Refactor data-in-code annotations.

Use a dedicated MachO load command to annotate data-in-code regions.
This is the same format the linker produces for final executable images,
allowing consistency of representation and use of introspection tools
for both object and executable files.

Data-in-code regions are annotated via ".data_region"/".end_data_region"
directive pairs, with an optional region type.

data_region_directive := ".data_region" { region_type }
region_type := "jt8" | "jt16" | "jt32" | "jta32"
end_data_region_directive := ".end_data_region"

The previous handling of ARM-style "$d.*" labels was broken and has
been removed. Specifically, it didn't handle ARM vs. Thumb mode when
marking the end of the section.

rdar://11459456

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@157062 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 51 insertions, 2 deletions

diff --git a/lib/MC/MachObjectWriter.cpp b/lib/MC/MachObjectWriter.cpp
index 8e4066c..5820a22 100644
--- a/lib/MC/MachObjectWriter.cpp
+++ b/lib/MC/MachObjectWriter.cpp
@@ -21,6 +21,7 @@
 #include "llvm/MC/MCMachOSymbolFlags.h"
 #include "llvm/MC/MCValue.h"
 #include "llvm/Object/MachOFormat.h"
+#include "llvm/Support/Debug.h"
 #include "llvm/Support/ErrorHandling.h"
 
 #include <vector>
@@ -351,6 +352,21 @@ void MachObjectWriter::WriteNlist(MachSymbolData &MSD,
     Write32(Address);
 }
 
+void MachObjectWriter::WriteLinkeditLoadCommand(uint32_t Type,
+                                                uint32_t DataOffset,
+                                                uint32_t DataSize) {
+  uint64_t Start = OS.tell();
+  (void) Start;
+
+  Write32(Type);
+  Write32(macho::LinkeditLoadCommandSize);
+  Write32(DataOffset);
+  Write32(DataSize);
+
+  assert(OS.tell() - Start == macho::LinkeditLoadCommandSize);
+}
+
+
 void MachObjectWriter::RecordRelocation(const MCAssembler &Asm,
                                         const MCAsmLayout &Layout,
                                         const MCFragment *Fragment,
@@ -654,6 +670,13 @@ void MachObjectWriter::WriteObject(MCAssembler &Asm,
                          macho::DysymtabLoadCommandSize);
   }
 
+  // Add the data-in-code load command size, if used.
+  unsigned NumDataRegions = Asm.getDataRegions().size();
+  if (NumDataRegions) {
+    ++NumLoadCommands;
+    LoadCommandsSize += macho::LinkeditLoadCommandSize;
+  }
+
   // Compute the total size of the section data, as well as its file size and vm
   // size.
   uint64_t SectionDataStart = (is64Bit() ? macho::Header64Size :
@@ -701,6 +724,15 @@ void MachObjectWriter::WriteObject(MCAssembler &Asm,
     RelocTableEnd += NumRelocs * macho::RelocationInfoSize;
   }
 
+  // Write the data-in-code load command, if used.
+  uint64_t DataInCodeTableEnd = RelocTableEnd + NumDataRegions * 8;
+  if (NumDataRegions) {
+    uint64_t DataRegionsOffset = RelocTableEnd;
+    uint64_t DataRegionsSize = NumDataRegions * 8;
+    WriteLinkeditLoadCommand(macho::LCT_DataInCode, DataRegionsOffset,
+                             DataRegionsSize);
+  }
+
   // Write the symbol table load command, if used.
   if (NumSymbols) {
     unsigned FirstLocalSymbol = 0;
@@ -717,10 +749,10 @@ void MachObjectWriter::WriteObject(MCAssembler &Asm,
 
     // If used, the indirect symbols are written after the section data.
     if (NumIndirectSymbols)
-      IndirectSymbolOffset = RelocTableEnd;
+      IndirectSymbolOffset = DataInCodeTableEnd;
 
     // The symbol table is written after the indirect symbol data.
-    uint64_t SymbolTableOffset = RelocTableEnd + IndirectSymbolSize;
+    uint64_t SymbolTableOffset = DataInCodeTableEnd + IndirectSymbolSize;
 
     // The string table is written after symbol table.
     uint64_t StringTableOffset =
@@ -760,6 +792,23 @@ void MachObjectWriter::WriteObject(MCAssembler &Asm,
     }
   }
 
+  // Write out the data-in-code region payload, if there is one.
+  for (MCAssembler::const_data_region_iterator
+         it = Asm.data_region_begin(), ie = Asm.data_region_end();
+         it != ie; ++it) {
+    const DataRegionData *Data = &(*it);
+    uint64_t Start = getSymbolAddress(&Layout.getAssembler().getSymbolData(*Data->Start), Layout);
+    uint64_t End = getSymbolAddress(&Layout.getAssembler().getSymbolData(*Data->End), Layout);
+    DEBUG(dbgs() << "data in code region-- kind: " << Data->Kind
+                 << "  start: " << Start << "(" << Data->Start->getName() << ")"
+                 << "  end: " << End << "(" << Data->End->getName() << ")"
+                 << "  size: " << End - Start
+                 << "\n");
+    Write32(Start);
+    Write16(End - Start);
+    Write16(Data->Kind);
+  }
+
   // Write the symbol table data, if used.
   if (NumSymbols) {
     // Write the indirect symbol entries.