1 //===-- MipsMCExpr.cpp - Mips 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 #include "MipsMCExpr.h"
10 #include "llvm/BinaryFormat/ELF.h"
11 #include "llvm/MC/MCAsmInfo.h"
12 #include "llvm/MC/MCAssembler.h"
13 #include "llvm/MC/MCContext.h"
14 #include "llvm/MC/MCStreamer.h"
15 #include "llvm/MC/MCSymbolELF.h"
16 #include "llvm/MC/MCValue.h"
17 #include "llvm/Support/Casting.h"
18 #include "llvm/Support/ErrorHandling.h"
19 #include "llvm/Support/MathExtras.h"
20 #include "llvm/Support/raw_ostream.h"
21 #include <cstdint>
22
23 using namespace llvm;
24
25 #define DEBUG_TYPE "mipsmcexpr"
26
create(MipsMCExpr::MipsExprKind Kind,const MCExpr * Expr,MCContext & Ctx)27 const MipsMCExpr *MipsMCExpr::create(MipsMCExpr::MipsExprKind Kind,
28 const MCExpr *Expr, MCContext &Ctx) {
29 return new (Ctx) MipsMCExpr(Kind, Expr);
30 }
31
createGpOff(MipsMCExpr::MipsExprKind Kind,const MCExpr * Expr,MCContext & Ctx)32 const MipsMCExpr *MipsMCExpr::createGpOff(MipsMCExpr::MipsExprKind Kind,
33 const MCExpr *Expr, MCContext &Ctx) {
34 return create(Kind, create(MEK_NEG, create(MEK_GPREL, Expr, Ctx), Ctx), Ctx);
35 }
36
printImpl(raw_ostream & OS,const MCAsmInfo * MAI) const37 void MipsMCExpr::printImpl(raw_ostream &OS, const MCAsmInfo *MAI) const {
38 int64_t AbsVal;
39
40 switch (Kind) {
41 case MEK_None:
42 case MEK_Special:
43 llvm_unreachable("MEK_None and MEK_Special are invalid");
44 break;
45 case MEK_DTPREL:
46 // MEK_DTPREL is used for marking TLS DIEExpr only
47 // and contains a regular sub-expression.
48 getSubExpr()->print(OS, MAI, true);
49 return;
50 case MEK_CALL_HI16:
51 OS << "%call_hi";
52 break;
53 case MEK_CALL_LO16:
54 OS << "%call_lo";
55 break;
56 case MEK_DTPREL_HI:
57 OS << "%dtprel_hi";
58 break;
59 case MEK_DTPREL_LO:
60 OS << "%dtprel_lo";
61 break;
62 case MEK_GOT:
63 OS << "%got";
64 break;
65 case MEK_GOTTPREL:
66 OS << "%gottprel";
67 break;
68 case MEK_GOT_CALL:
69 OS << "%call16";
70 break;
71 case MEK_GOT_DISP:
72 OS << "%got_disp";
73 break;
74 case MEK_GOT_HI16:
75 OS << "%got_hi";
76 break;
77 case MEK_GOT_LO16:
78 OS << "%got_lo";
79 break;
80 case MEK_GOT_PAGE:
81 OS << "%got_page";
82 break;
83 case MEK_GOT_OFST:
84 OS << "%got_ofst";
85 break;
86 case MEK_GPREL:
87 OS << "%gp_rel";
88 break;
89 case MEK_HI:
90 OS << "%hi";
91 break;
92 case MEK_HIGHER:
93 OS << "%higher";
94 break;
95 case MEK_HIGHEST:
96 OS << "%highest";
97 break;
98 case MEK_LO:
99 OS << "%lo";
100 break;
101 case MEK_NEG:
102 OS << "%neg";
103 break;
104 case MEK_PCREL_HI16:
105 OS << "%pcrel_hi";
106 break;
107 case MEK_PCREL_LO16:
108 OS << "%pcrel_lo";
109 break;
110 case MEK_TLSGD:
111 OS << "%tlsgd";
112 break;
113 case MEK_TLSLDM:
114 OS << "%tlsldm";
115 break;
116 case MEK_TPREL_HI:
117 OS << "%tprel_hi";
118 break;
119 case MEK_TPREL_LO:
120 OS << "%tprel_lo";
121 break;
122 }
123
124 OS << '(';
125 if (Expr->evaluateAsAbsolute(AbsVal))
126 OS << AbsVal;
127 else
128 Expr->print(OS, MAI, true);
129 OS << ')';
130 }
131
132 bool
evaluateAsRelocatableImpl(MCValue & Res,const MCAsmLayout * Layout,const MCFixup * Fixup) const133 MipsMCExpr::evaluateAsRelocatableImpl(MCValue &Res,
134 const MCAsmLayout *Layout,
135 const MCFixup *Fixup) const {
136 // Look for the %hi(%neg(%gp_rel(X))) and %lo(%neg(%gp_rel(X))) special cases.
137 if (isGpOff()) {
138 const MCExpr *SubExpr =
139 cast<MipsMCExpr>(cast<MipsMCExpr>(getSubExpr())->getSubExpr())
140 ->getSubExpr();
141 if (!SubExpr->evaluateAsRelocatable(Res, Layout, Fixup))
142 return false;
143
144 Res = MCValue::get(Res.getSymA(), Res.getSymB(), Res.getConstant(),
145 MEK_Special);
146 return true;
147 }
148
149 if (!getSubExpr()->evaluateAsRelocatable(Res, Layout, Fixup))
150 return false;
151
152 if (Res.getRefKind() != MCSymbolRefExpr::VK_None)
153 return false;
154
155 // evaluateAsAbsolute() and evaluateAsValue() require that we evaluate the
156 // %hi/%lo/etc. here. Fixup is a null pointer when either of these is the
157 // caller.
158 if (Res.isAbsolute() && Fixup == nullptr) {
159 int64_t AbsVal = Res.getConstant();
160 switch (Kind) {
161 case MEK_None:
162 case MEK_Special:
163 llvm_unreachable("MEK_None and MEK_Special are invalid");
164 case MEK_DTPREL:
165 // MEK_DTPREL is used for marking TLS DIEExpr only
166 // and contains a regular sub-expression.
167 return getSubExpr()->evaluateAsRelocatable(Res, Layout, Fixup);
168 case MEK_DTPREL_HI:
169 case MEK_DTPREL_LO:
170 case MEK_GOT:
171 case MEK_GOTTPREL:
172 case MEK_GOT_CALL:
173 case MEK_GOT_DISP:
174 case MEK_GOT_HI16:
175 case MEK_GOT_LO16:
176 case MEK_GOT_OFST:
177 case MEK_GOT_PAGE:
178 case MEK_GPREL:
179 case MEK_PCREL_HI16:
180 case MEK_PCREL_LO16:
181 case MEK_TLSGD:
182 case MEK_TLSLDM:
183 case MEK_TPREL_HI:
184 case MEK_TPREL_LO:
185 return false;
186 case MEK_LO:
187 case MEK_CALL_LO16:
188 AbsVal = SignExtend64<16>(AbsVal);
189 break;
190 case MEK_CALL_HI16:
191 case MEK_HI:
192 AbsVal = SignExtend64<16>((AbsVal + 0x8000) >> 16);
193 break;
194 case MEK_HIGHER:
195 AbsVal = SignExtend64<16>((AbsVal + 0x80008000LL) >> 32);
196 break;
197 case MEK_HIGHEST:
198 AbsVal = SignExtend64<16>((AbsVal + 0x800080008000LL) >> 48);
199 break;
200 case MEK_NEG:
201 AbsVal = -AbsVal;
202 break;
203 }
204 Res = MCValue::get(AbsVal);
205 return true;
206 }
207
208 // We want to defer it for relocatable expressions since the constant is
209 // applied to the whole symbol value.
210 //
211 // The value of getKind() that is given to MCValue is only intended to aid
212 // debugging when inspecting MCValue objects. It shouldn't be relied upon
213 // for decision making.
214 Res =
215 MCValue::get(Res.getSymA(), Res.getSymB(), Res.getConstant(), getKind());
216
217 return true;
218 }
219
visitUsedExpr(MCStreamer & Streamer) const220 void MipsMCExpr::visitUsedExpr(MCStreamer &Streamer) const {
221 Streamer.visitUsedExpr(*getSubExpr());
222 }
223
fixELFSymbolsInTLSFixupsImpl(const MCExpr * Expr,MCAssembler & Asm)224 static void fixELFSymbolsInTLSFixupsImpl(const MCExpr *Expr, MCAssembler &Asm) {
225 switch (Expr->getKind()) {
226 case MCExpr::Target:
227 fixELFSymbolsInTLSFixupsImpl(cast<MipsMCExpr>(Expr)->getSubExpr(), Asm);
228 break;
229 case MCExpr::Constant:
230 break;
231 case MCExpr::Binary: {
232 const MCBinaryExpr *BE = cast<MCBinaryExpr>(Expr);
233 fixELFSymbolsInTLSFixupsImpl(BE->getLHS(), Asm);
234 fixELFSymbolsInTLSFixupsImpl(BE->getRHS(), Asm);
235 break;
236 }
237 case MCExpr::SymbolRef: {
238 // We're known to be under a TLS fixup, so any symbol should be
239 // modified. There should be only one.
240 const MCSymbolRefExpr &SymRef = *cast<MCSymbolRefExpr>(Expr);
241 cast<MCSymbolELF>(SymRef.getSymbol()).setType(ELF::STT_TLS);
242 break;
243 }
244 case MCExpr::Unary:
245 fixELFSymbolsInTLSFixupsImpl(cast<MCUnaryExpr>(Expr)->getSubExpr(), Asm);
246 break;
247 }
248 }
249
fixELFSymbolsInTLSFixups(MCAssembler & Asm) const250 void MipsMCExpr::fixELFSymbolsInTLSFixups(MCAssembler &Asm) const {
251 switch (getKind()) {
252 case MEK_None:
253 case MEK_Special:
254 llvm_unreachable("MEK_None and MEK_Special are invalid");
255 break;
256 case MEK_CALL_HI16:
257 case MEK_CALL_LO16:
258 case MEK_GOT:
259 case MEK_GOT_CALL:
260 case MEK_GOT_DISP:
261 case MEK_GOT_HI16:
262 case MEK_GOT_LO16:
263 case MEK_GOT_OFST:
264 case MEK_GOT_PAGE:
265 case MEK_GPREL:
266 case MEK_HI:
267 case MEK_HIGHER:
268 case MEK_HIGHEST:
269 case MEK_LO:
270 case MEK_NEG:
271 case MEK_PCREL_HI16:
272 case MEK_PCREL_LO16:
273 // If we do have nested target-specific expressions, they will be in
274 // a consecutive chain.
275 if (const MipsMCExpr *E = dyn_cast<const MipsMCExpr>(getSubExpr()))
276 E->fixELFSymbolsInTLSFixups(Asm);
277 break;
278 case MEK_DTPREL:
279 case MEK_DTPREL_HI:
280 case MEK_DTPREL_LO:
281 case MEK_TLSLDM:
282 case MEK_TLSGD:
283 case MEK_GOTTPREL:
284 case MEK_TPREL_HI:
285 case MEK_TPREL_LO:
286 fixELFSymbolsInTLSFixupsImpl(getSubExpr(), Asm);
287 break;
288 }
289 }
290
isGpOff(MipsExprKind & Kind) const291 bool MipsMCExpr::isGpOff(MipsExprKind &Kind) const {
292 if (getKind() == MEK_HI || getKind() == MEK_LO) {
293 if (const MipsMCExpr *S1 = dyn_cast<const MipsMCExpr>(getSubExpr())) {
294 if (const MipsMCExpr *S2 = dyn_cast<const MipsMCExpr>(S1->getSubExpr())) {
295 if (S1->getKind() == MEK_NEG && S2->getKind() == MEK_GPREL) {
296 Kind = getKind();
297 return true;
298 }
299 }
300 }
301 }
302 return false;
303 }
304