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