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
23using namespace llvm;
24
25#define DEBUG_TYPE "mipsmcexpr"
26
27const MipsMCExpr *MipsMCExpr::create(MipsMCExpr::MipsExprKind Kind,
28                                     const MCExpr *Expr, MCContext &Ctx) {
29  return new (Ctx) MipsMCExpr(Kind, Expr);
30}
31
32const 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
37void 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
132bool
133MipsMCExpr::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
220void MipsMCExpr::visitUsedExpr(MCStreamer &Streamer) const {
221  Streamer.visitUsedExpr(*getSubExpr());
222}
223
224static 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
250void 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
291bool 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