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			372 lines
		
	
	
		
			12 KiB
		
	
	
	
		
			C++
		
	
	
	
	
	
			
		
		
	
	
			372 lines
		
	
	
		
			12 KiB
		
	
	
	
		
			C++
		
	
	
	
	
	
//===-- X86Subtarget.cpp - X86 Subtarget Information ------------*- C++ -*-===//
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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 X86 specific subclass of TargetSubtarget.
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//
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//===----------------------------------------------------------------------===//
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#define DEBUG_TYPE "subtarget"
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#include "X86Subtarget.h"
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#include "X86InstrInfo.h"
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#include "X86GenSubtarget.inc"
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#include "llvm/GlobalValue.h"
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#include "llvm/Support/Debug.h"
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#include "llvm/Support/raw_ostream.h"
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#include "llvm/System/Host.h"
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#include "llvm/Target/TargetMachine.h"
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#include "llvm/Target/TargetOptions.h"
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#include "llvm/ADT/SmallVector.h"
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using namespace llvm;
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#if defined(_MSC_VER)
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#include <intrin.h>
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#endif
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/// ClassifyBlockAddressReference - Classify a blockaddress reference for the
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/// current subtarget according to how we should reference it in a non-pcrel
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/// context.
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unsigned char X86Subtarget::
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ClassifyBlockAddressReference() const {
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  if (isPICStyleGOT())    // 32-bit ELF targets.
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    return X86II::MO_GOTOFF;
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  if (isPICStyleStubPIC())   // Darwin/32 in PIC mode.
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    return X86II::MO_PIC_BASE_OFFSET;
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  // Direct static reference to label.
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  return X86II::MO_NO_FLAG;
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}
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/// ClassifyGlobalReference - Classify a global variable reference for the
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/// current subtarget according to how we should reference it in a non-pcrel
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/// context.
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unsigned char X86Subtarget::
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ClassifyGlobalReference(const GlobalValue *GV, const TargetMachine &TM) const {
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  // DLLImport only exists on windows, it is implemented as a load from a
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  // DLLIMPORT stub.
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  if (GV->hasDLLImportLinkage())
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    return X86II::MO_DLLIMPORT;
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  // Determine whether this is a reference to a definition or a declaration.
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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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  // X86-64 in PIC mode.
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  if (isPICStyleRIPRel()) {
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    // Large model never uses stubs.
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    if (TM.getCodeModel() == CodeModel::Large)
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      return X86II::MO_NO_FLAG;
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    if (isTargetDarwin()) {
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      // If symbol visibility is hidden, the extra load is not needed if
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      // target is x86-64 or the symbol is definitely defined in the current
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      // translation unit.
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      if (GV->hasDefaultVisibility() &&
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          (isDecl || GV->isWeakForLinker()))
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        return X86II::MO_GOTPCREL;
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    } else {
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      assert(isTargetELF() && "Unknown rip-relative target");
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      // Extra load is needed for all externally visible.
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      if (!GV->hasLocalLinkage() && GV->hasDefaultVisibility())
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        return X86II::MO_GOTPCREL;
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    }
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    return X86II::MO_NO_FLAG;
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  }
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  if (isPICStyleGOT()) {   // 32-bit ELF targets.
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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 X86II::MO_GOTOFF;
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    return X86II::MO_GOT;
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  }
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  if (isPICStyleStubPIC()) {  // Darwin/32 in PIC mode.
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    // Determine whether we have a stub reference and/or whether the reference
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    // is relative to the PIC base or not.
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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 X86II::MO_PIC_BASE_OFFSET;
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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 X86II::MO_DARWIN_NONLAZY_PIC_BASE;
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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 X86II::MO_DARWIN_HIDDEN_NONLAZY_PIC_BASE;
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    }
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    // Otherwise, no stub.
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    return X86II::MO_PIC_BASE_OFFSET;
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  }
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  if (isPICStyleStubNoDynamic()) {  // Darwin/32 in -mdynamic-no-pic mode.
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    // Determine whether we have a stub reference.
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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 X86II::MO_NO_FLAG;
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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 X86II::MO_DARWIN_NONLAZY;
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    // Otherwise, no stub.
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    return X86II::MO_NO_FLAG;
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  }
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  // Direct static reference to global.
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  return X86II::MO_NO_FLAG;
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}
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/// getBZeroEntry - This function returns the name of a function which has an
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/// interface like the non-standard bzero function, if such a function exists on
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/// the current subtarget and it is considered prefereable over memset with zero
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/// passed as the second argument. Otherwise it returns null.
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const char *X86Subtarget::getBZeroEntry() const {
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  // Darwin 10 has a __bzero entry point for this purpose.
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  if (getDarwinVers() >= 10)
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    return "__bzero";
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  return 0;
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}
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/// IsLegalToCallImmediateAddr - Return true if the subtarget allows calls
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/// to immediate address.
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bool X86Subtarget::IsLegalToCallImmediateAddr(const TargetMachine &TM) const {
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  if (Is64Bit)
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    return false;
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  return isTargetELF() || TM.getRelocationModel() == Reloc::Static;
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}
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/// getSpecialAddressLatency - For targets where it is beneficial to
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/// backschedule instructions that compute addresses, return a value
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/// indicating the number of scheduling cycles of backscheduling that
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/// should be attempted.
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unsigned X86Subtarget::getSpecialAddressLatency() const {
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  // For x86 out-of-order targets, back-schedule address computations so
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  // that loads and stores aren't blocked.
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  // This value was chosen arbitrarily.
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  return 200;
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}
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/// GetCpuIDAndInfo - Execute the specified cpuid and return the 4 values in the
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/// specified arguments.  If we can't run cpuid on the host, return true.
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static bool GetCpuIDAndInfo(unsigned value, unsigned *rEAX,
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                            unsigned *rEBX, unsigned *rECX, unsigned *rEDX) {
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#if defined(__x86_64__) || defined(_M_AMD64) || defined (_M_X64)
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  #if defined(__GNUC__)
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    // gcc doesn't know cpuid would clobber ebx/rbx. Preseve it manually.
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    asm ("movq\t%%rbx, %%rsi\n\t"
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         "cpuid\n\t"
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         "xchgq\t%%rbx, %%rsi\n\t"
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         : "=a" (*rEAX),
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           "=S" (*rEBX),
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           "=c" (*rECX),
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           "=d" (*rEDX)
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         :  "a" (value));
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    return false;
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  #elif defined(_MSC_VER)
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    int registers[4];
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    __cpuid(registers, value);
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    *rEAX = registers[0];
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    *rEBX = registers[1];
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    *rECX = registers[2];
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    *rEDX = registers[3];
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    return false;
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  #endif
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#elif defined(i386) || defined(__i386__) || defined(__x86__) || defined(_M_IX86)
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  #if defined(__GNUC__)
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    asm ("movl\t%%ebx, %%esi\n\t"
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         "cpuid\n\t"
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         "xchgl\t%%ebx, %%esi\n\t"
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         : "=a" (*rEAX),
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           "=S" (*rEBX),
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           "=c" (*rECX),
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           "=d" (*rEDX)
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         :  "a" (value));
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    return false;
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  #elif defined(_MSC_VER)
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    __asm {
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      mov   eax,value
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      cpuid
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      mov   esi,rEAX
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      mov   dword ptr [esi],eax
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      mov   esi,rEBX
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      mov   dword ptr [esi],ebx
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      mov   esi,rECX
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      mov   dword ptr [esi],ecx
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      mov   esi,rEDX
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      mov   dword ptr [esi],edx
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    }
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    return false;
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  #endif
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#endif
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  return true;
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}
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static void DetectFamilyModel(unsigned EAX, unsigned &Family, unsigned &Model) {
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  Family = (EAX >> 8) & 0xf; // Bits 8 - 11
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  Model  = (EAX >> 4) & 0xf; // Bits 4 - 7
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  if (Family == 6 || Family == 0xf) {
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    if (Family == 0xf)
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      // Examine extended family ID if family ID is F.
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      Family += (EAX >> 20) & 0xff;    // Bits 20 - 27
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    // Examine extended model ID if family ID is 6 or F.
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    Model += ((EAX >> 16) & 0xf) << 4; // Bits 16 - 19
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  }
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}
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void X86Subtarget::AutoDetectSubtargetFeatures() {
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  unsigned EAX = 0, EBX = 0, ECX = 0, EDX = 0;
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  union {
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    unsigned u[3];
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    char     c[12];
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  } text;
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  if (GetCpuIDAndInfo(0, &EAX, text.u+0, text.u+2, text.u+1))
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    return;
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  GetCpuIDAndInfo(0x1, &EAX, &EBX, &ECX, &EDX);
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  if ((EDX >> 15) & 1) HasCMov = true;
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  if ((EDX >> 23) & 1) X86SSELevel = MMX;
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  if ((EDX >> 25) & 1) X86SSELevel = SSE1;
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  if ((EDX >> 26) & 1) X86SSELevel = SSE2;
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  if (ECX & 0x1)       X86SSELevel = SSE3;
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  if ((ECX >> 9)  & 1) X86SSELevel = SSSE3;
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  if ((ECX >> 19) & 1) X86SSELevel = SSE41;
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  if ((ECX >> 20) & 1) X86SSELevel = SSE42;
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  bool IsIntel = memcmp(text.c, "GenuineIntel", 12) == 0;
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  bool IsAMD   = !IsIntel && memcmp(text.c, "AuthenticAMD", 12) == 0;
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  HasCLMUL = IsIntel && ((ECX >> 1) & 0x1);
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  HasFMA3  = IsIntel && ((ECX >> 12) & 0x1);
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  HasAVX   = ((ECX >> 28) & 0x1);
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  HasAES   = IsIntel && ((ECX >> 25) & 0x1);
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  if (IsIntel || IsAMD) {
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    // Determine if bit test memory instructions are slow.
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    unsigned Family = 0;
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    unsigned Model  = 0;
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    DetectFamilyModel(EAX, Family, Model);
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    IsBTMemSlow = IsAMD || (Family == 6 && Model >= 13);
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    // If it's Nehalem, unaligned memory access is fast.
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    if (Family == 15 && Model == 26)
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      IsUAMemFast = true;
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    GetCpuIDAndInfo(0x80000001, &EAX, &EBX, &ECX, &EDX);
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    HasX86_64 = (EDX >> 29) & 0x1;
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    HasSSE4A = IsAMD && ((ECX >> 6) & 0x1);
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    HasFMA4 = IsAMD && ((ECX >> 16) & 0x1);
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  }
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}
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X86Subtarget::X86Subtarget(const std::string &TT, const std::string &FS, 
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                           bool is64Bit)
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  : PICStyle(PICStyles::None)
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  , X86SSELevel(NoMMXSSE)
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  , X863DNowLevel(NoThreeDNow)
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  , HasCMov(false)
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  , HasX86_64(false)
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  , HasSSE4A(false)
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  , HasAVX(false)
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  , HasAES(false)
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  , HasCLMUL(false)
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  , HasFMA3(false)
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  , HasFMA4(false)
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  , IsBTMemSlow(false)
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  , IsUAMemFast(false)
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  , HasVectorUAMem(false)
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  , stackAlignment(8)
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  // FIXME: this is a known good value for Yonah. How about others?
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  , MaxInlineSizeThreshold(128)
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  , TargetTriple(TT)
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  , Is64Bit(is64Bit) {
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  // default to hard float ABI
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  if (FloatABIType == FloatABI::Default)
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    FloatABIType = FloatABI::Hard;
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  // Determine default and user specified characteristics
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  if (!FS.empty()) {
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    // If feature string is not empty, parse features string.
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    std::string CPU = sys::getHostCPUName();
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    ParseSubtargetFeatures(FS, CPU);
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    // All X86-64 CPUs also have SSE2, however user might request no SSE via 
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    // -mattr, so don't force SSELevel here.
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  } else {
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    // Otherwise, use CPUID to auto-detect feature set.
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    AutoDetectSubtargetFeatures();
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    // Make sure SSE2 is enabled; it is available on all X86-64 CPUs.
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    if (Is64Bit && X86SSELevel < SSE2)
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      X86SSELevel = SSE2;
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  }
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  // If requesting codegen for X86-64, make sure that 64-bit features
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  // are enabled.
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  if (Is64Bit) {
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    HasX86_64 = true;
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    // All 64-bit cpus have cmov support.
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    HasCMov = true;
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  }
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  DEBUG(dbgs() << "Subtarget features: SSELevel " << X86SSELevel
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               << ", 3DNowLevel " << X863DNowLevel
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               << ", 64bit " << HasX86_64 << "\n");
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  assert((!Is64Bit || HasX86_64) &&
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         "64-bit code requested on a subtarget that doesn't support it!");
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  // Stack alignment is 16 bytes on Darwin (both 32 and 64 bit) and for all 64
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  // bit targets.
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  if (isTargetDarwin() || Is64Bit)
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    stackAlignment = 16;
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  if (StackAlignment)
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    stackAlignment = StackAlignment;
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}
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/// IsCalleePop - Determines whether the callee is required to pop its
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/// own arguments. Callee pop is necessary to support tail calls.
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bool X86Subtarget::IsCalleePop(bool IsVarArg,
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                               CallingConv::ID CallingConv) const {
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  if (IsVarArg)
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    return false;
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  switch (CallingConv) {
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  default:
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    return false;
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  case CallingConv::X86_StdCall:
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    return !is64Bit();
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  case CallingConv::X86_FastCall:
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    return !is64Bit();
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  case CallingConv::X86_ThisCall:
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    return !is64Bit();
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  case CallingConv::Fast:
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    return GuaranteedTailCallOpt;
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  case CallingConv::GHC:
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    return GuaranteedTailCallOpt;
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  }
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}
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