lib/Target/ARM/ARMSubtarget.cpp

   1 //===-- ARMSubtarget.cpp - ARM Subtarget Information ------------*- C++ -*-===//
   2 //
   3 //                     The LLVM Compiler Infrastructure
   4 //
   5 // This file is distributed under the University of Illinois Open Source
   6 // License. See LICENSE.TXT for details.
   7 //
   8 //===----------------------------------------------------------------------===//
   9 //
  10 // This file implements the ARM specific subclass of TargetSubtarget.
  11 //
  12 //===----------------------------------------------------------------------===//
  13
  14 #include "ARMSubtarget.h"
  15 #include "ARMGenSubtarget.inc"
  16 #include "llvm/GlobalValue.h"
  17 #include "llvm/Target/TargetOptions.h"
  18 #include "llvm/Support/CommandLine.h"
  19 using namespace llvm;
  20
  21 static cl::opt<bool>
  22 ReserveR9("arm-reserve-r9", cl::Hidden,
  23           cl::desc("Reserve R9, making it unavailable as GPR"));
  24
  25 ARMSubtarget::ARMSubtarget(const std::string &TT, const std::string &FS,
  26                            bool isThumb)
  27   : ARMArchVersion(V4T)
  28   , ARMFPUType(None)
  29   , UseNEONForSinglePrecisionFP(false)
  30   , IsThumb(isThumb)
  31   , ThumbMode(Thumb1)
  32   , IsR9Reserved(ReserveR9)
  33   , stackAlignment(4)
  34   , CPUString("generic")
  35   , TargetType(isELF) // Default to ELF unless otherwise specified.
  36   , TargetABI(ARM_ABI_APCS) {
  37   // default to soft float ABI
  38   if (FloatABIType == FloatABI::Default)
  39     FloatABIType = FloatABI::Soft;
  40
  41   // Determine default and user specified characteristics
  42
  43   // Parse features string.
  44   CPUString = ParseSubtargetFeatures(FS, CPUString);
  45
  46   // Set the boolean corresponding to the current target triple, or the default
  47   // if one cannot be determined, to true.
  48   unsigned Len = TT.length();
  49   unsigned Idx = 0;
  50
  51   if (Len >= 5 && TT.substr(0, 4) == "armv")
  52     Idx = 4;
  53   else if (Len >= 6 && TT.substr(0, 5) == "thumb") {
  54     IsThumb = true;
  55     if (Len >= 7 && TT[5] == 'v')
  56       Idx = 6;
  57   }
  58   if (Idx) {
  59     unsigned SubVer = TT[Idx];
  60     if (SubVer > '4' && SubVer <= '9') {
  61       if (SubVer >= '7') {
  62         ARMArchVersion = V7A;
  63       } else if (SubVer == '6') {
  64         ARMArchVersion = V6;
  65         if (Len >= Idx+3 && TT[Idx+1] == 't' && TT[Idx+2] == '2')
  66           ARMArchVersion = V6T2;
  67       } else if (SubVer == '5') {
  68         ARMArchVersion = V5T;
  69         if (Len >= Idx+3 && TT[Idx+1] == 't' && TT[Idx+2] == 'e')
  70           ARMArchVersion = V5TE;
  71       }
  72       if (ARMArchVersion >= V6T2)
  73         ThumbMode = Thumb2;
  74     }
  75   }
  76
  77   // Thumb2 implies at least V6T2.
  78   if (ARMArchVersion < V6T2 && ThumbMode >= Thumb2)
  79     ARMArchVersion = V6T2;
  80
  81   if (Len >= 10) {
  82     if (TT.find("-darwin") != std::string::npos)
  83       // arm-darwin
  84       TargetType = isDarwin;
  85   }
  86
  87   if (TT.find("eabi") != std::string::npos)
  88     TargetABI = ARM_ABI_AAPCS;
  89
  90   if (isAAPCS_ABI())
  91     stackAlignment = 8;
  92
  93   if (isTargetDarwin())
  94     IsR9Reserved = ReserveR9 | (ARMArchVersion < V6);
  95 }
  96
  97 /// GVIsIndirectSymbol - true if the GV will be accessed via an indirect symbol.
  98 bool
  99 ARMSubtarget::GVIsIndirectSymbol(GlobalValue *GV, Reloc::Model RelocM) const {
 100   if (RelocM == Reloc::Static)
 101     return false;
 102
 103   // GV with ghost linkage (in JIT lazy compilation mode) do not require an
 104   // extra load from stub.
 105   bool isDecl = GV->isDeclaration() && !GV->hasNotBeenReadFromBitcode();
 106
 107   if (!isTargetDarwin()) {
 108     // Extra load is needed for all externally visible.
 109     if (GV->hasLocalLinkage() || GV->hasHiddenVisibility())
 110       return false;
 111     return true;
 112   } else {
 113     if (RelocM == Reloc::PIC_) {
 114       // If this is a strong reference to a definition, it is definitely not
 115       // through a stub.
 116       if (!isDecl && !GV->isWeakForLinker())
 117         return false;
 118
 119       // Unless we have a symbol with hidden visibility, we have to go through a
 120       // normal $non_lazy_ptr stub because this symbol might be resolved late.
 121       if (!GV->hasHiddenVisibility())  // Non-hidden $non_lazy_ptr reference.
 122         return true;
 123
 124       // If symbol visibility is hidden, we have a stub for common symbol
 125       // references and external declarations.
 126       if (isDecl || GV->hasCommonLinkage())
 127         // Hidden $non_lazy_ptr reference.
 128         return true;
 129
 130       return false;
 131     } else {
 132       // If this is a strong reference to a definition, it is definitely not
 133       // through a stub.
 134       if (!isDecl && !GV->isWeakForLinker())
 135         return false;
 136
 137       // Unless we have a symbol with hidden visibility, we have to go through a
 138       // normal $non_lazy_ptr stub because this symbol might be resolved late.
 139       if (!GV->hasHiddenVisibility())  // Non-hidden $non_lazy_ptr reference.
 140         return true;
 141     }
 142   }
 143
 144   return false;
 145 }