From a94c33942373cb504b6e64c95415165907a89d34 Mon Sep 17 00:00:00 2001
From: Daniel Dunbar <daniel@zuster.org>
Date: Fri, 18 Jan 2013 01:26:07 +0000
Subject: [MC/Mach-O] Add support for linker options in Mach-O files.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@172779 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/MC/MachObjectWriter.cpp | 56 +++++++++++++++++++++++++++++++++++++++++----
 1 file changed, 51 insertions(+), 5 deletions(-)

(limited to 'lib/MC/MachObjectWriter.cpp')

diff --git a/lib/MC/MachObjectWriter.cpp b/lib/MC/MachObjectWriter.cpp
index 0098bead45..d13c178a9c 100644
--- a/lib/MC/MachObjectWriter.cpp
+++ b/lib/MC/MachObjectWriter.cpp
@@ -376,6 +376,39 @@ void MachObjectWriter::WriteLinkeditLoadCommand(uint32_t Type,
   assert(OS.tell() - Start == macho::LinkeditLoadCommandSize);
 }
 
+static unsigned ComputeLinkerOptionsLoadCommandSize(
+  const std::vector<std::string> &Options)
+{
+  unsigned Size = sizeof(macho::LinkerOptionsLoadCommand);
+  for (unsigned i = 0, e = Options.size(); i != e; ++i)
+    Size += Options[i].size() + 1;
+  return RoundUpToAlignment(Size, 4);
+}
+
+void MachObjectWriter::WriteLinkerOptionsLoadCommand(
+  const std::vector<std::string> &Options)
+{
+  unsigned Size = ComputeLinkerOptionsLoadCommandSize(Options);
+  uint64_t Start = OS.tell();
+  (void) Start;
+
+  Write32(macho::LCT_LinkerOptions);
+  Write32(Size);
+  Write32(Options.size());
+  uint64_t BytesWritten = 0;
+  for (unsigned i = 0, e = Options.size(); i != e; ++i) {
+    // Write each string, including the null byte.
+    const std::string &Option = Options[i];
+    WriteBytes(Option.c_str(), Option.size() + 1);
+    BytesWritten += Option.size() + 1;
+  }
+
+  // Pad to a multiple of 4.
+  WriteBytes("", OffsetToAlignment(BytesWritten, 4));
+
+  assert(OS.tell() - Start == Size);
+}
+
 
 void MachObjectWriter::RecordRelocation(const MCAssembler &Asm,
                                         const MCAsmLayout &Layout,
@@ -693,6 +726,13 @@ void MachObjectWriter::WriteObject(MCAssembler &Asm,
     macho::SegmentLoadCommand64Size + NumSections * macho::Section64Size :
     macho::SegmentLoadCommand32Size + NumSections * macho::Section32Size;
 
+  // Add the data-in-code load command size, if used.
+  unsigned NumDataRegions = Asm.getDataRegions().size();
+  if (NumDataRegions) {
+    ++NumLoadCommands;
+    LoadCommandsSize += macho::LinkeditLoadCommandSize;
+  }
+
   // Add the symbol table load command sizes, if used.
   unsigned NumSymbols = LocalSymbolData.size() + ExternalSymbolData.size() +
     UndefinedSymbolData.size();
@@ -702,13 +742,14 @@ void MachObjectWriter::WriteObject(MCAssembler &Asm,
                          macho::DysymtabLoadCommandSize);
   }
 
-  // Add the data-in-code load command size, if used.
-  unsigned NumDataRegions = Asm.getDataRegions().size();
-  if (NumDataRegions) {
+  // Add the linker option load commands sizes.
+  const std::vector<std::vector<std::string> > &LinkerOptions =
+    Asm.getLinkerOptions();
+  for (unsigned i = 0, e = LinkerOptions.size(); i != e; ++i) {
     ++NumLoadCommands;
-    LoadCommandsSize += macho::LinkeditLoadCommandSize;
+    LoadCommandsSize += ComputeLinkerOptionsLoadCommandSize(LinkerOptions[i]);
   }
-
+  
   // Compute the total size of the section data, as well as its file size and vm
   // size.
   uint64_t SectionDataStart = (is64Bit() ? macho::Header64Size :
@@ -799,6 +840,11 @@ void MachObjectWriter::WriteObject(MCAssembler &Asm,
                              IndirectSymbolOffset, NumIndirectSymbols);
   }
 
+  // Write the linker options load commands.
+  for (unsigned i = 0, e = LinkerOptions.size(); i != e; ++i) {
+    WriteLinkerOptionsLoadCommand(LinkerOptions[i]);
+  }
+
   // Write the actual section data.
   for (MCAssembler::const_iterator it = Asm.begin(),
          ie = Asm.end(); it != ie; ++it) {
-- 
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