1 //===-- RISCVMCExpr.cpp - RISCV specific MC expression classes ------------===//
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 // This file contains the implementation of the assembly expression modifiers
10 // accepted by the RISCV architecture (e.g. ":lo12:", ":gottprel_g1:", ...).
11 //
12 //===----------------------------------------------------------------------===//
13
14 #include "RISCVMCExpr.h"
15 #include "MCTargetDesc/RISCVAsmBackend.h"
16 #include "RISCV.h"
17 #include "RISCVFixupKinds.h"
18 #include "llvm/BinaryFormat/ELF.h"
19 #include "llvm/MC/MCAsmLayout.h"
20 #include "llvm/MC/MCAssembler.h"
21 #include "llvm/MC/MCContext.h"
22 #include "llvm/MC/MCStreamer.h"
23 #include "llvm/MC/MCSymbolELF.h"
24 #include "llvm/MC/MCValue.h"
25 #include "llvm/Support/ErrorHandling.h"
26
27 using namespace llvm;
28
29 #define DEBUG_TYPE "riscvmcexpr"
30
create(const MCExpr * Expr,VariantKind Kind,MCContext & Ctx)31 const RISCVMCExpr *RISCVMCExpr::create(const MCExpr *Expr, VariantKind Kind,
32 MCContext &Ctx) {
33 return new (Ctx) RISCVMCExpr(Expr, Kind);
34 }
35
printImpl(raw_ostream & OS,const MCAsmInfo * MAI) const36 void RISCVMCExpr::printImpl(raw_ostream &OS, const MCAsmInfo *MAI) const {
37 VariantKind Kind = getKind();
38 bool HasVariant = ((Kind != VK_RISCV_None) && (Kind != VK_RISCV_CALL) &&
39 (Kind != VK_RISCV_CALL_PLT));
40
41 if (HasVariant)
42 OS << '%' << getVariantKindName(getKind()) << '(';
43 Expr->print(OS, MAI);
44 if (Kind == VK_RISCV_CALL_PLT)
45 OS << "@plt";
46 if (HasVariant)
47 OS << ')';
48 }
49
getPCRelHiFixup(const MCFragment ** DFOut) const50 const MCFixup *RISCVMCExpr::getPCRelHiFixup(const MCFragment **DFOut) const {
51 MCValue AUIPCLoc;
52 if (!getSubExpr()->evaluateAsRelocatable(AUIPCLoc, nullptr, nullptr))
53 return nullptr;
54
55 const MCSymbolRefExpr *AUIPCSRE = AUIPCLoc.getSymA();
56 if (!AUIPCSRE)
57 return nullptr;
58
59 const MCSymbol *AUIPCSymbol = &AUIPCSRE->getSymbol();
60 const auto *DF = dyn_cast_or_null<MCDataFragment>(AUIPCSymbol->getFragment());
61
62 if (!DF)
63 return nullptr;
64
65 uint64_t Offset = AUIPCSymbol->getOffset();
66 if (DF->getContents().size() == Offset) {
67 DF = dyn_cast_or_null<MCDataFragment>(DF->getNextNode());
68 if (!DF)
69 return nullptr;
70 Offset = 0;
71 }
72
73 for (const MCFixup &F : DF->getFixups()) {
74 if (F.getOffset() != Offset)
75 continue;
76
77 switch ((unsigned)F.getKind()) {
78 default:
79 continue;
80 case RISCV::fixup_riscv_got_hi20:
81 case RISCV::fixup_riscv_tls_got_hi20:
82 case RISCV::fixup_riscv_tls_gd_hi20:
83 case RISCV::fixup_riscv_pcrel_hi20:
84 if (DFOut)
85 *DFOut = DF;
86 return &F;
87 }
88 }
89
90 return nullptr;
91 }
92
evaluateAsRelocatableImpl(MCValue & Res,const MCAsmLayout * Layout,const MCFixup * Fixup) const93 bool RISCVMCExpr::evaluateAsRelocatableImpl(MCValue &Res,
94 const MCAsmLayout *Layout,
95 const MCFixup *Fixup) const {
96 if (!getSubExpr()->evaluateAsRelocatable(Res, Layout, Fixup))
97 return false;
98
99 // Some custom fixup types are not valid with symbol difference expressions
100 if (Res.getSymA() && Res.getSymB()) {
101 switch (getKind()) {
102 default:
103 return true;
104 case VK_RISCV_LO:
105 case VK_RISCV_HI:
106 case VK_RISCV_PCREL_LO:
107 case VK_RISCV_PCREL_HI:
108 case VK_RISCV_GOT_HI:
109 case VK_RISCV_TPREL_LO:
110 case VK_RISCV_TPREL_HI:
111 case VK_RISCV_TPREL_ADD:
112 case VK_RISCV_TLS_GOT_HI:
113 case VK_RISCV_TLS_GD_HI:
114 return false;
115 }
116 }
117
118 return true;
119 }
120
visitUsedExpr(MCStreamer & Streamer) const121 void RISCVMCExpr::visitUsedExpr(MCStreamer &Streamer) const {
122 Streamer.visitUsedExpr(*getSubExpr());
123 }
124
getVariantKindForName(StringRef name)125 RISCVMCExpr::VariantKind RISCVMCExpr::getVariantKindForName(StringRef name) {
126 return StringSwitch<RISCVMCExpr::VariantKind>(name)
127 .Case("lo", VK_RISCV_LO)
128 .Case("hi", VK_RISCV_HI)
129 .Case("pcrel_lo", VK_RISCV_PCREL_LO)
130 .Case("pcrel_hi", VK_RISCV_PCREL_HI)
131 .Case("got_pcrel_hi", VK_RISCV_GOT_HI)
132 .Case("tprel_lo", VK_RISCV_TPREL_LO)
133 .Case("tprel_hi", VK_RISCV_TPREL_HI)
134 .Case("tprel_add", VK_RISCV_TPREL_ADD)
135 .Case("tls_ie_pcrel_hi", VK_RISCV_TLS_GOT_HI)
136 .Case("tls_gd_pcrel_hi", VK_RISCV_TLS_GD_HI)
137 .Default(VK_RISCV_Invalid);
138 }
139
getVariantKindName(VariantKind Kind)140 StringRef RISCVMCExpr::getVariantKindName(VariantKind Kind) {
141 switch (Kind) {
142 default:
143 llvm_unreachable("Invalid ELF symbol kind");
144 case VK_RISCV_LO:
145 return "lo";
146 case VK_RISCV_HI:
147 return "hi";
148 case VK_RISCV_PCREL_LO:
149 return "pcrel_lo";
150 case VK_RISCV_PCREL_HI:
151 return "pcrel_hi";
152 case VK_RISCV_GOT_HI:
153 return "got_pcrel_hi";
154 case VK_RISCV_TPREL_LO:
155 return "tprel_lo";
156 case VK_RISCV_TPREL_HI:
157 return "tprel_hi";
158 case VK_RISCV_TPREL_ADD:
159 return "tprel_add";
160 case VK_RISCV_TLS_GOT_HI:
161 return "tls_ie_pcrel_hi";
162 case VK_RISCV_TLS_GD_HI:
163 return "tls_gd_pcrel_hi";
164 }
165 }
166
fixELFSymbolsInTLSFixupsImpl(const MCExpr * Expr,MCAssembler & Asm)167 static void fixELFSymbolsInTLSFixupsImpl(const MCExpr *Expr, MCAssembler &Asm) {
168 switch (Expr->getKind()) {
169 case MCExpr::Target:
170 llvm_unreachable("Can't handle nested target expression");
171 break;
172 case MCExpr::Constant:
173 break;
174
175 case MCExpr::Binary: {
176 const MCBinaryExpr *BE = cast<MCBinaryExpr>(Expr);
177 fixELFSymbolsInTLSFixupsImpl(BE->getLHS(), Asm);
178 fixELFSymbolsInTLSFixupsImpl(BE->getRHS(), Asm);
179 break;
180 }
181
182 case MCExpr::SymbolRef: {
183 // We're known to be under a TLS fixup, so any symbol should be
184 // modified. There should be only one.
185 const MCSymbolRefExpr &SymRef = *cast<MCSymbolRefExpr>(Expr);
186 cast<MCSymbolELF>(SymRef.getSymbol()).setType(ELF::STT_TLS);
187 break;
188 }
189
190 case MCExpr::Unary:
191 fixELFSymbolsInTLSFixupsImpl(cast<MCUnaryExpr>(Expr)->getSubExpr(), Asm);
192 break;
193 }
194 }
195
fixELFSymbolsInTLSFixups(MCAssembler & Asm) const196 void RISCVMCExpr::fixELFSymbolsInTLSFixups(MCAssembler &Asm) const {
197 switch (getKind()) {
198 default:
199 return;
200 case VK_RISCV_TPREL_HI:
201 case VK_RISCV_TLS_GOT_HI:
202 case VK_RISCV_TLS_GD_HI:
203 break;
204 }
205
206 fixELFSymbolsInTLSFixupsImpl(getSubExpr(), Asm);
207 }
208
evaluateAsConstant(int64_t & Res) const209 bool RISCVMCExpr::evaluateAsConstant(int64_t &Res) const {
210 MCValue Value;
211
212 if (Kind == VK_RISCV_PCREL_HI || Kind == VK_RISCV_PCREL_LO ||
213 Kind == VK_RISCV_GOT_HI || Kind == VK_RISCV_TPREL_HI ||
214 Kind == VK_RISCV_TPREL_LO || Kind == VK_RISCV_TPREL_ADD ||
215 Kind == VK_RISCV_TLS_GOT_HI || Kind == VK_RISCV_TLS_GD_HI ||
216 Kind == VK_RISCV_CALL || Kind == VK_RISCV_CALL_PLT)
217 return false;
218
219 if (!getSubExpr()->evaluateAsRelocatable(Value, nullptr, nullptr))
220 return false;
221
222 if (!Value.isAbsolute())
223 return false;
224
225 Res = evaluateAsInt64(Value.getConstant());
226 return true;
227 }
228
evaluateAsInt64(int64_t Value) const229 int64_t RISCVMCExpr::evaluateAsInt64(int64_t Value) const {
230 switch (Kind) {
231 default:
232 llvm_unreachable("Invalid kind");
233 case VK_RISCV_LO:
234 return SignExtend64<12>(Value);
235 case VK_RISCV_HI:
236 // Add 1 if bit 11 is 1, to compensate for low 12 bits being negative.
237 return ((Value + 0x800) >> 12) & 0xfffff;
238 }
239 }
240