1//===-- X86MachORelocationInfo.cpp ----------------------------------------===//
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#include "MCTargetDesc/X86MCTargetDesc.h"
11#include "llvm/MC/MCContext.h"
12#include "llvm/MC/MCExpr.h"
13#include "llvm/MC/MCInst.h"
14#include "llvm/MC/MCRelocationInfo.h"
15#include "llvm/MC/MCSymbol.h"
16#include "llvm/Object/MachO.h"
17
18using namespace llvm;
19using namespace object;
20using namespace MachO;
21
22namespace {
23class X86_64MachORelocationInfo : public MCRelocationInfo {
24public:
25  X86_64MachORelocationInfo(MCContext &Ctx) : MCRelocationInfo(Ctx) {}
26
27  const MCExpr *createExprForRelocation(RelocationRef Rel) override {
28    const MachOObjectFile *Obj = cast<MachOObjectFile>(Rel.getObject());
29
30    uint64_t RelType = Rel.getType();
31    symbol_iterator SymI = Rel.getSymbol();
32
33    ErrorOr<StringRef> SymNameOrErr = SymI->getName();
34    if (std::error_code EC = SymNameOrErr.getError())
35      report_fatal_error(EC.message());
36    StringRef SymName = *SymNameOrErr;
37    uint64_t SymAddr = SymI->getValue();
38
39    any_relocation_info RE = Obj->getRelocation(Rel.getRawDataRefImpl());
40    bool isPCRel = Obj->getAnyRelocationPCRel(RE);
41
42    MCSymbol *Sym = Ctx.getOrCreateSymbol(SymName);
43    // FIXME: check that the value is actually the same.
44    if (!Sym->isVariable())
45      Sym->setVariableValue(MCConstantExpr::create(SymAddr, Ctx));
46    const MCExpr *Expr = nullptr;
47
48    switch(RelType) {
49    case X86_64_RELOC_TLV:
50      Expr = MCSymbolRefExpr::create(Sym, MCSymbolRefExpr::VK_TLVP, Ctx);
51      break;
52    case X86_64_RELOC_SIGNED_4:
53      Expr = MCBinaryExpr::createAdd(MCSymbolRefExpr::create(Sym, Ctx),
54                                     MCConstantExpr::create(4, Ctx),
55                                     Ctx);
56      break;
57    case X86_64_RELOC_SIGNED_2:
58      Expr = MCBinaryExpr::createAdd(MCSymbolRefExpr::create(Sym, Ctx),
59                                     MCConstantExpr::create(2, Ctx),
60                                     Ctx);
61      break;
62    case X86_64_RELOC_SIGNED_1:
63      Expr = MCBinaryExpr::createAdd(MCSymbolRefExpr::create(Sym, Ctx),
64                                     MCConstantExpr::create(1, Ctx),
65                                     Ctx);
66      break;
67    case X86_64_RELOC_GOT_LOAD:
68      Expr = MCSymbolRefExpr::create(Sym, MCSymbolRefExpr::VK_GOTPCREL, Ctx);
69      break;
70    case X86_64_RELOC_GOT:
71      Expr = MCSymbolRefExpr::create(Sym, isPCRel ?
72                                     MCSymbolRefExpr::VK_GOTPCREL :
73                                     MCSymbolRefExpr::VK_GOT,
74                                     Ctx);
75      break;
76    case X86_64_RELOC_SUBTRACTOR:
77      {
78        Rel.moveNext();
79        any_relocation_info RENext =
80            Obj->getRelocation(Rel.getRawDataRefImpl());
81
82        // X86_64_SUBTRACTOR must be followed by a relocation of type
83        // X86_64_RELOC_UNSIGNED.
84        // NOTE: Scattered relocations don't exist on x86_64.
85        unsigned RType = Obj->getAnyRelocationType(RENext);
86        if (RType != X86_64_RELOC_UNSIGNED)
87          report_fatal_error("Expected X86_64_RELOC_UNSIGNED after "
88                             "X86_64_RELOC_SUBTRACTOR.");
89
90        const MCExpr *LHS = MCSymbolRefExpr::create(Sym, Ctx);
91
92        symbol_iterator RSymI = Rel.getSymbol();
93        uint64_t RSymAddr = RSymI->getValue();
94        ErrorOr<StringRef> RSymName = RSymI->getName();
95        if (std::error_code EC = RSymName.getError())
96          report_fatal_error(EC.message());
97
98        MCSymbol *RSym = Ctx.getOrCreateSymbol(*RSymName);
99        if (!RSym->isVariable())
100          RSym->setVariableValue(MCConstantExpr::create(RSymAddr, Ctx));
101
102        const MCExpr *RHS = MCSymbolRefExpr::create(RSym, Ctx);
103
104        Expr = MCBinaryExpr::createSub(LHS, RHS, Ctx);
105        break;
106      }
107    default:
108      Expr = MCSymbolRefExpr::create(Sym, Ctx);
109      break;
110    }
111    return Expr;
112  }
113};
114} // End unnamed namespace
115
116/// createX86_64MachORelocationInfo - Construct an X86-64 Mach-O RelocationInfo.
117MCRelocationInfo *llvm::createX86_64MachORelocationInfo(MCContext &Ctx) {
118  return new X86_64MachORelocationInfo(Ctx);
119}
120