1 //===- AMDGPUELFObjectWriter.cpp - AMDGPU ELF 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 "AMDGPUMCTargetDesc.h"
11 #include "llvm/BinaryFormat/ELF.h"
12 #include "llvm/MC/MCELFObjectWriter.h"
13 #include "llvm/MC/MCExpr.h"
14 #include "llvm/MC/MCFixup.h"
15 #include "llvm/MC/MCObjectWriter.h"
16 #include "llvm/MC/MCSymbol.h"
17 #include "llvm/MC/MCValue.h"
18 #include "llvm/Support/ErrorHandling.h"
19 
20 using namespace llvm;
21 
22 namespace {
23 
24 class AMDGPUELFObjectWriter : public MCELFObjectTargetWriter {
25 public:
26   AMDGPUELFObjectWriter(bool Is64Bit, uint8_t OSABI, bool HasRelocationAddend);
27 
28 protected:
29   unsigned getRelocType(MCContext &Ctx, const MCValue &Target,
30                         const MCFixup &Fixup, bool IsPCRel) const override;
31 };
32 
33 
34 } // end anonymous namespace
35 
36 AMDGPUELFObjectWriter::AMDGPUELFObjectWriter(bool Is64Bit,
37                                              uint8_t OSABI,
38                                              bool HasRelocationAddend)
39   : MCELFObjectTargetWriter(Is64Bit, OSABI, ELF::EM_AMDGPU,
40                             HasRelocationAddend) {}
41 
42 unsigned AMDGPUELFObjectWriter::getRelocType(MCContext &Ctx,
43                                              const MCValue &Target,
44                                              const MCFixup &Fixup,
45                                              bool IsPCRel) const {
46   if (const auto *SymA = Target.getSymA()) {
47     // SCRATCH_RSRC_DWORD[01] is a special global variable that represents
48     // the scratch buffer.
49     if (SymA->getSymbol().getName() == "SCRATCH_RSRC_DWORD0")
50       return ELF::R_AMDGPU_ABS32_LO;
51 
52     if (SymA->getSymbol().getName() == "SCRATCH_RSRC_DWORD1")
53       return ELF::R_AMDGPU_ABS32_HI;
54   }
55 
56   switch (Target.getAccessVariant()) {
57   default:
58     break;
59   case MCSymbolRefExpr::VK_GOTPCREL:
60     return ELF::R_AMDGPU_GOTPCREL;
61   case MCSymbolRefExpr::VK_AMDGPU_GOTPCREL32_LO:
62     return ELF::R_AMDGPU_GOTPCREL32_LO;
63   case MCSymbolRefExpr::VK_AMDGPU_GOTPCREL32_HI:
64     return ELF::R_AMDGPU_GOTPCREL32_HI;
65   case MCSymbolRefExpr::VK_AMDGPU_REL32_LO:
66     return ELF::R_AMDGPU_REL32_LO;
67   case MCSymbolRefExpr::VK_AMDGPU_REL32_HI:
68     return ELF::R_AMDGPU_REL32_HI;
69   }
70 
71   switch (Fixup.getKind()) {
72   default: break;
73   case FK_PCRel_4:
74     return ELF::R_AMDGPU_REL32;
75   case FK_Data_4:
76   case FK_SecRel_4:
77     return ELF::R_AMDGPU_ABS32;
78   case FK_Data_8:
79     return ELF::R_AMDGPU_ABS64;
80   }
81 
82   llvm_unreachable("unhandled relocation type");
83 }
84 
85 std::unique_ptr<MCObjectWriter>
86 llvm::createAMDGPUELFObjectWriter(bool Is64Bit, uint8_t OSABI,
87                                   bool HasRelocationAddend,
88                                   raw_pwrite_stream &OS) {
89   auto MOTW = llvm::make_unique<AMDGPUELFObjectWriter>(Is64Bit, OSABI,
90                                                        HasRelocationAddend);
91   return createELFObjectWriter(std::move(MOTW), OS, true);
92 }
93