llvm/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.getName() == "__cfstring")
  33     return false;
  34
  35   if (SMO.getSegmentName() == "__DATA" && SMO.getName() == "__objc_classrefs")
  36     return false;
  37
  38   switch (SMO.getType()) {
  39   default:
  40     return true;
  41
  42   // These sections are atomized at the element boundaries without using
  43   // symbols.
  44   case MachO::S_4BYTE_LITERALS:
  45   case MachO::S_8BYTE_LITERALS:
  46   case MachO::S_16BYTE_LITERALS:
  47   case MachO::S_LITERAL_POINTERS:
  48   case MachO::S_NON_LAZY_SYMBOL_POINTERS:
  49   case MachO::S_LAZY_SYMBOL_POINTERS:
  50   case MachO::S_THREAD_LOCAL_VARIABLE_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
  79   // FIXME: Change this once MC is the system assembler.
  80   HasAggressiveSymbolFolding = false;
  81
  82   HiddenVisibilityAttr = MCSA_PrivateExtern;
  83   HiddenDeclarationVisibilityAttr = MCSA_Invalid;
  84
  85   // Doesn't support protected visibility.
  86   ProtectedVisibilityAttr = MCSA_Invalid;
  87
  88   HasDotTypeDotSizeDirective = false;
  89   HasNoDeadStrip = true;
  90   HasAltEntry = true;
  91
  92   DwarfUsesRelocationsAcrossSections = false;
  93   SetDirectiveSuppressesReloc = true;
  94 }