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			417 lines
		
	
	
		
			13 KiB
		
	
	
	
		
			C++
		
	
	
	
	
	
			
		
		
	
	
			417 lines
		
	
	
		
			13 KiB
		
	
	
	
		
			C++
		
	
	
	
	
	
| //===-- TargetAsmInfo.cpp - Asm Info ---------------------------------------==//
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| //
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| //                     The LLVM Compiler Infrastructure
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| //
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| // This file is distributed under the University of Illinois Open Source
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| // License. See LICENSE.TXT for details.
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| //
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| //===----------------------------------------------------------------------===//
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| //
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| // This file defines target asm properties related what form asm statements
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| // should take.
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| //
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| //===----------------------------------------------------------------------===//
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| 
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| #include "llvm/Constants.h"
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| #include "llvm/GlobalVariable.h"
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| #include "llvm/Function.h"
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| #include "llvm/Module.h"
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| #include "llvm/Type.h"
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| #include "llvm/Target/TargetAsmInfo.h"
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| #include "llvm/Target/TargetOptions.h"
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| #include "llvm/Support/Dwarf.h"
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| #include <cctype>
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| #include <cstring>
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| 
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| using namespace llvm;
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| 
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| TargetAsmInfo::TargetAsmInfo() :
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|   TextSection("\t.text"),
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|   TextSection_(0),
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|   DataSection("\t.data"),
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|   DataSection_(0),
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|   BSSSection("\t.bss"),
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|   BSSSection_(0),
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|   ReadOnlySection(0),
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|   ReadOnlySection_(0),
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|   SmallDataSection(0),
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|   SmallBSSSection(0),
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|   SmallRODataSection(0),
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|   TLSDataSection("\t.section .tdata,\"awT\",@progbits"),
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|   TLSDataSection_(0),
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|   TLSBSSSection("\t.section .tbss,\"awT\",@nobits"),
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|   TLSBSSSection_(0),
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|   ZeroFillDirective(0),
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|   NonexecutableStackDirective(0),
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|   NeedsSet(false),
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|   MaxInstLength(4),
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|   PCSymbol("$"),
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|   SeparatorChar(';'),
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|   CommentString("#"),
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|   GlobalPrefix(""),
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|   PrivateGlobalPrefix("."),
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|   JumpTableSpecialLabelPrefix(0),
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|   GlobalVarAddrPrefix(""),
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|   GlobalVarAddrSuffix(""),
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|   FunctionAddrPrefix(""),
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|   FunctionAddrSuffix(""),
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|   PersonalityPrefix(""),
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|   PersonalitySuffix(""),
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|   NeedsIndirectEncoding(false),
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|   InlineAsmStart("#APP"),
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|   InlineAsmEnd("#NO_APP"),
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|   AssemblerDialect(0),
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|   StringConstantPrefix(".str"),
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|   ZeroDirective("\t.zero\t"),
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|   ZeroDirectiveSuffix(0),
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|   AsciiDirective("\t.ascii\t"),
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|   AscizDirective("\t.asciz\t"),
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|   Data8bitsDirective("\t.byte\t"),
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|   Data16bitsDirective("\t.short\t"),
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|   Data32bitsDirective("\t.long\t"),
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|   Data64bitsDirective("\t.quad\t"),
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|   AlignDirective("\t.align\t"),
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|   AlignmentIsInBytes(true),
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|   TextAlignFillValue(0),
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|   SwitchToSectionDirective("\t.section\t"),
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|   TextSectionStartSuffix(""),
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|   DataSectionStartSuffix(""),
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|   SectionEndDirectiveSuffix(0),
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|   ConstantPoolSection("\t.section .rodata"),
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|   JumpTableDataSection("\t.section .rodata"),
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|   JumpTableDirective(0),
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|   CStringSection(0),
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|   CStringSection_(0),
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|   StaticCtorsSection("\t.section .ctors,\"aw\",@progbits"),
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|   StaticDtorsSection("\t.section .dtors,\"aw\",@progbits"),
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|   FourByteConstantSection(0),
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|   FourByteConstantSection_(0),
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|   EightByteConstantSection(0),
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|   EightByteConstantSection_(0),
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|   SixteenByteConstantSection(0),
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|   SixteenByteConstantSection_(0),
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|   GlobalDirective("\t.globl\t"),
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|   SetDirective(0),
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|   LCOMMDirective(0),
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|   COMMDirective("\t.comm\t"),
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|   COMMDirectiveTakesAlignment(true),
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|   HasDotTypeDotSizeDirective(true),
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|   UsedDirective(0),
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|   WeakRefDirective(0),
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|   WeakDefDirective(0),
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|   HiddenDirective("\t.hidden\t"),
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|   ProtectedDirective("\t.protected\t"),
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|   AbsoluteDebugSectionOffsets(false),
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|   AbsoluteEHSectionOffsets(false),
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|   HasLEB128(false),
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|   HasDotLocAndDotFile(false),
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|   SupportsDebugInformation(false),
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|   SupportsExceptionHandling(false),
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|   DwarfRequiresFrameSection(true),
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|   GlobalEHDirective(0),
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|   SupportsWeakOmittedEHFrame(true),
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|   DwarfSectionOffsetDirective(0),
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|   DwarfAbbrevSection(".debug_abbrev"),
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|   DwarfInfoSection(".debug_info"),
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|   DwarfLineSection(".debug_line"),
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|   DwarfFrameSection(".debug_frame"),
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|   DwarfPubNamesSection(".debug_pubnames"),
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|   DwarfPubTypesSection(".debug_pubtypes"),
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|   DwarfStrSection(".debug_str"),
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|   DwarfLocSection(".debug_loc"),
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|   DwarfARangesSection(".debug_aranges"),
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|   DwarfRangesSection(".debug_ranges"),
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|   DwarfMacInfoSection(".debug_macinfo"),
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|   DwarfEHFrameSection(".eh_frame"),
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|   DwarfExceptionSection(".gcc_except_table"),
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|   AsmTransCBE(0) {
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|   TextSection_ = getUnnamedSection(TextSection);
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|   DataSection_ = getUnnamedSection(DataSection);
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| }
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| 
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| TargetAsmInfo::~TargetAsmInfo() {
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| }
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| 
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| /// Measure the specified inline asm to determine an approximation of its
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| /// length.
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| /// Comments (which run till the next SeparatorChar or newline) do not
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| /// count as an instruction.
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| /// Any other non-whitespace text is considered an instruction, with
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| /// multiple instructions separated by SeparatorChar or newlines.
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| /// Variable-length instructions are not handled here; this function
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| /// may be overloaded in the target code to do that.
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| unsigned TargetAsmInfo::getInlineAsmLength(const char *Str) const {
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|   // Count the number of instructions in the asm.
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|   bool atInsnStart = true;
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|   unsigned Length = 0;
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|   for (; *Str; ++Str) {
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|     if (*Str == '\n' || *Str == SeparatorChar)
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|       atInsnStart = true;
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|     if (atInsnStart && !isspace(*Str)) {
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|       Length += MaxInstLength;
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|       atInsnStart = false;
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|     }
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|     if (atInsnStart && strncmp(Str, CommentString, strlen(CommentString))==0)
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|       atInsnStart = false;
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|   }
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| 
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|   return Length;
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| }
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| 
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| unsigned TargetAsmInfo::PreferredEHDataFormat(DwarfEncoding::Target Reason,
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|                                               bool Global) const {
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|   return dwarf::DW_EH_PE_absptr;
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| }
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| 
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| static bool isSuitableForBSS(const GlobalVariable *GV) {
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|   if (!GV->hasInitializer())
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|     return true;
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| 
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|   // Leave constant zeros in readonly constant sections, so they can be shared
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|   Constant *C = GV->getInitializer();
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|   return (C->isNullValue() && !GV->isConstant() && !NoZerosInBSS);
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| }
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| 
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| SectionKind::Kind
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| TargetAsmInfo::SectionKindForGlobal(const GlobalValue *GV) const {
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|   // Early exit - functions should be always in text sections.
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|   if (isa<Function>(GV))
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|     return SectionKind::Text;
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| 
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|   const GlobalVariable* GVar = dyn_cast<GlobalVariable>(GV);
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|   bool isThreadLocal = GVar->isThreadLocal();
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|   assert(GVar && "Invalid global value for section selection");
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| 
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|   if (isSuitableForBSS(GVar)) {
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|     // Variable can be easily put to BSS section.
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|     return (isThreadLocal ? SectionKind::ThreadBSS : SectionKind::BSS);
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|   } else if (GVar->isConstant() && !isThreadLocal) {
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|     // Now we know, that varible has initializer and it is constant. We need to
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|     // check its initializer to decide, which section to output it into. Also
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|     // note, there is no thread-local r/o section.
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|     Constant *C = GVar->getInitializer();
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|     if (C->ContainsRelocations())
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|       return SectionKind::ROData;
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|     else {
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|       const ConstantArray *CVA = dyn_cast<ConstantArray>(C);
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|       // Check, if initializer is a null-terminated string
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|       if (CVA && CVA->isCString())
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|         return SectionKind::RODataMergeStr;
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|       else
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|         return SectionKind::RODataMergeConst;
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|     }
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|   }
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| 
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|   // Variable is not constant or thread-local - emit to generic data section.
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|   return (isThreadLocal ? SectionKind::ThreadData : SectionKind::Data);
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| }
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| 
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| unsigned
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| TargetAsmInfo::SectionFlagsForGlobal(const GlobalValue *GV,
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|                                      const char* Name) const {
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|   unsigned Flags = SectionFlags::None;
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| 
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|   // Decode flags from global itself.
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|   if (GV) {
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|     SectionKind::Kind Kind = SectionKindForGlobal(GV);
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|     switch (Kind) {
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|      case SectionKind::Text:
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|       Flags |= SectionFlags::Code;
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|       break;
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|      case SectionKind::ThreadData:
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|      case SectionKind::ThreadBSS:
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|       Flags |= SectionFlags::TLS;
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|       // FALLS THROUGH
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|      case SectionKind::Data:
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|      case SectionKind::BSS:
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|       Flags |= SectionFlags::Writeable;
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|       break;
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|      case SectionKind::ROData:
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|      case SectionKind::RODataMergeStr:
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|      case SectionKind::RODataMergeConst:
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|       // No additional flags here
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|       break;
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|      case SectionKind::SmallData:
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|      case SectionKind::SmallBSS:
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|       Flags |= SectionFlags::Writeable;
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|       // FALLS THROUGH
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|      case SectionKind::SmallROData:
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|       Flags |= SectionFlags::Small;
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|       break;
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|      default:
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|       assert(0 && "Unexpected section kind!");
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|     }
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| 
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|     if (GV->isWeakForLinker())
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|       Flags |= SectionFlags::Linkonce;
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|   }
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| 
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|   // Add flags from sections, if any.
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|   if (Name && *Name) {
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|     Flags |= SectionFlags::Named;
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| 
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|     // Some lame default implementation based on some magic section names.
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|     if (strncmp(Name, ".gnu.linkonce.b.", 16) == 0 ||
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|         strncmp(Name, ".llvm.linkonce.b.", 17) == 0 ||
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|         strncmp(Name, ".gnu.linkonce.sb.", 17) == 0 ||
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|         strncmp(Name, ".llvm.linkonce.sb.", 18) == 0)
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|       Flags |= SectionFlags::BSS;
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|     else if (strcmp(Name, ".tdata") == 0 ||
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|              strncmp(Name, ".tdata.", 7) == 0 ||
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|              strncmp(Name, ".gnu.linkonce.td.", 17) == 0 ||
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|              strncmp(Name, ".llvm.linkonce.td.", 18) == 0)
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|       Flags |= SectionFlags::TLS;
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|     else if (strcmp(Name, ".tbss") == 0 ||
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|              strncmp(Name, ".tbss.", 6) == 0 ||
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|              strncmp(Name, ".gnu.linkonce.tb.", 17) == 0 ||
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|              strncmp(Name, ".llvm.linkonce.tb.", 18) == 0)
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|       Flags |= SectionFlags::BSS | SectionFlags::TLS;
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|   }
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| 
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|   return Flags;
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| }
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| 
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| std::string
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| TargetAsmInfo::SectionForGlobal(const GlobalValue *GV) const {
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|   const Section* S;
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|   // Select section name
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|   if (GV->hasSection()) {
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|     // Honour section already set, if any
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|     unsigned Flags = SectionFlagsForGlobal(GV,
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|                                            GV->getSection().c_str());
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|     S = getNamedSection(GV->getSection().c_str(), Flags);
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|   } else {
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|     // Use default section depending on the 'type' of global
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|     S = SelectSectionForGlobal(GV);
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|   }
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| 
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|   if (!S->isNamed())
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|     return S->Name;
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| 
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|   // If section is named we need to switch into it via special '.section'
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|   // directive and also append funky flags. Otherwise - section name is just
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|   // some magic assembler directive.
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|   return getSwitchToSectionDirective() + S->Name + getSectionFlags(S->Flags);
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| }
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| 
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| // Lame default implementation. Calculate the section name for global.
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| const Section*
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| TargetAsmInfo::SelectSectionForGlobal(const GlobalValue *GV) const {
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|   SectionKind::Kind Kind = SectionKindForGlobal(GV);
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| 
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|   if (GV->isWeakForLinker()) {
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|     std::string Name = UniqueSectionForGlobal(GV, Kind);
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|     unsigned Flags = SectionFlagsForGlobal(GV, Name.c_str());
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|     return getNamedSection(Name.c_str(), Flags);
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|   } else {
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|     if (Kind == SectionKind::Text)
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|       return getTextSection_();
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|     else if (isBSS(Kind) && getBSSSection_())
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|       return getBSSSection_();
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|     else if (getReadOnlySection_() && SectionKind::isReadOnly(Kind))
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|       return getReadOnlySection_();
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|   }
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| 
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|   return getDataSection_();
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| }
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| 
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| // Lame default implementation. Calculate the section name for machine const.
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| const Section*
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| TargetAsmInfo::SelectSectionForMachineConst(const Type *Ty) const {
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|   // FIXME: Support data.rel stuff someday
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|   return getDataSection_();
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| }
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| 
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| std::string
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| TargetAsmInfo::UniqueSectionForGlobal(const GlobalValue* GV,
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|                                       SectionKind::Kind Kind) const {
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|   switch (Kind) {
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|    case SectionKind::Text:
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|     return ".gnu.linkonce.t." + GV->getName();
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|    case SectionKind::Data:
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|     return ".gnu.linkonce.d." + GV->getName();
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|    case SectionKind::SmallData:
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|     return ".gnu.linkonce.s." + GV->getName();
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|    case SectionKind::BSS:
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|     return ".gnu.linkonce.b." + GV->getName();
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|    case SectionKind::SmallBSS:
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|     return ".gnu.linkonce.sb." + GV->getName();
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|    case SectionKind::ROData:
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|    case SectionKind::RODataMergeConst:
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|    case SectionKind::RODataMergeStr:
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|     return ".gnu.linkonce.r." + GV->getName();
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|    case SectionKind::SmallROData:
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|     return ".gnu.linkonce.s2." + GV->getName();
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|    case SectionKind::ThreadData:
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|     return ".gnu.linkonce.td." + GV->getName();
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|    case SectionKind::ThreadBSS:
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|     return ".gnu.linkonce.tb." + GV->getName();
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|    default:
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|     assert(0 && "Unknown section kind");
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|   }
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| }
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| 
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| const Section*
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| TargetAsmInfo::getNamedSection(const char *Name, unsigned Flags,
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|                                bool Override) const {
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|   Section& S = Sections[Name];
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| 
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|   // This is newly-created section, set it up properly.
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|   if (S.Flags == SectionFlags::Invalid || Override) {
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|     S.Flags = Flags | SectionFlags::Named;
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|     S.Name = Name;
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|   }
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| 
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|   return &S;
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| }
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| 
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| const Section*
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| TargetAsmInfo::getUnnamedSection(const char *Directive, unsigned Flags,
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|                                  bool Override) const {
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|   Section& S = Sections[Directive];
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| 
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|   // This is newly-created section, set it up properly.
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|   if (S.Flags == SectionFlags::Invalid || Override) {
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|     S.Flags = Flags & ~SectionFlags::Named;
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|     S.Name = Directive;
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|   }
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| 
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|   return &S;
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| }
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| 
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| const std::string&
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| TargetAsmInfo::getSectionFlags(unsigned Flags) const {
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|   SectionFlags::FlagsStringsMapType::iterator I = FlagsStrings.find(Flags);
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| 
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|   // We didn't print these flags yet, print and save them to map. This reduces
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|   // amount of heap trashing due to std::string construction / concatenation.
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|   if (I == FlagsStrings.end())
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|     I = FlagsStrings.insert(std::make_pair(Flags,
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|                                            printSectionFlags(Flags))).first;
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| 
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|   return I->second;
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| }
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| 
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| unsigned TargetAsmInfo::getULEB128Size(unsigned Value) {
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|   unsigned Size = 0;
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|   do {
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|     Value >>= 7;
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|     Size += sizeof(int8_t);
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|   } while (Value);
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|   return Size;
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| }
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| 
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| unsigned TargetAsmInfo::getSLEB128Size(int Value) {
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|   unsigned Size = 0;
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|   int Sign = Value >> (8 * sizeof(Value) - 1);
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|   bool IsMore;
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| 
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|   do {
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|     unsigned Byte = Value & 0x7f;
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|     Value >>= 7;
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|     IsMore = Value != Sign || ((Byte ^ Sign) & 0x40) != 0;
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|     Size += sizeof(int8_t);
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|   } while (IsMore);
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|   return Size;
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| }
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