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/DerivedTypes.h"
17 #include "llvm/GlobalVariable.h"
18 #include "llvm/Function.h"
19 #include "llvm/Module.h"
20 #include "llvm/Type.h"
21 #include "llvm/Target/TargetAsmInfo.h"
22 #include "llvm/Target/TargetMachine.h"
23 #include "llvm/Target/TargetOptions.h"
24 #include "llvm/Support/Dwarf.h"
29 TargetAsmInfo::TargetAsmInfo(const TargetMachine &tm)
31 BSSSection = "\t.bss";
36 SmallRODataSection = 0;
39 ZeroFillDirective = 0;
40 NonexecutableStackDirective = 0;
47 PrivateGlobalPrefix = ".";
48 LessPrivateGlobalPrefix = "";
49 JumpTableSpecialLabelPrefix = 0;
50 GlobalVarAddrPrefix = "";
51 GlobalVarAddrSuffix = "";
52 FunctionAddrPrefix = "";
53 FunctionAddrSuffix = "";
54 PersonalityPrefix = "";
55 PersonalitySuffix = "";
56 NeedsIndirectEncoding = false;
57 InlineAsmStart = "#APP";
58 InlineAsmEnd = "#NO_APP";
60 StringConstantPrefix = ".str";
61 AllowQuotesInName = false;
62 ZeroDirective = "\t.zero\t";
63 ZeroDirectiveSuffix = 0;
64 AsciiDirective = "\t.ascii\t";
65 AscizDirective = "\t.asciz\t";
66 Data8bitsDirective = "\t.byte\t";
67 Data16bitsDirective = "\t.short\t";
68 Data32bitsDirective = "\t.long\t";
69 Data64bitsDirective = "\t.quad\t";
70 AlignDirective = "\t.align\t";
71 AlignmentIsInBytes = true;
72 TextAlignFillValue = 0;
73 SwitchToSectionDirective = "\t.section\t";
74 TextSectionStartSuffix = "";
75 DataSectionStartSuffix = "";
76 SectionEndDirectiveSuffix = 0;
77 ConstantPoolSection = "\t.section .rodata";
78 JumpTableDataSection = "\t.section .rodata";
79 JumpTableDirective = 0;
82 // FIXME: Flags are ELFish - replace with normal section stuff.
83 StaticCtorsSection = "\t.section .ctors,\"aw\",@progbits";
84 StaticDtorsSection = "\t.section .dtors,\"aw\",@progbits";
85 GlobalDirective = "\t.globl\t";
88 COMMDirective = "\t.comm\t";
89 COMMDirectiveTakesAlignment = true;
90 HasDotTypeDotSizeDirective = true;
91 HasSingleParameterDotFile = true;
95 // FIXME: These are ELFish - move to ELFTAI.
96 HiddenDirective = "\t.hidden\t";
97 ProtectedDirective = "\t.protected\t";
98 AbsoluteDebugSectionOffsets = false;
99 AbsoluteEHSectionOffsets = false;
101 HasDotLocAndDotFile = false;
102 SupportsDebugInformation = false;
103 SupportsExceptionHandling = false;
104 DwarfRequiresFrameSection = true;
105 DwarfUsesInlineInfoSection = false;
106 NonLocalEHFrameLabel = false;
107 GlobalEHDirective = 0;
108 SupportsWeakOmittedEHFrame = true;
109 DwarfSectionOffsetDirective = 0;
110 DwarfAbbrevSection = ".debug_abbrev";
111 DwarfInfoSection = ".debug_info";
112 DwarfLineSection = ".debug_line";
113 DwarfFrameSection = ".debug_frame";
114 DwarfPubNamesSection = ".debug_pubnames";
115 DwarfPubTypesSection = ".debug_pubtypes";
116 DwarfDebugInlineSection = ".debug_inlined";
117 DwarfStrSection = ".debug_str";
118 DwarfLocSection = ".debug_loc";
119 DwarfARangesSection = ".debug_aranges";
120 DwarfRangesSection = ".debug_ranges";
121 DwarfMacroInfoSection = ".debug_macinfo";
122 DwarfEHFrameSection = ".eh_frame";
123 DwarfExceptionSection = ".gcc_except_table";
125 TextSection = getUnnamedSection("\t.text", SectionFlags::Code);
126 DataSection = getUnnamedSection("\t.data", SectionFlags::Writeable);
129 TargetAsmInfo::~TargetAsmInfo() {
132 /// Measure the specified inline asm to determine an approximation of its
134 /// Comments (which run till the next SeparatorChar or newline) do not
135 /// count as an instruction.
136 /// Any other non-whitespace text is considered an instruction, with
137 /// multiple instructions separated by SeparatorChar or newlines.
138 /// Variable-length instructions are not handled here; this function
139 /// may be overloaded in the target code to do that.
140 unsigned TargetAsmInfo::getInlineAsmLength(const char *Str) const {
141 // Count the number of instructions in the asm.
142 bool atInsnStart = true;
144 for (; *Str; ++Str) {
145 if (*Str == '\n' || *Str == SeparatorChar)
147 if (atInsnStart && !isspace(*Str)) {
148 Length += MaxInstLength;
151 if (atInsnStart && strncmp(Str, CommentString, strlen(CommentString))==0)
158 unsigned TargetAsmInfo::PreferredEHDataFormat(DwarfEncoding::Target Reason,
160 return dwarf::DW_EH_PE_absptr;
163 static bool isSuitableForBSS(const GlobalVariable *GV) {
164 if (!GV->hasInitializer())
167 // Leave constant zeros in readonly constant sections, so they can be shared
168 Constant *C = GV->getInitializer();
169 return (C->isNullValue() && !GV->isConstant() && !NoZerosInBSS);
172 static bool isConstantString(const Constant *C) {
173 // First check: is we have constant array of i8 terminated with zero
174 const ConstantArray *CVA = dyn_cast<ConstantArray>(C);
175 // Check, if initializer is a null-terminated string
176 if (CVA && CVA->isCString())
179 // Another possibility: [1 x i8] zeroinitializer
180 if (isa<ConstantAggregateZero>(C)) {
181 if (const ArrayType *Ty = dyn_cast<ArrayType>(C->getType())) {
182 return (Ty->getElementType() == Type::Int8Ty &&
183 Ty->getNumElements() == 1);
190 unsigned TargetAsmInfo::RelocBehaviour() const {
191 // By default - all relocations in PIC mode would force symbol to be
192 // placed in r/w section.
193 return (TM.getRelocationModel() != Reloc::Static ?
194 Reloc::LocalOrGlobal : Reloc::None);
198 TargetAsmInfo::SectionKindForGlobal(const GlobalValue *GV) const {
199 // Early exit - functions should be always in text sections.
200 if (isa<Function>(GV))
201 return SectionKind::Text;
203 const GlobalVariable* GVar = dyn_cast<GlobalVariable>(GV);
204 bool isThreadLocal = GVar->isThreadLocal();
205 assert(GVar && "Invalid global value for section selection");
207 if (isSuitableForBSS(GVar)) {
208 // Variable can be easily put to BSS section.
209 return (isThreadLocal ? SectionKind::ThreadBSS : SectionKind::BSS);
210 } else if (GVar->isConstant() && !isThreadLocal) {
211 // Now we know, that varible has initializer and it is constant. We need to
212 // check its initializer to decide, which section to output it into. Also
213 // note, there is no thread-local r/o section.
214 Constant *C = GVar->getInitializer();
215 if (C->ContainsRelocations(Reloc::LocalOrGlobal)) {
216 // Decide, whether it is still possible to put symbol into r/o section.
217 unsigned Reloc = RelocBehaviour();
219 // We already did a query for 'all' relocs, thus - early exits.
220 if (Reloc == Reloc::LocalOrGlobal)
221 return SectionKind::Data;
222 else if (Reloc == Reloc::None)
223 return SectionKind::ROData;
225 // Ok, target wants something funny. Honour it.
226 return (C->ContainsRelocations(Reloc) ?
227 SectionKind::Data : SectionKind::ROData);
230 // Check, if initializer is a null-terminated string
231 if (isConstantString(C))
232 return SectionKind::RODataMergeStr;
234 return SectionKind::RODataMergeConst;
238 // Variable either is not constant or thread-local - output to data section.
239 return (isThreadLocal ? SectionKind::ThreadData : SectionKind::Data);
243 TargetAsmInfo::SectionFlagsForGlobal(const GlobalValue *GV,
244 const char* Name) const {
245 unsigned Flags = SectionFlags::None;
247 // Decode flags from global itself.
249 SectionKind::Kind Kind = SectionKindForGlobal(GV);
251 case SectionKind::Text:
252 Flags |= SectionFlags::Code;
254 case SectionKind::ThreadData:
255 case SectionKind::ThreadBSS:
256 Flags |= SectionFlags::TLS;
258 case SectionKind::Data:
259 case SectionKind::DataRel:
260 case SectionKind::DataRelLocal:
261 case SectionKind::DataRelRO:
262 case SectionKind::DataRelROLocal:
263 case SectionKind::BSS:
264 Flags |= SectionFlags::Writeable;
266 case SectionKind::ROData:
267 case SectionKind::RODataMergeStr:
268 case SectionKind::RODataMergeConst:
269 // No additional flags here
271 case SectionKind::SmallData:
272 case SectionKind::SmallBSS:
273 Flags |= SectionFlags::Writeable;
275 case SectionKind::SmallROData:
276 Flags |= SectionFlags::Small;
279 assert(0 && "Unexpected section kind!");
282 if (GV->isWeakForLinker())
283 Flags |= SectionFlags::Linkonce;
286 // Add flags from sections, if any.
288 Flags |= SectionFlags::Named;
290 // Some lame default implementation based on some magic section names.
291 if (strncmp(Name, ".gnu.linkonce.b.", 16) == 0 ||
292 strncmp(Name, ".llvm.linkonce.b.", 17) == 0 ||
293 strncmp(Name, ".gnu.linkonce.sb.", 17) == 0 ||
294 strncmp(Name, ".llvm.linkonce.sb.", 18) == 0)
295 Flags |= SectionFlags::BSS;
296 else if (strcmp(Name, ".tdata") == 0 ||
297 strncmp(Name, ".tdata.", 7) == 0 ||
298 strncmp(Name, ".gnu.linkonce.td.", 17) == 0 ||
299 strncmp(Name, ".llvm.linkonce.td.", 18) == 0)
300 Flags |= SectionFlags::TLS;
301 else if (strcmp(Name, ".tbss") == 0 ||
302 strncmp(Name, ".tbss.", 6) == 0 ||
303 strncmp(Name, ".gnu.linkonce.tb.", 17) == 0 ||
304 strncmp(Name, ".llvm.linkonce.tb.", 18) == 0)
305 Flags |= SectionFlags::BSS | SectionFlags::TLS;
312 TargetAsmInfo::SectionForGlobal(const GlobalValue *GV) const {
314 // Select section name
315 if (GV->hasSection()) {
316 // Honour section already set, if any
317 unsigned Flags = SectionFlagsForGlobal(GV,
318 GV->getSection().c_str());
319 S = getNamedSection(GV->getSection().c_str(), Flags);
321 // Use default section depending on the 'type' of global
322 S = SelectSectionForGlobal(GV);
328 // Lame default implementation. Calculate the section name for global.
330 TargetAsmInfo::SelectSectionForGlobal(const GlobalValue *GV) const {
331 SectionKind::Kind Kind = SectionKindForGlobal(GV);
333 if (GV->isWeakForLinker()) {
334 std::string Name = UniqueSectionForGlobal(GV, Kind);
335 unsigned Flags = SectionFlagsForGlobal(GV, Name.c_str());
336 return getNamedSection(Name.c_str(), Flags);
338 if (Kind == SectionKind::Text)
339 return getTextSection();
340 else if (isBSS(Kind) && getBSSSection_())
341 return getBSSSection_();
342 else if (getReadOnlySection() && SectionKind::isReadOnly(Kind))
343 return getReadOnlySection();
346 return getDataSection();
349 // Lame default implementation. Calculate the section name for machine const.
351 TargetAsmInfo::SelectSectionForMachineConst(const Type *Ty) const {
352 // FIXME: Support data.rel stuff someday
353 return getDataSection();
357 TargetAsmInfo::UniqueSectionForGlobal(const GlobalValue* GV,
358 SectionKind::Kind Kind) const {
360 case SectionKind::Text:
361 return ".gnu.linkonce.t." + GV->getName();
362 case SectionKind::Data:
363 return ".gnu.linkonce.d." + GV->getName();
364 case SectionKind::DataRel:
365 return ".gnu.linkonce.d.rel" + GV->getName();
366 case SectionKind::DataRelLocal:
367 return ".gnu.linkonce.d.rel.local" + GV->getName();
368 case SectionKind::DataRelRO:
369 return ".gnu.linkonce.d.rel.ro" + GV->getName();
370 case SectionKind::DataRelROLocal:
371 return ".gnu.linkonce.d.rel.ro.local" + GV->getName();
372 case SectionKind::SmallData:
373 return ".gnu.linkonce.s." + GV->getName();
374 case SectionKind::BSS:
375 return ".gnu.linkonce.b." + GV->getName();
376 case SectionKind::SmallBSS:
377 return ".gnu.linkonce.sb." + GV->getName();
378 case SectionKind::ROData:
379 case SectionKind::RODataMergeConst:
380 case SectionKind::RODataMergeStr:
381 return ".gnu.linkonce.r." + GV->getName();
382 case SectionKind::SmallROData:
383 return ".gnu.linkonce.s2." + GV->getName();
384 case SectionKind::ThreadData:
385 return ".gnu.linkonce.td." + GV->getName();
386 case SectionKind::ThreadBSS:
387 return ".gnu.linkonce.tb." + GV->getName();
389 assert(0 && "Unknown section kind");
395 TargetAsmInfo::getNamedSection(const char *Name, unsigned Flags,
396 bool Override) const {
397 Section& S = Sections[Name];
399 // This is newly-created section, set it up properly.
400 if (S.Flags == SectionFlags::Invalid || Override) {
401 S.Flags = Flags | SectionFlags::Named;
409 TargetAsmInfo::getUnnamedSection(const char *Directive, unsigned Flags,
410 bool Override) const {
411 Section& S = Sections[Directive];
413 // This is newly-created section, set it up properly.
414 if (S.Flags == SectionFlags::Invalid || Override) {
415 S.Flags = Flags & ~SectionFlags::Named;
423 TargetAsmInfo::getSectionFlags(unsigned Flags) const {
424 SectionFlags::FlagsStringsMapType::iterator I = FlagsStrings.find(Flags);
426 // We didn't print these flags yet, print and save them to map. This reduces
427 // amount of heap trashing due to std::string construction / concatenation.
428 if (I == FlagsStrings.end())
429 I = FlagsStrings.insert(std::make_pair(Flags,
430 printSectionFlags(Flags))).first;
435 unsigned TargetAsmInfo::getULEB128Size(unsigned Value) {
439 Size += sizeof(int8_t);
444 unsigned TargetAsmInfo::getSLEB128Size(int Value) {
446 int Sign = Value >> (8 * sizeof(Value) - 1);
450 unsigned Byte = Value & 0x7f;
452 IsMore = Value != Sign || ((Byte ^ Sign) & 0x40) != 0;
453 Size += sizeof(int8_t);