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      1 //===-- MCAsmInfoDarwin.cpp - Darwin asm properties -------------*- C++ -*-===//
      2 //
      3 //                     The LLVM Compiler Infrastructure
      4 //
      5 // This file is distributed under the University of Illinois Open Source
      6 // License. See LICENSE.TXT for details.
      7 //
      8 //===----------------------------------------------------------------------===//
      9 //
     10 // This file defines target asm properties related what form asm statements
     11 // should take in general on Darwin-based targets
     12 //
     13 //===----------------------------------------------------------------------===//
     14 
     15 #include "llvm/MC/MCAsmInfoDarwin.h"
     16 #include "llvm/MC/MCContext.h"
     17 #include "llvm/MC/MCExpr.h"
     18 #include "llvm/MC/MCSectionMachO.h"
     19 using namespace llvm;
     20 
     21 bool MCAsmInfoDarwin::isSectionAtomizableBySymbols(
     22     const MCSection &Section) const {
     23   const MCSectionMachO &SMO = static_cast<const MCSectionMachO &>(Section);
     24 
     25   // Sections holding 1 byte strings are atomized based on the data they
     26   // contain.
     27   // Sections holding 2 byte strings require symbols in order to be atomized.
     28   // There is no dedicated section for 4 byte strings.
     29   if (SMO.getType() == MachO::S_CSTRING_LITERALS)
     30     return false;
     31 
     32   if (SMO.getSegmentName() == "__DATA" && SMO.getSectionName() == "__cfstring")
     33     return false;
     34 
     35   if (SMO.getSegmentName() == "__DATA" &&
     36       SMO.getSectionName() == "__objc_classrefs")
     37     return false;
     38 
     39   switch (SMO.getType()) {
     40   default:
     41     return true;
     42 
     43   // These sections are atomized at the element boundaries without using
     44   // symbols.
     45   case MachO::S_4BYTE_LITERALS:
     46   case MachO::S_8BYTE_LITERALS:
     47   case MachO::S_16BYTE_LITERALS:
     48   case MachO::S_LITERAL_POINTERS:
     49   case MachO::S_NON_LAZY_SYMBOL_POINTERS:
     50   case MachO::S_LAZY_SYMBOL_POINTERS:
     51   case MachO::S_THREAD_LOCAL_VARIABLE_POINTERS:
     52   case MachO::S_MOD_INIT_FUNC_POINTERS:
     53   case MachO::S_MOD_TERM_FUNC_POINTERS:
     54   case MachO::S_INTERPOSING:
     55     return false;
     56   }
     57 }
     58 
     59 MCAsmInfoDarwin::MCAsmInfoDarwin() {
     60   // Common settings for all Darwin targets.
     61   // Syntax:
     62   LinkerPrivateGlobalPrefix = "l";
     63   HasSingleParameterDotFile = false;
     64   HasSubsectionsViaSymbols = true;
     65 
     66   AlignmentIsInBytes = false;
     67   COMMDirectiveAlignmentIsInBytes = false;
     68   LCOMMDirectiveAlignmentType = LCOMM::Log2Alignment;
     69   InlineAsmStart = " InlineAsm Start";
     70   InlineAsmEnd = " InlineAsm End";
     71 
     72   // Directives:
     73   HasWeakDefDirective = true;
     74   HasWeakDefCanBeHiddenDirective = true;
     75   WeakRefDirective = "\t.weak_reference ";
     76   ZeroDirective = "\t.space\t";  // ".space N" emits N zeros.
     77   HasMachoZeroFillDirective = true;  // Uses .zerofill
     78   HasMachoTBSSDirective = true; // Uses .tbss
     79   HasStaticCtorDtorReferenceInStaticMode = true;
     80 
     81   // FIXME: Change this once MC is the system assembler.
     82   HasAggressiveSymbolFolding = false;
     83 
     84   HiddenVisibilityAttr = MCSA_PrivateExtern;
     85   HiddenDeclarationVisibilityAttr = MCSA_Invalid;
     86 
     87   // Doesn't support protected visibility.
     88   ProtectedVisibilityAttr = MCSA_Invalid;
     89 
     90   HasDotTypeDotSizeDirective = false;
     91   HasNoDeadStrip = true;
     92   HasAltEntry = true;
     93 
     94   DwarfUsesRelocationsAcrossSections = false;
     95 
     96   UseIntegratedAssembler = true;
     97   SetDirectiveSuppressesReloc = true;
     98 }
     99