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
19 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 
31 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 
37 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   if (getCharacteristics() & COFF::IMAGE_SCN_LNK_INFO)
67     OS << 'i';
68   OS << '"';
69 
70   if (getCharacteristics() & COFF::IMAGE_SCN_LNK_COMDAT) {
71     if (COMDATSymbol)
72       OS << ",";
73     else
74       OS << "\n\t.linkonce\t";
75     switch (Selection) {
76       case COFF::IMAGE_COMDAT_SELECT_NODUPLICATES:
77         OS << "one_only";
78         break;
79       case COFF::IMAGE_COMDAT_SELECT_ANY:
80         OS << "discard";
81         break;
82       case COFF::IMAGE_COMDAT_SELECT_SAME_SIZE:
83         OS << "same_size";
84         break;
85       case COFF::IMAGE_COMDAT_SELECT_EXACT_MATCH:
86         OS << "same_contents";
87         break;
88       case COFF::IMAGE_COMDAT_SELECT_ASSOCIATIVE:
89         OS << "associative";
90         break;
91       case COFF::IMAGE_COMDAT_SELECT_LARGEST:
92         OS << "largest";
93         break;
94       case COFF::IMAGE_COMDAT_SELECT_NEWEST:
95         OS << "newest";
96         break;
97       default:
98         assert(false && "unsupported COFF selection type");
99         break;
100     }
101     if (COMDATSymbol) {
102       OS << ",";
103       COMDATSymbol->print(OS, &MAI);
104     }
105   }
106   OS << '\n';
107 }
108 
109 bool MCSectionCOFF::useCodeAlign() const { return getKind().isText(); }
110 
111 bool MCSectionCOFF::isVirtualSection() const {
112   return getCharacteristics() & COFF::IMAGE_SCN_CNT_UNINITIALIZED_DATA;
113 }
114 
115 StringRef MCSectionCOFF::getVirtualSectionKind() const {
116   return "IMAGE_SCN_CNT_UNINITIALIZED_DATA";
117 }
118