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"
25 #include "llvm/Support/ErrorHandling.h"
30 TargetAsmInfo::TargetAsmInfo(const TargetMachine &tm)
33 BSSSection = "\t.bss";
38 ZeroFillDirective = 0;
39 NonexecutableStackDirective = 0;
46 FirstOperandColumn = 0;
49 PrivateGlobalPrefix = ".";
50 LinkerPrivateGlobalPrefix = "";
51 JumpTableSpecialLabelPrefix = 0;
52 GlobalVarAddrPrefix = "";
53 GlobalVarAddrSuffix = "";
54 FunctionAddrPrefix = "";
55 FunctionAddrSuffix = "";
56 PersonalityPrefix = "";
57 PersonalitySuffix = "";
58 NeedsIndirectEncoding = false;
59 InlineAsmStart = "#APP";
60 InlineAsmEnd = "#NO_APP";
62 AllowQuotesInName = false;
63 ZeroDirective = "\t.zero\t";
64 ZeroDirectiveSuffix = 0;
65 AsciiDirective = "\t.ascii\t";
66 AscizDirective = "\t.asciz\t";
67 Data8bitsDirective = "\t.byte\t";
68 Data16bitsDirective = "\t.short\t";
69 Data32bitsDirective = "\t.long\t";
70 Data64bitsDirective = "\t.quad\t";
71 AlignDirective = "\t.align\t";
72 AlignmentIsInBytes = true;
73 TextAlignFillValue = 0;
74 SwitchToSectionDirective = "\t.section\t";
75 TextSectionStartSuffix = "";
76 DataSectionStartSuffix = "";
77 SectionEndDirectiveSuffix = 0;
78 ConstantPoolSection = "\t.section .rodata";
79 JumpTableDataSection = "\t.section .rodata";
80 JumpTableDirective = 0;
83 // FIXME: Flags are ELFish - replace with normal section stuff.
84 StaticCtorsSection = "\t.section .ctors,\"aw\",@progbits";
85 StaticDtorsSection = "\t.section .dtors,\"aw\",@progbits";
86 GlobalDirective = "\t.globl\t";
89 COMMDirective = "\t.comm\t";
90 COMMDirectiveTakesAlignment = true;
91 HasDotTypeDotSizeDirective = true;
92 HasSingleParameterDotFile = true;
96 // FIXME: These are ELFish - move to ELFTAI.
97 HiddenDirective = "\t.hidden\t";
98 ProtectedDirective = "\t.protected\t";
99 AbsoluteDebugSectionOffsets = false;
100 AbsoluteEHSectionOffsets = false;
102 HasDotLocAndDotFile = false;
103 SupportsDebugInformation = false;
104 SupportsExceptionHandling = false;
105 DwarfRequiresFrameSection = true;
106 DwarfUsesInlineInfoSection = false;
107 Is_EHSymbolPrivate = true;
108 GlobalEHDirective = 0;
109 SupportsWeakOmittedEHFrame = true;
110 DwarfSectionOffsetDirective = 0;
111 DwarfAbbrevSection = ".debug_abbrev";
112 DwarfInfoSection = ".debug_info";
113 DwarfLineSection = ".debug_line";
114 DwarfFrameSection = ".debug_frame";
115 DwarfPubNamesSection = ".debug_pubnames";
116 DwarfPubTypesSection = ".debug_pubtypes";
117 DwarfDebugInlineSection = ".debug_inlined";
118 DwarfStrSection = ".debug_str";
119 DwarfLocSection = ".debug_loc";
120 DwarfARangesSection = ".debug_aranges";
121 DwarfRangesSection = ".debug_ranges";
122 DwarfMacroInfoSection = ".debug_macinfo";
123 DwarfEHFrameSection = ".eh_frame";
124 DwarfExceptionSection = ".gcc_except_table";
126 TextSection = getUnnamedSection("\t.text", SectionFlags::Code);
127 DataSection = getUnnamedSection("\t.data", SectionFlags::Writeable);
130 TargetAsmInfo::~TargetAsmInfo() {
133 /// Measure the specified inline asm to determine an approximation of its
135 /// Comments (which run till the next SeparatorChar or newline) do not
136 /// count as an instruction.
137 /// Any other non-whitespace text is considered an instruction, with
138 /// multiple instructions separated by SeparatorChar or newlines.
139 /// Variable-length instructions are not handled here; this function
140 /// may be overloaded in the target code to do that.
141 unsigned TargetAsmInfo::getInlineAsmLength(const char *Str) const {
142 // Count the number of instructions in the asm.
143 bool atInsnStart = true;
145 for (; *Str; ++Str) {
146 if (*Str == '\n' || *Str == SeparatorChar)
148 if (atInsnStart && !isspace(*Str)) {
149 Length += MaxInstLength;
152 if (atInsnStart && strncmp(Str, CommentString, strlen(CommentString))==0)
159 unsigned TargetAsmInfo::PreferredEHDataFormat(DwarfEncoding::Target Reason,
161 return dwarf::DW_EH_PE_absptr;
164 static bool isSuitableForBSS(const GlobalVariable *GV) {
165 if (!GV->hasInitializer())
168 // Leave constant zeros in readonly constant sections, so they can be shared
169 Constant *C = GV->getInitializer();
170 return (C->isNullValue() && !GV->isConstant() && !NoZerosInBSS);
173 static bool isConstantString(const Constant *C) {
174 // First check: is we have constant array of i8 terminated with zero
175 const ConstantArray *CVA = dyn_cast<ConstantArray>(C);
176 // Check, if initializer is a null-terminated string
177 if (CVA && CVA->isCString())
180 // Another possibility: [1 x i8] zeroinitializer
181 if (isa<ConstantAggregateZero>(C)) {
182 if (const ArrayType *Ty = dyn_cast<ArrayType>(C->getType())) {
183 return (Ty->getElementType() == Type::Int8Ty &&
184 Ty->getNumElements() == 1);
192 TargetAsmInfo::SectionKindForGlobal(const GlobalValue *GV) const {
193 // Early exit - functions should be always in text sections.
194 if (isa<Function>(GV))
195 return SectionKind::Text;
197 const GlobalVariable* GVar = dyn_cast<GlobalVariable>(GV);
198 bool isThreadLocal = GVar->isThreadLocal();
199 assert(GVar && "Invalid global value for section selection");
201 if (isSuitableForBSS(GVar)) {
202 // Variable can be easily put to BSS section.
203 return isThreadLocal ? SectionKind::ThreadBSS : SectionKind::BSS;
204 } else if (GVar->isConstant() && !isThreadLocal) {
205 // Now we know, that variable has initializer and it is constant. We need to
206 // check its initializer to decide, which section to output it into. Also
207 // note, there is no thread-local r/o section.
208 Constant *C = GVar->getInitializer();
209 if (C->getRelocationInfo() != 0) {
210 // Decide whether it is still possible to put symbol into r/o section.
211 if (TM.getRelocationModel() != Reloc::Static)
212 return SectionKind::Data;
214 return SectionKind::ROData;
216 // Check, if initializer is a null-terminated string
217 if (isConstantString(C))
218 return SectionKind::RODataMergeStr;
220 return SectionKind::RODataMergeConst;
224 // Variable either is not constant or thread-local - output to data section.
225 return isThreadLocal ? SectionKind::ThreadData : SectionKind::Data;
229 TargetAsmInfo::SectionFlagsForGlobal(const GlobalValue *GV,
230 const char* Name) const {
231 unsigned Flags = SectionFlags::None;
233 // Decode flags from global itself.
235 SectionKind::Kind Kind = SectionKindForGlobal(GV);
237 case SectionKind::Text:
238 Flags |= SectionFlags::Code;
240 case SectionKind::ThreadData:
241 case SectionKind::ThreadBSS:
242 Flags |= SectionFlags::TLS;
244 case SectionKind::Data:
245 case SectionKind::DataRel:
246 case SectionKind::DataRelLocal:
247 case SectionKind::DataRelRO:
248 case SectionKind::DataRelROLocal:
249 case SectionKind::BSS:
250 Flags |= SectionFlags::Writeable;
252 case SectionKind::ROData:
253 case SectionKind::RODataMergeStr:
254 case SectionKind::RODataMergeConst:
255 // No additional flags here
258 llvm_unreachable("Unexpected section kind!");
261 if (GV->isWeakForLinker())
262 Flags |= SectionFlags::Linkonce;
265 // Add flags from sections, if any.
267 Flags |= SectionFlags::Named;
269 // Some lame default implementation based on some magic section names.
270 if (strncmp(Name, ".gnu.linkonce.b.", 16) == 0 ||
271 strncmp(Name, ".llvm.linkonce.b.", 17) == 0 ||
272 strncmp(Name, ".gnu.linkonce.sb.", 17) == 0 ||
273 strncmp(Name, ".llvm.linkonce.sb.", 18) == 0)
274 Flags |= SectionFlags::BSS;
275 else if (strcmp(Name, ".tdata") == 0 ||
276 strncmp(Name, ".tdata.", 7) == 0 ||
277 strncmp(Name, ".gnu.linkonce.td.", 17) == 0 ||
278 strncmp(Name, ".llvm.linkonce.td.", 18) == 0)
279 Flags |= SectionFlags::TLS;
280 else if (strcmp(Name, ".tbss") == 0 ||
281 strncmp(Name, ".tbss.", 6) == 0 ||
282 strncmp(Name, ".gnu.linkonce.tb.", 17) == 0 ||
283 strncmp(Name, ".llvm.linkonce.tb.", 18) == 0)
284 Flags |= SectionFlags::BSS | SectionFlags::TLS;
290 const Section *TargetAsmInfo::SectionForGlobal(const GlobalValue *GV) const {
291 // Select section name
292 if (GV->hasSection()) {
293 // Honour section already set, if any.
294 unsigned Flags = SectionFlagsForGlobal(GV, GV->getSection().c_str());
295 return getNamedSection(GV->getSection().c_str(), Flags);
298 // If this global is linkonce/weak and the target handles this by emitting it
299 // into a 'uniqued' section name, create and return the section now.
300 if (GV->isWeakForLinker()) {
301 if (const char *Prefix =
302 getSectionPrefixForUniqueGlobal(SectionKindForGlobal(GV))) {
303 // FIXME: Use mangler interface (PR4584).
304 std::string Name = Prefix+GV->getNameStr();
305 unsigned Flags = SectionFlagsForGlobal(GV, Name.c_str());
306 return getNamedSection(Name.c_str(), Flags);
310 // Use default section depending on the 'type' of global
311 return SelectSectionForGlobal(GV);
314 // Lame default implementation. Calculate the section name for global.
316 TargetAsmInfo::SelectSectionForGlobal(const GlobalValue *GV) const {
317 SectionKind::Kind Kind = SectionKindForGlobal(GV);
319 if (Kind == SectionKind::Text)
320 return getTextSection();
323 if (const Section *S = getBSSSection_())
326 if (SectionKind::isReadOnly(Kind))
327 if (const Section *S = getReadOnlySection())
330 return getDataSection();
333 /// getSectionForMergableConstant - Given a mergable constant with the
334 /// specified size and relocation information, return a section that it
335 /// should be placed in.
337 TargetAsmInfo::getSectionForMergableConstant(uint64_t Size,
338 unsigned ReloInfo) const {
339 // FIXME: Support data.rel stuff someday
340 // Lame default implementation. Calculate the section name for machine const.
341 return getDataSection();
348 TargetAsmInfo::getSectionPrefixForUniqueGlobal(SectionKind::Kind Kind) const {
350 default: llvm_unreachable("Unknown section kind");
351 case SectionKind::Text: return ".gnu.linkonce.t.";
352 case SectionKind::Data: return ".gnu.linkonce.d.";
353 case SectionKind::DataRel: return ".gnu.linkonce.d.rel.";
354 case SectionKind::DataRelLocal: return ".gnu.linkonce.d.rel.local.";
355 case SectionKind::DataRelRO: return ".gnu.linkonce.d.rel.ro.";
356 case SectionKind::DataRelROLocal: return ".gnu.linkonce.d.rel.ro.local.";
357 case SectionKind::BSS: return ".gnu.linkonce.b.";
358 case SectionKind::ROData:
359 case SectionKind::RODataMergeConst:
360 case SectionKind::RODataMergeStr: return ".gnu.linkonce.r.";
361 case SectionKind::ThreadData: return ".gnu.linkonce.td.";
362 case SectionKind::ThreadBSS: return ".gnu.linkonce.tb.";
366 const Section *TargetAsmInfo::getNamedSection(const char *Name, unsigned Flags,
367 bool Override) const {
368 Section &S = Sections[Name];
370 // This is newly-created section, set it up properly.
371 if (S.Flags == SectionFlags::Invalid || Override) {
372 S.Flags = Flags | SectionFlags::Named;
380 TargetAsmInfo::getUnnamedSection(const char *Directive, unsigned Flags,
381 bool Override) const {
382 Section& S = Sections[Directive];
384 // This is newly-created section, set it up properly.
385 if (S.Flags == SectionFlags::Invalid || Override) {
386 S.Flags = Flags & ~SectionFlags::Named;
394 TargetAsmInfo::getSectionFlags(unsigned Flags) const {
395 SectionFlags::FlagsStringsMapType::iterator I = FlagsStrings.find(Flags);
397 // We didn't print these flags yet, print and save them to map. This reduces
398 // amount of heap trashing due to std::string construction / concatenation.
399 if (I == FlagsStrings.end())
400 I = FlagsStrings.insert(std::make_pair(Flags,
401 printSectionFlags(Flags))).first;
406 unsigned TargetAsmInfo::getULEB128Size(unsigned Value) {
410 Size += sizeof(int8_t);
415 unsigned TargetAsmInfo::getSLEB128Size(int Value) {
417 int Sign = Value >> (8 * sizeof(Value) - 1);
421 unsigned Byte = Value & 0x7f;
423 IsMore = Value != Sign || ((Byte ^ Sign) & 0x40) != 0;
424 Size += sizeof(int8_t);