LLVM 20.0.0git
RISCVELFObjectWriter.cpp
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1//===-- RISCVELFObjectWriter.cpp - RISC-V 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
12#include "llvm/MC/MCContext.h"
14#include "llvm/MC/MCFixup.h"
16#include "llvm/MC/MCValue.h"
18
19using namespace llvm;
20
21namespace {
22class RISCVELFObjectWriter : public MCELFObjectTargetWriter {
23public:
24 RISCVELFObjectWriter(uint8_t OSABI, bool Is64Bit);
25
26 ~RISCVELFObjectWriter() override;
27
28 // Return true if the given relocation must be with a symbol rather than
29 // section plus offset.
30 bool needsRelocateWithSymbol(const MCValue &Val, const MCSymbol &Sym,
31 unsigned Type) const override {
32 // TODO: this is very conservative, update once RISC-V psABI requirements
33 // are clarified.
34 return true;
35 }
36
37protected:
38 unsigned getRelocType(MCContext &Ctx, const MCValue &Target,
39 const MCFixup &Fixup, bool IsPCRel) const override;
40};
41}
42
43RISCVELFObjectWriter::RISCVELFObjectWriter(uint8_t OSABI, bool Is64Bit)
44 : MCELFObjectTargetWriter(Is64Bit, OSABI, ELF::EM_RISCV,
45 /*HasRelocationAddend*/ true) {}
46
47RISCVELFObjectWriter::~RISCVELFObjectWriter() = default;
48
49unsigned RISCVELFObjectWriter::getRelocType(MCContext &Ctx,
50 const MCValue &Target,
51 const MCFixup &Fixup,
52 bool IsPCRel) const {
53 const MCExpr *Expr = Fixup.getValue();
54 // Determine the type of the relocation
55 unsigned Kind = Fixup.getTargetKind();
58 if (IsPCRel) {
59 switch (Kind) {
60 default:
61 Ctx.reportError(Fixup.getLoc(), "unsupported relocation type");
62 return ELF::R_RISCV_NONE;
63 case FK_Data_4:
64 case FK_PCRel_4:
65 return Target.getAccessVariant() == MCSymbolRefExpr::VK_PLT
66 ? ELF::R_RISCV_PLT32
67 : ELF::R_RISCV_32_PCREL;
69 return ELF::R_RISCV_PCREL_HI20;
71 return ELF::R_RISCV_PCREL_LO12_I;
73 return ELF::R_RISCV_PCREL_LO12_S;
75 return ELF::R_RISCV_GOT_HI20;
77 return ELF::R_RISCV_TLS_GOT_HI20;
79 return ELF::R_RISCV_TLS_GD_HI20;
81 return ELF::R_RISCV_TLSDESC_HI20;
83 return ELF::R_RISCV_TLSDESC_LOAD_LO12;
85 return ELF::R_RISCV_TLSDESC_ADD_LO12;
87 return ELF::R_RISCV_TLSDESC_CALL;
89 return ELF::R_RISCV_JAL;
91 return ELF::R_RISCV_BRANCH;
93 return ELF::R_RISCV_RVC_JUMP;
95 return ELF::R_RISCV_RVC_BRANCH;
97 return ELF::R_RISCV_CALL_PLT;
99 return ELF::R_RISCV_CALL_PLT;
100 }
101 }
102
103 switch (Kind) {
104 default:
105 Ctx.reportError(Fixup.getLoc(), "unsupported relocation type");
106 return ELF::R_RISCV_NONE;
108 return ELF::R_RISCV_TLSDESC_LOAD_LO12;
110 return ELF::R_RISCV_TLSDESC_ADD_LO12;
112 return ELF::R_RISCV_TLSDESC_CALL;
113
114 case FK_Data_1:
115 Ctx.reportError(Fixup.getLoc(), "1-byte data relocations not supported");
116 return ELF::R_RISCV_NONE;
117 case FK_Data_2:
118 Ctx.reportError(Fixup.getLoc(), "2-byte data relocations not supported");
119 return ELF::R_RISCV_NONE;
120 case FK_Data_4:
121 if (Expr->getKind() == MCExpr::Target &&
122 cast<RISCVMCExpr>(Expr)->getKind() == RISCVMCExpr::VK_RISCV_32_PCREL)
123 return ELF::R_RISCV_32_PCREL;
124 if (Target.getSymA()->getKind() == MCSymbolRefExpr::VK_GOTPCREL)
125 return ELF::R_RISCV_GOT32_PCREL;
126 return ELF::R_RISCV_32;
127 case FK_Data_8:
128 return ELF::R_RISCV_64;
130 return ELF::R_RISCV_HI20;
132 return ELF::R_RISCV_LO12_I;
134 return ELF::R_RISCV_LO12_S;
136 return ELF::R_RISCV_TPREL_HI20;
138 return ELF::R_RISCV_TPREL_LO12_I;
140 return ELF::R_RISCV_TPREL_LO12_S;
142 return ELF::R_RISCV_TPREL_ADD;
144 return ELF::R_RISCV_RELAX;
146 return ELF::R_RISCV_ALIGN;
147 }
148}
149
150std::unique_ptr<MCObjectTargetWriter>
151llvm::createRISCVELFObjectWriter(uint8_t OSABI, bool Is64Bit) {
152 return std::make_unique<RISCVELFObjectWriter>(OSABI, Is64Bit);
153}
basic Basic Alias true
Symbol * Sym
Definition: ELF_riscv.cpp:479
PowerPC TLS Dynamic Call Fixup
Context object for machine code objects.
Definition: MCContext.h:83
void reportError(SMLoc L, const Twine &Msg)
Definition: MCContext.cpp:1068
virtual bool needsRelocateWithSymbol(const MCValue &Val, const MCSymbol &Sym, unsigned Type) const
virtual unsigned getRelocType(MCContext &Ctx, const MCValue &Target, const MCFixup &Fixup, bool IsPCRel) const =0
Base class for the full range of assembler expressions which are needed for parsing.
Definition: MCExpr.h:34
@ Target
Target specific expression.
Definition: MCExpr.h:41
ExprKind getKind() const
Definition: MCExpr.h:78
Encode information on a single operation to perform on a byte sequence (e.g., an encoded instruction)...
Definition: MCFixup.h:71
MCSymbol - Instances of this class represent a symbol name in the MC file, and MCSymbols are created ...
Definition: MCSymbol.h:41
This represents an "assembler immediate".
Definition: MCValue.h:36
Target - Wrapper for Target specific information.
The instances of the Type class are immutable: once they are created, they are never changed.
Definition: Type.h:45
@ EM_RISCV
Definition: ELF.h:318
@ fixup_riscv_tprel_lo12_s
@ fixup_riscv_tls_got_hi20
@ fixup_riscv_pcrel_lo12_i
@ fixup_riscv_tlsdesc_call
@ fixup_riscv_pcrel_lo12_s
@ fixup_riscv_tprel_lo12_i
@ fixup_riscv_tlsdesc_load_lo12
@ fixup_riscv_tlsdesc_hi20
@ fixup_riscv_tlsdesc_add_lo12
This is an optimization pass for GlobalISel generic memory operations.
Definition: AddressRanges.h:18
std::unique_ptr< MCObjectTargetWriter > createRISCVELFObjectWriter(uint8_t OSABI, bool Is64Bit)
@ FK_PCRel_4
A four-byte pc relative fixup.
Definition: MCFixup.h:30
@ FirstLiteralRelocationKind
The range [FirstLiteralRelocationKind, MaxTargetFixupKind) is used for relocations coming from ....
Definition: MCFixup.h:50
@ FK_Data_8
A eight-byte fixup.
Definition: MCFixup.h:26
@ FK_Data_1
A one-byte fixup.
Definition: MCFixup.h:23
@ FK_Data_4
A four-byte fixup.
Definition: MCFixup.h:25
@ FK_Data_2
A two-byte fixup.
Definition: MCFixup.h:24