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This is being disabled because it is no longer needed for performance. It is only used by postRAscheduler which is also planned for removal, and it is implemented with an out-dated view of register liveness. It consideres aliases instead of register units, assumes valid kill flags, and assumes implicit uses on partial register defs. Kill flags and implicit operands are error prone and impossible to verify. We should gradually eliminate dependence on them in the postRA phases. Targets that still benefit from this should move to the MI scheduler. If that doesn't solve the problem, then we should add a hook to regalloc to optimize reload placement. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@191348 91177308-0d34-0410-b5e6-96231b3b80d8
288 lines
9.3 KiB
C++
288 lines
9.3 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/GlobalValue.h"
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#include "llvm/IR/Function.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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ARMSubtarget::ARMSubtarget(const std::string &TT, const std::string &CPU,
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const std::string &FS, 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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, TargetTriple(TT)
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, Options(Options)
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, TargetABI(ARM_ABI_APCS) {
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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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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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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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FPOnlySP = false;
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HasPerfMon = false;
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HasTrustZone = false;
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HasCrypto = 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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}
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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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// Thumb2 implies at least V6T2. FIXME: Fix tests to explicitly specify a
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// ARM version or CPU and then remove this.
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if (!HasV6T2Ops && hasThumb2())
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HasV4TOps = HasV5TOps = HasV5TEOps = HasV6Ops = HasV6T2Ops = true;
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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 ((TargetTriple.getTriple().find("eabi") != std::string::npos) ||
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(isTargetIOS() && isMClass()))
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// FIXME: We might want to separate AAPCS and EABI. Some systems, e.g.
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// Darwin-EABI conforms to AACPS but not the rest of EABI.
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TargetABI = ARM_ABI_AAPCS;
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if (isAAPCS_ABI())
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stackAlignment = 8;
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UseMovt = hasV6T2Ops() && ArmUseMOVT;
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if (!isTargetIOS()) {
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IsR9Reserved = ReserveR9;
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} else {
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IsR9Reserved = ReserveR9 | !HasV6Ops;
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SupportsTailCall = !getTargetTriple().isOSVersionLT(5, 0);
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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 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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(hasV6Ops() && isTargetDarwin()));
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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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// 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 (!isTargetDarwin()) {
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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::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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