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) : TM(tm) {
31 BSSSection = "\t.bss";
36 ZeroFillDirective = 0;
37 NonexecutableStackDirective = 0;
44 FirstOperandColumn = 0;
47 PrivateGlobalPrefix = ".";
48 LinkerPrivateGlobalPrefix = "";
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 AllowQuotesInName = false;
61 ZeroDirective = "\t.zero\t";
62 ZeroDirectiveSuffix = 0;
63 AsciiDirective = "\t.ascii\t";
64 AscizDirective = "\t.asciz\t";
65 Data8bitsDirective = "\t.byte\t";
66 Data16bitsDirective = "\t.short\t";
67 Data32bitsDirective = "\t.long\t";
68 Data64bitsDirective = "\t.quad\t";
69 AlignDirective = "\t.align\t";
70 AlignmentIsInBytes = true;
71 TextAlignFillValue = 0;
72 SwitchToSectionDirective = "\t.section\t";
73 TextSectionStartSuffix = "";
74 DataSectionStartSuffix = "";
75 SectionEndDirectiveSuffix = 0;
76 ConstantPoolSection = "\t.section .rodata";
77 JumpTableDataSection = "\t.section .rodata";
78 JumpTableDirective = 0;
81 // FIXME: Flags are ELFish - replace with normal section stuff.
82 StaticCtorsSection = "\t.section .ctors,\"aw\",@progbits";
83 StaticDtorsSection = "\t.section .dtors,\"aw\",@progbits";
84 GlobalDirective = "\t.globl\t";
87 COMMDirective = "\t.comm\t";
88 COMMDirectiveTakesAlignment = true;
89 HasDotTypeDotSizeDirective = true;
90 HasSingleParameterDotFile = true;
94 // FIXME: These are ELFish - move to ELFTAI.
95 HiddenDirective = "\t.hidden\t";
96 ProtectedDirective = "\t.protected\t";
97 AbsoluteDebugSectionOffsets = false;
98 AbsoluteEHSectionOffsets = false;
100 HasDotLocAndDotFile = false;
101 SupportsDebugInformation = false;
102 SupportsExceptionHandling = false;
103 DwarfRequiresFrameSection = true;
104 DwarfUsesInlineInfoSection = false;
105 Is_EHSymbolPrivate = true;
106 GlobalEHDirective = 0;
107 SupportsWeakOmittedEHFrame = true;
108 DwarfSectionOffsetDirective = 0;
109 DwarfAbbrevSection = ".debug_abbrev";
110 DwarfInfoSection = ".debug_info";
111 DwarfLineSection = ".debug_line";
112 DwarfFrameSection = ".debug_frame";
113 DwarfPubNamesSection = ".debug_pubnames";
114 DwarfPubTypesSection = ".debug_pubtypes";
115 DwarfDebugInlineSection = ".debug_inlined";
116 DwarfStrSection = ".debug_str";
117 DwarfLocSection = ".debug_loc";
118 DwarfARangesSection = ".debug_aranges";
119 DwarfRangesSection = ".debug_ranges";
120 DwarfMacroInfoSection = ".debug_macinfo";
121 DwarfEHFrameSection = ".eh_frame";
122 DwarfExceptionSection = ".gcc_except_table";
124 TextSection = getUnnamedSection("\t.text", SectionFlags::Code);
125 DataSection = getUnnamedSection("\t.data", SectionFlags::Writable);
128 TargetAsmInfo::~TargetAsmInfo() {
131 /// Measure the specified inline asm to determine an approximation of its
133 /// Comments (which run till the next SeparatorChar or newline) do not
134 /// count as an instruction.
135 /// Any other non-whitespace text is considered an instruction, with
136 /// multiple instructions separated by SeparatorChar or newlines.
137 /// Variable-length instructions are not handled here; this function
138 /// may be overloaded in the target code to do that.
139 unsigned TargetAsmInfo::getInlineAsmLength(const char *Str) const {
140 // Count the number of instructions in the asm.
141 bool atInsnStart = true;
143 for (; *Str; ++Str) {
144 if (*Str == '\n' || *Str == SeparatorChar)
146 if (atInsnStart && !isspace(*Str)) {
147 Length += MaxInstLength;
150 if (atInsnStart && strncmp(Str, CommentString, strlen(CommentString))==0)
157 unsigned TargetAsmInfo::PreferredEHDataFormat(DwarfEncoding::Target Reason,
159 return dwarf::DW_EH_PE_absptr;
162 static bool isSuitableForBSS(const GlobalVariable *GV) {
163 Constant *C = GV->getInitializer();
165 // Must have zero initializer.
166 if (!C->isNullValue())
169 // Leave constant zeros in readonly constant sections, so they can be shared.
170 if (GV->isConstant())
173 // If the global has an explicit section specified, don't put it in BSS.
174 if (!GV->getSection().empty())
177 // If -nozero-initialized-in-bss is specified, don't ever use BSS.
181 // Otherwise, put it in BSS!
185 static bool isConstantString(const Constant *C) {
186 // First check: is we have constant array of i8 terminated with zero
187 const ConstantArray *CVA = dyn_cast<ConstantArray>(C);
188 // Check, if initializer is a null-terminated string
189 if (CVA && CVA->isCString())
192 // Another possibility: [1 x i8] zeroinitializer
193 if (isa<ConstantAggregateZero>(C))
194 if (const ArrayType *Ty = dyn_cast<ArrayType>(C->getType()))
195 return (Ty->getElementType() == Type::Int8Ty &&
196 Ty->getNumElements() == 1);
201 static unsigned SectionFlagsForGlobal(const GlobalValue *GV,
203 // Decode flags from global and section kind.
204 unsigned Flags = SectionFlags::None;
205 if (GV->isWeakForLinker())
206 Flags |= SectionFlags::Linkonce;
207 if (Kind.isBSS() || Kind.isThreadBSS())
208 Flags |= SectionFlags::BSS;
209 if (Kind.isThreadLocal())
210 Flags |= SectionFlags::TLS;
212 Flags |= SectionFlags::Code;
213 if (Kind.isWritable())
214 Flags |= SectionFlags::Writable;
219 static SectionKind SectionKindForGlobal(const GlobalValue *GV,
220 Reloc::Model ReloModel) {
221 // Early exit - functions should be always in text sections.
222 const GlobalVariable *GVar = dyn_cast<GlobalVariable>(GV);
224 return SectionKind::getText();
226 bool isThreadLocal = GVar->isThreadLocal();
228 // Variable can be easily put to BSS section.
229 if (isSuitableForBSS(GVar))
230 return isThreadLocal ? SectionKind::getThreadBSS() : SectionKind::getBSS();
232 // If this is thread-local, put it in the general "thread_data" section.
234 return SectionKind::getThreadData();
236 Constant *C = GVar->getInitializer();
238 // If the global is marked constant, we can put it into a mergable section,
239 // a mergable string section, or general .data if it contains relocations.
240 if (GVar->isConstant()) {
241 // If the initializer for the global contains something that requires a
242 // relocation, then we may have to drop this into a wriable data section
243 // even though it is marked const.
244 switch (C->getRelocationInfo()) {
245 default: llvm_unreachable("unknown relocation info kind");
246 case Constant::NoRelocation:
247 // If initializer is a null-terminated string, put it in a "cstring"
248 // section if the target has it.
249 if (isConstantString(C))
250 return SectionKind::getMergableCString();
252 // Otherwise, just drop it into a mergable constant section.
253 return SectionKind::getMergableConst();
255 case Constant::LocalRelocation:
256 // In static relocation model, the linker will resolve all addresses, so
257 // the relocation entries will actually be constants by the time the app
259 if (ReloModel == Reloc::Static)
260 return SectionKind::getReadOnly();
262 // Otherwise, the dynamic linker needs to fix it up, put it in the
263 // writable data.rel.local section.
264 return SectionKind::getReadOnlyWithRelLocal();
266 case Constant::GlobalRelocations:
267 // In static relocation model, the linker will resolve all addresses, so
268 // the relocation entries will actually be constants by the time the app
270 if (ReloModel == Reloc::Static)
271 return SectionKind::getReadOnly();
273 // Otherwise, the dynamic linker needs to fix it up, put it in the
274 // writable data.rel section.
275 return SectionKind::getReadOnlyWithRel();
279 // Okay, this isn't a constant. If the initializer for the global is going
280 // to require a runtime relocation by the dynamic linker, put it into a more
281 // specific section to improve startup time of the app. This coalesces these
282 // globals together onto fewer pages, improving the locality of the dynamic
284 if (ReloModel == Reloc::Static)
285 return SectionKind::getDataNoRel();
287 switch (C->getRelocationInfo()) {
288 default: llvm_unreachable("unknown relocation info kind");
289 case Constant::NoRelocation: return SectionKind::getDataNoRel();
290 case Constant::LocalRelocation: return SectionKind::getDataRelLocal();
291 case Constant::GlobalRelocations: return SectionKind::getDataRel();
295 /// SectionForGlobal - This method computes the appropriate section to emit
296 /// the specified global variable or function definition. This should not
297 /// be passed external (or available externally) globals.
298 const Section *TargetAsmInfo::SectionForGlobal(const GlobalValue *GV) const {
299 assert(!GV->isDeclaration() && !GV->hasAvailableExternallyLinkage() &&
300 "Can only be used for global definitions");
302 SectionKind Kind = SectionKindForGlobal(GV, TM.getRelocationModel());
304 // Select section name.
305 if (GV->hasSection()) {
306 // If the target has special section hacks for specifically named globals,
308 if (const Section *TS = getSpecialCasedSectionGlobals(GV, Kind))
311 // Honour section already set, if any.
312 unsigned Flags = SectionFlagsForGlobal(GV, Kind);
314 // This is an explicitly named section.
315 Flags |= SectionFlags::Named;
317 // If the target has magic semantics for certain section names, make sure to
318 // pick up the flags. This allows the user to write things with attribute
319 // section and still get the appropriate section flags printed.
320 Flags |= getFlagsForNamedSection(GV->getSection().c_str());
322 return getNamedSection(GV->getSection().c_str(), Flags);
325 // If this global is linkonce/weak and the target handles this by emitting it
326 // into a 'uniqued' section name, create and return the section now.
327 if (GV->isWeakForLinker()) {
328 if (const char *Prefix = getSectionPrefixForUniqueGlobal(Kind)) {
329 unsigned Flags = SectionFlagsForGlobal(GV, Kind);
331 // FIXME: Use mangler interface (PR4584).
332 std::string Name = Prefix+GV->getNameStr();
333 return getNamedSection(Name.c_str(), Flags);
337 // Use default section depending on the 'type' of global
338 return SelectSectionForGlobal(GV, Kind);
341 // Lame default implementation. Calculate the section name for global.
343 TargetAsmInfo::SelectSectionForGlobal(const GlobalValue *GV,
344 SectionKind Kind) const {
345 assert(!Kind.isThreadLocal() && "Doesn't support TLS");
348 return getTextSection();
351 if (const Section *S = getBSSSection_())
354 if (Kind.isReadOnly())
355 if (const Section *S = getReadOnlySection())
358 return getDataSection();
361 /// getSectionForMergableConstant - Given a mergable constant with the
362 /// specified size and relocation information, return a section that it
363 /// should be placed in.
365 TargetAsmInfo::getSectionForMergableConstant(uint64_t Size,
366 unsigned ReloInfo) const {
368 if (const Section *S = getReadOnlySection())
371 return getDataSection();
375 const Section *TargetAsmInfo::getNamedSection(const char *Name, unsigned Flags,
376 bool Override) const {
377 Section &S = Sections[Name];
379 // This is newly-created section, set it up properly.
380 if (S.Flags == SectionFlags::Invalid || Override) {
381 S.Flags = Flags | SectionFlags::Named;
389 TargetAsmInfo::getUnnamedSection(const char *Directive, unsigned Flags,
390 bool Override) const {
391 Section& S = Sections[Directive];
393 // This is newly-created section, set it up properly.
394 if (S.Flags == SectionFlags::Invalid || Override) {
395 S.Flags = Flags & ~SectionFlags::Named;
403 TargetAsmInfo::getSectionFlags(unsigned Flags) const {
404 SectionFlags::FlagsStringsMapType::iterator I = FlagsStrings.find(Flags);
406 // We didn't print these flags yet, print and save them to map. This reduces
407 // amount of heap trashing due to std::string construction / concatenation.
408 if (I == FlagsStrings.end())
409 I = FlagsStrings.insert(std::make_pair(Flags,
410 printSectionFlags(Flags))).first;
415 unsigned TargetAsmInfo::getULEB128Size(unsigned Value) {
419 Size += sizeof(int8_t);
424 unsigned TargetAsmInfo::getSLEB128Size(int Value) {
426 int Sign = Value >> (8 * sizeof(Value) - 1);
430 unsigned Byte = Value & 0x7f;
432 IsMore = Value != Sign || ((Byte ^ Sign) & 0x40) != 0;
433 Size += sizeof(int8_t);