lib/MC/MCAsmInfoDarwin.cpp

   1 //===- MCAsmInfoDarwin.cpp - Darwin asm properties ------------------------===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8 //
   9 // This file defines target asm properties related what form asm statements
  10 // should take in general on Darwin-based targets
  11 //
  12 //===----------------------------------------------------------------------===//
  13
  14 #include "llvm/MC/MCAsmInfoDarwin.h"
  15 #include "llvm/BinaryFormat/MachO.h"
  16 #include "llvm/MC/MCDirectives.h"
  17 #include "llvm/MC/MCSectionMachO.h"
  18
  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
  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   HasAltEntry = true;
  92
  93   DwarfUsesRelocationsAcrossSections = false;
  94
  95   UseIntegratedAssembler = true;
  96   SetDirectiveSuppressesReloc = true;
  97 }