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 }
131