD1d64Q), NextReg)
+ .addReg(ARM::R4).addImm(16)
+ .addReg(SupReg, RegState::ImplicitDefine));
+ NextReg += 4;
+ NumAlignedDPRCS2Regs -= 4;
+ }
+
+ // 16-byte aligned vld1.64 with 2 d-regs.
+ if (NumAlignedDPRCS2Regs >= 2) {
+ unsigned SupReg = TRI->getMatchingSuperReg(NextReg, ARM::dsub_0,
+ ARM::QPRRegisterClass);
+ AddDefaultPred(BuildMI(MBB, MI, DL, TII.get(ARM::VLD1q64), NextReg)
+ .addReg(ARM::R4).addImm(16)
+ .addReg(SupReg, RegState::ImplicitDefine));
+ NextReg += 2;
+ NumAlignedDPRCS2Regs -= 2;
+ }
+
+ // Finally, use a vanilla vldr.64 for the remaining odd register.
+ if (NumAlignedDPRCS2Regs)
+ AddDefaultPred(BuildMI(MBB, MI, DL, TII.get(ARM::VLDRD), NextReg)
+ .addReg(ARM::R4).addImm(2*(NextReg-R4BaseReg)));
+
+ // Last store kills r4.
+ llvm::prior(MI)->addRegisterKilled(ARM::R4, TRI);
+}
+
bool ARMFrameLowering::spillCalleeSavedRegisters(MachineBasicBlock &MBB,
MachineBasicBlock::iterator MI,
const std::vector<CalleeSavedInfo> &CSI,
unsigned PushOneOpc = AFI->isThumbFunction() ?
ARM::t2STR_PRE : ARM::STR_PRE_IMM;
unsigned FltOpc = ARM::VSTMDDB_UPD;
- emitPushInst(MBB, MI, CSI, PushOpc, PushOneOpc, false, &isARMArea1Register,
+ unsigned NumAlignedDPRCS2Regs = AFI->getNumAlignedDPRCS2Regs();
+ emitPushInst(MBB, MI, CSI, PushOpc, PushOneOpc, false, &isARMArea1Register, 0,
MachineInstr::FrameSetup);
- emitPushInst(MBB, MI, CSI, PushOpc, PushOneOpc, false, &isARMArea2Register,
+ emitPushInst(MBB, MI, CSI, PushOpc, PushOneOpc, false, &isARMArea2Register, 0,
MachineInstr::FrameSetup);
emitPushInst(MBB, MI, CSI, FltOpc, 0, true, &isARMArea3Register,
- MachineInstr::FrameSetup);
+ NumAlignedDPRCS2Regs, MachineInstr::FrameSetup);
+
+ // The code above does not insert spill code for the aligned DPRCS2 registers.
+ // The stack realignment code will be inserted between the push instructions
+ // and these spills.
+ if (NumAlignedDPRCS2Regs)
+ emitAlignedDPRCS2Spills(MBB, MI, NumAlignedDPRCS2Regs, CSI, TRI);
return true;
}
MachineFunction &MF = *MBB.getParent();
ARMFunctionInfo *AFI = MF.getInfo<ARMFunctionInfo>();
bool isVarArg = AFI->getVarArgsRegSaveSize() > 0;
+ unsigned NumAlignedDPRCS2Regs = AFI->getNumAlignedDPRCS2Regs();
+
+ // The emitPopInst calls below do not insert reloads for the aligned DPRCS2
+ // registers. Do that here instead.
+ if (NumAlignedDPRCS2Regs)
+ emitAlignedDPRCS2Restores(MBB, MI, NumAlignedDPRCS2Regs, CSI, TRI);
unsigned PopOpc = AFI->isThumbFunction() ? ARM::t2LDMIA_UPD : ARM::LDMIA_UPD;
unsigned LdrOpc = AFI->isThumbFunction() ? ARM::t2LDR_POST :ARM::LDR_POST_IMM;
unsigned FltOpc = ARM::VLDMDIA_UPD;
- emitPopInst(MBB, MI, CSI, FltOpc, 0, isVarArg, true, &isARMArea3Register);
+ emitPopInst(MBB, MI, CSI, FltOpc, 0, isVarArg, true, &isARMArea3Register,
+ NumAlignedDPRCS2Regs);
emitPopInst(MBB, MI, CSI, PopOpc, LdrOpc, isVarArg, false,
- &isARMArea2Register);
+ &isARMArea2Register, 0);
emitPopInst(MBB, MI, CSI, PopOpc, LdrOpc, isVarArg, false,
- &isARMArea1Register);
+ &isARMArea1Register, 0);
return true;
}
return Limit;
}
+// In functions that realign the stack, it can be an advantage to spill the
+// callee-saved vector registers after realigning the stack. The vst1 and vld1
+// instructions take alignment hints that can improve performance.
+//
+static void checkNumAlignedDPRCS2Regs(MachineFunction &MF) {
+ MF.getInfo<ARMFunctionInfo>()->setNumAlignedDPRCS2Regs(0);
+ if (!SpillAlignedNEONRegs)
+ return;
+
+ // Naked functions don't spill callee-saved registers.
+ if (MF.getFunction()->hasFnAttr(Attribute::Naked))
+ return;
+
+ // We are planning to use NEON instructions vst1 / vld1.
+ if (!MF.getTarget().getSubtarget<ARMSubtarget>().hasNEON())
+ return;
+
+ // Don't bother if the default stack alignment is sufficiently high.
+ if (MF.getTarget().getFrameLowering()->getStackAlignment() >= 8)
+ return;
+
+ // Aligned spills require stack realignment.
+ const ARMBaseRegisterInfo *RegInfo =
+ static_cast<const ARMBaseRegisterInfo*>(MF.getTarget().getRegisterInfo());
+ if (!RegInfo->canRealignStack(MF))
+ return;
+
+ // We always spill contiguous d-registers starting from d8. Count how many
+ // needs spilling. The register allocator will almost always use the
+ // callee-saved registers in order, but it can happen that there are holes in
+ // the range. Registers above the hole will be spilled to the standard DPRCS
+ // area.
+ MachineRegisterInfo &MRI = MF.getRegInfo();
+ unsigned NumSpills = 0;
+ for (; NumSpills < 8; ++NumSpills)
+ if (!MRI.isPhysRegOrOverlapUsed(ARM::D8 + NumSpills))
+ break;
+
+ // Don't do this for just one d-register. It's not worth it.
+ if (NumSpills < 2)
+ return;
+
+ // Spill the first NumSpills D-registers after realigning the stack.
+ MF.getInfo<ARMFunctionInfo>()->setNumAlignedDPRCS2Regs(NumSpills);
+
+ // A scratch register is required for the vst1 / vld1 instructions.
+ MF.getRegInfo().setPhysRegUsed(ARM::R4);
+}
+
void
ARMFrameLowering::processFunctionBeforeCalleeSavedScan(MachineFunction &MF,
RegScavenger *RS) const {
MF.getRegInfo().setPhysRegUsed(ARM::R4);
}
+ // See if we can spill vector registers to aligned stack.
+ checkNumAlignedDPRCS2Regs(MF);
+
// Spill the BasePtr if it's used.
if (RegInfo->hasBasePointer(MF))
MF.getRegInfo().setPhysRegUsed(RegInfo->getBaseRegister());
projects / oota-llvm.git / commitdiff