1 //===- AMDGPUELFObjectWriter.cpp - AMDGPU ELF Writer ----------------------===//
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 "AMDGPUMCTargetDesc.h"
10 #include "llvm/BinaryFormat/ELF.h"
11 #include "llvm/MC/MCELFObjectWriter.h"
12 #include "llvm/MC/MCExpr.h"
13 #include "llvm/MC/MCFixup.h"
14 #include "llvm/MC/MCObjectWriter.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                         uint8_t ABIVersion);
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                                              uint8_t ABIVersion)
40   : MCELFObjectTargetWriter(Is64Bit, OSABI, ELF::EM_AMDGPU,
41                             HasRelocationAddend, ABIVersion) {}
42 
43 unsigned AMDGPUELFObjectWriter::getRelocType(MCContext &Ctx,
44                                              const MCValue &Target,
45                                              const MCFixup &Fixup,
46                                              bool IsPCRel) const {
47   if (const auto *SymA = Target.getSymA()) {
48     // SCRATCH_RSRC_DWORD[01] is a special global variable that represents
49     // the scratch buffer.
50     if (SymA->getSymbol().getName() == "SCRATCH_RSRC_DWORD0" ||
51         SymA->getSymbol().getName() == "SCRATCH_RSRC_DWORD1")
52       return ELF::R_AMDGPU_ABS32_LO;
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   case MCSymbolRefExpr::VK_AMDGPU_REL64:
69     return ELF::R_AMDGPU_REL64;
70   }
71 
72   switch (Fixup.getKind()) {
73   default: break;
74   case FK_PCRel_4:
75     return ELF::R_AMDGPU_REL32;
76   case FK_Data_4:
77   case FK_SecRel_4:
78     return ELF::R_AMDGPU_ABS32;
79   case FK_Data_8:
80     return ELF::R_AMDGPU_ABS64;
81   }
82 
83   llvm_unreachable("unhandled relocation type");
84 }
85 
86 std::unique_ptr<MCObjectTargetWriter>
87 llvm::createAMDGPUELFObjectWriter(bool Is64Bit, uint8_t OSABI,
88                                   bool HasRelocationAddend,
89                                   uint8_t ABIVersion) {
90   return std::make_unique<AMDGPUELFObjectWriter>(Is64Bit, OSABI,
91                                                   HasRelocationAddend,
92                                                   ABIVersion);
93 }
94