1 //===-- ARMWinCOFFObjectWriter.cpp - ARM Windows COFF Object Writer -- C++ -==//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 
9 #include "MCTargetDesc/ARMFixupKinds.h"
10 #include "llvm/ADT/Twine.h"
11 #include "llvm/BinaryFormat/COFF.h"
12 #include "llvm/MC/MCAsmBackend.h"
13 #include "llvm/MC/MCExpr.h"
14 #include "llvm/MC/MCFixup.h"
15 #include "llvm/MC/MCFixupKindInfo.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 #include "llvm/Support/raw_ostream.h"
21 #include <cassert>
22 
23 using namespace llvm;
24 
25 namespace {
26 
27 class ARMWinCOFFObjectWriter : public MCWinCOFFObjectTargetWriter {
28 public:
29   ARMWinCOFFObjectWriter()
30     : MCWinCOFFObjectTargetWriter(COFF::IMAGE_FILE_MACHINE_ARMNT) {
31   }
32 
33   ~ARMWinCOFFObjectWriter() override = default;
34 
35   unsigned getRelocType(MCContext &Ctx, const MCValue &Target,
36                         const MCFixup &Fixup, bool IsCrossSection,
37                         const MCAsmBackend &MAB) const override;
38 
39   bool recordRelocation(const MCFixup &) const override;
40 };
41 
42 } // end anonymous namespace
43 
44 unsigned ARMWinCOFFObjectWriter::getRelocType(MCContext &Ctx,
45                                               const MCValue &Target,
46                                               const MCFixup &Fixup,
47                                               bool IsCrossSection,
48                                               const MCAsmBackend &MAB) const {
49   MCSymbolRefExpr::VariantKind Modifier =
50     Target.isAbsolute() ? MCSymbolRefExpr::VK_None : Target.getSymA()->getKind();
51 
52   switch (static_cast<unsigned>(Fixup.getKind())) {
53   default: {
54     const MCFixupKindInfo &Info = MAB.getFixupKindInfo(Fixup.getKind());
55     report_fatal_error(Twine("unsupported relocation type: ") + Info.Name);
56   }
57   case FK_Data_4:
58     switch (Modifier) {
59     case MCSymbolRefExpr::VK_COFF_IMGREL32:
60       return COFF::IMAGE_REL_ARM_ADDR32NB;
61     case MCSymbolRefExpr::VK_SECREL:
62       return COFF::IMAGE_REL_ARM_SECREL;
63     default:
64       return COFF::IMAGE_REL_ARM_ADDR32;
65     }
66   case FK_SecRel_2:
67     return COFF::IMAGE_REL_ARM_SECTION;
68   case FK_SecRel_4:
69     return COFF::IMAGE_REL_ARM_SECREL;
70   case ARM::fixup_t2_condbranch:
71     return COFF::IMAGE_REL_ARM_BRANCH20T;
72   case ARM::fixup_t2_uncondbranch:
73   case ARM::fixup_arm_thumb_bl:
74     return COFF::IMAGE_REL_ARM_BRANCH24T;
75   case ARM::fixup_arm_thumb_blx:
76     return COFF::IMAGE_REL_ARM_BLX23T;
77   case ARM::fixup_t2_movw_lo16:
78   case ARM::fixup_t2_movt_hi16:
79     return COFF::IMAGE_REL_ARM_MOV32T;
80   }
81 }
82 
83 bool ARMWinCOFFObjectWriter::recordRelocation(const MCFixup &Fixup) const {
84   return static_cast<unsigned>(Fixup.getKind()) != ARM::fixup_t2_movt_hi16;
85 }
86 
87 namespace llvm {
88 
89 std::unique_ptr<MCObjectTargetWriter>
90 createARMWinCOFFObjectWriter() {
91   return std::make_unique<ARMWinCOFFObjectWriter>();
92 }
93 
94 } // end namespace llvm
95