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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_MOD_INIT_FUNC_POINTERS:
     52   case MachO::S_MOD_TERM_FUNC_POINTERS:
     53   case MachO::S_INTERPOSING:
     54     return false;
     55   }
     56 }
     57 
     58 MCAsmInfoDarwin::MCAsmInfoDarwin() {
     59   // Common settings for all Darwin targets.
     60   // Syntax:
     61   LinkerPrivateGlobalPrefix = "l";
     62   HasSingleParameterDotFile = false;
     63   HasSubsectionsViaSymbols = true;
     64 
     65   AlignmentIsInBytes = false;
     66   COMMDirectiveAlignmentIsInBytes = false;
     67   LCOMMDirectiveAlignmentType = LCOMM::Log2Alignment;
     68   InlineAsmStart = " InlineAsm Start";
     69   InlineAsmEnd = " InlineAsm End";
     70 
     71   // Directives:
     72   HasWeakDefDirective = true;
     73   HasWeakDefCanBeHiddenDirective = true;
     74   WeakRefDirective = "\t.weak_reference ";
     75   ZeroDirective = "\t.space\t";  // ".space N" emits N zeros.
     76   HasMachoZeroFillDirective = true;  // Uses .zerofill
     77   HasMachoTBSSDirective = true; // Uses .tbss
     78   HasStaticCtorDtorReferenceInStaticMode = true;
     79 
     80   // FIXME: Change this once MC is the system assembler.
     81   HasAggressiveSymbolFolding = false;
     82 
     83   HiddenVisibilityAttr = MCSA_PrivateExtern;
     84   HiddenDeclarationVisibilityAttr = MCSA_Invalid;
     85 
     86   // Doesn't support protected visibility.
     87   ProtectedVisibilityAttr = MCSA_Invalid;
     88 
     89   HasDotTypeDotSizeDirective = false;
     90   HasNoDeadStrip = true;
     91 
     92   DwarfUsesRelocationsAcrossSections = false;
     93 
     94   UseIntegratedAssembler = true;
     95   SetDirectiveSuppressesReloc = true;
     96 }
     97