xref: /freebsd/contrib/llvm-project/llvm/lib/MC/MCSectionELF.cpp (revision 093cf790569775b80662926efea6d9d3464bde94)
1 //===- lib/MC/MCSectionELF.cpp - ELF Code Section Representation ----------===//
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 "llvm/MC/MCSectionELF.h"
10 #include "llvm/ADT/Triple.h"
11 #include "llvm/BinaryFormat/ELF.h"
12 #include "llvm/MC/MCAsmInfo.h"
13 #include "llvm/MC/MCExpr.h"
14 #include "llvm/Support/ErrorHandling.h"
15 #include "llvm/Support/raw_ostream.h"
16 #include <cassert>
17 
18 using namespace llvm;
19 
20 // Decides whether a '.section' directive
21 // should be printed before the section name.
22 bool MCSectionELF::ShouldOmitSectionDirective(StringRef Name,
23                                               const MCAsmInfo &MAI) const {
24   if (isUnique())
25     return false;
26 
27   return MAI.shouldOmitSectionDirective(Name);
28 }
29 
30 static void printName(raw_ostream &OS, StringRef Name) {
31   if (Name.find_first_not_of("0123456789_."
32                              "abcdefghijklmnopqrstuvwxyz"
33                              "ABCDEFGHIJKLMNOPQRSTUVWXYZ") == Name.npos) {
34     OS << Name;
35     return;
36   }
37   OS << '"';
38   for (const char *B = Name.begin(), *E = Name.end(); B < E; ++B) {
39     if (*B == '"') // Unquoted "
40       OS << "\\\"";
41     else if (*B != '\\') // Neither " or backslash
42       OS << *B;
43     else if (B + 1 == E) // Trailing backslash
44       OS << "\\\\";
45     else {
46       OS << B[0] << B[1]; // Quoted character
47       ++B;
48     }
49   }
50   OS << '"';
51 }
52 
53 void MCSectionELF::PrintSwitchToSection(const MCAsmInfo &MAI, const Triple &T,
54                                         raw_ostream &OS,
55                                         const MCExpr *Subsection) const {
56   if (ShouldOmitSectionDirective(getName(), MAI)) {
57     OS << '\t' << getName();
58     if (Subsection) {
59       OS << '\t';
60       Subsection->print(OS, &MAI);
61     }
62     OS << '\n';
63     return;
64   }
65 
66   OS << "\t.section\t";
67   printName(OS, getName());
68 
69   // Handle the weird solaris syntax if desired.
70   if (MAI.usesSunStyleELFSectionSwitchSyntax() &&
71       !(Flags & ELF::SHF_MERGE)) {
72     if (Flags & ELF::SHF_ALLOC)
73       OS << ",#alloc";
74     if (Flags & ELF::SHF_EXECINSTR)
75       OS << ",#execinstr";
76     if (Flags & ELF::SHF_WRITE)
77       OS << ",#write";
78     if (Flags & ELF::SHF_EXCLUDE)
79       OS << ",#exclude";
80     if (Flags & ELF::SHF_TLS)
81       OS << ",#tls";
82     OS << '\n';
83     return;
84   }
85 
86   OS << ",\"";
87   if (Flags & ELF::SHF_ALLOC)
88     OS << 'a';
89   if (Flags & ELF::SHF_EXCLUDE)
90     OS << 'e';
91   if (Flags & ELF::SHF_EXECINSTR)
92     OS << 'x';
93   if (Flags & ELF::SHF_GROUP)
94     OS << 'G';
95   if (Flags & ELF::SHF_WRITE)
96     OS << 'w';
97   if (Flags & ELF::SHF_MERGE)
98     OS << 'M';
99   if (Flags & ELF::SHF_STRINGS)
100     OS << 'S';
101   if (Flags & ELF::SHF_TLS)
102     OS << 'T';
103   if (Flags & ELF::SHF_LINK_ORDER)
104     OS << 'o';
105   if (Flags & ELF::SHF_GNU_RETAIN)
106     OS << 'R';
107 
108   // If there are target-specific flags, print them.
109   Triple::ArchType Arch = T.getArch();
110   if (Arch == Triple::xcore) {
111     if (Flags & ELF::XCORE_SHF_CP_SECTION)
112       OS << 'c';
113     if (Flags & ELF::XCORE_SHF_DP_SECTION)
114       OS << 'd';
115   } else if (T.isARM() || T.isThumb()) {
116     if (Flags & ELF::SHF_ARM_PURECODE)
117       OS << 'y';
118   } else if (Arch == Triple::hexagon) {
119     if (Flags & ELF::SHF_HEX_GPREL)
120       OS << 's';
121   }
122 
123   OS << '"';
124 
125   OS << ',';
126 
127   // If comment string is '@', e.g. as on ARM - use '%' instead
128   if (MAI.getCommentString()[0] == '@')
129     OS << '%';
130   else
131     OS << '@';
132 
133   if (Type == ELF::SHT_INIT_ARRAY)
134     OS << "init_array";
135   else if (Type == ELF::SHT_FINI_ARRAY)
136     OS << "fini_array";
137   else if (Type == ELF::SHT_PREINIT_ARRAY)
138     OS << "preinit_array";
139   else if (Type == ELF::SHT_NOBITS)
140     OS << "nobits";
141   else if (Type == ELF::SHT_NOTE)
142     OS << "note";
143   else if (Type == ELF::SHT_PROGBITS)
144     OS << "progbits";
145   else if (Type == ELF::SHT_X86_64_UNWIND)
146     OS << "unwind";
147   else if (Type == ELF::SHT_MIPS_DWARF)
148     // Print hex value of the flag while we do not have
149     // any standard symbolic representation of the flag.
150     OS << "0x7000001e";
151   else if (Type == ELF::SHT_LLVM_ODRTAB)
152     OS << "llvm_odrtab";
153   else if (Type == ELF::SHT_LLVM_LINKER_OPTIONS)
154     OS << "llvm_linker_options";
155   else if (Type == ELF::SHT_LLVM_CALL_GRAPH_PROFILE)
156     OS << "llvm_call_graph_profile";
157   else if (Type == ELF::SHT_LLVM_DEPENDENT_LIBRARIES)
158     OS << "llvm_dependent_libraries";
159   else if (Type == ELF::SHT_LLVM_SYMPART)
160     OS << "llvm_sympart";
161   else if (Type == ELF::SHT_LLVM_BB_ADDR_MAP)
162     OS << "llvm_bb_addr_map";
163   else
164     report_fatal_error("unsupported type 0x" + Twine::utohexstr(Type) +
165                        " for section " + getName());
166 
167   if (EntrySize) {
168     assert(Flags & ELF::SHF_MERGE);
169     OS << "," << EntrySize;
170   }
171 
172   if (Flags & ELF::SHF_GROUP) {
173     OS << ",";
174     printName(OS, Group.getPointer()->getName());
175     if (isComdat())
176       OS << ",comdat";
177   }
178 
179   if (Flags & ELF::SHF_LINK_ORDER) {
180     OS << ",";
181     if (LinkedToSym)
182       printName(OS, LinkedToSym->getName());
183     else
184       OS << '0';
185   }
186 
187   if (isUnique())
188     OS << ",unique," << UniqueID;
189 
190   OS << '\n';
191 
192   if (Subsection) {
193     OS << "\t.subsection\t";
194     Subsection->print(OS, &MAI);
195     OS << '\n';
196   }
197 }
198 
199 bool MCSectionELF::UseCodeAlign() const {
200   return getFlags() & ELF::SHF_EXECINSTR;
201 }
202 
203 bool MCSectionELF::isVirtualSection() const {
204   return getType() == ELF::SHT_NOBITS;
205 }
206 
207 StringRef MCSectionELF::getVirtualSectionKind() const { return "SHT_NOBITS"; }
208