1 //===- lib/MC/MCSectionCOFF.cpp - COFF 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/MCSectionCOFF.h"
10 #include "llvm/BinaryFormat/COFF.h"
11 #include "llvm/MC/MCSymbol.h"
12 #include "llvm/Support/raw_ostream.h"
13 #include <cassert>
14 
15 using namespace llvm;
16 
17 // ShouldOmitSectionDirective - Decides whether a '.section' directive
18 // should be printed before the section name
ShouldOmitSectionDirective(StringRef Name,const MCAsmInfo & MAI) const19 bool MCSectionCOFF::ShouldOmitSectionDirective(StringRef Name,
20                                                const MCAsmInfo &MAI) const {
21   if (COMDATSymbol)
22     return false;
23 
24   // FIXME: Does .section .bss/.data/.text work everywhere??
25   if (Name == ".text" || Name == ".data" || Name == ".bss")
26     return true;
27 
28   return false;
29 }
30 
setSelection(int Selection) const31 void MCSectionCOFF::setSelection(int Selection) const {
32   assert(Selection != 0 && "invalid COMDAT selection type");
33   this->Selection = Selection;
34   Characteristics |= COFF::IMAGE_SCN_LNK_COMDAT;
35 }
36 
PrintSwitchToSection(const MCAsmInfo & MAI,const Triple & T,raw_ostream & OS,const MCExpr * Subsection) const37 void MCSectionCOFF::PrintSwitchToSection(const MCAsmInfo &MAI, const Triple &T,
38                                          raw_ostream &OS,
39                                          const MCExpr *Subsection) const {
40   // standard sections don't require the '.section'
41   if (ShouldOmitSectionDirective(getName(), MAI)) {
42     OS << '\t' << getName() << '\n';
43     return;
44   }
45 
46   OS << "\t.section\t" << getName() << ",\"";
47   if (getCharacteristics() & COFF::IMAGE_SCN_CNT_INITIALIZED_DATA)
48     OS << 'd';
49   if (getCharacteristics() & COFF::IMAGE_SCN_CNT_UNINITIALIZED_DATA)
50     OS << 'b';
51   if (getCharacteristics() & COFF::IMAGE_SCN_MEM_EXECUTE)
52     OS << 'x';
53   if (getCharacteristics() & COFF::IMAGE_SCN_MEM_WRITE)
54     OS << 'w';
55   else if (getCharacteristics() & COFF::IMAGE_SCN_MEM_READ)
56     OS << 'r';
57   else
58     OS << 'y';
59   if (getCharacteristics() & COFF::IMAGE_SCN_LNK_REMOVE)
60     OS << 'n';
61   if (getCharacteristics() & COFF::IMAGE_SCN_MEM_SHARED)
62     OS << 's';
63   if ((getCharacteristics() & COFF::IMAGE_SCN_MEM_DISCARDABLE) &&
64       !isImplicitlyDiscardable(getName()))
65     OS << 'D';
66   OS << '"';
67 
68   if (getCharacteristics() & COFF::IMAGE_SCN_LNK_COMDAT) {
69     if (COMDATSymbol)
70       OS << ",";
71     else
72       OS << "\n\t.linkonce\t";
73     switch (Selection) {
74       case COFF::IMAGE_COMDAT_SELECT_NODUPLICATES:
75         OS << "one_only";
76         break;
77       case COFF::IMAGE_COMDAT_SELECT_ANY:
78         OS << "discard";
79         break;
80       case COFF::IMAGE_COMDAT_SELECT_SAME_SIZE:
81         OS << "same_size";
82         break;
83       case COFF::IMAGE_COMDAT_SELECT_EXACT_MATCH:
84         OS << "same_contents";
85         break;
86       case COFF::IMAGE_COMDAT_SELECT_ASSOCIATIVE:
87         OS << "associative";
88         break;
89       case COFF::IMAGE_COMDAT_SELECT_LARGEST:
90         OS << "largest";
91         break;
92       case COFF::IMAGE_COMDAT_SELECT_NEWEST:
93         OS << "newest";
94         break;
95       default:
96         assert(false && "unsupported COFF selection type");
97         break;
98     }
99     if (COMDATSymbol) {
100       OS << ",";
101       COMDATSymbol->print(OS, &MAI);
102     }
103   }
104   OS << '\n';
105 }
106 
UseCodeAlign() const107 bool MCSectionCOFF::UseCodeAlign() const {
108   return getKind().isText();
109 }
110 
isVirtualSection() const111 bool MCSectionCOFF::isVirtualSection() const {
112   return getCharacteristics() & COFF::IMAGE_SCN_CNT_UNINITIALIZED_DATA;
113 }
114 
getVirtualSectionKind() const115 StringRef MCSectionCOFF::getVirtualSectionKind() const {
116   return "IMAGE_SCN_CNT_UNINITIALIZED_DATA";
117 }
118