llvm/lib/MC/MCSectionXCOFF.cpp

   1 //===- lib/MC/MCSectionXCOFF.cpp - XCOFF 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/MCSectionXCOFF.h"
  10 #include "llvm/MC/MCAsmInfo.h"
  11 #include "llvm/Support/Format.h"
  12 #include "llvm/Support/raw_ostream.h"
  13 namespace llvm {
  14 class MCExpr;
  15 class Triple;
  16 } // namespace llvm
  17
  18 using namespace llvm;
  19
  20 MCSectionXCOFF::~MCSectionXCOFF() = default;
  21
  22 void MCSectionXCOFF::printCsectDirective(raw_ostream &OS) const {
  23   OS << "\t.csect " << QualName->getName() << "," << Log2(getAlign()) << '\n';
  24 }
  25
  26 void MCSectionXCOFF::printSwitchToSection(const MCAsmInfo &MAI, const Triple &T,
  27                                           raw_ostream &OS,
  28                                           const MCExpr *Subsection) const {
  29   if (getKind().isText()) {
  30     if (getMappingClass() != XCOFF::XMC_PR)
  31       report_fatal_error("Unhandled storage-mapping class for .text csect");
  32
  33     printCsectDirective(OS);
  34     return;
  35   }
  36
  37   if (getKind().isReadOnly()) {
  38     if (getMappingClass() != XCOFF::XMC_RO &&
  39         getMappingClass() != XCOFF::XMC_TD)
  40       report_fatal_error("Unhandled storage-mapping class for .rodata csect.");
  41     printCsectDirective(OS);
  42     return;
  43   }
  44
  45   if (getKind().isReadOnlyWithRel()) {
  46     if (getMappingClass() != XCOFF::XMC_RW &&
  47         getMappingClass() != XCOFF::XMC_RO &&
  48         getMappingClass() != XCOFF::XMC_TD)
  49       report_fatal_error(
  50           "Unexepected storage-mapping class for ReadOnlyWithRel kind");
  51     printCsectDirective(OS);
  52     return;
  53   }
  54
  55   // Initialized TLS data.
  56   if (getKind().isThreadData()) {
  57     // We only expect XMC_TL here for initialized TLS data.
  58     if (getMappingClass() != XCOFF::XMC_TL)
  59       report_fatal_error("Unhandled storage-mapping class for .tdata csect.");
  60     printCsectDirective(OS);
  61     return;
  62   }
  63
  64   if (getKind().isData()) {
  65     switch (getMappingClass()) {
  66     case XCOFF::XMC_RW:
  67     case XCOFF::XMC_DS:
  68     case XCOFF::XMC_TD:
  69       printCsectDirective(OS);
  70       break;
  71     case XCOFF::XMC_TC:
  72     case XCOFF::XMC_TE:
  73       break;
  74     case XCOFF::XMC_TC0:
  75       OS << "\t.toc\n";
  76       break;
  77     default:
  78       report_fatal_error(
  79           "Unhandled storage-mapping class for .data csect.");
  80     }
  81     return;
  82   }
  83
  84   if (isCsect() && getMappingClass() == XCOFF::XMC_TD) {
  85     assert((getKind().isBSSExtern() || getKind().isBSSLocal()) &&
  86            "Unexepected section kind for toc-data");
  87     printCsectDirective(OS);
  88     return;
  89   }
  90   // Common csect type (uninitialized storage) does not have to print csect
  91   // directive for section switching.
  92   if (isCsect() && getCSectType() == XCOFF::XTY_CM) {
  93     assert((getMappingClass() == XCOFF::XMC_RW ||
  94             getMappingClass() == XCOFF::XMC_BS ||
  95             getMappingClass() == XCOFF::XMC_UL) &&
  96            "Generated a storage-mapping class for a common/bss/tbss csect we "
  97            "don't "
  98            "understand how to switch to.");
  99     // Common symbols and local zero-initialized symbols for TLS and Non-TLS are
 100     // eligible for .bss/.tbss csect, getKind().isThreadBSS() is used to cover
 101     // TLS common and zero-initialized local symbols since linkage type (in the
 102     // GlobalVariable) is not accessible in this class.
 103     assert((getKind().isBSSLocal() || getKind().isCommon() ||
 104             getKind().isThreadBSS()) &&
 105            "wrong symbol type for .bss/.tbss csect");
 106     // Don't have to print a directive for switching to section for commons and
 107     // zero-initialized TLS data. The '.comm' and '.lcomm' directives of the
 108     // variable will create the needed csect.
 109     return;
 110   }
 111
 112   // Zero-initialized TLS data with weak or external linkage are not eligible to
 113   // be put into common csect.
 114   if (getKind().isThreadBSS()) {
 115     printCsectDirective(OS);
 116     return;
 117   }
 118
 119   // XCOFF debug sections.
 120   if (getKind().isMetadata() && isDwarfSect()) {
 121     OS << "\n\t.dwsect " << format("0x%" PRIx32, *getDwarfSubtypeFlags())
 122        << '\n';
 123     OS << MAI.getPrivateLabelPrefix() << getName() << ':' << '\n';
 124     return;
 125   }
 126
 127   report_fatal_error("Printing for this SectionKind is unimplemented.");
 128 }
 129
 130 bool MCSectionXCOFF::useCodeAlign() const { return getKind().isText(); }
 131
 132 bool MCSectionXCOFF::isVirtualSection() const {
 133   // DWARF sections are always not virtual.
 134   if (isDwarfSect())
 135     return false;
 136   assert(isCsect() &&
 137          "Handling for isVirtualSection not implemented for this section!");
 138   return XCOFF::XTY_CM == CsectProp->Type;
 139 }