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      1 //=--- AArch64MCExpr.h - AArch64 specific MC expression classes ---*- 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 describes AArch64-specific MCExprs, used for modifiers like
     11 // ":lo12:" or ":gottprel_g1:".
     12 //
     13 //===----------------------------------------------------------------------===//
     14 
     15 #ifndef LLVM_AArch64MCEXPR_H
     16 #define LLVM_AArch64MCEXPR_H
     17 
     18 #include "llvm/MC/MCExpr.h"
     19 #include "llvm/Support/ErrorHandling.h"
     20 
     21 namespace llvm {
     22 
     23 class AArch64MCExpr : public MCTargetExpr {
     24 public:
     25   enum VariantKind {
     26     VK_NONE     = 0x000,
     27 
     28     // Symbol locations specifying (roughly speaking) what calculation should be
     29     // performed to construct the final address for the relocated
     30     // symbol. E.g. direct, via the GOT, ...
     31     VK_ABS      = 0x001,
     32     VK_SABS     = 0x002,
     33     VK_GOT      = 0x003,
     34     VK_DTPREL   = 0x004,
     35     VK_GOTTPREL = 0x005,
     36     VK_TPREL    = 0x006,
     37     VK_TLSDESC  = 0x007,
     38     VK_SymLocBits = 0x00f,
     39 
     40     // Variants specifying which part of the final address calculation is
     41     // used. E.g. the low 12 bits for an ADD/LDR, the middle 16 bits for a
     42     // MOVZ/MOVK.
     43     VK_PAGE     = 0x010,
     44     VK_PAGEOFF  = 0x020,
     45     VK_HI12     = 0x030,
     46     VK_G0       = 0x040,
     47     VK_G1       = 0x050,
     48     VK_G2       = 0x060,
     49     VK_G3       = 0x070,
     50     VK_AddressFragBits = 0x0f0,
     51 
     52     // Whether the final relocation is a checked one (where a linker should
     53     // perform a range-check on the final address) or not. Note that this field
     54     // is unfortunately sometimes omitted from the assembly syntax. E.g. :lo12:
     55     // on its own is a non-checked relocation. We side with ELF on being
     56     // explicit about this!
     57     VK_NC       = 0x100,
     58 
     59     // Convenience definitions for referring to specific textual representations
     60     // of relocation specifiers. Note that this means the "_NC" is sometimes
     61     // omitted in line with assembly syntax here (VK_LO12 rather than VK_LO12_NC
     62     // since a user would write ":lo12:").
     63     VK_CALL              = VK_ABS,
     64     VK_ABS_PAGE          = VK_ABS      | VK_PAGE,
     65     VK_ABS_G3            = VK_ABS      | VK_G3,
     66     VK_ABS_G2            = VK_ABS      | VK_G2,
     67     VK_ABS_G2_S          = VK_SABS     | VK_G2,
     68     VK_ABS_G2_NC         = VK_ABS      | VK_G2      | VK_NC,
     69     VK_ABS_G1            = VK_ABS      | VK_G1,
     70     VK_ABS_G1_S          = VK_SABS     | VK_G1,
     71     VK_ABS_G1_NC         = VK_ABS      | VK_G1      | VK_NC,
     72     VK_ABS_G0            = VK_ABS      | VK_G0,
     73     VK_ABS_G0_S          = VK_SABS     | VK_G0,
     74     VK_ABS_G0_NC         = VK_ABS      | VK_G0      | VK_NC,
     75     VK_LO12              = VK_ABS      | VK_PAGEOFF | VK_NC,
     76     VK_GOT_LO12          = VK_GOT      | VK_PAGEOFF | VK_NC,
     77     VK_GOT_PAGE          = VK_GOT      | VK_PAGE,
     78     VK_DTPREL_G2         = VK_DTPREL   | VK_G2,
     79     VK_DTPREL_G1         = VK_DTPREL   | VK_G1,
     80     VK_DTPREL_G1_NC      = VK_DTPREL   | VK_G1      | VK_NC,
     81     VK_DTPREL_G0         = VK_DTPREL   | VK_G0,
     82     VK_DTPREL_G0_NC      = VK_DTPREL   | VK_G0      | VK_NC,
     83     VK_DTPREL_HI12       = VK_DTPREL   | VK_HI12,
     84     VK_DTPREL_LO12       = VK_DTPREL   | VK_PAGEOFF,
     85     VK_DTPREL_LO12_NC    = VK_DTPREL   | VK_PAGEOFF | VK_NC,
     86     VK_GOTTPREL_PAGE     = VK_GOTTPREL | VK_PAGE,
     87     VK_GOTTPREL_LO12_NC  = VK_GOTTPREL | VK_PAGEOFF | VK_NC,
     88     VK_GOTTPREL_G1       = VK_GOTTPREL | VK_G1,
     89     VK_GOTTPREL_G0_NC    = VK_GOTTPREL | VK_G0      | VK_NC,
     90     VK_TPREL_G2          = VK_TPREL    | VK_G2,
     91     VK_TPREL_G1          = VK_TPREL    | VK_G1,
     92     VK_TPREL_G1_NC       = VK_TPREL    | VK_G1      | VK_NC,
     93     VK_TPREL_G0          = VK_TPREL    | VK_G0,
     94     VK_TPREL_G0_NC       = VK_TPREL    | VK_G0      | VK_NC,
     95     VK_TPREL_HI12        = VK_TPREL    | VK_HI12,
     96     VK_TPREL_LO12        = VK_TPREL    | VK_PAGEOFF,
     97     VK_TPREL_LO12_NC     = VK_TPREL    | VK_PAGEOFF | VK_NC,
     98     VK_TLSDESC_LO12      = VK_TLSDESC  | VK_PAGEOFF | VK_NC,
     99     VK_TLSDESC_PAGE      = VK_TLSDESC  | VK_PAGE,
    100 
    101     VK_INVALID  = 0xfff
    102   };
    103 
    104 private:
    105   const MCExpr *Expr;
    106   const VariantKind Kind;
    107 
    108   explicit AArch64MCExpr(const MCExpr *Expr, VariantKind Kind)
    109     : Expr(Expr), Kind(Kind) {}
    110 
    111 public:
    112   /// @name Construction
    113   /// @{
    114 
    115   static const AArch64MCExpr *Create(const MCExpr *Expr, VariantKind Kind,
    116                                    MCContext &Ctx);
    117 
    118   /// @}
    119   /// @name Accessors
    120   /// @{
    121 
    122   /// Get the kind of this expression.
    123   VariantKind getKind() const { return static_cast<VariantKind>(Kind); }
    124 
    125   /// Get the expression this modifier applies to.
    126   const MCExpr *getSubExpr() const { return Expr; }
    127 
    128   /// @}
    129   /// @name VariantKind information extractors.
    130   /// @{
    131 
    132   static VariantKind getSymbolLoc(VariantKind Kind) {
    133     return static_cast<VariantKind>(Kind & VK_SymLocBits);
    134   }
    135 
    136   static VariantKind getAddressFrag(VariantKind Kind) {
    137     return static_cast<VariantKind>(Kind & VK_AddressFragBits);
    138   }
    139 
    140   static bool isNotChecked(VariantKind Kind) { return Kind & VK_NC; }
    141 
    142   /// @}
    143 
    144   /// Convert the variant kind into an ELF-appropriate modifier
    145   /// (e.g. ":got:", ":lo12:").
    146   StringRef getVariantKindName() const;
    147 
    148   void PrintImpl(raw_ostream &OS) const override;
    149 
    150   void visitUsedExpr(MCStreamer &Streamer) const override;
    151 
    152   const MCSection *FindAssociatedSection() const override;
    153 
    154   bool EvaluateAsRelocatableImpl(MCValue &Res,
    155                                  const MCAsmLayout *Layout) const override;
    156 
    157   void fixELFSymbolsInTLSFixups(MCAssembler &Asm) const override;
    158 
    159   static bool classof(const MCExpr *E) {
    160     return E->getKind() == MCExpr::Target;
    161   }
    162 
    163   static bool classof(const AArch64MCExpr *) { return true; }
    164 
    165 };
    166 } // end namespace llvm
    167 
    168 #endif
    169