1 //===-- TargetAsmInfo.cpp - Asm Info ---------------------------------------==//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file defines target asm properties related what form asm statements
13 //===----------------------------------------------------------------------===//
15 #include "llvm/Constants.h"
16 #include "llvm/GlobalVariable.h"
17 #include "llvm/Function.h"
18 #include "llvm/Module.h"
19 #include "llvm/Type.h"
20 #include "llvm/Target/TargetAsmInfo.h"
21 #include "llvm/Target/TargetOptions.h"
22 #include "llvm/Support/Dwarf.h"
28 void TargetAsmInfo::fillDefaultValues() {
29 BSSSection = "\t.bss";
34 SmallRODataSection = 0;
37 ZeroFillDirective = 0;
38 NonexecutableStackDirective = 0;
45 PrivateGlobalPrefix = ".";
46 LessPrivateGlobalPrefix = "";
47 JumpTableSpecialLabelPrefix = 0;
48 GlobalVarAddrPrefix = "";
49 GlobalVarAddrSuffix = "";
50 FunctionAddrPrefix = "";
51 FunctionAddrSuffix = "";
52 PersonalityPrefix = "";
53 PersonalitySuffix = "";
54 NeedsIndirectEncoding = false;
55 InlineAsmStart = "#APP";
56 InlineAsmEnd = "#NO_APP";
58 StringConstantPrefix = ".str";
59 ZeroDirective = "\t.zero\t";
60 ZeroDirectiveSuffix = 0;
61 AsciiDirective = "\t.ascii\t";
62 AscizDirective = "\t.asciz\t";
63 Data8bitsDirective = "\t.byte\t";
64 Data16bitsDirective = "\t.short\t";
65 Data32bitsDirective = "\t.long\t";
66 Data64bitsDirective = "\t.quad\t";
67 AlignDirective = "\t.align\t";
68 AlignmentIsInBytes = true;
69 TextAlignFillValue = 0;
70 SwitchToSectionDirective = "\t.section\t";
71 TextSectionStartSuffix = "";
72 DataSectionStartSuffix = "";
73 SectionEndDirectiveSuffix = 0;
74 ConstantPoolSection = "\t.section .rodata";
75 JumpTableDataSection = "\t.section .rodata";
76 JumpTableDirective = 0;
79 // FIXME: Flags are ELFish - replace with normal section stuff.
80 StaticCtorsSection = "\t.section .ctors,\"aw\",@progbits";
81 StaticDtorsSection = "\t.section .dtors,\"aw\",@progbits";
82 GlobalDirective = "\t.globl\t";
85 COMMDirective = "\t.comm\t";
86 COMMDirectiveTakesAlignment = true;
87 HasDotTypeDotSizeDirective = true;
91 // FIXME: These are ELFish - move to ELFTAI.
92 HiddenDirective = "\t.hidden\t";
93 ProtectedDirective = "\t.protected\t";
94 AbsoluteDebugSectionOffsets = false;
95 AbsoluteEHSectionOffsets = false;
97 HasDotLocAndDotFile = false;
98 SupportsDebugInformation = false;
99 SupportsExceptionHandling = false;
100 DwarfRequiresFrameSection = true;
101 GlobalEHDirective = 0;
102 SupportsWeakOmittedEHFrame = true;
103 DwarfSectionOffsetDirective = 0;
104 DwarfAbbrevSection = ".debug_abbrev";
105 DwarfInfoSection = ".debug_info";
106 DwarfLineSection = ".debug_line";
107 DwarfFrameSection = ".debug_frame";
108 DwarfPubNamesSection = ".debug_pubnames";
109 DwarfPubTypesSection = ".debug_pubtypes";
110 DwarfStrSection = ".debug_str";
111 DwarfLocSection = ".debug_loc";
112 DwarfARangesSection = ".debug_aranges";
113 DwarfRangesSection = ".debug_ranges";
114 DwarfMacInfoSection = ".debug_macinfo";
115 DwarfEHFrameSection = ".eh_frame";
116 DwarfExceptionSection = ".gcc_except_table";
118 TextSection = getUnnamedSection("\t.text", SectionFlags::Code);
119 DataSection = getUnnamedSection("\t.data", SectionFlags::Writeable);
122 TargetAsmInfo::TargetAsmInfo(const TargetMachine &tm)
127 TargetAsmInfo::~TargetAsmInfo() {
130 /// Measure the specified inline asm to determine an approximation of its
132 /// Comments (which run till the next SeparatorChar or newline) do not
133 /// count as an instruction.
134 /// Any other non-whitespace text is considered an instruction, with
135 /// multiple instructions separated by SeparatorChar or newlines.
136 /// Variable-length instructions are not handled here; this function
137 /// may be overloaded in the target code to do that.
138 unsigned TargetAsmInfo::getInlineAsmLength(const char *Str) const {
139 // Count the number of instructions in the asm.
140 bool atInsnStart = true;
142 for (; *Str; ++Str) {
143 if (*Str == '\n' || *Str == SeparatorChar)
145 if (atInsnStart && !isspace(*Str)) {
146 Length += MaxInstLength;
149 if (atInsnStart && strncmp(Str, CommentString, strlen(CommentString))==0)
156 unsigned TargetAsmInfo::PreferredEHDataFormat(DwarfEncoding::Target Reason,
158 return dwarf::DW_EH_PE_absptr;
161 static bool isSuitableForBSS(const GlobalVariable *GV) {
162 if (!GV->hasInitializer())
165 // Leave constant zeros in readonly constant sections, so they can be shared
166 Constant *C = GV->getInitializer();
167 return (C->isNullValue() && !GV->isConstant() && !NoZerosInBSS);
171 TargetAsmInfo::SectionKindForGlobal(const GlobalValue *GV) const {
172 // Early exit - functions should be always in text sections.
173 if (isa<Function>(GV))
174 return SectionKind::Text;
176 const GlobalVariable* GVar = dyn_cast<GlobalVariable>(GV);
177 bool isThreadLocal = GVar->isThreadLocal();
178 assert(GVar && "Invalid global value for section selection");
180 if (isSuitableForBSS(GVar)) {
181 // Variable can be easily put to BSS section.
182 return (isThreadLocal ? SectionKind::ThreadBSS : SectionKind::BSS);
183 } else if (GVar->isConstant() && !isThreadLocal) {
184 // Now we know, that varible has initializer and it is constant. We need to
185 // check its initializer to decide, which section to output it into. Also
186 // note, there is no thread-local r/o section.
187 Constant *C = GVar->getInitializer();
188 if (C->ContainsRelocations())
189 return SectionKind::ROData;
191 const ConstantArray *CVA = dyn_cast<ConstantArray>(C);
192 // Check, if initializer is a null-terminated string
193 if (CVA && CVA->isCString())
194 return SectionKind::RODataMergeStr;
196 return SectionKind::RODataMergeConst;
200 // Variable is not constant or thread-local - emit to generic data section.
201 return (isThreadLocal ? SectionKind::ThreadData : SectionKind::Data);
205 TargetAsmInfo::SectionFlagsForGlobal(const GlobalValue *GV,
206 const char* Name) const {
207 unsigned Flags = SectionFlags::None;
209 // Decode flags from global itself.
211 SectionKind::Kind Kind = SectionKindForGlobal(GV);
213 case SectionKind::Text:
214 Flags |= SectionFlags::Code;
216 case SectionKind::ThreadData:
217 case SectionKind::ThreadBSS:
218 Flags |= SectionFlags::TLS;
220 case SectionKind::Data:
221 case SectionKind::BSS:
222 Flags |= SectionFlags::Writeable;
224 case SectionKind::ROData:
225 case SectionKind::RODataMergeStr:
226 case SectionKind::RODataMergeConst:
227 // No additional flags here
229 case SectionKind::SmallData:
230 case SectionKind::SmallBSS:
231 Flags |= SectionFlags::Writeable;
233 case SectionKind::SmallROData:
234 Flags |= SectionFlags::Small;
237 assert(0 && "Unexpected section kind!");
240 if (GV->mayBeOverridden())
241 Flags |= SectionFlags::Linkonce;
244 // Add flags from sections, if any.
246 Flags |= SectionFlags::Named;
248 // Some lame default implementation based on some magic section names.
249 if (strncmp(Name, ".gnu.linkonce.b.", 16) == 0 ||
250 strncmp(Name, ".llvm.linkonce.b.", 17) == 0 ||
251 strncmp(Name, ".gnu.linkonce.sb.", 17) == 0 ||
252 strncmp(Name, ".llvm.linkonce.sb.", 18) == 0)
253 Flags |= SectionFlags::BSS;
254 else if (strcmp(Name, ".tdata") == 0 ||
255 strncmp(Name, ".tdata.", 7) == 0 ||
256 strncmp(Name, ".gnu.linkonce.td.", 17) == 0 ||
257 strncmp(Name, ".llvm.linkonce.td.", 18) == 0)
258 Flags |= SectionFlags::TLS;
259 else if (strcmp(Name, ".tbss") == 0 ||
260 strncmp(Name, ".tbss.", 6) == 0 ||
261 strncmp(Name, ".gnu.linkonce.tb.", 17) == 0 ||
262 strncmp(Name, ".llvm.linkonce.tb.", 18) == 0)
263 Flags |= SectionFlags::BSS | SectionFlags::TLS;
270 TargetAsmInfo::SectionForGlobal(const GlobalValue *GV) const {
272 // Select section name
273 if (GV->hasSection()) {
274 // Honour section already set, if any
275 unsigned Flags = SectionFlagsForGlobal(GV,
276 GV->getSection().c_str());
277 S = getNamedSection(GV->getSection().c_str(), Flags);
279 // Use default section depending on the 'type' of global
280 S = SelectSectionForGlobal(GV);
286 // Lame default implementation. Calculate the section name for global.
288 TargetAsmInfo::SelectSectionForGlobal(const GlobalValue *GV) const {
289 SectionKind::Kind Kind = SectionKindForGlobal(GV);
291 if (GV->mayBeOverridden()) {
292 std::string Name = UniqueSectionForGlobal(GV, Kind);
293 unsigned Flags = SectionFlagsForGlobal(GV, Name.c_str());
294 return getNamedSection(Name.c_str(), Flags);
296 if (Kind == SectionKind::Text)
297 return getTextSection();
298 else if (isBSS(Kind) && getBSSSection_())
299 return getBSSSection_();
300 else if (getReadOnlySection() && SectionKind::isReadOnly(Kind))
301 return getReadOnlySection();
304 return getDataSection();
307 // Lame default implementation. Calculate the section name for machine const.
309 TargetAsmInfo::SelectSectionForMachineConst(const Type *Ty) const {
310 // FIXME: Support data.rel stuff someday
311 return getDataSection();
315 TargetAsmInfo::UniqueSectionForGlobal(const GlobalValue* GV,
316 SectionKind::Kind Kind) const {
318 case SectionKind::Text:
319 return ".gnu.linkonce.t." + GV->getName();
320 case SectionKind::Data:
321 return ".gnu.linkonce.d." + GV->getName();
322 case SectionKind::SmallData:
323 return ".gnu.linkonce.s." + GV->getName();
324 case SectionKind::BSS:
325 return ".gnu.linkonce.b." + GV->getName();
326 case SectionKind::SmallBSS:
327 return ".gnu.linkonce.sb." + GV->getName();
328 case SectionKind::ROData:
329 case SectionKind::RODataMergeConst:
330 case SectionKind::RODataMergeStr:
331 return ".gnu.linkonce.r." + GV->getName();
332 case SectionKind::SmallROData:
333 return ".gnu.linkonce.s2." + GV->getName();
334 case SectionKind::ThreadData:
335 return ".gnu.linkonce.td." + GV->getName();
336 case SectionKind::ThreadBSS:
337 return ".gnu.linkonce.tb." + GV->getName();
339 assert(0 && "Unknown section kind");
344 TargetAsmInfo::getNamedSection(const char *Name, unsigned Flags,
345 bool Override) const {
346 Section& S = Sections[Name];
348 // This is newly-created section, set it up properly.
349 if (S.Flags == SectionFlags::Invalid || Override) {
350 S.Flags = Flags | SectionFlags::Named;
358 TargetAsmInfo::getUnnamedSection(const char *Directive, unsigned Flags,
359 bool Override) const {
360 Section& S = Sections[Directive];
362 // This is newly-created section, set it up properly.
363 if (S.Flags == SectionFlags::Invalid || Override) {
364 S.Flags = Flags & ~SectionFlags::Named;
372 TargetAsmInfo::getSectionFlags(unsigned Flags) const {
373 SectionFlags::FlagsStringsMapType::iterator I = FlagsStrings.find(Flags);
375 // We didn't print these flags yet, print and save them to map. This reduces
376 // amount of heap trashing due to std::string construction / concatenation.
377 if (I == FlagsStrings.end())
378 I = FlagsStrings.insert(std::make_pair(Flags,
379 printSectionFlags(Flags))).first;
384 unsigned TargetAsmInfo::getULEB128Size(unsigned Value) {
388 Size += sizeof(int8_t);
393 unsigned TargetAsmInfo::getSLEB128Size(int Value) {
395 int Sign = Value >> (8 * sizeof(Value) - 1);
399 unsigned Byte = Value & 0x7f;
401 IsMore = Value != Sign || ((Byte ^ Sign) & 0x40) != 0;
402 Size += sizeof(int8_t);