1 files changed, 47 insertions, 0 deletions

diff --git a/llvm/lib/MC/MCAssembler.cpp b/llvm/lib/MC/MCAssembler.cpp
index 910295c5d2b..fcf1b50a4f7 100644
--- a/llvm/lib/MC/MCAssembler.cpp
+++ b/llvm/lib/MC/MCAssembler.cpp
@@ -28,6 +28,9 @@
 #include "llvm/Support/LEB128.h"
 #include "llvm/Support/TargetRegistry.h"
 #include "llvm/Support/raw_ostream.h"
+#include "llvm/Support/MemoryBuffer.h"
+#include "llvm/Support/Compression.h"
+#include "llvm/Support/Host.h"
 
 using namespace llvm;
 
@@ -230,6 +233,39 @@ MCEncodedFragmentWithFixups::~MCEncodedFragmentWithFixups() {
 
 /* *** */
 
+const SmallVectorImpl<char> &MCCompressedFragment::getCompressedContents() const {
+  assert(getParent()->size() == 1 &&
+         "Only compress sections containing a single fragment");
+  if (CompressedContents.empty()) {
+    std::unique_ptr<MemoryBuffer> CompressedSection;
+    zlib::Status Success =
+        zlib::compress(StringRef(getContents().data(), getContents().size()),
+                       CompressedSection);
+    (void)Success;
+    assert(Success == zlib::StatusOK);
+    CompressedContents.push_back('Z');
+    CompressedContents.push_back('L');
+    CompressedContents.push_back('I');
+    CompressedContents.push_back('B');
+    uint64_t Size = getContents().size();
+    if (sys::IsLittleEndianHost)
+      Size = sys::SwapByteOrder(Size);
+    CompressedContents.append(reinterpret_cast<char *>(&Size),
+                              reinterpret_cast<char *>(&Size + 1));
+    CompressedContents.append(CompressedSection->getBuffer().begin(),
+                              CompressedSection->getBuffer().end());
+  }
+  return CompressedContents;
+}
+
+SmallVectorImpl<char> &MCCompressedFragment::getContents() {
+  assert(CompressedContents.empty() &&
+         "Fragment contents should not be altered after compression");
+  return MCDataFragment::getContents();
+}
+
+/* *** */
+
 MCSectionData::MCSectionData() : Section(0) {}
 
 MCSectionData::MCSectionData(const MCSection &_Section, MCAssembler *A)
@@ -430,6 +466,8 @@ uint64_t MCAssembler::computeFragmentSize(const MCAsmLayout &Layout,
   case MCFragment::FT_Relaxable:
   case MCFragment::FT_CompactEncodedInst:
     return cast<MCEncodedFragment>(F).getContents().size();
+  case MCFragment::FT_Compressed:
+    return cast<MCCompressedFragment>(F).getCompressedContents().size();
   case MCFragment::FT_Fill:
     return cast<MCFillFragment>(F).getSize();
 
@@ -618,6 +656,11 @@ static void writeFragment(const MCAssembler &Asm, const MCAsmLayout &Layout,
     break;
   }
 
+  case MCFragment::FT_Compressed:
+    ++stats::EmittedDataFragments;
+    OW->WriteBytes(cast<MCCompressedFragment>(F).getCompressedContents());
+    break;
+
   case MCFragment::FT_Data: 
     ++stats::EmittedDataFragments;
     writeFragmentContents(F, OW);
@@ -694,6 +737,7 @@ void MCAssembler::writeSectionData(const MCSectionData *SD,
            ie = SD->end(); it != ie; ++it) {
       switch (it->getKind()) {
       default: llvm_unreachable("Invalid fragment in virtual section!");
+      case MCFragment::FT_Compressed:
       case MCFragment::FT_Data: {
         // Check that we aren't trying to write a non-zero contents (or fixups)
         // into a virtual section. This is to support clients which use standard
@@ -1021,6 +1065,8 @@ void MCFragment::dump() {
   switch (getKind()) {
   case MCFragment::FT_Align: OS << "MCAlignFragment"; break;
   case MCFragment::FT_Data:  OS << "MCDataFragment"; break;
+  case MCFragment::FT_Compressed:
+    OS << "MCCompressedFragment"; break;
   case MCFragment::FT_CompactEncodedInst:
     OS << "MCCompactEncodedInstFragment"; break;
   case MCFragment::FT_Fill:  OS << "MCFillFragment"; break;
@@ -1047,6 +1093,7 @@ void MCFragment::dump() {
        << " MaxBytesToEmit:" << AF->getMaxBytesToEmit() << ">";
     break;
   }
+  case MCFragment::FT_Compressed:
   case MCFragment::FT_Data:  {
     const MCDataFragment *DF = cast<MCDataFragment>(this);
     OS << "\n       ";