dd the option, -link-opt-hints to llvm-objdump used with -macho to print the

Mach-O AArch64 linker optimization hints for ADRP code optimization.

llvm-svn: 227246

include/llvm/Object/MachO.h

@@ -395,6 +395,7 @@ public:
   MachO::symtab_command getSymtabLoadCommand() const;
   MachO::dysymtab_command getDysymtabLoadCommand() const;
   MachO::linkedit_data_command getDataInCodeLoadCommand() const;
+  MachO::linkedit_data_command getLinkOptHintsLoadCommand() const;
   ArrayRef<uint8_t> getDyldInfoRebaseOpcodes() const;
   ArrayRef<uint8_t> getDyldInfoBindOpcodes() const;
   ArrayRef<uint8_t> getDyldInfoWeakBindOpcodes() const;
@@ -437,6 +438,7 @@ private:
   const char *SymtabLoadCmd;
   const char *DysymtabLoadCmd;
   const char *DataInCodeLoadCmd;
+  const char *LinkOptHintsLoadCmd;
   const char *DyldInfoLoadCmd;
   const char *UuidLoadCmd;
   bool HasPageZeroSegment;

lib/Object/MachOObjectFile.cpp

@@ -248,8 +248,9 @@ MachOObjectFile::MachOObjectFile(MemoryBufferRef Object, bool IsLittleEndian,
                                  bool Is64bits, std::error_code &EC)
     : ObjectFile(getMachOType(IsLittleEndian, Is64bits), Object),
       SymtabLoadCmd(nullptr), DysymtabLoadCmd(nullptr),
-      DataInCodeLoadCmd(nullptr), DyldInfoLoadCmd(nullptr),
-      UuidLoadCmd(nullptr), HasPageZeroSegment(false) {
+      DataInCodeLoadCmd(nullptr), LinkOptHintsLoadCmd(nullptr),
+      DyldInfoLoadCmd(nullptr), UuidLoadCmd(nullptr),
+      HasPageZeroSegment(false) {
   uint32_t LoadCommandCount = this->getHeader().ncmds;
   if (LoadCommandCount == 0)
     return;
@@ -280,6 +281,13 @@ MachOObjectFile::MachOObjectFile(MemoryBufferRef Object, bool IsLittleEndian,
         return;
       }
       DataInCodeLoadCmd = Load.Ptr;
+    } else if (Load.C.cmd == MachO::LC_LINKER_OPTIMIZATION_HINT) {
+      // Multiple linker optimization hint tables
+      if (LinkOptHintsLoadCmd) {
+        EC = object_error::parse_failed;
+        return;
+      }
+      LinkOptHintsLoadCmd = Load.Ptr;
     } else if (Load.C.cmd == MachO::LC_DYLD_INFO || 
                Load.C.cmd == MachO::LC_DYLD_INFO_ONLY) {
       // Multiple dyldinfo load commands
@@ -2497,6 +2505,21 @@ MachOObjectFile::getDataInCodeLoadCommand() const {
   return Cmd;
 }
 
+MachO::linkedit_data_command
+MachOObjectFile::getLinkOptHintsLoadCommand() const {
+  if (LinkOptHintsLoadCmd)
+    return getStruct<MachO::linkedit_data_command>(this, LinkOptHintsLoadCmd);
+
+  // If there is no LinkOptHintsLoadCmd return a load command with zero'ed
+  // fields.
+  MachO::linkedit_data_command Cmd;
+  Cmd.cmd = MachO::LC_LINKER_OPTIMIZATION_HINT;
+  Cmd.cmdsize = sizeof(MachO::linkedit_data_command);
+  Cmd.dataoff = 0;
+  Cmd.datasize = 0;
+  return Cmd;
+}
+
 ArrayRef<uint8_t> MachOObjectFile::getDyldInfoRebaseOpcodes() const {
   if (!DyldInfoLoadCmd) 
     return ArrayRef<uint8_t>();

test/tools/llvm-objdump/AArch64/macho-link-opt-hints.test

@@ -0,0 +1,11 @@
+RUN: llvm-objdump -m -link-opt-hints %p/Inputs/link-opt-hints.macho-aarch64 | FileCheck %s
+
+CHECK: Linker optimiztion hints (8 total bytes)
+CHECK:     identifier 8 AdrpLdrGot
+CHECK:     narguments 2
+CHECK: 	value 0x18
+CHECK: 	value 0x1c
+CHECK:     identifier 7 AdrpAdd
+CHECK:     narguments 2
+CHECK: 	value 0x6c
+CHECK: 	value 0x70

tools/llvm-objdump/MachODump.cpp

@@ -36,6 +36,7 @@
 #include "llvm/Support/Format.h"
 #include "llvm/Support/FormattedStream.h"
 #include "llvm/Support/GraphWriter.h"
+#include "llvm/Support/LEB128.h"
 #include "llvm/Support/MachO.h"
 #include "llvm/Support/MemoryBuffer.h"
 #include "llvm/Support/TargetRegistry.h"
@@ -85,6 +86,11 @@ cl::opt<bool>
                      cl::desc("Print the data in code table for Mach-O objects "
                               "(requires -macho)"));
 
+cl::opt<bool>
+    llvm::LinkOptHints("link-opt-hints",
+                       cl::desc("Print the linker optimization hints for "
+                                "Mach-O objects (requires -macho)"));
+
 static cl::list<std::string>
     ArchFlags("arch", cl::desc("architecture(s) from a Mach-O file to dump"),
               cl::ZeroOrMore);
@@ -436,6 +442,63 @@ static void PrintDataInCodeTable(MachOObjectFile *O, bool verbose) {
   }
 }
 
+static void PrintLinkOptHints(MachOObjectFile *O) {
+  MachO::linkedit_data_command LohLC = O->getLinkOptHintsLoadCommand();
+  const char *loh = O->getData().substr(LohLC.dataoff, 1).data();
+  uint32_t nloh = LohLC.datasize;
+  outs() << "Linker optimiztion hints (" << nloh << " total bytes)\n";
+  for (uint32_t i = 0; i < nloh;) {
+    unsigned n;
+    uint64_t identifier = decodeULEB128((const uint8_t *)(loh + i), &n);
+    i += n;
+    outs() << "    identifier " << identifier << " ";
+    if (i >= nloh)
+      return;
+    switch (identifier) {
+    case 1:
+      outs() << "AdrpAdrp\n";
+      break;
+    case 2:
+      outs() << "AdrpLdr\n";
+      break;
+    case 3:
+      outs() << "AdrpAddLdr\n";
+      break;
+    case 4:
+      outs() << "AdrpLdrGotLdr\n";
+      break;
+    case 5:
+      outs() << "AdrpAddStr\n";
+      break;
+    case 6:
+      outs() << "AdrpLdrGotStr\n";
+      break;
+    case 7:
+      outs() << "AdrpAdd\n";
+      break;
+    case 8:
+      outs() << "AdrpLdrGot\n";
+      break;
+    default:
+      outs() << "Unknown identifier value\n";
+      break;
+    }
+    uint64_t narguments = decodeULEB128((const uint8_t *)(loh + i), &n);
+    i += n;
+    outs() << "    narguments " << narguments << "\n";
+    if (i >= nloh)
+      return;
+
+    for (uint32_t j = 0; j < narguments; j++) {
+      uint64_t value = decodeULEB128((const uint8_t *)(loh + i), &n);
+      i += n;
+      outs() << "\tvalue " << format("0x%" PRIx64, value) << "\n";
+      if (i >= nloh)
+        return;
+    }
+  }
+}
+
 // checkMachOAndArchFlags() checks to see if the ObjectFile is a Mach-O file
 // and if it is and there is a list of architecture flags is specified then
 // check to make sure this Mach-O file is one of those architectures or all
@@ -483,7 +546,7 @@ static void ProcessMachO(StringRef Filename, MachOObjectFile *MachOOF,
   // info.  And don't print it otherwise like in the case of printing the
   // UniversalHeaders or ArchiveHeaders.
   if (Disassemble || PrivateHeaders || ExportsTrie || Rebase || Bind ||
-      LazyBind || WeakBind || IndirectSymbols || DataInCode) {
+      LazyBind || WeakBind || IndirectSymbols || DataInCode || LinkOptHints) {
     outs() << Filename;
     if (!ArchiveMemberName.empty())
       outs() << '(' << ArchiveMemberName << ')';
@@ -498,6 +561,8 @@ static void ProcessMachO(StringRef Filename, MachOObjectFile *MachOOF,
     PrintIndirectSymbols(MachOOF, true);
   if (DataInCode)
     PrintDataInCodeTable(MachOOF, true);
+  if (LinkOptHints)
+    PrintLinkOptHints(MachOOF);
   if (Relocations)
     PrintRelocations(MachOOF);
   if (SectionHeaders)

tools/llvm-objdump/llvm-objdump.cpp

@@ -905,7 +905,8 @@ int main(int argc, char **argv) {
       && !(UniversalHeaders && MachOOpt)
       && !(ArchiveHeaders && MachOOpt)
       && !(IndirectSymbols && MachOOpt)
-      && !(DataInCode && MachOOpt)) {
+      && !(DataInCode && MachOOpt)
+      && !(LinkOptHints && MachOOpt)) {
     cl::PrintHelpMessage();
     return 2;
   }

tools/llvm-objdump/llvm-objdump.h

@@ -38,6 +38,7 @@ extern cl::opt<bool> UniversalHeaders;
 extern cl::opt<bool> ArchiveHeaders;
 extern cl::opt<bool> IndirectSymbols;
 extern cl::opt<bool> DataInCode;
+extern cl::opt<bool> LinkOptHints;
 extern cl::opt<bool> Relocations;
 extern cl::opt<bool> SectionHeaders;
 extern cl::opt<bool> SectionContents;