1 //===- lib/MC/MCSectionCOFF.cpp - COFF Code Section Representation --------===//
2 //
3 //                     The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 
10 #include "llvm/MC/MCSectionCOFF.h"
11 #include "llvm/MC/MCAsmInfo.h"
12 #include "llvm/MC/MCContext.h"
13 #include "llvm/MC/MCSymbol.h"
14 #include "llvm/Support/raw_ostream.h"
15 using namespace llvm;
16 
17 MCSectionCOFF::~MCSectionCOFF() {} // anchor.
18 
19 // ShouldOmitSectionDirective - Decides whether a '.section' directive
20 // should be printed before the section name
21 bool MCSectionCOFF::ShouldOmitSectionDirective(StringRef Name,
22                                                const MCAsmInfo &MAI) const {
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,
32                                  const MCSectionCOFF *Assoc) const {
33   assert(Selection != 0 && "invalid COMDAT selection type");
34   assert((Selection == COFF::IMAGE_COMDAT_SELECT_ASSOCIATIVE) ==
35          (Assoc != 0) &&
36     "associative COMDAT section must have an associated section");
37   this->Selection = Selection;
38   this->Assoc = Assoc;
39   Characteristics |= COFF::IMAGE_SCN_LNK_COMDAT;
40 }
41 
42 static bool isAcceptableSectionNameChar(char C) {
43   return (C >= 'a' && C <= 'z') ||
44          (C >= 'A' && C <= 'Z') ||
45          (C >= '0' && C <= '9') ||
46          C == '_' || C == '$' || C == '.';
47 }
48 
49 /// NameNeedsQuoting - Return true if the identifier \p Str needs quotes to be
50 /// syntactically correct.
51 static bool sectionNameNeedsQuoting(StringRef Name) {
52   for (unsigned i = 0, e = Name.size(); i != e; ++i)
53     if (!isAcceptableSectionNameChar(Name[i]))
54       return true;
55   return false;
56 }
57 
58 void MCSectionCOFF::PrintSwitchToSection(const MCAsmInfo &MAI,
59                                          raw_ostream &OS,
60                                          const MCExpr *Subsection) const {
61 
62   // standard sections don't require the '.section'
63   if (ShouldOmitSectionDirective(SectionName, MAI)) {
64     OS << '\t' << getSectionName() << '\n';
65     return;
66   }
67 
68   if (sectionNameNeedsQuoting(getSectionName()))
69     OS << "\t.section\t" << '"' << getSectionName() << '"' << ",\"";
70   else
71     OS << "\t.section\t" << getSectionName() << ",\"";
72   if (getKind().isText())
73     OS << 'x';
74   if (getKind().isWriteable())
75     OS << 'w';
76   else
77     OS << 'r';
78   if (getCharacteristics() & COFF::IMAGE_SCN_MEM_DISCARDABLE)
79     OS << 'n';
80   OS << "\"\n";
81 
82   if (getCharacteristics() & COFF::IMAGE_SCN_LNK_COMDAT) {
83     switch (Selection) {
84       case COFF::IMAGE_COMDAT_SELECT_NODUPLICATES:
85         OS << "\t.linkonce one_only\n";
86         break;
87       case COFF::IMAGE_COMDAT_SELECT_ANY:
88         OS << "\t.linkonce discard\n";
89         break;
90       case COFF::IMAGE_COMDAT_SELECT_SAME_SIZE:
91         OS << "\t.linkonce same_size\n";
92         break;
93       case COFF::IMAGE_COMDAT_SELECT_EXACT_MATCH:
94         OS << "\t.linkonce same_contents\n";
95         break;
96       case COFF::IMAGE_COMDAT_SELECT_ASSOCIATIVE:
97         OS << "\t.linkonce associative " << Assoc->getSectionName() << "\n";
98         break;
99       case COFF::IMAGE_COMDAT_SELECT_LARGEST:
100         OS << "\t.linkonce largest\n";
101         break;
102       case COFF::IMAGE_COMDAT_SELECT_NEWEST:
103         OS << "\t.linkonce newest\n";
104         break;
105       default:
106         assert (0 && "unsupported COFF selection type");
107         break;
108     }
109   }
110 }
111 
112 bool MCSectionCOFF::UseCodeAlign() const {
113   return getKind().isText();
114 }
115 
116 bool MCSectionCOFF::isVirtualSection() const {
117   return getCharacteristics() & COFF::IMAGE_SCN_CNT_UNINITIALIZED_DATA;
118 }
119