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   // Initialized TLS data.
  46   if (getKind().isThreadData()) {
  47     // We only expect XMC_TL here for initialized TLS data.
  48     if (getMappingClass() != XCOFF::XMC_TL)
  49       report_fatal_error("Unhandled storage-mapping class for .tdata csect.");
  50     printCsectDirective(OS);
  51     return;
  52   }
  53
  54   if (getKind().isData()) {
  55     switch (getMappingClass()) {
  56     case XCOFF::XMC_RW:
  57     case XCOFF::XMC_DS:
  58     case XCOFF::XMC_TD:
  59       printCsectDirective(OS);
  60       break;
  61     case XCOFF::XMC_TC:
  62     case XCOFF::XMC_TE:
  63       break;
  64     case XCOFF::XMC_TC0:
  65       OS << "\t.toc\n";
  66       break;
  67     default:
  68       report_fatal_error(
  69           "Unhandled storage-mapping class for .data csect.");
  70     }
  71     return;
  72   }
  73
  74   if (isCsect() && getMappingClass() == XCOFF::XMC_TD) {
  75     assert((getKind().isBSSExtern() || getKind().isBSSLocal() ||
  76             getKind().isReadOnlyWithRel()) &&
  77            "Unexepected section kind for toc-data");
  78     printCsectDirective(OS);
  79     return;
  80   }
  81   // Common csect type (uninitialized storage) does not have to print csect
  82   // directive for section switching.
  83   if (isCsect() && getCSectType() == XCOFF::XTY_CM) {
  84     assert((getMappingClass() == XCOFF::XMC_RW ||
  85             getMappingClass() == XCOFF::XMC_BS ||
  86             getMappingClass() == XCOFF::XMC_UL) &&
  87            "Generated a storage-mapping class for a common/bss/tbss csect we "
  88            "don't "
  89            "understand how to switch to.");
  90     // Common symbols and local zero-initialized symbols for TLS and Non-TLS are
  91     // eligible for .bss/.tbss csect, getKind().isThreadBSS() is used to cover
  92     // TLS common and zero-initialized local symbols since linkage type (in the
  93     // GlobalVariable) is not accessible in this class.
  94     assert((getKind().isBSSLocal() || getKind().isCommon() ||
  95             getKind().isThreadBSS()) &&
  96            "wrong symbol type for .bss/.tbss csect");
  97     // Don't have to print a directive for switching to section for commons and
  98     // zero-initialized TLS data. The '.comm' and '.lcomm' directives of the
  99     // variable will create the needed csect.
 100     return;
 101   }
 102
 103   // Zero-initialized TLS data with weak or external linkage are not eligible to
 104   // be put into common csect.
 105   if (getKind().isThreadBSS()) {
 106     printCsectDirective(OS);
 107     return;
 108   }
 109
 110   // XCOFF debug sections.
 111   if (getKind().isMetadata() && isDwarfSect()) {
 112     OS << "\n\t.dwsect " << format("0x%" PRIx32, *getDwarfSubtypeFlags())
 113        << '\n';
 114     OS << MAI.getPrivateLabelPrefix() << getName() << ':' << '\n';
 115     return;
 116   }
 117
 118   report_fatal_error("Printing for this SectionKind is unimplemented.");
 119 }
 120
 121 bool MCSectionXCOFF::useCodeAlign() const { return getKind().isText(); }
 122
 123 bool MCSectionXCOFF::isVirtualSection() const {
 124   // DWARF sections are always not virtual.
 125   if (isDwarfSect())
 126     return false;
 127   assert(isCsect() &&
 128          "Handling for isVirtualSection not implemented for this section!");
 129   return XCOFF::XTY_CM == CsectProp->Type;
 130 }