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	Update the subtarget information for Windows on ARM. This enables using the MC layer to target Windows on ARM. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@205459 91177308-0d34-0410-b5e6-96231b3b80d8
		
			
				
	
	
		
			360 lines
		
	
	
		
			11 KiB
		
	
	
	
		
			C++
		
	
	
	
	
	
			
		
		
	
	
			360 lines
		
	
	
		
			11 KiB
		
	
	
	
		
			C++
		
	
	
	
	
	
//===-- ARMSubtarget.cpp - ARM Subtarget Information ----------------------===//
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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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//
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// This file implements the ARM specific subclass of TargetSubtargetInfo.
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//
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//===----------------------------------------------------------------------===//
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#include "ARMSubtarget.h"
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#include "ARMBaseInstrInfo.h"
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#include "ARMBaseRegisterInfo.h"
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#include "llvm/IR/Attributes.h"
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#include "llvm/IR/Function.h"
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#include "llvm/IR/GlobalValue.h"
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#include "llvm/Support/CommandLine.h"
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#include "llvm/Target/TargetInstrInfo.h"
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#include "llvm/Target/TargetOptions.h"
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#define GET_SUBTARGETINFO_TARGET_DESC
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#define GET_SUBTARGETINFO_CTOR
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#include "ARMGenSubtargetInfo.inc"
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using namespace llvm;
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static cl::opt<bool>
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ReserveR9("arm-reserve-r9", cl::Hidden,
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          cl::desc("Reserve R9, making it unavailable as GPR"));
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static cl::opt<bool>
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ArmUseMOVT("arm-use-movt", cl::init(true), cl::Hidden);
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static cl::opt<bool>
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UseFusedMulOps("arm-use-mulops",
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               cl::init(true), cl::Hidden);
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enum AlignMode {
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  DefaultAlign,
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  StrictAlign,
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  NoStrictAlign
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};
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static cl::opt<AlignMode>
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Align(cl::desc("Load/store alignment support"),
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      cl::Hidden, cl::init(DefaultAlign),
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      cl::values(
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          clEnumValN(DefaultAlign,  "arm-default-align",
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                     "Generate unaligned accesses only on hardware/OS "
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                     "combinations that are known to support them"),
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          clEnumValN(StrictAlign,   "arm-strict-align",
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                     "Disallow all unaligned memory accesses"),
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          clEnumValN(NoStrictAlign, "arm-no-strict-align",
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                     "Allow unaligned memory accesses"),
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          clEnumValEnd));
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enum ITMode {
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  DefaultIT,
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  RestrictedIT,
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  NoRestrictedIT
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};
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static cl::opt<ITMode>
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IT(cl::desc("IT block support"), cl::Hidden, cl::init(DefaultIT),
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   cl::ZeroOrMore,
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   cl::values(clEnumValN(DefaultIT, "arm-default-it",
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                         "Generate IT block based on arch"),
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              clEnumValN(RestrictedIT, "arm-restrict-it",
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                         "Disallow deprecated IT based on ARMv8"),
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              clEnumValN(NoRestrictedIT, "arm-no-restrict-it",
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                         "Allow IT blocks based on ARMv7"),
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              clEnumValEnd));
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ARMSubtarget::ARMSubtarget(const std::string &TT, const std::string &CPU,
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                           const std::string &FS, bool IsLittle,
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                           const TargetOptions &Options)
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  : ARMGenSubtargetInfo(TT, CPU, FS)
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  , ARMProcFamily(Others)
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  , ARMProcClass(None)
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  , stackAlignment(4)
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  , CPUString(CPU)
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  , IsLittle(IsLittle)
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  , TargetTriple(TT)
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  , Options(Options)
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  , TargetABI(ARM_ABI_UNKNOWN) {
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  initializeEnvironment();
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  resetSubtargetFeatures(CPU, FS);
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}
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void ARMSubtarget::initializeEnvironment() {
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  HasV4TOps = false;
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  HasV5TOps = false;
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  HasV5TEOps = false;
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  HasV6Ops = false;
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  HasV6MOps = false;
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  HasV6T2Ops = false;
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  HasV7Ops = false;
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  HasV8Ops = false;
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  HasVFPv2 = false;
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  HasVFPv3 = false;
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  HasVFPv4 = false;
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  HasFPARMv8 = false;
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  HasNEON = false;
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  MinSize = false;
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  UseNEONForSinglePrecisionFP = false;
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  UseMulOps = UseFusedMulOps;
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  SlowFPVMLx = false;
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  HasVMLxForwarding = false;
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  SlowFPBrcc = false;
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  InThumbMode = false;
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  HasThumb2 = false;
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  NoARM = false;
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  PostRAScheduler = false;
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  IsR9Reserved = ReserveR9;
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  UseMovt = false;
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  SupportsTailCall = false;
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  HasFP16 = false;
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  HasD16 = false;
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  HasHardwareDivide = false;
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  HasHardwareDivideInARM = false;
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  HasT2ExtractPack = false;
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  HasDataBarrier = false;
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  Pref32BitThumb = false;
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  AvoidCPSRPartialUpdate = false;
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  AvoidMOVsShifterOperand = false;
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  HasRAS = false;
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  HasMPExtension = false;
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  HasVirtualization = false;
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  FPOnlySP = false;
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  HasPerfMon = false;
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  HasTrustZone = false;
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  HasCrypto = false;
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  HasCRC = false;
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  HasZeroCycleZeroing = false;
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  AllowsUnalignedMem = false;
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  Thumb2DSP = false;
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  UseNaClTrap = false;
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  UnsafeFPMath = false;
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}
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void ARMSubtarget::resetSubtargetFeatures(const MachineFunction *MF) {
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  AttributeSet FnAttrs = MF->getFunction()->getAttributes();
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  Attribute CPUAttr = FnAttrs.getAttribute(AttributeSet::FunctionIndex,
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                                           "target-cpu");
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  Attribute FSAttr = FnAttrs.getAttribute(AttributeSet::FunctionIndex,
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                                          "target-features");
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  std::string CPU =
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    !CPUAttr.hasAttribute(Attribute::None) ?CPUAttr.getValueAsString() : "";
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  std::string FS =
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    !FSAttr.hasAttribute(Attribute::None) ? FSAttr.getValueAsString() : "";
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  if (!FS.empty()) {
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    initializeEnvironment();
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    resetSubtargetFeatures(CPU, FS);
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  }
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  MinSize =
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      FnAttrs.hasAttribute(AttributeSet::FunctionIndex, Attribute::MinSize);
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}
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void ARMSubtarget::resetSubtargetFeatures(StringRef CPU, StringRef FS) {
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  if (CPUString.empty()) {
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    if (isTargetIOS() && TargetTriple.getArchName().endswith("v7s"))
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      // Default to the Swift CPU when targeting armv7s/thumbv7s.
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      CPUString = "swift";
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    else
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      CPUString = "generic";
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  }
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  // Insert the architecture feature derived from the target triple into the
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  // feature string. This is important for setting features that are implied
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  // based on the architecture version.
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  std::string ArchFS = ARM_MC::ParseARMTriple(TargetTriple.getTriple(),
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                                              CPUString);
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  if (!FS.empty()) {
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    if (!ArchFS.empty())
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      ArchFS = ArchFS + "," + FS.str();
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    else
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      ArchFS = FS;
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  }
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  ParseSubtargetFeatures(CPUString, ArchFS);
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  // FIXME: This used enable V6T2 support implicitly for Thumb2 mode.
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  // Assert this for now to make the change obvious.
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  assert(hasV6T2Ops() || !hasThumb2());
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  // Keep a pointer to static instruction cost data for the specified CPU.
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  SchedModel = getSchedModelForCPU(CPUString);
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  // Initialize scheduling itinerary for the specified CPU.
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  InstrItins = getInstrItineraryForCPU(CPUString);
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  if (TargetABI == ARM_ABI_UNKNOWN) {
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    switch (TargetTriple.getEnvironment()) {
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    case Triple::Android:
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    case Triple::EABI:
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    case Triple::EABIHF:
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    case Triple::GNUEABI:
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    case Triple::GNUEABIHF:
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      TargetABI = ARM_ABI_AAPCS;
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      break;
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    default:
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      if ((isTargetIOS() && isMClass()) ||
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          (TargetTriple.isOSBinFormatMachO() &&
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           TargetTriple.getOS() == Triple::UnknownOS))
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        TargetABI = ARM_ABI_AAPCS;
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      else
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        TargetABI = ARM_ABI_APCS;
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      break;
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    }
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  }
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  // FIXME: this is invalid for WindowsCE
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  if (isTargetWindows()) {
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    TargetABI = ARM_ABI_AAPCS;
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    NoARM = true;
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  }
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  if (isAAPCS_ABI())
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    stackAlignment = 8;
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  if (isTargetNaCl())
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    stackAlignment = 16;
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  UseMovt = hasV6T2Ops() && ArmUseMOVT;
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  if (isTargetMachO()) {
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    IsR9Reserved = ReserveR9 | !HasV6Ops;
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    SupportsTailCall = !isTargetIOS() || !getTargetTriple().isOSVersionLT(5, 0);
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  } else {
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    IsR9Reserved = ReserveR9;
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    SupportsTailCall = !isThumb1Only();
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  }
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  if (!isThumb() || hasThumb2())
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    PostRAScheduler = true;
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  switch (Align) {
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    case DefaultAlign:
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      // Assume pre-ARMv6 doesn't support unaligned accesses.
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      //
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      // ARMv6 may or may not support unaligned accesses depending on the
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      // SCTLR.U bit, which is architecture-specific. We assume ARMv6
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      // Darwin and NetBSD targets support unaligned accesses, and others don't.
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      //
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      // ARMv7 always has SCTLR.U set to 1, but it has a new SCTLR.A bit
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      // which raises an alignment fault on unaligned accesses. Linux
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      // defaults this bit to 0 and handles it as a system-wide (not
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      // per-process) setting. It is therefore safe to assume that ARMv7+
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      // Linux targets support unaligned accesses. The same goes for NaCl.
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      //
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      // The above behavior is consistent with GCC.
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      AllowsUnalignedMem =
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          (hasV7Ops() && (isTargetLinux() || isTargetNaCl() ||
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                          isTargetNetBSD())) ||
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          (hasV6Ops() && (isTargetMachO() || isTargetNetBSD()));
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      // The one exception is cortex-m0, which despite being v6, does not
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      // support unaligned accesses. Rather than make the above boolean
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      // expression even more obtuse, just override the value here.
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      if (isThumb1Only() && isMClass())
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        AllowsUnalignedMem = false;
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      break;
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    case StrictAlign:
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      AllowsUnalignedMem = false;
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      break;
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    case NoStrictAlign:
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      AllowsUnalignedMem = true;
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      break;
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  }
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  switch (IT) {
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  case DefaultIT:
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    RestrictIT = hasV8Ops() ? true : false;
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    break;
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  case RestrictedIT:
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    RestrictIT = true;
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    break;
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  case NoRestrictedIT:
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    RestrictIT = false;
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    break;
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  }
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  // NEON f32 ops are non-IEEE 754 compliant. Darwin is ok with it by default.
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  uint64_t Bits = getFeatureBits();
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  if ((Bits & ARM::ProcA5 || Bits & ARM::ProcA8) && // Where this matters
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      (Options.UnsafeFPMath || isTargetDarwin()))
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    UseNEONForSinglePrecisionFP = true;
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}
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/// GVIsIndirectSymbol - true if the GV will be accessed via an indirect symbol.
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bool
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ARMSubtarget::GVIsIndirectSymbol(const GlobalValue *GV,
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                                 Reloc::Model RelocM) const {
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  if (RelocM == Reloc::Static)
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    return false;
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  // Materializable GVs (in JIT lazy compilation mode) do not require an extra
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  // load from stub.
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  bool isDecl = GV->hasAvailableExternallyLinkage();
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  if (GV->isDeclaration() && !GV->isMaterializable())
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    isDecl = true;
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  if (!isTargetMachO()) {
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    // Extra load is needed for all externally visible.
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    if (GV->hasLocalLinkage() || GV->hasHiddenVisibility())
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      return false;
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    return true;
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  } else {
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    if (RelocM == Reloc::PIC_) {
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      // If this is a strong reference to a definition, it is definitely not
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      // through a stub.
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      if (!isDecl && !GV->isWeakForLinker())
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        return false;
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      // Unless we have a symbol with hidden visibility, we have to go through a
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      // normal $non_lazy_ptr stub because this symbol might be resolved late.
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      if (!GV->hasHiddenVisibility())  // Non-hidden $non_lazy_ptr reference.
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        return true;
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      // If symbol visibility is hidden, we have a stub for common symbol
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      // references and external declarations.
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      if (isDecl || GV->hasCommonLinkage())
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        // Hidden $non_lazy_ptr reference.
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        return true;
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      return false;
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    } else {
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      // If this is a strong reference to a definition, it is definitely not
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      // through a stub.
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      if (!isDecl && !GV->isWeakForLinker())
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        return false;
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      // Unless we have a symbol with hidden visibility, we have to go through a
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      // normal $non_lazy_ptr stub because this symbol might be resolved late.
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      if (!GV->hasHiddenVisibility())  // Non-hidden $non_lazy_ptr reference.
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        return true;
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    }
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  }
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  return false;
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}
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unsigned ARMSubtarget::getMispredictionPenalty() const {
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  return SchedModel->MispredictPenalty;
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}
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bool ARMSubtarget::hasSinCos() const {
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  return getTargetTriple().getOS() == Triple::IOS &&
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    !getTargetTriple().isOSVersionLT(7, 0);
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}
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bool ARMSubtarget::enablePostRAScheduler(
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           CodeGenOpt::Level OptLevel,
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           TargetSubtargetInfo::AntiDepBreakMode& Mode,
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           RegClassVector& CriticalPathRCs) const {
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  Mode = TargetSubtargetInfo::ANTIDEP_NONE;
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  return PostRAScheduler && OptLevel >= CodeGenOpt::Default;
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}
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