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_32(getAlignment())
24      << '\n';
25 }
26 
27 void MCSectionXCOFF::printSwitchToSection(const MCAsmInfo &MAI, const Triple &T,
28                                           raw_ostream &OS,
29                                           const MCExpr *Subsection) const {
30   if (getKind().isText()) {
31     if (getMappingClass() != XCOFF::XMC_PR)
32       report_fatal_error("Unhandled storage-mapping class for .text csect");
33 
34     printCsectDirective(OS);
35     return;
36   }
37 
38   if (getKind().isReadOnly()) {
39     if (getMappingClass() != XCOFF::XMC_RO &&
40         getMappingClass() != XCOFF::XMC_TD)
41       report_fatal_error("Unhandled storage-mapping class for .rodata csect.");
42     printCsectDirective(OS);
43     return;
44   }
45 
46   // Initialized TLS data.
47   if (getKind().isThreadData()) {
48     // We only expect XMC_TL here for initialized TLS data.
49     if (getMappingClass() != XCOFF::XMC_TL)
50       report_fatal_error("Unhandled storage-mapping class for .tdata csect.");
51     printCsectDirective(OS);
52     return;
53   }
54 
55   if (getKind().isData()) {
56     switch (getMappingClass()) {
57     case XCOFF::XMC_RW:
58     case XCOFF::XMC_DS:
59     case XCOFF::XMC_TD:
60       printCsectDirective(OS);
61       break;
62     case XCOFF::XMC_TC:
63     case XCOFF::XMC_TE:
64       break;
65     case XCOFF::XMC_TC0:
66       OS << "\t.toc\n";
67       break;
68     default:
69       report_fatal_error(
70           "Unhandled storage-mapping class for .data csect.");
71     }
72     return;
73   }
74 
75   if (isCsect() && getMappingClass() == XCOFF::XMC_TD) {
76     assert((getKind().isBSSExtern() || getKind().isBSSLocal() ||
77             getKind().isReadOnlyWithRel()) &&
78            "Unexepected section kind for toc-data");
79     printCsectDirective(OS);
80     return;
81   }
82   // Common csect type (uninitialized storage) does not have to print csect
83   // directive for section switching.
84   if (isCsect() && getCSectType() == XCOFF::XTY_CM) {
85     assert((getMappingClass() == XCOFF::XMC_RW ||
86             getMappingClass() == XCOFF::XMC_BS ||
87             getMappingClass() == XCOFF::XMC_UL) &&
88            "Generated a storage-mapping class for a common/bss/tbss csect we "
89            "don't "
90            "understand how to switch to.");
91     // Common symbols and local zero-initialized symbols for TLS and Non-TLS are
92     // eligible for .bss/.tbss csect, getKind().isThreadBSS() is used to cover
93     // TLS common and zero-initialized local symbols since linkage type (in the
94     // GlobalVariable) is not accessible in this class.
95     assert((getKind().isBSSLocal() || getKind().isCommon() ||
96             getKind().isThreadBSS()) &&
97            "wrong symbol type for .bss/.tbss csect");
98     // Don't have to print a directive for switching to section for commons and
99     // zero-initialized TLS data. The '.comm' and '.lcomm' directives of the
100     // variable will create the needed csect.
101     return;
102   }
103 
104   // Zero-initialized TLS data with weak or external linkage are not eligible to
105   // be put into common csect.
106   if (getKind().isThreadBSS()) {
107     printCsectDirective(OS);
108     return;
109   }
110 
111   // XCOFF debug sections.
112   if (getKind().isMetadata() && isDwarfSect()) {
113     OS << "\n\t.dwsect " << format("0x%" PRIx32, getDwarfSubtypeFlags().value())
114        << '\n';
115     OS << MAI.getPrivateLabelPrefix() << getName() << ':' << '\n';
116     return;
117   }
118 
119   report_fatal_error("Printing for this SectionKind is unimplemented.");
120 }
121 
122 bool MCSectionXCOFF::useCodeAlign() const { return getKind().isText(); }
123 
124 bool MCSectionXCOFF::isVirtualSection() const {
125   // DWARF sections are always not virtual.
126   if (isDwarfSect())
127     return false;
128   assert(isCsect() &&
129          "Handling for isVirtualSection not implemented for this section!");
130   return XCOFF::XTY_CM == CsectProp->Type;
131 }
132