1 //===-- X86WinCOFFObjectWriter.cpp - X86 Win COFF Writer ------------------===//
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/X86FixupKinds.h"
11 #include "MCTargetDesc/X86MCTargetDesc.h"
12 #include "llvm/BinaryFormat/COFF.h"
13 #include "llvm/MC/MCContext.h"
14 #include "llvm/MC/MCExpr.h"
15 #include "llvm/MC/MCFixup.h"
16 #include "llvm/MC/MCObjectWriter.h"
17 #include "llvm/MC/MCValue.h"
18 #include "llvm/MC/MCWinCOFFObjectWriter.h"
19 #include "llvm/Support/ErrorHandling.h"
20 
21 using namespace llvm;
22 
23 namespace {
24 
25 class X86WinCOFFObjectWriter : public MCWinCOFFObjectTargetWriter {
26 public:
27   X86WinCOFFObjectWriter(bool Is64Bit);
28   ~X86WinCOFFObjectWriter() override = default;
29 
30   unsigned getRelocType(MCContext &Ctx, const MCValue &Target,
31                         const MCFixup &Fixup, bool IsCrossSection,
32                         const MCAsmBackend &MAB) const override;
33 };
34 
35 } // end anonymous namespace
36 
37 X86WinCOFFObjectWriter::X86WinCOFFObjectWriter(bool Is64Bit)
38     : MCWinCOFFObjectTargetWriter(Is64Bit ? COFF::IMAGE_FILE_MACHINE_AMD64
39                                           : COFF::IMAGE_FILE_MACHINE_I386) {}
40 
41 unsigned X86WinCOFFObjectWriter::getRelocType(MCContext &Ctx,
42                                               const MCValue &Target,
43                                               const MCFixup &Fixup,
44                                               bool IsCrossSection,
45                                               const MCAsmBackend &MAB) const {
46   unsigned FixupKind = Fixup.getKind();
47   if (IsCrossSection) {
48     if (FixupKind != FK_Data_4 && FixupKind != llvm::X86::reloc_signed_4byte) {
49       Ctx.reportError(Fixup.getLoc(), "Cannot represent this expression");
50       return COFF::IMAGE_REL_AMD64_ADDR32;
51     }
52     FixupKind = FK_PCRel_4;
53   }
54 
55   MCSymbolRefExpr::VariantKind Modifier = Target.isAbsolute() ?
56     MCSymbolRefExpr::VK_None : Target.getSymA()->getKind();
57 
58   if (getMachine() == COFF::IMAGE_FILE_MACHINE_AMD64) {
59     switch (FixupKind) {
60     case FK_PCRel_4:
61     case X86::reloc_riprel_4byte:
62     case X86::reloc_riprel_4byte_movq_load:
63     case X86::reloc_riprel_4byte_relax:
64     case X86::reloc_riprel_4byte_relax_rex:
65       return COFF::IMAGE_REL_AMD64_REL32;
66     case FK_Data_4:
67     case X86::reloc_signed_4byte:
68     case X86::reloc_signed_4byte_relax:
69       if (Modifier == MCSymbolRefExpr::VK_COFF_IMGREL32)
70         return COFF::IMAGE_REL_AMD64_ADDR32NB;
71       if (Modifier == MCSymbolRefExpr::VK_SECREL)
72         return COFF::IMAGE_REL_AMD64_SECREL;
73       return COFF::IMAGE_REL_AMD64_ADDR32;
74     case FK_Data_8:
75       return COFF::IMAGE_REL_AMD64_ADDR64;
76     case FK_SecRel_2:
77       return COFF::IMAGE_REL_AMD64_SECTION;
78     case FK_SecRel_4:
79       return COFF::IMAGE_REL_AMD64_SECREL;
80     default:
81       llvm_unreachable("unsupported relocation type");
82     }
83   } else if (getMachine() == COFF::IMAGE_FILE_MACHINE_I386) {
84     switch (FixupKind) {
85     case FK_PCRel_4:
86     case X86::reloc_riprel_4byte:
87     case X86::reloc_riprel_4byte_movq_load:
88       return COFF::IMAGE_REL_I386_REL32;
89     case FK_Data_4:
90     case X86::reloc_signed_4byte:
91     case X86::reloc_signed_4byte_relax:
92       if (Modifier == MCSymbolRefExpr::VK_COFF_IMGREL32)
93         return COFF::IMAGE_REL_I386_DIR32NB;
94       if (Modifier == MCSymbolRefExpr::VK_SECREL)
95         return COFF::IMAGE_REL_AMD64_SECREL;
96       return COFF::IMAGE_REL_I386_DIR32;
97     case FK_SecRel_2:
98       return COFF::IMAGE_REL_I386_SECTION;
99     case FK_SecRel_4:
100       return COFF::IMAGE_REL_I386_SECREL;
101     default:
102       llvm_unreachable("unsupported relocation type");
103     }
104   } else
105     llvm_unreachable("Unsupported COFF machine type.");
106 }
107 
108 std::unique_ptr<MCObjectWriter>
109 llvm::createX86WinCOFFObjectWriter(raw_pwrite_stream &OS, bool Is64Bit) {
110   auto MOTW = llvm::make_unique<X86WinCOFFObjectWriter>(Is64Bit);
111   return createWinCOFFObjectWriter(std::move(MOTW), OS);
112 }
113