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 "AMDGPUFixupKinds.h"
10 #include "AMDGPUMCTargetDesc.h"
11 #include "llvm/MC/MCContext.h"
12 #include "llvm/MC/MCELFObjectWriter.h"
13 #include "llvm/MC/MCValue.h"
14 
15 using namespace llvm;
16 
17 namespace {
18 
19 class AMDGPUELFObjectWriter : public MCELFObjectTargetWriter {
20 public:
21   AMDGPUELFObjectWriter(bool Is64Bit, uint8_t OSABI, bool HasRelocationAddend,
22                         uint8_t ABIVersion);
23 
24 protected:
25   unsigned getRelocType(MCContext &Ctx, const MCValue &Target,
26                         const MCFixup &Fixup, bool IsPCRel) const override;
27 };
28 
29 
30 } // end anonymous namespace
31 
32 AMDGPUELFObjectWriter::AMDGPUELFObjectWriter(bool Is64Bit,
33                                              uint8_t OSABI,
34                                              bool HasRelocationAddend,
35                                              uint8_t ABIVersion)
36   : MCELFObjectTargetWriter(Is64Bit, OSABI, ELF::EM_AMDGPU,
37                             HasRelocationAddend, ABIVersion) {}
38 
39 unsigned AMDGPUELFObjectWriter::getRelocType(MCContext &Ctx,
40                                              const MCValue &Target,
41                                              const MCFixup &Fixup,
42                                              bool IsPCRel) const {
43   if (const auto *SymA = Target.getSymA()) {
44     // SCRATCH_RSRC_DWORD[01] is a special global variable that represents
45     // the scratch buffer.
46     if (SymA->getSymbol().getName() == "SCRATCH_RSRC_DWORD0" ||
47         SymA->getSymbol().getName() == "SCRATCH_RSRC_DWORD1")
48       return ELF::R_AMDGPU_ABS32_LO;
49   }
50 
51   switch (Target.getAccessVariant()) {
52   default:
53     break;
54   case MCSymbolRefExpr::VK_GOTPCREL:
55     return ELF::R_AMDGPU_GOTPCREL;
56   case MCSymbolRefExpr::VK_AMDGPU_GOTPCREL32_LO:
57     return ELF::R_AMDGPU_GOTPCREL32_LO;
58   case MCSymbolRefExpr::VK_AMDGPU_GOTPCREL32_HI:
59     return ELF::R_AMDGPU_GOTPCREL32_HI;
60   case MCSymbolRefExpr::VK_AMDGPU_REL32_LO:
61     return ELF::R_AMDGPU_REL32_LO;
62   case MCSymbolRefExpr::VK_AMDGPU_REL32_HI:
63     return ELF::R_AMDGPU_REL32_HI;
64   case MCSymbolRefExpr::VK_AMDGPU_REL64:
65     return ELF::R_AMDGPU_REL64;
66   case MCSymbolRefExpr::VK_AMDGPU_ABS32_LO:
67     return ELF::R_AMDGPU_ABS32_LO;
68   case MCSymbolRefExpr::VK_AMDGPU_ABS32_HI:
69     return ELF::R_AMDGPU_ABS32_HI;
70   }
71 
72   MCFixupKind Kind = Fixup.getKind();
73   if (Kind >= FirstLiteralRelocationKind)
74     return Kind - FirstLiteralRelocationKind;
75   switch (Kind) {
76   default: break;
77   case FK_PCRel_4:
78     return ELF::R_AMDGPU_REL32;
79   case FK_Data_4:
80   case FK_SecRel_4:
81     return IsPCRel ? ELF::R_AMDGPU_REL32 : ELF::R_AMDGPU_ABS32;
82   case FK_Data_8:
83     return IsPCRel ? ELF::R_AMDGPU_REL64 : ELF::R_AMDGPU_ABS64;
84   }
85 
86   if (Fixup.getTargetKind() == AMDGPU::fixup_si_sopp_br) {
87     const auto *SymA = Target.getSymA();
88     assert(SymA);
89 
90     if (SymA->getSymbol().isUndefined()) {
91       Ctx.reportError(Fixup.getLoc(), Twine("undefined label '") +
92                                           SymA->getSymbol().getName() + "'");
93       return ELF::R_AMDGPU_NONE;
94     }
95     return ELF::R_AMDGPU_REL16;
96   }
97 
98   llvm_unreachable("unhandled relocation type");
99 }
100 
101 std::unique_ptr<MCObjectTargetWriter>
102 llvm::createAMDGPUELFObjectWriter(bool Is64Bit, uint8_t OSABI,
103                                   bool HasRelocationAddend,
104                                   uint8_t ABIVersion) {
105   return std::make_unique<AMDGPUELFObjectWriter>(Is64Bit, OSABI,
106                                                   HasRelocationAddend,
107                                                   ABIVersion);
108 }
109