MCSectionCOFF.cpp revision 267654 
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"
15using namespace llvm;
16
17MCSectionCOFF::~MCSectionCOFF() {} // anchor.
18
19// ShouldOmitSectionDirective - Decides whether a '.section' directive
20// should be printed before the section name
21bool 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
31void 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
42void MCSectionCOFF::PrintSwitchToSection(const MCAsmInfo &MAI,
43                                         raw_ostream &OS,
44                                         const MCExpr *Subsection) const {
45
46  // standard sections don't require the '.section'
47  if (ShouldOmitSectionDirective(SectionName, MAI)) {
48    OS << '\t' << getSectionName() << '\n';
49    return;
50  }
51
52  OS << "\t.section\t" << getSectionName() << ",\"";
53  if (getKind().isText())
54    OS << 'x';
55  if (getKind().isWriteable())
56    OS << 'w';
57  else
58    OS << 'r';
59  if (getCharacteristics() & COFF::IMAGE_SCN_MEM_DISCARDABLE)
60    OS << 'n';
61  OS << "\"\n";
62
63  if (getCharacteristics() & COFF::IMAGE_SCN_LNK_COMDAT) {
64    switch (Selection) {
65      case COFF::IMAGE_COMDAT_SELECT_NODUPLICATES:
66        OS << "\t.linkonce one_only\n";
67        break;
68      case COFF::IMAGE_COMDAT_SELECT_ANY:
69        OS << "\t.linkonce discard\n";
70        break;
71      case COFF::IMAGE_COMDAT_SELECT_SAME_SIZE:
72        OS << "\t.linkonce same_size\n";
73        break;
74      case COFF::IMAGE_COMDAT_SELECT_EXACT_MATCH:
75        OS << "\t.linkonce same_contents\n";
76        break;
77      case COFF::IMAGE_COMDAT_SELECT_ASSOCIATIVE:
78        OS << "\t.linkonce associative " << Assoc->getSectionName() << "\n";
79        break;
80      case COFF::IMAGE_COMDAT_SELECT_LARGEST:
81        OS << "\t.linkonce largest\n";
82        break;
83      case COFF::IMAGE_COMDAT_SELECT_NEWEST:
84        OS << "\t.linkonce newest\n";
85        break;
86      default:
87        assert (0 && "unsupported COFF selection type");
88        break;
89    }
90  }
91}
92
93bool MCSectionCOFF::UseCodeAlign() const {
94  return getKind().isText();
95}
96
97bool MCSectionCOFF::isVirtualSection() const {
98  return getCharacteristics() & COFF::IMAGE_SCN_CNT_UNINITIALIZED_DATA;
99}
100